Materiały źródłowe

• #1 Heart block – Wikipedia

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

  Heart block (HB) is a disorder in the heart’s rhythm due to a fault in the natural pacemaker. This is caused by an obstruction a block in the electrical conduction system of the heart. […] Sometimes a disorder can be inherited. […] The human heart uses electrical signals to maintain and initiate the regular heartbeat in a living person; incorrect conduction or interference from external sources can lead to mild or serious symptoms depending upon the location of the blockage and how severely conduction is being blocked. […] Blockages are therefore classified based on where the blockage occurs namely the SA node („Sinoatrial block”), AV node („AV block” or AVB), and at or below the bundle of His („Intra-Hisian” or „Infra-Hisian block” respectively). […] Of these types of infra-Hisian block, Mobitz II heart block is considered most important because of the possible progression to complete heart block.

• #1 Heart Block: Types, Causes, Symptoms, Treatment

  https://www.healthline.com/health/heart-disease/what-is-a-heart-block

  Heart block is usually the result of a trauma that affects the hearts electrical system. […] Other risk factors include a history of heart attack, heart structure problems, such as hypertrophic cardiomyopathy, heart valve disease, and high potassium levels. […] Several medical conditions may also increase the risk of heart block, including acute rheumatic fever, cardiac tumors, hyperthyroidism, Lyme disease, lymphoma, and other malignancies. […] A 2019 study also suggests that two key cardiovascular risk factors high blood pressure and elevated blood glucose levels are associated with higher risks of developing heart block. […] Open-heart surgery may also raise the risk of heart block or other heart rhythm disturbances (arrhythmias). […] Additionally, heart block can be a side effect of some types of drugs. […] Although rare, heart block can also be a congenital condition, affecting an estimated 1 out of 15,000 to 22,000 live births.

• #1 3rd Degree Heart Block: Causes, Symptoms, Outlook

  https://www.healthline.com/health/heart-disease/3rd-degree-heart-block

  A family history of heart block may also raise the risk of third degree heart block, though a 2021 study suggests that inherited heart block is rare. […] Third-degree heart block may also be present at birth. More than half of all cases of congenital heart block may be due to the mother having an autoimmune condition, such as lupus or Sjogrens syndrome. […] A heart attack can often trigger third-degree heart block, but there can be other causes like other types of heart disease or medication side effects.

• #1 Atrioventricular Block – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK459147/

  An AV block could be congenital or acquired. Congenital AV block can be associated with congenital heart diseases, including AV canal defects, transposition of great arteries, heterotaxy syndrome, left atrial isomerism, and tetralogy of Fallot. Congenital AV block without structural heart disease is relatively more common than those associated with congenital heart disease. Immune-mediated conduction system dysfunction is the main reason for congenital AV block in patients without congenital heart disease. Systemic lupus erythematosus is one of the common autoimmune diseases associated with congenital AV block. Maternal viral infection is another cause of congenital AV block in offspring. […] Myocardial ischemia/infarction, drugs, electrolyte abnormalities, endocrine disorders, and toxins cause acquired AV block. However, age-related degeneration of conduction system diseases is the most common cause of acquired AV block. About half of such cases result from chronic idiopathic fibrosis and sclerosis of the conduction system, as seen in Lengre disease and Lev disease. Higher vagal tone also causes AV block, especially in young individuals. The vagally mediated AV block is nodal in origin; it is benign and rarely requires pacemaker implantation. Some atrial cardiomyopathies and muscular dystrophies also lead to bradyarrhythmias and AV blocks.

• #1 Fetal Congenital Heart Block | Texas Children’s

  https://www.texaschildrens.org/content/conditions/fetal-congenital-heart-block

  Congenital heart block, also called atrioventricular (AV) block, is a disruption of the intricate electrical nerve impulse system that regulates the pumping action of the heart. […] In most cases, the cause is not known, but babies of mothers with lupus or other autoimmune diseases, or babies with congenital heart disorders, are at higher risk. […] Also, a tumor on the baby’s heart can cause heart block.

• #1 Progressive familial heart block: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/progressive-familial-heart-block/

  Progressive familial heart block is a genetic condition that alters the normal beating of the heart. […] Heart block occurs when the electrical signaling is obstructed anywhere from the atria to the ventricles. […] Most cases of heart block are not genetic and are not considered progressive familial heart block. The most common cause of heart block is fibrosis of the heart, which occurs as a normal process of aging. Other causes of heart block can include the use of certain medications or an infection of the heart tissue. […] Mutations in the SCN5A and TRPM4 genes cause most cases of progressive familial heart block types IA and IB, respectively. […] The SCN5A and TRPM4 gene mutations that cause progressive familial heart block alter the normal function of the channels. […] Mutations in other genes, some of which are unknown, account for the remaining cases of progressive familial heart block.

