Complete atrioventricular (AV) block is a failure of atrial electrical impulse conduction to reach the ventricles. This may be persistent or paroxysmal and is associated with a junctional or ventricular escape rhythm. This results in significant bradycardia and a lack of coordinated atrial and ventricular contraction, which can significantly decrease cardiac output. Intermittent complete AV block can cause syncope or presyncope.

Etiologies include neonatal lupus erythematosus, congenital cardiac defects, myocarditis, rheumatic fever, Lyme carditis, bacterial endocarditis, myocardial ischemia, and infiltrative cardiomyopathy due to amyloidosis, sarcoidosis, systemic sclerosis, or systemic lupus erythematosus. Some AV nodal blocking medications such as beta blockers, non-dihydropyridine calcium channel blockers, and digoxin may also cause complete AV block. Manipulations such as cardiac surgery, central venous catheter placement, percutaneous coronary intervention, catheter ablation, percutaneous valve intervention, and alcohol septal ablation can cause complete AV block. Some cases are idiopathic.

Presentations vary with the age of onset. Congenital complete heart block is generally irreversible. Cases resulting from neonatal lupus may present in utero or during infancy. Complications can include hydrops fetalis, pericardial effusion, and endocardial fibroelastosis.

Related topics: first-degree atrioventricular block, second-degree atrioventricular block