Materiały źródłowe

• #1 Atrioventricular Canal Defects – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557511/

  Atrioventricular canal defects comprise a spectrum of defects such as exclusive ventricular or atrial defects, septal defects, atrioventricular anomalies, and endocardial cushion defects. […] AV canal has superior and inferior endocardial cushions that fuse around 4 to 5 weeks of gestation. The failure of fusion of this endocardial cushion at various levels leads to septal defects ranging from partial to complete defects. […] The abnormal fusion of the interatrial septum leads to communication in the inferior part of the septum called ostium primum defect. […] The AV canal defects can primarily be classified into complete vs. partial defects based on the anatomical abnormalities. […] The complete AV canal defect may further be classified based on the AV valve morphology (Rastelli classification).

• #2 Atrioventricular Canal Defects – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557511/

  Forming a four-chambered heart involves coordination and organized fusion of several mesenchymal tissues. […] Most of the AV canal defects are almost always associated with a syndromic abnormality. […] The incidence of AV canal defects obtained from several studies ranges from 0.24 to 0.31 per 1000 live births. […] There is no gender preponderance, although some studies state that there is a slight female predilection (1:1.3), especially in cases associated with Down syndrome. […] Certain studies have proved that factors such as maternal gestational diabetes mellitus (GDM), pregestational diabetes mellitus, and obesity carry a significant association with the development of non-syndromic AV canal defects. […] The definitive management of complete atrioventricular canal defect (CAVCD) is the surgical correction of the defect as early as possible.

• #2 Atrioventricular Canal Defects | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/17972

  Most of the AV canal defects are almost always associated with a syndromic abnormality. The syndromes that carry an association with AV canal defects are CHARGE, Down, Ellis-van-Creveld, Ivemark, Kaufman McKusick, Ritscher-Schinzel, Smith-Lemli-Opitz, and 3p. Down syndrome has a very strong association with AV canal defects. […] Forming a four-chambered heart involves coordination and organized fusion of several mesenchymal tissues. Mesenchymal tissue deposition on these endocardial cushions aids in the process of fusion, which in turn leads to the separation of the common AV canal. AV canal has superior and inferior endocardial cushions that fuse around 4 to 5 weeks of gestation. The failure of fusion of this endocardial cushion at various levels leads to septal defects ranging from partial to complete defects. The abnormal fusion of the interatrial septum leads to communication in the inferior part of the septum called ostium primum defect.

• #3 Genetics of atrioventricular canal defects | Italian Journal of Pediatrics | Full Text

  https://ijponline.biomedcentral.com/articles/10.1186/s13052-020-00825-4

  Atrioventricular canal defect (AVCD) represents a quite common congenital heart defect (CHD) accounting for 7.4% of all cardiac malformations. AVCD is a very heterogeneous malformation that can occur as a phenotypical cardiac aspect in the context of different genetic syndromes but also as an isolated, non-syndromic cardiac defect. […] Given the complexity of cardiac embryology, it is not surprising that multiple genes deeply implicated in cardiogenesis have been described mutated in patients with AVCD. This review attempts to examine the recent advances in understanding the molecular basis of this complex CHD in the setting of genetic syndromes or in non-syndromic patients. […] From an embryological point of view, AVCD was traditionally considered caused by a primary intracardiac mechanism consisting in the maldevelopment of atrioventricular endocardial cushions in relation to defects of extracellular matrix, leading to absent or incomplete fusion of ventral (antero-superior) and dorsal (postero-inferior) atrioventricular cushions. Nevertheless, the hypothesis that extracardiac progenitor cells contribute also to the growth of the inlet part of the heart has been postulated following the experimental studies in chick embryos performed by Maria Victoria de la Cruz from 1977 on.

• #3 Atrioventricular (AV) Canal Defect | Boston Children’s Hospital

  https://www.childrenshospital.org/conditions/atrioventricular-canal-defect

  An atrioventricular canal defect, or AV canal, is a combination of several closely associated heart problems that result in a large defect in the center of the heart. […] When the heart is forming during the first eight weeks of fetal development, it begins as a hollow tube. Over time, partitions that form within the tube eventually become the walls dividing the right side of the heart from the left. Atrial and ventricular septal defects occur when the partitioning process doesn’t occur completely, leaving openings in the atrial and ventricular walls. The valves that separate the upper and lower heart chambers are formed toward the end of this eight-week period, and often they don’t develop properly. Frequently, instead of two separate AV valves (tricuspid and mitral valve), there is a single large common valve that sits between the upper and lower chambers of the heart, allowing blood to flow freely between the chambers above and below the valve — mixing oxygen-rich and oxygen-poor blood.

• #4 The Pathogenesis of Atrial and Atrioventricular Septal Defects with Special Emphasis on the Role of the Dorsal Mesenchymal Protrusion

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3389176/

  Partitioning of the four-chambered heart requires the proper formation, interaction and fusion of several mesenchymal tissues derived from different precursor populations that together form the atrioventricular mesenchymal complex. […] More recent work, however, has demonstrated that perturbation of DMP development also results in AVSD. […] Here, we discuss in detail the formation of the DMP, its contribution to cardiac septation and describe the morphological features as well as potential etiologies of ASDs and AVSDs. […] Much like their morphological features, classification, and clinical presentation, the etiology of septal defects is complex. These defects may arise from perturbation of any one component of the AV septal complex and development of each component is governed by multiple molecular pathways.

• #5 The Pathogenesis of Atrial and Atrioventricular Septal Defects with Special Emphasis on the Role of the Dorsal Mesenchymal Protrusion

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3389176/

  For many years, maldevelopment of the endocardial cushions was thought to be the primary etiology of atrioventricular septal defects. More recently, however, analysis of AVSDs in mouse models, as well as observations in human fetuses with Down Syndrome, have revealed that defective development of the DMP also contributes to the pathogenesis of these defects. […] The DMP is an essential component of the AV septal complex and thus, AV septation, but the molecular mechanisms underpinning its proper development and maturation are not fully understood. […] If this precursor population fails to proliferate, then the DMP may be hypoplastic. […] If the DMP fails to form, or if its proportions are abnormally small, it will be unable to partition the dorsal-inferior region of the AV junction. […] Aberrant apoptosis is another mechanism that could contribute to maldevelopment of the DMP.

• #6 The Dorsal Mesenchymal Protrusion and the Pathogenesis of Atrioventricular Septal Defects

  https://www.mdpi.com/2308-3425/3/4/29

  The pathogenesis of AVSDs has been the topic of research and discussion for many years. […] Specifically, these studies have linked abnormal development of the Dorsal Mesenchymal Protrusion (DMP) to the development of this congenital defect. […] The most convincing experimental data linking dysmorphogenesis of the DMP with the pathogenesis of the pASD, the common component in all forms of AVSDs, comes from studies with mouse models in which the development of the DMP has been perturbed using tissue-specific cre-recombinase mice in combination with mice carrying floxed alleles of genes playing a role in DMP development. […] Studies described in this review show that failure of proper development of the SHF-derived DMP leads to a primary atrial septal defect (pASD), the common septal defect seen in complete and incomplete AVSDs. This new insight has led to a paradigm shift in the understanding of AVSDs as the prevailing paradigm for many years was that failure of proper development of the AV cushions was the sole defect responsible for AVSDs.

• #7 The Dorsal Mesenchymal Protrusion and the Pathogenesis of Atrioventricular Septal Defects

  https://www.mdpi.com/2308-3425/3/4/29

  The pathogenesis of AVSDs has been the topic of research and discussion for many years. […] Specifically, these studies have linked abnormal development of the Dorsal Mesenchymal Protrusion (DMP) to the development of this congenital defect. […] The most convincing experimental data linking dysmorphogenesis of the DMP with the pathogenesis of the pASD, the common component in all forms of AVSDs, comes from studies with mouse models in which the development of the DMP has been perturbed using tissue-specific cre-recombinase mice in combination with mice carrying floxed alleles of genes playing a role in DMP development. […] Studies described in this review show that failure of proper development of the SHF-derived DMP leads to a primary atrial septal defect (pASD), the common septal defect seen in complete and incomplete AVSDs. This new insight has led to a paradigm shift in the understanding of AVSDs as the prevailing paradigm for many years was that failure of proper development of the AV cushions was the sole defect responsible for AVSDs.

• #8 The Pathogenesis of Atrial and Atrioventricular Septal Defects with Special Emphasis on the Role of the Dorsal Mesenchymal Protrusion

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3389176/

  For many years, maldevelopment of the endocardial cushions was thought to be the primary etiology of atrioventricular septal defects. More recently, however, analysis of AVSDs in mouse models, as well as observations in human fetuses with Down Syndrome, have revealed that defective development of the DMP also contributes to the pathogenesis of these defects. […] The DMP is an essential component of the AV septal complex and thus, AV septation, but the molecular mechanisms underpinning its proper development and maturation are not fully understood. […] If this precursor population fails to proliferate, then the DMP may be hypoplastic. […] If the DMP fails to form, or if its proportions are abnormally small, it will be unable to partition the dorsal-inferior region of the AV junction. […] Aberrant apoptosis is another mechanism that could contribute to maldevelopment of the DMP.