• #1 Heart block: Types, causes, symptoms, and risk factors

  https://www.medicalnewstoday.com/articles/180986

  Heart block can result from an injury or damage to the heart muscle or valves. […] Some people are born with heart block. It can happen as a result of a heart defect or a condition the baby’s mother had during pregnancy, known as congenital heart block. […] However, it is more common for heart block to develop over time. As a person ages, the nerves that connect the top and bottom of the heart may start to fail. […] Other factors may also increase a person’s risk of developing heart block, such as: a heart attack that results in damage to the heart’s electrical system, another heart condition, such as coronary artery disease, cardiomyopathy, or heart failure, other health conditions, such as diabetes, high blood pressure, or Lyme disease, medications that slow the heart’s electrical impulses, such as beta-blockers or calcium channel blockers, heart surgery that leaves scar tissue in the heart, electrolyte abnormalities that can cause a temporary disruption to the heart’s electrical system, degeneration, or aging of the heart’s electrical system.

• #1 Atrioventricular Block – Cardiovascular Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/cardiovascular-disorders/specific-cardiac-arrhythmias/atrioventricular-block

  Atrioventricular (AV) block is partial or complete interruption of impulse transmission from the atria to the ventricles. The most common cause is idiopathic fibrosis and sclerosis of the conduction system. […] The most common causes of AV block are (1) Idiopathic fibrosis and sclerosis of the conduction system (about 40% of patients) […] Ischemic heart disease (20%). […] The remaining cases of AV block are caused by Medications (eg, beta-blockers, calcium channel blockers, digoxin, amiodarone) […] Increased vagal tone […] Cardiac sarcoidosis […] Valvulopathy […] Congenital heart, genetic, or other disorders. […] Up to one-third of patients age 18 years to 60 years with new-onset Mobitz II second-degree or third-degree AV block without evident structural heart disease are diagnosed with cardiac sarcoidosis after targeted investigations.

• #1 Heart Block: Types, Causes, Symptoms, and Risk Factors

  https://www.verywellhealth.com/heart-block-8709735

  Heart block is a delay or disruption within the heart’s electrical conduction system that controls the rhythm and beats, causing the heart to beat slowly or skip beats. Several possible causes of heart block exist. It may stem from aging of the conduction system, a prior heart attack, heart surgery, medication, or an infection. […] Common causes include: Certain infections for example, Lyme disease or bacterial endocarditis with abscess may lead to heart block. Complications of heart procedures or operations like catheter ablation or heart valve surgery may produce heart block. Congenital heart block occurs in the fetus or a newborn up to 28 days of life. It’s usually caused by an autoimmune disease (when the body attacks itself) in the pregnant person, like lupus or Sjgrens disease. Electrolyte disturbances are imbalances of charged minerals in the bloodstream for example, high potassium levels in the blood (hyperkalemia). Heart attack (myocardial infarction) is a complication of coronary artery disease (CAD) in which a part of the heart muscle dies or is damaged due to its blood supply being interrupted. High vagal tone, perhaps secondary to obstructive sleep apnea or vigorous athletic conditioning may lead to heart block. Lenegre disease occurs when the heart’s conduction system scars slowly over time. It affects people under age 60 and may be inherited. Lev disease refers to the thickening or calcification of the heart muscle’s tissues and, eventually, the conduction system. It affects people over the age of 70. Secondary restrictive cardiomyopathy is the deposition of abnormal substances within the heart muscle due to an underlying disease, such as sarcoidosis or amyloidosis. Thyroid dysfunction, either underactive thyroid gland (hypothyroidism) or overactive thyroid gland (hyperthyroidism), may lead to heart block.

• #1

  https://myhealth.alberta.ca/Health/pages/conditions.aspx?hwid=te7144abc

  Heart block can be caused by many things that affect the electrical system of the heart. Examples include: […] Scarring (fibrosis) of the heart’s electrical system, which may be related to aging. This is a common cause of heart block. […] Heart block is more common in older people and may be the result of age and a combination of factors listed above. […] Complete heart block can be caused by many things. These include scarring of the electrical system of the heart, certain heart diseases, and infections. It may also occur after a heart surgery or heart procedure. It can be present from birth (congenital).

