Sinoatrial Conduction Time in Patients with Atrioventricular Block

In 20 patients with atrioventricular (A-V) block, sinoatrial conduction time (SACT) was measured in order to establish the incidence of sinoatrial conduction defects. 10 patients had complete A-V block, 5 patients second-degree A-V block type I, 2 patients second-degree A-V block type II, and 3 patients first-degree A-V block. Prolonged bidirectional SACT was found in 8 cases (40%). The mean value ( ± SD) of SACT was 206 ± 69 ms. In comparison with SACT in a group of 11 patients without symptoms and signs of sinus node disorder (mean value 156 ± 25 ms) the difference was significant (p < 0.05). On the other side, the values of SACT were shorter in patients with A-V block than in 13 patients with sick sinus syndrome (mean value 311 ± 82 ms); the difference was statistically significant (p < 0.001). The study shows that impairment of sinoatrial conduction frequently coexists with A-V conduction defects.