• #9 The Pathogenesis of Atrial and Atrioventricular Septal Defects with Special Emphasis on the Role of the Dorsal Mesenchymal Protrusion

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3389176/

  For many years, maldevelopment of the endocardial cushions was thought to be the primary etiology of atrioventricular septal defects. More recently, however, analysis of AVSDs in mouse models, as well as observations in human fetuses with Down Syndrome, have revealed that defective development of the DMP also contributes to the pathogenesis of these defects. […] The DMP is an essential component of the AV septal complex and thus, AV septation, but the molecular mechanisms underpinning its proper development and maturation are not fully understood. […] If this precursor population fails to proliferate, then the DMP may be hypoplastic. […] If the DMP fails to form, or if its proportions are abnormally small, it will be unable to partition the dorsal-inferior region of the AV junction. […] Aberrant apoptosis is another mechanism that could contribute to maldevelopment of the DMP.

• #10 The Pathogenesis of Atrial and Atrioventricular Septal Defects with Special Emphasis on the Role of the Dorsal Mesenchymal Protrusion

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3389176/

  If apoptosis were to occur prematurely, either within the DMP or within its SHF precursor population, the contribution of the DMP to the AV septal complex may be absent or abnormally small. […] The DMP may fail to properly form due to decreased proliferation of these cells, increased apoptosis, or premature mesenchymal-to-myocardialization. […] Importantly, this ligand is expressed in a manner that is spatiotemporally consistent with development of the DMP but is not expressed within the epicardium, endocardium, or myocardium of the AV canal or ventricles. […] These results indicate that Wnt2 signaling is required for proliferation and expansion of the SHF population that gives rise to the DMP and confirms what had been described in the Ts16 mouse, that maldevelopment of the DMP is associated with AVSD.

• #11 The Pathogenesis of Atrial and Atrioventricular Septal Defects with Special Emphasis on the Role of the Dorsal Mesenchymal Protrusion

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3389176/

  For many years, maldevelopment of the endocardial cushions was thought to be the primary etiology of atrioventricular septal defects. More recently, however, analysis of AVSDs in mouse models, as well as observations in human fetuses with Down Syndrome, have revealed that defective development of the DMP also contributes to the pathogenesis of these defects. […] The DMP is an essential component of the AV septal complex and thus, AV septation, but the molecular mechanisms underpinning its proper development and maturation are not fully understood. […] If this precursor population fails to proliferate, then the DMP may be hypoplastic. […] If the DMP fails to form, or if its proportions are abnormally small, it will be unable to partition the dorsal-inferior region of the AV junction. […] Aberrant apoptosis is another mechanism that could contribute to maldevelopment of the DMP.

• #12 Genetics of atrioventricular canal defects | Italian Journal of Pediatrics | Full Text

  https://ijponline.biomedcentral.com/articles/10.1186/s13052-020-00825-4

  The AVCD is associated with extracardiac defects in about 75% of the cases and presents strong genetic association. […] It is noteworthy that AVCD displays anatomic variability possibly related to different and distinct genetic causes. Nevertheless, a common point seems to be causally implicated in several disorders linked to AVCD. In fact, clinical and molecular studies have demonstrated that several disease genes implicated in syndromes with AVCD encode proteins that participate in ciliary function. […] A link between AVCD and cilia abnormalities through a specific pathogenetic pathway involving Hedgehog signaling has been recognized in several syndromes with AVCD. […] The pathogenesis of both syndromic and isolated AVCD, however, appears to be as complex as still not completely understood. Targeted NGS offers a great opportunity to improve sensibility and specifity of genetic analysis for AVCD.

• #13 The Pathogenesis of Atrial and Atrioventricular Septal Defects with Special Emphasis on the Role of the Dorsal Mesenchymal Protrusion

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3389176/

  If apoptosis were to occur prematurely, either within the DMP or within its SHF precursor population, the contribution of the DMP to the AV septal complex may be absent or abnormally small. […] The DMP may fail to properly form due to decreased proliferation of these cells, increased apoptosis, or premature mesenchymal-to-myocardialization. […] Importantly, this ligand is expressed in a manner that is spatiotemporally consistent with development of the DMP but is not expressed within the epicardium, endocardium, or myocardium of the AV canal or ventricles. […] These results indicate that Wnt2 signaling is required for proliferation and expansion of the SHF population that gives rise to the DMP and confirms what had been described in the Ts16 mouse, that maldevelopment of the DMP is associated with AVSD.

• #14

  https://www.omim.org/entry/606215

  An AVSD susceptibility locus (AVSD1) maps to chromosome 1p31-p21; AVSD2 (606217) is caused by mutation in the CRELD1 gene (607170) on chromosome 3p25; AVSD4 (614430) is caused by mutation in the GATA4 gene (600576) on chromosome 8p23.1; and AVSD5 (614474) is caused by mutation in the GATA6 gene (601656) on chromosome 18q11. […] Somatic mutations in the HAND1 gene (602406) have been identified in tissue samples from patients with AVSDs. […] A locus for AVSD on chromosome 21 was suggested by the high incidence of AVSD in cases of Down syndrome (190685). […] Sheffield et al. (1997) used a combination of DNA pooling and shared segment analysis to perform a high density screen of the entire autosomal human genome in an extended kindred segregating isolated AVSD. In so doing they identified a genetic locus, which they symbolized AVCD, on chromosome 1p31-p21 shared by all affected individuals.

• #15

  https://www.omim.org/entry/606215

  Because of a striking association between 8p deletion and atrioventricular canal defect, Amati et al. (1995) studied 2 pedigrees with autosomal dominant AVCD using a set of DNA markers from the 8pter-q12 region. These 2 families included affected individuals and subjects who had transmitted the defect but were not clinically affected. Significantly negative 2-point lod scores were observed for all markers at penetrance levels of 90% and 50%. Results corroborated heterogeneity of this heart defect and indicated that the genetic basis of familial AVCD is different from that associated with either Down syndrome (trisomy 21) or 8p deletion. […] Smith et al. (2009) sequenced 32 candidate genes known to be important in development of the atrioventricular septum (AVS) in 190 patients with AVS defects, and identified 2 missense variants in the ACVR1 gene (102576) that were not found in 350 controls, only 1 of which showed a functional difference compared to wildtype.

• #16 Complete atrioventricular canal | Orphanet Journal of Rare Diseases | Full Text

  https://ojrd.biomedcentral.com/articles/10.1186/1750-1172-1-8

  Experimental studies showed that environmental teratogens or endogenous metabolic abnormalities might result in abnormal development of the atrioventricular area, which may be due to altered apoptosis of these forming cells. […] Trancription factors (TBX2, Foxp1 among the others) and signal pathways (ErbB receptor activation) involved during embryogenesis in the heart development process have been strongly suggested to have a role in atrioventricular septation.

• #17

  https://www.omim.org/entry/606215

  An AVSD susceptibility locus (AVSD1) maps to chromosome 1p31-p21; AVSD2 (606217) is caused by mutation in the CRELD1 gene (607170) on chromosome 3p25; AVSD4 (614430) is caused by mutation in the GATA4 gene (600576) on chromosome 8p23.1; and AVSD5 (614474) is caused by mutation in the GATA6 gene (601656) on chromosome 18q11. […] Somatic mutations in the HAND1 gene (602406) have been identified in tissue samples from patients with AVSDs. […] A locus for AVSD on chromosome 21 was suggested by the high incidence of AVSD in cases of Down syndrome (190685). […] Sheffield et al. (1997) used a combination of DNA pooling and shared segment analysis to perform a high density screen of the entire autosomal human genome in an extended kindred segregating isolated AVSD. In so doing they identified a genetic locus, which they symbolized AVCD, on chromosome 1p31-p21 shared by all affected individuals.

• #18 Genetics of atrioventricular canal defects | Italian Journal of Pediatrics | Full Text

  https://ijponline.biomedcentral.com/articles/10.1186/s13052-020-00825-4

  The AVCD is associated with extracardiac defects in about 75% of the cases and presents strong genetic association. […] It is noteworthy that AVCD displays anatomic variability possibly related to different and distinct genetic causes. Nevertheless, a common point seems to be causally implicated in several disorders linked to AVCD. In fact, clinical and molecular studies have demonstrated that several disease genes implicated in syndromes with AVCD encode proteins that participate in ciliary function. […] A link between AVCD and cilia abnormalities through a specific pathogenetic pathway involving Hedgehog signaling has been recognized in several syndromes with AVCD. […] The pathogenesis of both syndromic and isolated AVCD, however, appears to be as complex as still not completely understood. Targeted NGS offers a great opportunity to improve sensibility and specifity of genetic analysis for AVCD.

• #19 Av canal defect | PPT

  https://www.slideshare.net/drsrb/av-canal-defect

  Approximately 40% to 45% of children with Down syndrome have congenital heart disease, and among these, 45% have an AVSD. Most patients with Down syndrome, who have congenital heart disease, have the complete form of AVSD (75%). Conversely, 50% of patients with AVSD have Down syndrome. […] The repair of AVSD has been one of the success stories in the field of congenital heart surgery over the last 5 decades. […] All of these patients require lifelong surveillance for development of LVOT obstruction and left AV valve regurgitation.

