Sickle cells and sudden death: morphologic abnormalities of the cardiac conduction system.

Sudden unexpected death has become increasingly recognized as an important clinical feature of both homozygous and heterozygous sickling syndromes, but the exact nature of its cause has remained unexplained. We have conducted special postmortem examinations of the cardiac conduction system and a coronary chemoreceptor from the hearts of two black males who had sickled erythrocytes. There were abundant foci of old and recent degeneration in the sinus node, atrioventricular node, and His bundle, as well as the coronary chemoreceptor.

A multipurpose catheter for electrophysiologic and hemodynamic monitoring plus atrial pacing.

A new multipurpose flow-directed pulmonary arterial catheter has been developed and evaluated in 30 patients with acute cardiopulmonary dysfunction. The catheter permits monitoring of the bipolar atrial electrogram, pulmonary arterial or wedge pressure, central venous pressure, and cardiac output, plus atrial pacing. The standard Swan-Ganz thermistor-equipped catheter was modified to incorporate two ring electrodes on the shaft at 25 and 26 cm from the tip.

Spontaneous atrial premature depolarizations during paroxysmal reentrant tachycardia.

The spontaneous onset and termination of many episodes of paroxysmal tachycardia, each initiated by an atrial premature depolarization, were studied in one patient. Surface electrocardiograms alone were inadequate to define the mechanisms underlying the frequent irregularity of atrial and ventricular cycle lengths during the tachycardia and the nature of spontaneous termination of the tachycardia. Unipolar atrial electrograms demonstrated that the irregularity during the tachycardia was due to premature atrial depolarizations that reset the reentrant cycle sustaining the tachycardia, and each spontaneous termination was due to an even more premature atrial depolarization interrupting the reentrant pathway.

Anatomical configuration of the His bundle and bundle branches in the human heart.

The relationships among the His bundle, the origin of both bundle branches, and the interventricular (IV) septum were examined histologically in 32 human hearts, and the entire bundle branch systems were delineated in 13 of these. The His bundle in five hearts traversed the right IV septal crest, and the LBB origin was a very narrow stem (maximum 1.5 mm in cross-section) crossing from right to left through the inferior margin of the membranous septum.