title: First-degree sinoatrial heart block: sinoatrial block in the sick-sinus syndrome.
abstract: Sinoatrial conduction time (SACT) was estimated from the delay in the atrial recovery period after premature depolarization applied in that portion of atrial diastole when increasing prematurity resulted in a constant recovery interval. In 20 normal patients SACT was 169 msec. +/- 91 (2 S.D.). At least nine of 19 patients with "sick-sinus syndrome" (SSS) demonstrated SACT that were longer than seen in these normal subjects. SACT was prolonged in seven of nine SSS patients with abnormal A-V nodal conduction. Among 10 SSS patients with normal A-V conduction, only two had prolonged SACT. This study identifies first-degree sinoatrial block as a frequent manifestation of SSS associated with the presence of A-V node conduction abnormalities.
mesh_terms: D001146:Arrhythmia, Sinus / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006327:Heart Block / Q000503:physiopathology*; D008297:Male; D012848:Sinoatrial Block / Q000503:physiopathology*; D012849:Sinoatrial Node / Q000503:physiopathology*; D013577:Syndrome