• #20 Av canal defect | PPT

  https://www.slideshare.net/drsrb/av-canal-defect

  Approximately 40% to 45% of children with Down syndrome have congenital heart disease, and among these, 45% have an AVSD. Most patients with Down syndrome, who have congenital heart disease, have the complete form of AVSD (75%). Conversely, 50% of patients with AVSD have Down syndrome. […] The repair of AVSD has been one of the success stories in the field of congenital heart surgery over the last 5 decades. […] All of these patients require lifelong surveillance for development of LVOT obstruction and left AV valve regurgitation.

• #21 Av canal defect | PPT

  https://www.slideshare.net/drsrb/av-canal-defect

  Approximately 40% to 45% of children with Down syndrome have congenital heart disease, and among these, 45% have an AVSD. Most patients with Down syndrome, who have congenital heart disease, have the complete form of AVSD (75%). Conversely, 50% of patients with AVSD have Down syndrome. […] The repair of AVSD has been one of the success stories in the field of congenital heart surgery over the last 5 decades. […] All of these patients require lifelong surveillance for development of LVOT obstruction and left AV valve regurgitation.

• #22 Atrioventricular septal defect – Wikipedia

  https://en.wikipedia.org/wiki/Atrioventricular_septal_defect

  Atrioventricular canal defect (AVCD) is caused by an abnormal or inadequate fusion of the superior and inferior endocardial cushions with the mid portion of the atrial septum and the muscular portion of the ventricular septum. […] Defective embryonic formation of the heart results in multiple holes between the heart chambers. In AVSD, all four chambers are connected, but the exact characteristics of holes and malformations may vary between patients. Even within the categories of „complete” and „partial” AVSD, multiple morphologies exist, with varying clinical consequences. Clinical and physiological manifestations of disease may also change over time, in response to continued stress. […] Like other congenital heart defects, major associations have been found between AVCD and genes regulating embryonic cell cilia. These human cell cilia normally contain receptors for signal molecules that regulate the healthy and organized tissue. Dysfunctional cilia can create multiple disease manifestations, leading to broad syndromes. Chromosome 21 harbors important regulators for cilia, and trisomy 21 (Down syndrome) can de-regulate them.

• #23 Atrioventricular septal defect – Wikipedia

  https://en.wikipedia.org/wiki/Atrioventricular_septal_defect

  Atrioventricular canal defect (AVCD) is caused by an abnormal or inadequate fusion of the superior and inferior endocardial cushions with the mid portion of the atrial septum and the muscular portion of the ventricular septum. […] Defective embryonic formation of the heart results in multiple holes between the heart chambers. In AVSD, all four chambers are connected, but the exact characteristics of holes and malformations may vary between patients. Even within the categories of „complete” and „partial” AVSD, multiple morphologies exist, with varying clinical consequences. Clinical and physiological manifestations of disease may also change over time, in response to continued stress. […] Like other congenital heart defects, major associations have been found between AVCD and genes regulating embryonic cell cilia. These human cell cilia normally contain receptors for signal molecules that regulate the healthy and organized tissue. Dysfunctional cilia can create multiple disease manifestations, leading to broad syndromes. Chromosome 21 harbors important regulators for cilia, and trisomy 21 (Down syndrome) can de-regulate them.

• #24 Atrioventricular Canal Defects | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/17972

  Most of the AV canal defects are almost always associated with a syndromic abnormality. The syndromes that carry an association with AV canal defects are CHARGE, Down, Ellis-van-Creveld, Ivemark, Kaufman McKusick, Ritscher-Schinzel, Smith-Lemli-Opitz, and 3p. Down syndrome has a very strong association with AV canal defects. […] Forming a four-chambered heart involves coordination and organized fusion of several mesenchymal tissues. Mesenchymal tissue deposition on these endocardial cushions aids in the process of fusion, which in turn leads to the separation of the common AV canal. AV canal has superior and inferior endocardial cushions that fuse around 4 to 5 weeks of gestation. The failure of fusion of this endocardial cushion at various levels leads to septal defects ranging from partial to complete defects. The abnormal fusion of the interatrial septum leads to communication in the inferior part of the septum called ostium primum defect.

• #25 Atrioventricular Canal Defects | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/17972

  Most of the AV canal defects are almost always associated with a syndromic abnormality. The syndromes that carry an association with AV canal defects are CHARGE, Down, Ellis-van-Creveld, Ivemark, Kaufman McKusick, Ritscher-Schinzel, Smith-Lemli-Opitz, and 3p. Down syndrome has a very strong association with AV canal defects. […] Forming a four-chambered heart involves coordination and organized fusion of several mesenchymal tissues. Mesenchymal tissue deposition on these endocardial cushions aids in the process of fusion, which in turn leads to the separation of the common AV canal. AV canal has superior and inferior endocardial cushions that fuse around 4 to 5 weeks of gestation. The failure of fusion of this endocardial cushion at various levels leads to septal defects ranging from partial to complete defects. The abnormal fusion of the interatrial septum leads to communication in the inferior part of the septum called ostium primum defect.

• #26

  https://www.omim.org/entry/606215

  The term 'atrioventricular septal defect’ (AVSD) covers a spectrum of congenital heart malformations characterized by a common atrioventricular junction coexisting with deficient atrioventricular septation. In ostium primum atrial septal defect (ASD) there are separate atrioventricular valvar orifices despite a common junction, whereas in complete AVSD the valve itself is also shared (summary by Craig, 2006). […] AVSD, also designated endocardial cushion defect or atrioventricular canal defect (AVCD), is known to occur in either a nonsyndromic (isolated) form or, more commonly, as part of a malformation syndrome. The 2 syndromes most frequently associated with AVSD are Down syndrome (190685), in which AVSD is the most frequent congenital heart defect, and Ivemark syndrome (208530) (summary by Carmi et al., 1992).

• #27 Atrioventricular canal defect in patients with RASopathies | European Journal of Human Genetics

  https://www.nature.com/articles/ejhg2012145

  Congenital heart defects affect 60-85% of patients with RASopathies. […] A defect of the extracellular matrix has been considered a likely pathogenic mechanism for the defects in the spectrum of AVCD. […] Anatomic peculiarities of AVCD previously reported in patients with NS include the partial-type defect, and the association with subaortic stenosis. […] Therefore, a perturbed developmental mechanism of left ventricular myocardium and mitral valve should be contemplated in the pathogenesis of CHDs in these patients. […] The coexistence of both AVCD and HCM in the same patient affected by RASopathy can lead to the speculation that a defect of the extracellular matrix, known to be pathogenetically associated with AVCD, could be linked also to HCM. […] In conclusion, AVCD is a part of the phenotypic spectrum of CHDs found in patients with RASopathies, in particular those caused by PTPN11 and RAF1 mutations.

• #28

  https://www.omim.org/entry/606215

  An AVSD susceptibility locus (AVSD1) maps to chromosome 1p31-p21; AVSD2 (606217) is caused by mutation in the CRELD1 gene (607170) on chromosome 3p25; AVSD4 (614430) is caused by mutation in the GATA4 gene (600576) on chromosome 8p23.1; and AVSD5 (614474) is caused by mutation in the GATA6 gene (601656) on chromosome 18q11. […] Somatic mutations in the HAND1 gene (602406) have been identified in tissue samples from patients with AVSDs. […] A locus for AVSD on chromosome 21 was suggested by the high incidence of AVSD in cases of Down syndrome (190685). […] Sheffield et al. (1997) used a combination of DNA pooling and shared segment analysis to perform a high density screen of the entire autosomal human genome in an extended kindred segregating isolated AVSD. In so doing they identified a genetic locus, which they symbolized AVCD, on chromosome 1p31-p21 shared by all affected individuals.

• #29

  https://www.omim.org/entry/606215

  An AVSD susceptibility locus (AVSD1) maps to chromosome 1p31-p21; AVSD2 (606217) is caused by mutation in the CRELD1 gene (607170) on chromosome 3p25; AVSD4 (614430) is caused by mutation in the GATA4 gene (600576) on chromosome 8p23.1; and AVSD5 (614474) is caused by mutation in the GATA6 gene (601656) on chromosome 18q11. […] Somatic mutations in the HAND1 gene (602406) have been identified in tissue samples from patients with AVSDs. […] A locus for AVSD on chromosome 21 was suggested by the high incidence of AVSD in cases of Down syndrome (190685). […] Sheffield et al. (1997) used a combination of DNA pooling and shared segment analysis to perform a high density screen of the entire autosomal human genome in an extended kindred segregating isolated AVSD. In so doing they identified a genetic locus, which they symbolized AVCD, on chromosome 1p31-p21 shared by all affected individuals.

