Provocation of higher-degree atrioventricular blocks by ajmaline and rapid ventricular pacing in patients with fascicular block.

In order to induce higher-degree AV block, ventricular pacing at a rate of 150/min after ajmaline administration (max. doses 100 mg) was performed in patients with fascicular block. Out of 109 patients with clinically and electrocardiographically documented intermittent complete AV block (group A) and 61 patients with a typical history without ECG manifestations of higher-degree AV block (group B), a total of 145 patients (85.3%) showed 2nd or 3rd degree AV block after pacing. In contrast to this, only 3 out of 38 patients with bifascicular block without syncope (group C) presented positive results. The method is regarded as being suitable for detecting latent trifascicular blocks.