• #1 Third-Degree Atrioventricular Block – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK545199/

  The underlying cause of AV blocks is varied and the same for all degrees of blocks. These causes include idiopathic fibrosis and underlying chronic cardiac diseases such as structural heart disease, acute ischemic heart disease, medication toxicity, nodal ablation, electrolyte abnormalities, and post-operative heart block, such as after surgical or transcatheter aortic valve replacement. […] Additional causes of AV block include Lyme disease and some systemic diseases such as collagen vascular disorders, amyloidosis, sarcoidosis, and systemic lupus erythematosus. […] Drugs associated with third-degree heart block include: Antiarrhythmics from all four classes, Digoxin. […] An anterior wall MI with an intranodal complete heart block is a life-threatening condition. About 5 to 10% of patients with an inferior wall MI will develop a complete heart block, which may resolve within 2 to 48 hours. […] AV block can occur after open-heart surgery, septal alcohol infusion, and percutaneous coronary interventions. After aortic valve surgery, complete heart block is more commonly seen in female patients and those with annular calcification.

• #1 Heart Block: Causes, Symptoms, Disgnosis, Treatment

  https://www.webmd.com/heart-disease/what-is-heart-block

  Some people are born with heart block. In others, it develops later in life. […] If you have heart block that you weren’t born with, doctors call it acquired heart block. It’s the most common type. Causes include: […] Certain types of surgery that affect the heart’s electrical system […] Changes in your genes […] Damage from a heart attack […] Heart issues like clogged arteries, inflammation of the heart muscle, and heart failure […] Muscle disorders or other diseases […] Some medicines.

• #1 Heart Block | Cedars-Sinai

  https://www.cedars-sinai.org/health-library/diseases-and-conditions/h/heart-block.html

  Heart block is categorized as first-, second-, or third-degree: […] What causes heart block? […] If you are born with heart block, it’s called congenital heart block. It’s caused by a condition your mother had during her pregnancy or heart problems you were born with. […] For most people, heart block develops as you get older. It happens when the electrical signals that connect the top and bottom of the heart develop fibrosis and eventually fail. Sometimes this may happen because of advancing age. Any process that can damage these electrical signals can result in heart block. Coronary artery disease with and without a heart attack is 1 of the most common causes of heart block. Diseases that weaken the heart muscle (cardiomyopathies) can also damage the electrical signals. Heart block can also be caused by any disease that can affect the heart, such as sarcoidosis and certain cancers, or any disease that results in heart inflammation. This can be an autoimmune disease or infection. Electrolyte problems, such as high potassium levels, can also result in heart block. Additionally, some heart surgeries can damage the conduction pathway leading to heart block. Certain heart medicines can also cause varying degrees of heart block.

• #1 First Degree Heart Block • LITFL • ECG Library Diagnosis

  https://litfl.com/first-degree-heart-block-ecg-library/

  There is delay, without interruption, in conduction from atria to ventricles […] Increased vagal tone […] Athletic training […] Inferior MI […] Mitral valve surgery […] Myocarditis (e.g. Lyme disease) […] Electrolyte disturbances (e.g. Hyperkalaemia) […] AV nodal blocking drugs (beta-blockers, calcium channel blockers, digoxin, amiodarone) […] May be a normal variant.

• #1 Bundle branch block – Symptoms & causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/bundle-branch-block/symptoms-causes/syc-20370514

  Bundle branch block might not need treatment. When it does, treatment involves managing the underlying health condition, such as heart disease, that caused bundle branch block. […] If one or both of these branch bundles are damaged due to a heart attack, for example the electrical impulses can become blocked. As a result, the heart beats irregularly. […] The cause for bundle branch blocks can differ depending on whether the left or the right bundle branch is affected. Sometimes, there is no known cause. […] Causes can include: […] Heart attack (myocardial infarction) […] High blood pressure (hypertension) […] Inflammation of the heart muscle (myocarditis) […] Thickened, stiffened or weakened heart muscle (cardiomyopathy) […] Blood clot in the lungs (pulmonary embolism) […] Heart structure problems that are present at birth (congenital heart defects) such as a hole in the wall separating the upper chambers of the heart (atrial septal defect) […] High blood pressure in the pulmonary arteries (pulmonary hypertension).

• #1 Atrioventricular Block – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK459147/

  The other causes of acquired AV block include infiltrative cardiomyopathies, myocarditis, Lyme disease, rheumatic fever, and endocarditis. Cardiac surgery is also a risk factor for developing an AV block, and aortic and valve surgeries are commonly associated with an AV block due to its proximity to the conduction system. Transcatheter aortic valve replacement is also found to be associated with an AV block. Male patients have a higher incidence of an AV block after transcatheter aortic valve replacement, especially in the presence of underlying conduction system diseases.