• #30

  https://www.omim.org/entry/606215

  An AVSD susceptibility locus (AVSD1) maps to chromosome 1p31-p21; AVSD2 (606217) is caused by mutation in the CRELD1 gene (607170) on chromosome 3p25; AVSD4 (614430) is caused by mutation in the GATA4 gene (600576) on chromosome 8p23.1; and AVSD5 (614474) is caused by mutation in the GATA6 gene (601656) on chromosome 18q11. […] Somatic mutations in the HAND1 gene (602406) have been identified in tissue samples from patients with AVSDs. […] A locus for AVSD on chromosome 21 was suggested by the high incidence of AVSD in cases of Down syndrome (190685). […] Sheffield et al. (1997) used a combination of DNA pooling and shared segment analysis to perform a high density screen of the entire autosomal human genome in an extended kindred segregating isolated AVSD. In so doing they identified a genetic locus, which they symbolized AVCD, on chromosome 1p31-p21 shared by all affected individuals.

• #31

  https://omim.org/entry/606215

  An AVSD susceptibility locus (AVSD1) maps to chromosome 1p31-p21; AVSD2 (606217) is caused by mutation in the CRELD1 gene (607170) on chromosome 3p25; AVSD4 (614430) is caused by mutation in the GATA4 gene (600576) on chromosome 8p23.1; and AVSD5 (614474) is caused by mutation in the GATA6 gene (601656) on chromosome 18q11. […] Somatic mutations in the HAND1 gene (602406) have been identified in tissue samples from patients with AVSDs. […] A locus for AVSD on chromosome 21 was suggested by the high incidence of AVSD in cases of Down syndrome (190685). […] Sheffield et al. (1997) used a combination of DNA pooling and shared segment analysis to perform a high density screen of the entire autosomal human genome in an extended kindred segregating isolated AVSD. In so doing they identified a genetic locus, which they symbolized AVCD, on chromosome 1p31-p21 shared by all affected individuals.

• #32

  https://www.omim.org/entry/606215

  D’Alessandro et al. (2016) performed whole-exome sequencing in 81 unrelated probands with AVSD to identify potential causal variants in a comprehensive set of 112 genes with strong biological relevance to AVSD. A significant enrichment of rare and rare damaging variants was identified in the gene set, compared with controls (odds ratio (OR) 1.52; 95% confidence interval (CI), 1.35-1.71; p = 4.8 x 10(-11)). The enrichment was specific to AVSD probands, compared with a cohort without AVSD with tetralogy of Fallot (OR 2.25; 95% CI, 1.84-2.76; p = 2.2 x 10(-16)).

• #33 Atrioventricular Canal Defects – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557511/

  Forming a four-chambered heart involves coordination and organized fusion of several mesenchymal tissues. […] Most of the AV canal defects are almost always associated with a syndromic abnormality. […] The incidence of AV canal defects obtained from several studies ranges from 0.24 to 0.31 per 1000 live births. […] There is no gender preponderance, although some studies state that there is a slight female predilection (1:1.3), especially in cases associated with Down syndrome. […] Certain studies have proved that factors such as maternal gestational diabetes mellitus (GDM), pregestational diabetes mellitus, and obesity carry a significant association with the development of non-syndromic AV canal defects. […] The definitive management of complete atrioventricular canal defect (CAVCD) is the surgical correction of the defect as early as possible.

• #34 About Atrioventricular Septal Defect | Congenital Heart Defects (CHDs) | CDC

  https://www.cdc.gov/heart-defects/about/atrioventricular-septal-defect.html

  The causes of AVSDs among most babies are unknown. Some babies have heart defects because of changes in their genes or chromosomes. A combination of genes and other risk factors may increase the risk for AVSD. These factors can include things in a mother’s environment, what she eats or drinks, or the medications she uses during pregnancy.

• #35 Atrioventricular Canal Defect (AVCD) | surjen | Surjen care

  https://www.surjen.com/surgery-detail/atrioventricular-canal-defect-avc

  Genetic predisposition is believed to play a significant role in the development of atrioventricular canal defects. Several genetic syndromes are strongly associated with AV canal defect, including: […] Mutations in specific genes involved in cardiac development and function may also contribute to the development of AV canal defects. […] In addition to genetic factors, environmental exposures during pregnancy may influence the risk of atrioventricular canal defects. […] Certain maternal health conditions, lifestyle factors, and exposures to toxins or medications have been implicated as potential environmental risk factors for AV canal defects. […] Factors that may enlarge a baby’s risk of developing atrioventricular canal defect prior to birth include: Down syndrome […] How is an Atrioventricular canal defect detected?

• #36 About Atrioventricular Septal Defect | Congenital Heart Defects (CHDs) | CDC

  https://www.cdc.gov/heart-defects/about/atrioventricular-septal-defect.html

  The causes of AVSDs among most babies are unknown. Some babies have heart defects because of changes in their genes or chromosomes. A combination of genes and other risk factors may increase the risk for AVSD. These factors can include things in a mother’s environment, what she eats or drinks, or the medications she uses during pregnancy.

• #37 About Atrioventricular Septal Defect | Congenital Heart Defects (CHDs) | CDC

  https://www.cdc.gov/heart-defects/about/atrioventricular-septal-defect.html

  The causes of AVSDs among most babies are unknown. Some babies have heart defects because of changes in their genes or chromosomes. A combination of genes and other risk factors may increase the risk for AVSD. These factors can include things in a mother’s environment, what she eats or drinks, or the medications she uses during pregnancy.

• #38 Atrioventricular Canal Defect – Children’s Hospital of Orange County

  https://choc.org/heart/congenital-heart-defects/atrioventricular-canal-defect/

  Genetic influences may contribute to the development of atrioventricular canal defect. […] Other chromosome abnormalities (in addition to Down syndrome) are linked to this condition. Maternal age can have an effect on the prevalence of the defect. […] If not treated, this heart defect can cause lung disease from too much blood flow going to the lungs. […] The lungs are able to cope with this extra volume of blood at high pressure for a while. […] As the arteries in the lungs get thicker, the flow of blood from the left side of the heart to the right side and on to the lungs will reduce. […] Bacteria in the bloodstream can occasionally infect the abnormal valves in the heart (the abnormal mitral and tricuspid valves associated with AV canal defect), causing a serious illness known as bacterial endocarditis.

• #39 Atrioventricular septal defect pathophysiology – wikidoc

  https://www.wikidoc.org/index.php/Atrioventricular_septal_defect_pathophysiology

  There are many underlying mechanisms resulting in atrioventricular septal defect depends largely on the nature of interaction of blood flow between the right and left sides of the heart. Factors influencing the severity include: ventricular imbalance, the size of AV septal defects, AVV competence, the degree of right-sided or left-sided outflow obstruction, pulmonary vascular resistance, the amount of atrioventricular valve regurgitation and the magnitude of blood flow through the ventricular septum. […] Newborns may experience little left-to-right shunting as a result of a less compliant right ventricle and a relatively high PVR. Larger defects may result in mixing of a common or near-common atrium and create components of right-to-left shunting. The propensity for left-to-right shunting increases with age as a result of a decrease in PVR and right ventricle compliance increase.

• #40 Atrioventricular Canal Defects – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557511/

  The timing of correction is preferably before 6 months of age, as the risk of developing the pulmonary vascular disease is directly related to the duration of the disease. […] Surgical management of CAVCD is dependent on various factors such as the type of defect, valve morphology, associated valvular and conduction abnormalities, the presence of shunt, and other vascular anomalies. […] The patients will eventually start to develop left to right shunt irrespective of the type of defect, although the magnitude of the shunting depends on the type of defect. […] Due to the increased flow to the right heart, the pulmonary vasculature develops pulmonary hypertension. […] There is a significant regurgitation of blood in the heart chambers due to incompetent AV valves.

• #41 Complete Atrioventricular Canal defect (CAVC) | American Heart Association

  https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/complete-atrioventricular-canal-defect-cavc

  Atrioventricular (AV) canal defect is a large hole in the center of the heart. It’s located where the wall (septum) between the upper chambers (atria) joins the wall between the lower chambers (ventricles). This septal defect involves both upper and lower chambers. The tricuspid and mitral valves that normally separate the heart’s upper and lower chambers aren’t formed as individual valves. Instead a single large valve forms that crosses the defect in the wall between the two sides of the heart. […] In most children, the cause isn’t known. It’s a very common type of heart defect in children with a chromosome problem, Trisomy 21 (Down syndrome). Some children can have other heart defects along with AV canal. […] Normally, the left side of the heart only pumps blood to the body, and the heart’s right side only pumps blood to the lungs. In a child with AV canal defect, blood can travel across the holes from the left heart chambers to the right heart chambers and out into the lung arteries. The extra blood being pumped into the lung arteries makes the heart and lungs work harder and the lungs can become congested.

• #42 Atrioventricular Canal Defects – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557511/

  The timing of correction is preferably before 6 months of age, as the risk of developing the pulmonary vascular disease is directly related to the duration of the disease. […] Surgical management of CAVCD is dependent on various factors such as the type of defect, valve morphology, associated valvular and conduction abnormalities, the presence of shunt, and other vascular anomalies. […] The patients will eventually start to develop left to right shunt irrespective of the type of defect, although the magnitude of the shunting depends on the type of defect. […] Due to the increased flow to the right heart, the pulmonary vasculature develops pulmonary hypertension. […] There is a significant regurgitation of blood in the heart chambers due to incompetent AV valves.

