ISSN: 1305-385X
Hakkında: Özel sayılar şeklinde yayınlanır.
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Atrioventricular Conduction Disturbances
Dr. Çağatay ERTAN,a Dr. Bülent ÖZİNa
aKardiyoloji AD, Başkent Üniversitesi Tıp Fakültesi, ANKARA
Atrioventricular (AV) node is the most important structure modulating the conduction of atrial impulses to the ventricles. The compact AV node is the most important functional unit of this structure. Atrioventricular conduction disturbances are classified as first degree, second degree and third degree (complete) AV block. The most important prognostic factors in the AV conduction disturbances are the localisation of the block in the conduction system and the type and severity of the underlying heart disease. First degree AV block is defined as prolongation of the PR duration and the cut-off value for the PR interval is 200 miliseconds. Second degree AV blocks are further classified into type I and type II. Type I block is recognised when a P wave is not conducted to the ventricles in the presence of progressive increase in the PR duration in the previous conducted P waves. Type II AV block is recognised when a P wave is not conducted to the ventricles, in the presence of constant PR duration in the conducted compexes before the blocked P wave. Type I second degree AV block is mostly due to a block at the AV nodal level while type II second degree AV block is almost always infranodal. Third degree AV block is defined as independent activity of atria and ventricles with no atrial activity conducted to the ventricles. In this article, basic pathophysiologic mechanisms underlying the atrioventricular conduction disturbances as well as the clinical aspects of AV blocks are reviewed.Keywords: First degree atrioventricular block, second degree atrioventricular block, complete heart block, permanent pacemakersTurkiye Klinikleri J Int Med Sci 2006, 2(24):15-20
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