• #1 Third-Degree Atrioventricular Block (Complete Heart Block): Background, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/162007-overview

  Atrioventricular (AV) block results from various pathologic states that cause infiltration, fibrosis, or loss of connection in portions of the healthy conduction system. Third-degree AV block (complete heart block) can be either congenital or acquired. […] The congenital form of complete heart block usually occurs at the level of the AVN. Patients are relatively asymptomatic at rest but later develop symptoms, because the fixed heart rate is not able to adjust for exertion. […] Common causes of acquired AV block are as follows: Drugs (see below), Degenerative diseases: Lengre disease (sclerodegenerative process involving only the conduction system) and Lev disease (calcification of the conduction system and valves), noncompaction cardiomyopathy, nail-patella syndrome, mitochondrial myopathy, Infectious causes: Lyme borreliosis (particularly in endemic areas), Trypanosoma cruzi infection, rheumatic fever, myocarditis, Chagas disease, Aspergillus myocarditis, varicella-zoster virus infection, valve ring abscess, Rheumatic diseases: Ankylosing spondylitis, Reiter syndrome, relapsing polychondritis, rheumatoid arthritis, scleroderma, Infiltrative processes: Amyloidosis, sarcoidosis, tumors, Hodgkin disease, multiple myeloma, Neuromuscular disorders: Becker muscular dystrophy, myotonic muscular dystrophy, Ischemic or infarctive causes: AV node (AVN) block associated with inferior wall myocardial infarction (MI), His-Purkinje block associated with anterior wall MI, Metabolic causes: Hypoxia, hyperkalemia, hypothyroidism, Toxins: Mad honey (grayanotoxin), cardiac glycosides (eg, oleandrin), and others, Phase IV block (also known as bradycardia-related block), Iatrogenic causes. […] Complete heart block can develop from an isolated single-agent overdose or as is often the case from combined or iatrogenic coadministration of AV nodal, beta-adrenergic, and calcium channel blocking agents.

• #1 Atrioventricular Block: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/151597-overview

  Causes of Mobitz II second-degree AV block include the following: Degenerative disease of the His-Purkinje system; Damage of the conduction system from coronary artery disease, valve surgery, myocardial infarction, myocarditis, infiltrative cardiomyopathies (sarcoidosis, hemochromatosis), myxedema, Lyme disease, neuromuscular disease, and AV junction ablation. […] Causes of third-degree AV block include the following: Reversible causes: AV node-blocking drugs and ischemia; Pathologic causes: Include cardiomyopathy (infiltrative, idiopathic, and infarction), myocarditis (Lyme disease), endocarditis with abscess formation, and hyperkalemia; Anterior myocardial infarction causing ischemia or infarction of the bundle branches; Cardiac surgery, catheter ablation of the AV node, alcohol septal ablation, or neuromuscular disease.

• #1 Bifascicular Block: Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/22922-bifascicular-block

  A bifascicular block is a type of heart block. It slows the transmission of electrical signals between two of your hearts three bundle branches. […] Congenital heart disease and heart (cardiovascular) disease can cause a bifascicular block. […] Congenital heart disease typically causes a bifascicular heart block. Congenital means a person is born with structural changes to their hearts anatomy. […] Less commonly, people inherit a gene change (mutation) that causes a progressive familial heart block. This gene change causes scar tissue (fibrosis) to form on your heart. Sometimes, it also causes calcium deposits (calcification). These changes can cause a heart block. […] Heart damage may also cause a bifascicular block. This damage may be due to: Heart attack (myocardial infarction). Heart (cardiovascular) disease. Heart valve disease. High potassium (hyperkalemia).

• #1 Atrioventricular block causes – wikidoc

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

  Atrioventricular block can be due to several causes. It could be idiopathic, hereditary, metabolic, or iatrogenic. […] Congenital […] Degenerative (Levs and Lenegres) […] Ischemia […] Infiltrative (Sarcoidosis, Amyloidosis, Hemochromatosis) […] Inflammatory (Systemic lupus erythematosus (SLE), scleroderma, rheumatoid arthritis (RA)) […] Myopathic (Myotonic Dystrophy, Erb’s palsy) […] Infectious (Lyme disease, endocarditis, Chagas disease) […] Trauma (Valve replacement, intravenous therapy) […] Autonomic (Carotid sinus hypersensitivity, situational syncope, vagal reaction) […] Medications (Beta blockers, calcium-channel blocker (CCB), digoxin, clonidine, antiarrhythmics) […] Hypothyroidism […] Hypothermia […] Neurologic […] Electrolytes (Hyperkalemia, hypokalemia) […] Chronic AV block in patients with HTN is thought to be due to CAD or sclerosis of the left side of the cardiac skeleton exacerbated by hypertension […] It used to be thought that CAD was the most frequent cause of chronic complete AV block, but it actually causes only 15% of cases.