• #43 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  Atrioventricular (AV) septal defect consists of an ostium primum type atrial septal defect and a common AV valve, with or without an associated inlet (AV septal type) ventricular septal defect (VSD). These defects result from maldevelopment of the endocardial cushions. […] A complete AV septal defect is a single large central defect in the septation of the heart. A left-to-right shunt occurs at the atrial and ventricular levels and is often large. AV valve regurgitation may be significant, sometimes causing a direct left ventricle-to-right atrial shunt. These abnormalities result in enlargement of all 4 cardiac chambers. Large defects result in direct transmission of the systemic left ventricular pressure to the right ventricle and pulmonary arteries. Hemodynamic findings are similar to those of a large ventricular septal defect (VSD).

• #44 Atrioventricular Canal Defects | Thoracic Key

  https://thoracickey.com/atrioventricular-canal-defects-2/

  A left-to-right shunt is present in patients with AV canal defects, unless PVOD or coexistent right ventricular (RV) outflow tract obstruction is present. Patient presentation depends on the extent of left-to-right shunting, which in turn depends on pulmonary vascular resistance. […] The pathophysiology in complete AV canal defects is similar to that of a large nonrestrictive VSD with two additional features. First, an atrial level shunt is present, with the potential for a left-ventricle-to-right-atrium shunt and increased volume loading of the ventricle. Second, AV valve regurgitation may be present, further increasing the volume load. […] Irreversible changes in the pulmonary vasculature are seen as early as 6 months in patients with unrepaired complete AV canal defects. The presence of Down syndrome accelerates the development of PVOD.

• #45 Atrioventricular Canal Defects | Thoracic Key

  https://thoracickey.com/atrioventricular-canal-defects-2/

  A left-to-right shunt is present in patients with AV canal defects, unless PVOD or coexistent right ventricular (RV) outflow tract obstruction is present. Patient presentation depends on the extent of left-to-right shunting, which in turn depends on pulmonary vascular resistance. […] The pathophysiology in complete AV canal defects is similar to that of a large nonrestrictive VSD with two additional features. First, an atrial level shunt is present, with the potential for a left-ventricle-to-right-atrium shunt and increased volume loading of the ventricle. Second, AV valve regurgitation may be present, further increasing the volume load. […] Irreversible changes in the pulmonary vasculature are seen as early as 6 months in patients with unrepaired complete AV canal defects. The presence of Down syndrome accelerates the development of PVOD.

• #46 Atrioventricular Canal Defects – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK557511/

  The timing of correction is preferably before 6 months of age, as the risk of developing the pulmonary vascular disease is directly related to the duration of the disease. […] Surgical management of CAVCD is dependent on various factors such as the type of defect, valve morphology, associated valvular and conduction abnormalities, the presence of shunt, and other vascular anomalies. […] The patients will eventually start to develop left to right shunt irrespective of the type of defect, although the magnitude of the shunting depends on the type of defect. […] Due to the increased flow to the right heart, the pulmonary vasculature develops pulmonary hypertension. […] There is a significant regurgitation of blood in the heart chambers due to incompetent AV valves.

• #47 Atrioventricular canal defect – Symptoms & causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/atrioventricular-canal-defect/symptoms-causes/syc-20361492

  Atrioventricular canal defect is a mix of problems affecting the center of the heart. The heart condition is present at birth. That means it’s a congenital heart defect. Children born with this condition have a hole in the wall between the heart’s chambers. They also have problems with the valves that control blood flow in the heart. […] Atrioventricular canal defect allows extra blood to flow to the lungs. The extra blood forces the heart to work too hard, causing the heart muscle to grow larger. […] In a partial atrioventricular canal defect: […] There are also changes in the tricuspid and mitral valves. […] The changes prevent the valves from closing all the way. […] In a complete atrioventricular canal defect: […] There’s a large hole in the center of the heart. The hole is where the walls between the upper and the lower chambers meet.

• #48 Atrioventricular canal defect – Symptoms & causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/atrioventricular-canal-defect/symptoms-causes/syc-20361492

  Oxygen-rich and oxygen-poor blood mix through the hole. […] There’s one large valve between the heart’s upper and lower chambers, instead of separate ones. […] Blood leaks through the one large valve into the lower heart chambers. […] The heart must work harder to pump blood. The heart becomes larger. […] Atrioventricular canal defect is a type of congenital heart defect. A person born with atrioventricular canal defect has a hole in the wall separating the heart’s chambers and problems with the heart valves. The condition may be partial, involving only the two upper chambers, or complete, involving all four chambers.

• #49 About Atrioventricular Septal Defect | Congenital Heart Defects (CHDs) | CDC

  https://www.cdc.gov/heart-defects/about/atrioventricular-septal-defect.html

  An AVSD occurs when there are holes between the chambers of the right and left sides of the heart. This condition is also called atrioventricular canal (AV canal) defect or endocardial cushion defect. In people with AVSD, the valves that control blood flow between these chambers may not form correctly. […] A complete AVSD arises during pregnancy when: The common valve fails to separate into the two distinct valves, the tricuspid valve on the right side of the heart and the mitral valve on the left side, and The walls that split the upper and lower chambers of the heart do not grow all they way to meet in the center of the heart. […] A partial or incomplete AVSD occurs when the heart has some, but not all of the defects of a complete AVSD. There is usually a hole in the atrial wall or in the ventricular wall near the center of the heart. A partial AVSD usually has both mitral and tricuspid valves, but one of the valves (usually mitral) may not close completely. This allows blood to leak backward from the left ventricle into the left atrium.

• #50 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  In a subset of patients, the common AV valve is positioned more over one ventricle than the other. This condition, referred to as unbalanced AV septal defect, results in one ventricle receiving more blood flow and becoming dominant (larger) and the other ventricle being underdeveloped. […] Complete atrioventricular septal defect with a large left-to-right shunt causes signs of heart failure (eg, tachypnea, dyspnea during feeding, poor weight gain, diaphoresis) by age 4 to 6 weeks. […] Symptoms in partial AV septal defects vary with the degree of mitral regurgitation; if mild or absent, symptoms may develop during adolescence or early adulthood, but infants with moderate or severe mitral regurgitation often have manifestations of heart failure. […] Symptoms in transitional AV septal defect fall on a spectrum, depending on the size of the VSD. […] Defects are repaired surgically between age 2 to 4 months or 1 to 3 years, depending on the specific defect and severity of symptoms.

• #51 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  Atrioventricular (AV) septal defect consists of an ostium primum type atrial septal defect and a common AV valve, with or without an associated inlet (AV septal type) ventricular septal defect (VSD). These defects result from maldevelopment of the endocardial cushions. […] A complete AV septal defect is a single large central defect in the septation of the heart. A left-to-right shunt occurs at the atrial and ventricular levels and is often large. AV valve regurgitation may be significant, sometimes causing a direct left ventricle-to-right atrial shunt. These abnormalities result in enlargement of all 4 cardiac chambers. Large defects result in direct transmission of the systemic left ventricular pressure to the right ventricle and pulmonary arteries. Hemodynamic findings are similar to those of a large ventricular septal defect (VSD).

• #52 Atrioventricular canal defect – Symptoms & causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/atrioventricular-canal-defect/symptoms-causes/syc-20361492

  Oxygen-rich and oxygen-poor blood mix through the hole. […] There’s one large valve between the heart’s upper and lower chambers, instead of separate ones. […] Blood leaks through the one large valve into the lower heart chambers. […] The heart must work harder to pump blood. The heart becomes larger. […] Atrioventricular canal defect is a type of congenital heart defect. A person born with atrioventricular canal defect has a hole in the wall separating the heart’s chambers and problems with the heart valves. The condition may be partial, involving only the two upper chambers, or complete, involving all four chambers.

• #53 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  In a subset of patients, the common AV valve is positioned more over one ventricle than the other. This condition, referred to as unbalanced AV septal defect, results in one ventricle receiving more blood flow and becoming dominant (larger) and the other ventricle being underdeveloped. […] Complete atrioventricular septal defect with a large left-to-right shunt causes signs of heart failure (eg, tachypnea, dyspnea during feeding, poor weight gain, diaphoresis) by age 4 to 6 weeks. […] Symptoms in partial AV septal defects vary with the degree of mitral regurgitation; if mild or absent, symptoms may develop during adolescence or early adulthood, but infants with moderate or severe mitral regurgitation often have manifestations of heart failure. […] Symptoms in transitional AV septal defect fall on a spectrum, depending on the size of the VSD. […] Defects are repaired surgically between age 2 to 4 months or 1 to 3 years, depending on the specific defect and severity of symptoms.

