Apoptosis as a possible cause of gradual development of complete heart block and fatal arrhythmias associated with absence of the AV node, sinus node, and internodal pathways.
BACKGROUND
Gradually progressive development of complete heart block in young people often is associated with cardiac arrhythmia and sudden death, but the pathogenesis remains unexplained.


RESULTS
A young woman with complete heart block died suddenly. Her mother had serological but no clinical evidence of antiphospholipid syndrome. Five brothers of another family had arrhythmia and heart block. Three died suddenly; the other two have automatic defibrillators and are alive. The hearts from the young woman and two of the three brothers who died were available for our histological examination of their cardiac conduction systems. In two of the three hearts, the AV node was absent; in the third heart, only fragments of the AV node remained. In all three hearts, the sinus node was nearly destroyed by a noninflammatory degeneration with no abnormal fibrosis or infiltrate. In each heart, the interatrial and internodal pathways were similarly involved, and in the young woman, there were no myocardial cells in which these pathways normally exist.


CONCLUSIONS
In these three subjects with progressive development of complete heart block and various arrhythmias, all of whom died suddenly, the histological abnormalities of their cardiac conduction systems are best interpreted as resulting from apoptosis. Programmed cell death is a logical explanation for the pathogenesis of this puzzling clinical picture.
James
T N
TN
Department of Medicine, World Health Organization Cardiovascular Center, University of Texas Medical Branch, Galveston 77555-0129, USA.
St Martin
E
E
Willis
P W
PW
Lohr
T O
TO
D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D017209:Apoptosis; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000473:pathology; D001283:Atrioventricular Node / Q000473:pathology*; D001919:Bradycardia / Q000209:etiology; D002304:Cardiac Pacing, Artificial; D002648:Child; D016757:Death, Sudden, Cardiac / Q000209:etiology* / Q000473:pathology; D017147:Defibrillators, Implantable; D018450:Disease Progression; D017809:Fatal Outcome; D005260:Female; D006327:Heart Block / Q000150:complications* / Q000209:etiology* / Q000235:genetics / Q000473:pathology / Q000628:therapy; D006329:Heart Conduction System / Q000473:pathology*; D006330:Heart Defects, Congenital / Q000150:complications; D006801:Humans; D008297:Male; D009206:Myocardium / Q000473:pathology*; D012849:Sinoatrial Node / Q000473:pathology*; D013575:Syncope / Q000209:etiology
D000319:Adrenergic beta-Antagonists