• #1 Identifying and Treating First-Degree AV Block (First-Degree Heart Block)

  https://www.aclsonline.us/rhythms/1st-degree-AV-block/

  An atrioventricular (AV) block is also called a heart block. A first-degree AV block occurs when electrical conduction through the AV node of the heart is delayed and the impulse between the atria and ventricles is slowed. […] In younger patients, the cause of this rhythm tends to result from increased vagal tone, whereas in older patients, this rhythm is frequently due to fibrosis within the cardiac conduction system. […] Risk factors for the development of a first-degree AV block include: Myocarditis, Medications (such as adenosine, amiodarone, beta-blockers, digitalis, or non-dihydropyridine calcium channel blockers), Cardiac surgery, Increased vagal tone (as can occur in athletes), Myocardial infarction, Heart disease, Electrolyte abnormalities, such as hypomagnesemia and hypokalemia, Infections such as endocarditis, Lyme disease, and rheumatic fever (as examples), Scleroderma, Systemic lupus erythematosus, Rheumatoid arthritis, Sarcoidosis, Neuromuscular disorders.

• #1 Atrioventricular block – Wikipedia

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

  There are many causes of AV block, ranging from a normal variant among people to the result of a heart attack. […] Mobitz II second-degree block and third-degree AV block are not normal variants and are associated with an underlying condition. Common causes include ischemia (lack of blood flow and oxygen to the heart muscle) or progressive fibrosis (excessive scarring) of the heart. […] Reversible causes of Mobitz II and third-degree heart block include untreated Lyme disease, hypothyroidism, hyperkalemia (high levels of potassium), and drug toxicity. Drugs that slow the conduction of the electrical signal through AV node, such as beta-blockers, digoxin, calcium channel blockers, and amiodarone, can cause heart block if they are taken in excessive amounts, or the levels in the blood get too high.

• #1 Understanding Atrioventricular Blocks – ACLS.com

  https://acls.com/articles/understanding-atrioventricular-block/

  AV blocks are conduction delays or a complete block of impulses from the atria into the ventricles. AV block may be due to increased vagal tone that may be elicited during sleep, athletic training, pain, or stimulation of the carotid sinus. […] Damage of the conduction system secondary to hereditary fibrosis or sclerosis of the cardiac skeleton are known as idiopathic progressive cardiac conduction disease. Ischemic heart disease causes 40% of AV blocks. […] AV blocks are also seen in cardiomyopathies, myocarditis, congenital heart diseases, and familial diseases. A plasma potassium concentration above 6.3 mEq/L may also cause AV block. […] They may be iatrogenic, from medications such as Verapamil, Diltiazem, Amiodarone, and Adenosine, or from cardiac surgeries and catheter ablations for arrhythmias.

• #1 Atrioventricular block – Knowledge @ AMBOSS

  https://www.amboss.com/us/knowledge/atrioventricular-block/

  Toxic/metabolic Electrolyte disorders: e.g., hyperkalemia Acid-base disorders Cardiotoxic drugs: e.g., beta blockers, calcium channel blockers, or digoxin (therapeutic doses or overdoses) Other toxicity: e.g., carbon monoxide, cyanide […] Infectious Bacterial endocarditis Lyme carditis Acute rheumatic fever […] Endocrine Thyroid disease Adrenal disease […] Neuromuscular Myotonic dystrophy

• #1 Atrioventricular (AV) Block

  https://www.washingtonhra.com/arrhythmias/atrioventricular-av-block.php

  AV block can be the result of normal wear and tear on the AV node that occurs with age. […] In addition, patients post-cardiac surgery, particularly valvular surgery, are at a high-risk of complete AV block necessitating permanent pacemaker implantation. […] Medications, particularly for hypertension, can exacerbate already slow conduction through a diseased AV node leading to symptomatic AV block. […] Acute coronary syndromes, i.e. heart attacks, can lead to transient versus permanent degrees of AV block. […] Patients undergoing alcohol septal ablation for hypertrophic cardiomyopathy are also at risk for developing complete heart block.