• #54 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  If a complete AV septal defect is unrepaired, over time the increase in pulmonary blood flow, pulmonary artery pressure, and pulmonary vascular resistance may lead to reversal of shunt direction with cyanosis and Eisenmenger syndrome. […] A transitional atrioventricular septal defect, also called a transitional AV canal defect, consists of an ostium primum atrial septal defect, a restrictive inlet ventricular septal defect, which may be small or moderate in size, and a common AV valve, which may or may not be partitioned into a left and right orifice. […] The hemodynamics depend largely on the size of the VSD and whether there is significant AV valve regurgitation. […] A partial AV septal defect consists of an ostium primum atrial septal defect and partitioning of the common AV valve into 2 separate AV orifices, resulting in a so-called cleft in the mitral valve (left AV orifice). The ventricular septum is intact. Hemodynamic abnormalities are similar to those of ostium secundum ASD (eg, left-to-right shunt at the atrial level, enlarged right heart chambers, increased pulmonary blood flow) with the additional finding of variable degrees of AV valve regurgitation.

• #55 Complete Atrioventricular Canal defect (CAVC) | American Heart Association

  https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/complete-atrioventricular-canal-defect-cavc

  High pressure may occur in the blood vessels in the lungs because more blood than normal is being pumped there. Over time this causes permanent damage to the lung blood vessels. […] Surgical repair of an AV canal usually restores the blood circulation to normal. However, the reconstructed valve may not work normally. The valve structures can leak or narrow. But, for many children, the long-term outlook is good, and usually no medicines or additional surgery are needed. […] Many adults who have not had previous repair have pulmonary hypertension (see Eisenmenger’s syndrome). This complication is more common than in patients with an ASD or a VSD. Even in adults without Eisenmenger’s syndrome, symptoms including shortness of breath, intolerance to exercise and palpitations are common. […] The decision to repair an AV canal defect in adulthood is complicated. It depends on the pressures in the lung and the heart’s pumping function. However, when the pressures aren’t too high and the pump function is good, these defects can be repaired and adult patients are likely to improve.

• #56 Atrioventricular (AV) Canal in Children – Stanford Medicine Children’s Health

  https://www.stanfordchildrens.org/en/topic/default?id=atrioventricular-av-canal-in-children-90-P01767

  An atrioventricular (AV) canal defect is a congenital heart defect. This means that your child is born with it. AV canal defect is a large hole in the center of the heart. It is caused by a combination of problems with the heart’s structure. […] Genes and family history may play a part in AV canal defects. They may be caused by Down syndrome or other chromosome problems. […] Over time, the pressure in your child’s lungs will force blood back to his or her heart. This blood has low oxygen levels, and its sent to the rest body. This causes your child’s lips, nailbeds, and skin to turn blue (cyanosis). […] If left untreated, an AV canal defect can cause several problems. […] As the arteries in the lungs get thicker, less blood will flow from the left to the right side of the heart and to the lungs. It will be easier for oxygen-poor (blue) blood to flow from the right side into the left side of the heart, and on to the rest of the body. This stops the body from getting enough oxygen. This causes a blue coloring to your child’s skin, lips, and nails.

• #57 Pediatric Atrioventricular Canal (AV canal or AVC) – Conditions and Treatments | Children’s National Hospital

  https://www.childrensnational.org/get-care/health-library/atrioventricular-canal-av-canal-or-avc

  If left untreated, an AV canal defect can cause several problems. […] This is because of higher than normal pressure in the blood vessels and lungs. This lung damage doesn’t happen right away. The lungs are able to cope with extra volume of blood for a while. […] As the arteries in the lungs get thicker, less blood will flow from the left to the right side of the heart and to the lungs. It will be easier for oxygen-poor (blue) blood to flow from the right side into the left side of the heart and on to the rest of the body. This stops the body from getting enough oxygen. This causes a blue coloring to your child’s skin, lips and nails.

• #58 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  Atrioventricular (AV) septal defect consists of an ostium primum type atrial septal defect and a common AV valve, with or without an associated inlet (AV septal type) ventricular septal defect (VSD). These defects result from maldevelopment of the endocardial cushions. […] A complete AV septal defect is a single large central defect in the septation of the heart. A left-to-right shunt occurs at the atrial and ventricular levels and is often large. AV valve regurgitation may be significant, sometimes causing a direct left ventricle-to-right atrial shunt. These abnormalities result in enlargement of all 4 cardiac chambers. Large defects result in direct transmission of the systemic left ventricular pressure to the right ventricle and pulmonary arteries. Hemodynamic findings are similar to those of a large ventricular septal defect (VSD).

• #59 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  If a complete AV septal defect is unrepaired, over time the increase in pulmonary blood flow, pulmonary artery pressure, and pulmonary vascular resistance may lead to reversal of shunt direction with cyanosis and Eisenmenger syndrome. […] A transitional atrioventricular septal defect, also called a transitional AV canal defect, consists of an ostium primum atrial septal defect, a restrictive inlet ventricular septal defect, which may be small or moderate in size, and a common AV valve, which may or may not be partitioned into a left and right orifice. […] The hemodynamics depend largely on the size of the VSD and whether there is significant AV valve regurgitation. […] A partial AV septal defect consists of an ostium primum atrial septal defect and partitioning of the common AV valve into 2 separate AV orifices, resulting in a so-called cleft in the mitral valve (left AV orifice). The ventricular septum is intact. Hemodynamic abnormalities are similar to those of ostium secundum ASD (eg, left-to-right shunt at the atrial level, enlarged right heart chambers, increased pulmonary blood flow) with the additional finding of variable degrees of AV valve regurgitation.

• #60 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  Atrioventricular (AV) septal defect consists of an ostium primum type atrial septal defect and a common AV valve, with or without an associated inlet (AV septal type) ventricular septal defect (VSD). These defects result from maldevelopment of the endocardial cushions. […] A complete AV septal defect is a single large central defect in the septation of the heart. A left-to-right shunt occurs at the atrial and ventricular levels and is often large. AV valve regurgitation may be significant, sometimes causing a direct left ventricle-to-right atrial shunt. These abnormalities result in enlargement of all 4 cardiac chambers. Large defects result in direct transmission of the systemic left ventricular pressure to the right ventricle and pulmonary arteries. Hemodynamic findings are similar to those of a large ventricular septal defect (VSD).

• #61 Atrioventricular Canal (AVC) Defects | Children’s Hospital of Philadelphia

  https://www.chop.edu/conditions-diseases/atrioventricular-canal-defects

  A common atrioventricular (AV) canal defect (also known as an atrioventricular septal defect) is a problem in the part of the heart that connects the upper chambers (atria) to the lower chambers (ventricles). […] Complete common atrioventricular canal (CAVC) defect is a congenital heart disease in which there is a large hole in the tissue (the septum) that separates the left and right sides of the heart. […] As the heart formed abnormally, the valves that separate the upper and lower chambers also developed abnormally. […] As a result of the abnormal passageway between the two sides of the heart, blood from both sides mix, and too much blood circulates back to the lungs before it travels through the body. […] Complete CAVC requires surgery, usually within the first two or three months of life. […] The surgeon will also separate the single large valve into two valves and will reconstruct the valves so they are as close to normal as possible, depending on the child’s heart anatomy. […] Partial CAVC also requires surgery, whether diagnosed in childhood or adulthood.

• #62 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  Atrioventricular (AV) septal defect consists of an ostium primum type atrial septal defect and a common AV valve, with or without an associated inlet (AV septal type) ventricular septal defect (VSD). These defects result from maldevelopment of the endocardial cushions. […] A complete AV septal defect is a single large central defect in the septation of the heart. A left-to-right shunt occurs at the atrial and ventricular levels and is often large. AV valve regurgitation may be significant, sometimes causing a direct left ventricle-to-right atrial shunt. These abnormalities result in enlargement of all 4 cardiac chambers. Large defects result in direct transmission of the systemic left ventricular pressure to the right ventricle and pulmonary arteries. Hemodynamic findings are similar to those of a large ventricular septal defect (VSD).

• #63 Atrioventricular Canal Defects | Thoracic Key

  https://thoracickey.com/atrioventricular-canal-defects-2/

  A left-to-right shunt is present in patients with AV canal defects, unless PVOD or coexistent right ventricular (RV) outflow tract obstruction is present. Patient presentation depends on the extent of left-to-right shunting, which in turn depends on pulmonary vascular resistance. […] The pathophysiology in complete AV canal defects is similar to that of a large nonrestrictive VSD with two additional features. First, an atrial level shunt is present, with the potential for a left-ventricle-to-right-atrium shunt and increased volume loading of the ventricle. Second, AV valve regurgitation may be present, further increasing the volume load. […] Irreversible changes in the pulmonary vasculature are seen as early as 6 months in patients with unrepaired complete AV canal defects. The presence of Down syndrome accelerates the development of PVOD.

• #64 Atrioventricular Canal Defects | Thoracic Key

  https://thoracickey.com/atrioventricular-canal-defects-2/

  A left-to-right shunt is present in patients with AV canal defects, unless PVOD or coexistent right ventricular (RV) outflow tract obstruction is present. Patient presentation depends on the extent of left-to-right shunting, which in turn depends on pulmonary vascular resistance. […] The pathophysiology in complete AV canal defects is similar to that of a large nonrestrictive VSD with two additional features. First, an atrial level shunt is present, with the potential for a left-ventricle-to-right-atrium shunt and increased volume loading of the ventricle. Second, AV valve regurgitation may be present, further increasing the volume load. […] Irreversible changes in the pulmonary vasculature are seen as early as 6 months in patients with unrepaired complete AV canal defects. The presence of Down syndrome accelerates the development of PVOD.

