[Complete atrioventricular block and sudden death in isolated corrected transposition].

The rate of av conduction disturbances in corrected transposition of the great arteries is high, possibly as consequence of mechanical injury by ventricular output along with the mis-positioned specialized av junction. A sudden death occurred in a 54 year old female affected by a chronic "idiopathic" complete av block, who showed at autopsy a heart with av and ventricular arterial discordance in the absence of other anomalies (isolated corrected transposition). The cardiac arrest had the ecg features of ventricular fibrillation, preceded by sustained ventricular tachycardia. Histologic study of the conduction system by serial sections confirmed the anterior position of the connected av node, with a long subendocardial course of the bundle in the pulmonary outflow tract. The histologic basis of the block consisted of sclero-atrophy of the common bundle, quite similar to the substrate of acquired av block in heart with normal connections. Possible etiologies, responsible of the relation between the av block and onset of ventricular arrhythmias, are discussed.