• #1 Atrioventricular Block: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/151597-overview

  Delay or lack of conduction through the atrioventricular (AV) node and below has multiple causes. Degenerative changes (eg, fibrosis, calcification, or infiltration) are the most common cause of non-ischemic AV block. Idiopathic fibrosis or calcification of the AV conduction system, commonly seen in the elderly, can cause complete AV block. […] Causes of first-degree AV block include the following: Delayed conduction within the AV node or His-Purkinje system; Intrinsic disease of the AV node, high vagal tone, or dual AV nodal pathways (two separate PR intervals); Medications that block the AV node (beta-blockers, calcium channel antagonists, digitalis, and select antiarrhythmic medications) may prolong the PR interval. […] Causes of Mobitz I second-degree AV block include the following: Increased vagal tone (functional block); Degenerative disease of the AV conduction system (commonly seen in the elderly); Occurs physiologically at high heart rates (especially with pacing) as a result of increased refractoriness of the AV node; AV node-blocking medications; Lyme disease, myocarditis, and radiofrequency ablation of the slow pathway.

• #1 Heart blocks: first, second and third degree | Deranged Physiology

  https://derangedphysiology.com/main/required-reading/cardiovascular-intensive-care/Chapter-513/heart-blocks-first-second-and-third-degree

  These are atrioventricular blocks, arising from some abnormality of conduction between the atria and the ventricle. The PR interval describes this conduction. […] Causes of atrioventricular block: Increased vagal tone, eg in athletes, or during sleep […] Idiopathic progressive conduction system disease: 50% of cases. One example Is Lenegres disease […] Ischaemic heart disease: 40% of cases […] Cardiac surgery […] Inherited familial AV block […] Drugs: Verapamil, Digoxin, Amiodarone, Adenosine, Beta-blockers, Quinidine, Procainamide.

• #1 Heart block | Heart and Stroke Foundation

  https://www.heartandstroke.ca/heart-disease/conditions/heart-block

  Heart block may develop in adults or children. Babies can be born with a heart block if they have a congenital heart defect or their mom has an autoimmune disease like lupus. This is called congenital heart block. Sometimes, no cause can be identified. […] Heart block can occur at any age, but it is most likely to occur in the elderly especially people who have other forms of heart disease such as: damage to the heart from a heart attack, coronary artery disease, cardiomyopathy, rheumatic heart disease, heart failure. […] Some medications including digoxin, beta-blockers and calcium channel blockers may cause heart block. If you take any of these medications, your healthcare team will watch you closely for signs of heart block. […] Trained athletes and young people with a high vagal tone may also have first-degree heart block. There is one vagus nerve running from your brain to your abdomen on each side of your body. Vagus nerve activity slows the heart rate.

• #1 Heart Block: Causes, Symptoms, Diagnosis, & Treatment » Cardiology Bangladesh – কার্ডিওলজি বাংলাদেশ

  https://cardiologybd.com/health-wellness/heart-block-causes-symptoms-diagnosis-treatment/

  Infections: Infections such as Lyme disease, which can affect the heart, or viral infections that infiltrate the heart muscle, may lead to heart block. […] Inherited Factors: Certain genetic conditions may predispose individuals to heart block, such as congenital heart defects and inherited arrhythmia syndromes. […] Autoimmune Diseases: Autoimmune conditions like lupus or sarcoidosis can damage the hearts electrical conduction system and cause heart block. […] Trauma: Physical trauma or injury to the chest, such as a direct blow or cardiac surgery, can disrupt the electrical pathways within the heart. […] Electrolyte Imbalances: An imbalance in electrolytes like potassium, sodium, and calcium can affect the hearts electrical conduction and lead to heart block. […] Idiopathic Causes: In some cases, heart block may occur without an identifiable cause and is referred to as idiopathic heart block.

• #1 Bundle Branch Block > Fact Sheets > Yale Medicine

  https://www.yalemedicine.org/conditions/bundle-branch-block

  A bundle branch block refers to a condition that arises from a blocked electrical pathway in the heart, causing the left and right sides of your heart to beat out of sync. […] Different conditions can cause a bundle branch block, including: High blood pressure (hypertension), Heart disease, Inflammation of the heart muscle (myocarditis), Heart-muscle disease (cardiomyopathy), Hardening of the arteries within the heart (arteriosclerosis), A blood clot that enters the lungs (pulmonary embolism), A congenital (or present at birth) heart abnormality. […] Its important to know that in about half of cases, the exact cause of a bundle branch block is unknown. […] Scar tissue, which can form after a heart attack or as a result of inflammation or an infection in the heart, may damage the left or right bundle branch, leading to an abnormal heart rhythm.