• #65 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  If a complete AV septal defect is unrepaired, over time the increase in pulmonary blood flow, pulmonary artery pressure, and pulmonary vascular resistance may lead to reversal of shunt direction with cyanosis and Eisenmenger syndrome. […] A transitional atrioventricular septal defect, also called a transitional AV canal defect, consists of an ostium primum atrial septal defect, a restrictive inlet ventricular septal defect, which may be small or moderate in size, and a common AV valve, which may or may not be partitioned into a left and right orifice. […] The hemodynamics depend largely on the size of the VSD and whether there is significant AV valve regurgitation. […] A partial AV septal defect consists of an ostium primum atrial septal defect and partitioning of the common AV valve into 2 separate AV orifices, resulting in a so-called cleft in the mitral valve (left AV orifice). The ventricular septum is intact. Hemodynamic abnormalities are similar to those of ostium secundum ASD (eg, left-to-right shunt at the atrial level, enlarged right heart chambers, increased pulmonary blood flow) with the additional finding of variable degrees of AV valve regurgitation.

• #66 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  If a complete AV septal defect is unrepaired, over time the increase in pulmonary blood flow, pulmonary artery pressure, and pulmonary vascular resistance may lead to reversal of shunt direction with cyanosis and Eisenmenger syndrome. […] A transitional atrioventricular septal defect, also called a transitional AV canal defect, consists of an ostium primum atrial septal defect, a restrictive inlet ventricular septal defect, which may be small or moderate in size, and a common AV valve, which may or may not be partitioned into a left and right orifice. […] The hemodynamics depend largely on the size of the VSD and whether there is significant AV valve regurgitation. […] A partial AV septal defect consists of an ostium primum atrial septal defect and partitioning of the common AV valve into 2 separate AV orifices, resulting in a so-called cleft in the mitral valve (left AV orifice). The ventricular septum is intact. Hemodynamic abnormalities are similar to those of ostium secundum ASD (eg, left-to-right shunt at the atrial level, enlarged right heart chambers, increased pulmonary blood flow) with the additional finding of variable degrees of AV valve regurgitation.

• #67 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  If a complete AV septal defect is unrepaired, over time the increase in pulmonary blood flow, pulmonary artery pressure, and pulmonary vascular resistance may lead to reversal of shunt direction with cyanosis and Eisenmenger syndrome. […] A transitional atrioventricular septal defect, also called a transitional AV canal defect, consists of an ostium primum atrial septal defect, a restrictive inlet ventricular septal defect, which may be small or moderate in size, and a common AV valve, which may or may not be partitioned into a left and right orifice. […] The hemodynamics depend largely on the size of the VSD and whether there is significant AV valve regurgitation. […] A partial AV septal defect consists of an ostium primum atrial septal defect and partitioning of the common AV valve into 2 separate AV orifices, resulting in a so-called cleft in the mitral valve (left AV orifice). The ventricular septum is intact. Hemodynamic abnormalities are similar to those of ostium secundum ASD (eg, left-to-right shunt at the atrial level, enlarged right heart chambers, increased pulmonary blood flow) with the additional finding of variable degrees of AV valve regurgitation.

• #68 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  If a complete AV septal defect is unrepaired, over time the increase in pulmonary blood flow, pulmonary artery pressure, and pulmonary vascular resistance may lead to reversal of shunt direction with cyanosis and Eisenmenger syndrome. […] A transitional atrioventricular septal defect, also called a transitional AV canal defect, consists of an ostium primum atrial septal defect, a restrictive inlet ventricular septal defect, which may be small or moderate in size, and a common AV valve, which may or may not be partitioned into a left and right orifice. […] The hemodynamics depend largely on the size of the VSD and whether there is significant AV valve regurgitation. […] A partial AV septal defect consists of an ostium primum atrial septal defect and partitioning of the common AV valve into 2 separate AV orifices, resulting in a so-called cleft in the mitral valve (left AV orifice). The ventricular septum is intact. Hemodynamic abnormalities are similar to those of ostium secundum ASD (eg, left-to-right shunt at the atrial level, enlarged right heart chambers, increased pulmonary blood flow) with the additional finding of variable degrees of AV valve regurgitation.

• #69 Atrioventricular Septal Defects (AVSD) – TeachMePaediatrics

  https://teachmepaediatrics.com/cardiology/congenital-heart-defects/atrioventricular-septal-defects-avsd/

  This in turn causes excessive pulmonary blood flow leading to heart failure and eventually elevated pulmonary vascular resistance. The atrioventricular valves are usually abnormal and incompetent resulting in regurgitation. […] Partial defects have left to right shunting at the level of atrial septal defect (primum ASD). This causes volume overload of both right atrium and right ventricle and pulmonary over circulation, but the pulmonary artery pressures are usually normal to mildly elevated. Therefore, the symptoms may be minimal until adulthood or may present in late childhood. […] In AVSDs, the structural changes lead to an increased distance between the aorta and the apex of the heart. This results in an elongation of left ventricular outflow tract (LVOT) and abnormal position of the aortic valve which is displaced anterosuperior rather than being wedged between right and left AV valves. This anatomic change is visualized on echocardiography as goose neck deformity. Although the LVOT appears long and narrow, in most cases there is no obstruction.

• #70 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  If a complete AV septal defect is unrepaired, over time the increase in pulmonary blood flow, pulmonary artery pressure, and pulmonary vascular resistance may lead to reversal of shunt direction with cyanosis and Eisenmenger syndrome. […] A transitional atrioventricular septal defect, also called a transitional AV canal defect, consists of an ostium primum atrial septal defect, a restrictive inlet ventricular septal defect, which may be small or moderate in size, and a common AV valve, which may or may not be partitioned into a left and right orifice. […] The hemodynamics depend largely on the size of the VSD and whether there is significant AV valve regurgitation. […] A partial AV septal defect consists of an ostium primum atrial septal defect and partitioning of the common AV valve into 2 separate AV orifices, resulting in a so-called cleft in the mitral valve (left AV orifice). The ventricular septum is intact. Hemodynamic abnormalities are similar to those of ostium secundum ASD (eg, left-to-right shunt at the atrial level, enlarged right heart chambers, increased pulmonary blood flow) with the additional finding of variable degrees of AV valve regurgitation.

• #71 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  If a complete AV septal defect is unrepaired, over time the increase in pulmonary blood flow, pulmonary artery pressure, and pulmonary vascular resistance may lead to reversal of shunt direction with cyanosis and Eisenmenger syndrome. […] A transitional atrioventricular septal defect, also called a transitional AV canal defect, consists of an ostium primum atrial septal defect, a restrictive inlet ventricular septal defect, which may be small or moderate in size, and a common AV valve, which may or may not be partitioned into a left and right orifice. […] The hemodynamics depend largely on the size of the VSD and whether there is significant AV valve regurgitation. […] A partial AV septal defect consists of an ostium primum atrial septal defect and partitioning of the common AV valve into 2 separate AV orifices, resulting in a so-called cleft in the mitral valve (left AV orifice). The ventricular septum is intact. Hemodynamic abnormalities are similar to those of ostium secundum ASD (eg, left-to-right shunt at the atrial level, enlarged right heart chambers, increased pulmonary blood flow) with the additional finding of variable degrees of AV valve regurgitation.

• #72 Atrioventricular Septal Defect – Pediatrics – Merck Manual Professional Edition

  https://www.merckmanuals.com/en-ca/professional/pediatrics/congenital-cardiovascular-anomalies/atrioventricular-septal-defect

  In a subset of patients, the common AV valve is positioned more over one ventricle than the other. This condition, referred to as unbalanced AV septal defect, results in one ventricle receiving more blood flow and becoming dominant (larger) and the other ventricle being underdeveloped. […] Complete atrioventricular septal defect with a large left-to-right shunt causes signs of heart failure (eg, tachypnea, dyspnea during feeding, poor weight gain, diaphoresis) by age 4 to 6 weeks. […] Symptoms in partial AV septal defects vary with the degree of mitral regurgitation; if mild or absent, symptoms may develop during adolescence or early adulthood, but infants with moderate or severe mitral regurgitation often have manifestations of heart failure. […] Symptoms in transitional AV septal defect fall on a spectrum, depending on the size of the VSD. […] Defects are repaired surgically between age 2 to 4 months or 1 to 3 years, depending on the specific defect and severity of symptoms.

• #73 Complete AV Canal | Pediatric Echocardiography

  https://pedecho.org/library/fetal/fet-av-canal

  An AVSD is classified as balanced or unbalanced. In balanced AVSD the common AV valve is equally distributed to the right and left ventricle. An unbalanced AVSD accounts for 10% of all AVSDs and occurs when the AV valve is mostly or primarily committed to one ventricle. Approximately two thirds of unbalanced AVSDs are RV dominant. RV-dominant AVSD is frequently seen with hypoplastic LV, aortic valve hypoplasia, LVOT obstruction and aortic arch anomalies such as coarctation of the aorta. Similarly, in LV-dominant AVSD, the RV is hypoplastic, and there are associated RVOT obstruction and pulmonary stenosis or atresia. […] AVSD may be associated with conotruncal anomalies such as tetralogy of Fallot (TOF) and double outlet right ventricle (DORV). AVSD can also occur in heterotaxy syndrome and is more common in asplenia (bilateral right atrial isomerism) than in polysplenia (bilateral left atrial isomerism).

