[Reliability of premature atrial stimulation in the study of sinoatrial conduction time (author's transl)].

Premature atrial stimulation was carried out in 32 patients, and for each stimulus the basic cycle (A1A1), test cycle (A1A2), and the return cycle (A2A3) were analyzed. When A2A3 was plotted as the function of A1A2, a biphasic pattern, characterized by a slope phase followed by a "plateau", was observed in 25 subjects. Sinoatrial conduction time (SACT) was calculated using the Strauss method, which assumes that in the plateau A2A3 = A1A1 + SACT. Sinus arrhythmia was also determined in order to evaluate its importance in altering the results of premature atrial stimulation: it should be pointed out that when arrhythmia was marked it was impossible to calculate sinoatrial conduction time. An inverse correlation between A1A1 and the calculated SACT and between A1A1 and A2A3/A1A1 in the plateau was also demonstrated. The reliability of SACT obtained by premature atrial stimulation is discussed in relation to the results obtained and the data found in the literature.