• #1 Causes, Risk Factors of Heart Block – Bay Biosciences

  https://baybiosciences.com/causes-risk-factors-of-heart-block/

  Heart block can result from an injury or damage to the heart muscle or valves. […] Some individuals are born with heart block. It can happen as a result of a heart defect or a condition the baby’s mother had during pregnancy, known as congenital heart block. […] However, it is more common for heart block to develop over time. As a person ages, the nerves that connect the top and bottom of the heart may start to fail. […] Other factors may also increase a person’s risk of developing heart block, such as: A heart attack that results in damage to the heart’s electrical system, Another heart condition, such as coronary artery disease, cardiomyopathy, or heart failure, Electrolyte abnormalities that can cause a temporary disruption to the heart’s electrical system, Degeneration, or aging of the heart’s electrical system, Heart surgery that leaves scar tissue in the heart, Other health conditions, such as diabetes, high blood pressure, or Lyme disease, Medications that slow the heart’s electrical impulses, such as beta blockers or calcium channel blockers.

• #1 What Is a Heart Block?

  https://www.icliniq.com/articles/heart-circulatory-health/heart-block

  A heart block results from a trauma affecting the electrical conduction of the heart muscles. The risk of heart block also increases with age. The following risk factors include […] A history of a heart attack. […] Structural problems of the heart. […] Diseases of the heart valve. […] High potassium levels. […] Acute Rheumatic Fever – This condition develops when the streptococcal infection, especially of the throat, is not well treated. […] Cardiac Tumors – Tumorous growth in various parts of the heart. […] Hyperthyroidism – The thyroid gland secretes excessive thyroid hormones in this condition. […] Lymphoma – This is a cancer of the lymphatic system. […] Lyme’s Disease – This is a bacterial infection that spreads by the bite of an infected tick. […] Diabetes. […] Hypertension or high blood pressure.

• #1 Heart Block: Symptoms & Causes | NewYork-Presbyterian

  https://www.nyp.org/heart/arrhythmias/heart-block

  What causes heart block? Heart block is usually caused by other heart issues. Damage to the pathway of electrical signals from the top to the bottom of the heart can cause heart block. The most common causes of heart block include: […] Heart attack – Occurs when part of the heart does not receive enough blood or oxygen […] Coronary artery disease – Narrowing of the arteries is usually caused by plaque buildup […] Cardiomyopathy – A disease of the heart muscle that makes it more difficult for the organ to pump blood, which can lead to a heart attack […] Lyme disease – Damage to the heart’s tissue from the bacteria that causes Lyme disease can lead to heart block […] Thyroid disease A more rare cause of heart block.

• #2 Heart block – wikidoc

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

  Heart block is defined as impaired or abnormal conduction of electrical impulses in the heart. […] Damage to the heart muscle and its electrical system by diseases, surgery, or medicines can cause acquired heart block. Heart block can be either congenital or acquired. Acquired heart block is more common than congenital heart block. […] If a pregnant woman has an autoimmune disease, such as lupus, her fetus is at risk for heart block. […] Autoimmune diseases can cause the body to make proteins called antibodies that can cross the placenta. […] Congenital heart defects also may result in congenital heart block. […] People who have a history of heart disease or heart attacks are more likely to have heart block. […] Other diseases also may raise the risk of heart block. […] Exposure to toxic substances or taking certain medicines, such as digitalis, also can raise your risk of heart block. […] Well-trained athletes and young people are at higher risk for first-degree heart block caused by an overly active vagus nerve.

• #2 Complete Heart Block | Fetal Care Center

  https://www.cincinnatichildrens.org/service/f/fetal-care/conditions/heart-block

  Complete heart block is a disorder of the hearts electrical system, which controls the rate and rhythm of heartbeats. […] Pregnant women who have autoimmune diseases, such as lupus or Sjogrens syndrome, are at an increased risk of having a baby with congenital heart block. Antibodies produced by the pregnant womans body in response to the autoimmune disease can cross the placenta, damage to the heart of the fetus, and lead to congenital heart block. […] Congenital complete heart block usually occurs as an isolated anomaly but can be associated with other congenital problems with the structure of the fetal heart. A parent who has a congenital heart defect may be more likely than other parents to have a child with the same condition, so heredity may also be a factor. Often, however, the cause is unknown.