• #74 Complete AV Canal | Pediatric Echocardiography

  https://pedecho.org/library/fetal/fet-av-canal

  An AVSD is classified as balanced or unbalanced. In balanced AVSD the common AV valve is equally distributed to the right and left ventricle. An unbalanced AVSD accounts for 10% of all AVSDs and occurs when the AV valve is mostly or primarily committed to one ventricle. Approximately two thirds of unbalanced AVSDs are RV dominant. RV-dominant AVSD is frequently seen with hypoplastic LV, aortic valve hypoplasia, LVOT obstruction and aortic arch anomalies such as coarctation of the aorta. Similarly, in LV-dominant AVSD, the RV is hypoplastic, and there are associated RVOT obstruction and pulmonary stenosis or atresia. […] AVSD may be associated with conotruncal anomalies such as tetralogy of Fallot (TOF) and double outlet right ventricle (DORV). AVSD can also occur in heterotaxy syndrome and is more common in asplenia (bilateral right atrial isomerism) than in polysplenia (bilateral left atrial isomerism).

• #75 Complete AV Canal | Pediatric Echocardiography

  https://pedecho.org/library/fetal/fet-av-canal

  An AVSD is classified as balanced or unbalanced. In balanced AVSD the common AV valve is equally distributed to the right and left ventricle. An unbalanced AVSD accounts for 10% of all AVSDs and occurs when the AV valve is mostly or primarily committed to one ventricle. Approximately two thirds of unbalanced AVSDs are RV dominant. RV-dominant AVSD is frequently seen with hypoplastic LV, aortic valve hypoplasia, LVOT obstruction and aortic arch anomalies such as coarctation of the aorta. Similarly, in LV-dominant AVSD, the RV is hypoplastic, and there are associated RVOT obstruction and pulmonary stenosis or atresia. […] AVSD may be associated with conotruncal anomalies such as tetralogy of Fallot (TOF) and double outlet right ventricle (DORV). AVSD can also occur in heterotaxy syndrome and is more common in asplenia (bilateral right atrial isomerism) than in polysplenia (bilateral left atrial isomerism).

• #76 Atrioventricular Septal Defects (AVSD) – TeachMePaediatrics

  https://teachmepaediatrics.com/cardiology/congenital-heart-defects/atrioventricular-septal-defects-avsd/

  This in turn causes excessive pulmonary blood flow leading to heart failure and eventually elevated pulmonary vascular resistance. The atrioventricular valves are usually abnormal and incompetent resulting in regurgitation. […] Partial defects have left to right shunting at the level of atrial septal defect (primum ASD). This causes volume overload of both right atrium and right ventricle and pulmonary over circulation, but the pulmonary artery pressures are usually normal to mildly elevated. Therefore, the symptoms may be minimal until adulthood or may present in late childhood. […] In AVSDs, the structural changes lead to an increased distance between the aorta and the apex of the heart. This results in an elongation of left ventricular outflow tract (LVOT) and abnormal position of the aortic valve which is displaced anterosuperior rather than being wedged between right and left AV valves. This anatomic change is visualized on echocardiography as goose neck deformity. Although the LVOT appears long and narrow, in most cases there is no obstruction.

• #77 Atrioventricular Septal Defects (AVSD) – TeachMePaediatrics

  https://teachmepaediatrics.com/cardiology/congenital-heart-defects/atrioventricular-septal-defects-avsd/

  This in turn causes excessive pulmonary blood flow leading to heart failure and eventually elevated pulmonary vascular resistance. The atrioventricular valves are usually abnormal and incompetent resulting in regurgitation. […] Partial defects have left to right shunting at the level of atrial septal defect (primum ASD). This causes volume overload of both right atrium and right ventricle and pulmonary over circulation, but the pulmonary artery pressures are usually normal to mildly elevated. Therefore, the symptoms may be minimal until adulthood or may present in late childhood. […] In AVSDs, the structural changes lead to an increased distance between the aorta and the apex of the heart. This results in an elongation of left ventricular outflow tract (LVOT) and abnormal position of the aortic valve which is displaced anterosuperior rather than being wedged between right and left AV valves. This anatomic change is visualized on echocardiography as goose neck deformity. Although the LVOT appears long and narrow, in most cases there is no obstruction.

• #78 Atrioventricular Septal Defects (AVSD) – TeachMePaediatrics

  https://teachmepaediatrics.com/cardiology/congenital-heart-defects/atrioventricular-septal-defects-avsd/

  This in turn causes excessive pulmonary blood flow leading to heart failure and eventually elevated pulmonary vascular resistance. The atrioventricular valves are usually abnormal and incompetent resulting in regurgitation. […] Partial defects have left to right shunting at the level of atrial septal defect (primum ASD). This causes volume overload of both right atrium and right ventricle and pulmonary over circulation, but the pulmonary artery pressures are usually normal to mildly elevated. Therefore, the symptoms may be minimal until adulthood or may present in late childhood. […] In AVSDs, the structural changes lead to an increased distance between the aorta and the apex of the heart. This results in an elongation of left ventricular outflow tract (LVOT) and abnormal position of the aortic valve which is displaced anterosuperior rather than being wedged between right and left AV valves. This anatomic change is visualized on echocardiography as goose neck deformity. Although the LVOT appears long and narrow, in most cases there is no obstruction.

• #79 Av canal defect | PPT

  https://www.slideshare.net/drsrb/av-canal-defect

  In AVSDs, the disproportion between the two distances causes anterior displacement of the LVOT resulting in elongation and narrowing of the LVOT producing the characteristic gooseneck deformity. […] Incomplete fusion of the superior and inferior endocardial cushions results in a cleft in the midportion of the left AV valve anterior leaflet often associated with regurgitation. […] Lack of fusion between the superior and inferior cushions and, consequently, with the formation of separate anterior and posterior bridging leaflets along the subjacent ventricular septum. Characterized by a large septal defect with interatrial and interventricular components and a common AV valve that spans the entire septal defect. […] AVSDs account for 4% to 5% of congenital heart defects with an estimated occurrence of 0.19 in 1,000 live births.

• #80 Complete AV Canal | Pediatric Echocardiography

  https://pedecho.org/library/fetal/fet-av-canal

  An atrioventricular septal defect (AVSD) describes a constellation of defects defined by deficient atrioventricular septation and a common atrioventricular junction. The variability seen in atrioventricular septal defects is then determined by both the position of the common atrioventricular valve within the atrioventricular septal defect as well as the presence or absence of bridging tissue between the superior and inferior bridging leaflets. […] Secondary to deficiencies in both the atrial (primum ASD) and ventricular (inlet VSD) septae, the distance from the crux of the heart to the apex is foreshortened and the distance from the apex to the aorta is increased and results in an elongated LVOT (goose neck deformity) with anterior displacement of the aorta. […] Depending on the morphology of the superior leaflet of the common atrioventricular valve, three types of AVSD have been delineated (type A, B and C, according to Rastelli’s classification). The anatomic subgroups (Rastelli’s type A, B and C) can be classified on the basis of the chordal insertions and morphology of the superior bridging leaflet of the common atrioventricular valve.

• #81 Atrioventricular Septal Defects (AVSD) – TeachMePaediatrics

  https://teachmepaediatrics.com/cardiology/congenital-heart-defects/atrioventricular-septal-defects-avsd/

  This in turn causes excessive pulmonary blood flow leading to heart failure and eventually elevated pulmonary vascular resistance. The atrioventricular valves are usually abnormal and incompetent resulting in regurgitation. […] Partial defects have left to right shunting at the level of atrial septal defect (primum ASD). This causes volume overload of both right atrium and right ventricle and pulmonary over circulation, but the pulmonary artery pressures are usually normal to mildly elevated. Therefore, the symptoms may be minimal until adulthood or may present in late childhood. […] In AVSDs, the structural changes lead to an increased distance between the aorta and the apex of the heart. This results in an elongation of left ventricular outflow tract (LVOT) and abnormal position of the aortic valve which is displaced anterosuperior rather than being wedged between right and left AV valves. This anatomic change is visualized on echocardiography as goose neck deformity. Although the LVOT appears long and narrow, in most cases there is no obstruction.

• #82 Av canal defect | PPT

  https://www.slideshare.net/drsrb/av-canal-defect

  Approximately 40% to 45% of children with Down syndrome have congenital heart disease, and among these, 45% have an AVSD. Most patients with Down syndrome, who have congenital heart disease, have the complete form of AVSD (75%). Conversely, 50% of patients with AVSD have Down syndrome. […] The repair of AVSD has been one of the success stories in the field of congenital heart surgery over the last 5 decades. […] All of these patients require lifelong surveillance for development of LVOT obstruction and left AV valve regurgitation.

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