Acquired Atrioventricular Block

Abstract

There are many causes of atrioventricular (AV) block but progressive idiopathic fibrosis of the conduction system related to an aging process of the cardiac skeleton is the most common cause of chronic acquired AV block. Barring congenital AV block, Lyme disease is the most common cause of reversible third-degree AV block in young individuals and it is usually AV nodal. Before implantation of a permanent pacemaker, reversible causes of AV block such as Lyme disease, hypervagotonia, athletic heart, sleep apnea, ischemia, and drug, metabolic, or electrolytic imbalance must be excluded. Table 10.1 outlines the format used in the 2002 American College of Cardiology/American Heart Association/North American Society of Pacing and Electrophysiology (ACC/AHA/NASPE) guidelines for pacemaker implantation (1). The indications for permanent pacing in secondor thirddegree AV block unlikely to regress are often straightforward in symptomatic patients but they are more difficult in asymptomatic patients.