• #2 Atrioventricular Block > Fact Sheets > Yale Medicine

  https://www.yalemedicine.org/conditions/atrioventricular-block

  Atrioventricular block is a heart rhythm disorder that causes the heart to beat more slowly than it should. Its caused by communication problems within the hearts electrical conduction system. […] Atrioventricular block is more common in older adults, and is often linked to heart conditions, such as heart attack or coronary artery disease. […] Although some people are born with structural abnormalities in their heart that can cause atrioventricular block, most people develop atrioventricular block as they get older. […] For those who develop the condition later in life, atrioventricular block may be caused by the conditions or situations below, which interfere with the hearts electrical activity: Coronary artery disease, Congenital heart defects, Heart-valve disease, Heart attack, Prior heart surgery, Inflammation or scarring within the hearts electrical conduction system, An overactive vagus nerve, which may cause a persons heart rate to slow or blood pressure to drop, possibly leading to fainting, Lyme disease, thyroid disease, and certain other medical conditions, Certain medications, such as digoxin, calcium channel blockers, or beta blockers, which are used to slow down an elevated heart rate (tachycardia).

• #2 Third-Degree Atrioventricular Block (Complete Heart Block): Background, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/162007-overview

  Atrioventricular (AV) block results from various pathologic states that cause infiltration, fibrosis, or loss of connection in portions of the healthy conduction system. Third-degree AV block (complete heart block) can be either congenital or acquired. […] The congenital form of complete heart block usually occurs at the level of the AVN. Patients are relatively asymptomatic at rest but later develop symptoms, because the fixed heart rate is not able to adjust for exertion. […] Common causes of acquired AV block are as follows: Drugs (see below), Degenerative diseases: Lengre disease (sclerodegenerative process involving only the conduction system) and Lev disease (calcification of the conduction system and valves), noncompaction cardiomyopathy, nail-patella syndrome, mitochondrial myopathy, Infectious causes: Lyme borreliosis (particularly in endemic areas), Trypanosoma cruzi infection, rheumatic fever, myocarditis, Chagas disease, Aspergillus myocarditis, varicella-zoster virus infection, valve ring abscess, Rheumatic diseases: Ankylosing spondylitis, Reiter syndrome, relapsing polychondritis, rheumatoid arthritis, scleroderma, Infiltrative processes: Amyloidosis, sarcoidosis, tumors, Hodgkin disease, multiple myeloma, Neuromuscular disorders: Becker muscular dystrophy, myotonic muscular dystrophy, Ischemic or infarctive causes: AV node (AVN) block associated with inferior wall myocardial infarction (MI), His-Purkinje block associated with anterior wall MI, Metabolic causes: Hypoxia, hyperkalemia, hypothyroidism, Toxins: Mad honey (grayanotoxin), cardiac glycosides (eg, oleandrin), and others, Phase IV block (also known as bradycardia-related block), Iatrogenic causes. […] Complete heart block can develop from an isolated single-agent overdose or as is often the case from combined or iatrogenic coadministration of AV nodal, beta-adrenergic, and calcium channel blocking agents.

• #2 Atrioventricular Block – Cardiovascular Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/cardiovascular-disorders/specific-cardiac-arrhythmias/atrioventricular-block

  Transient or reversible causes of AV block can include Lyme carditis and neurologically mediated (vagal) heart blocks. […] AV block caused by acute inferior myocardial infarction usually reflects atrioventricular nodal dysfunction due to increased parasympathetic tone and/or local adenosine release. […] AV block caused by anterior myocardial infarction usually reflects extensive myocardial necrosis involving the His-Purkinje system and requires immediate transvenous pacemaker insertion with interim external pacing as necessary. […] Most patients with isolated congenital third-degree AV block have a junctional escape rhythm that maintains a reasonable rate, but they require a permanent pacemaker before they reach middle age.

• #2 Heart block – Wikipedia

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

  Heart block (HB) is a disorder in the heart’s rhythm due to a fault in the natural pacemaker. This is caused by an obstruction a block in the electrical conduction system of the heart. […] Sometimes a disorder can be inherited. […] The human heart uses electrical signals to maintain and initiate the regular heartbeat in a living person; incorrect conduction or interference from external sources can lead to mild or serious symptoms depending upon the location of the blockage and how severely conduction is being blocked. […] Blockages are therefore classified based on where the blockage occurs namely the SA node („Sinoatrial block”), AV node („AV block” or AVB), and at or below the bundle of His („Intra-Hisian” or „Infra-Hisian block” respectively). […] Of these types of infra-Hisian block, Mobitz II heart block is considered most important because of the possible progression to complete heart block.

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