Causes of Heart Block
The causes of heart block vary depending on whether the condition is congenital or acquired. Understanding the causes of heart block is crucial for effective treatment and long-term management.
Congenital heart block occurs when a baby is born with abnormalities in the heart’s electrical conduction system. It may develop as an isolated condition or in association with structural heart defects. In many cases, congenital heart block is linked to maternal autoimmune diseases, such as lupus or Sjögren’s syndrome, where maternal antibodies attack the fetal cardiac cells.
Acquired heart block is more common and typically results from damage or disruption to the heart’s electrical system. Common causes include:
Age-related degeneration: Fibrosis and calcification of the conduction pathways are common in older adults and can impair signal transmission.
Ischaemic heart disease: Conditions such as myocardial infarction (heart attack) can damage the AV node or surrounding tissue.
Cardiomyopathies: Enlarged or thickened heart muscles may distort electrical pathways.
Inflammatory conditions: Infections like Lyme disease, rheumatic fever, or myocarditis can affect the conduction system.
Causes of Heart Block
Surgical trauma: Procedures involving the heart valves or septum may inadvertently damage the AV node.
Medications: Certain drugs, especially beta-blockers, calcium channel blockers, digoxin, and antiarrhythmics, can slow electrical conduction.
Electrolyte imbalances: Abnormal levels of potassium, calcium, or magnesium can disrupt electrical activity.
Infiltrative diseases: Sarcoidosis, amyloidosis, and haemochromatosis may damage the conduction system through inflammation or tissue deposition.
In some cases, the cause of heart block remains unknown, especially in older adults. Identification of the underlying cause is essential in determining whether the block is likely to progress or respond to medical treatment.[Next: Diagnosis of Heart Block →]
