Orthostatic and exercise-induced advanced nodal atrioventricular block

Trifascicular block progressing to complete AV block on exercise: a rare presentation demonstrating the usefulness of exercise testing

A 41-year-old man presented with dyspnoea and giddiness on exertion for the last 1 month. A resting ECG during showed trifascicular block with complete right bundle branch block, left anterior fascicular block and a prolonged PR interval of >0.24 s. His echocardiography showed no evidence of wall motion abnormality. He was subjected to a treadmill test for exercise-induced ischaemia, which showed complete atrioventricular (AV) block during first stage of Bruce protocol. His symptoms of dyspnoea and giddiness were also reproduced. The test was terminated and ECG returned to trifascicular block, similar to that at his baseline ECG during recovery. Coronary angiogram (CAG) was performed to rule out any ischaemic cause for this exercise-induced AV block, which was normal. In view of his reproducible symptoms and demonstration of complete AV block on exercise, a dual-chamber pacemaker (DDD) was implanted. His symptoms disappeared and he remained asymptomatic on follow-up.

Exercise-induced myocardial ischaemia complicated by paroxysmal complete atrioventricular block

This study describes a case of exercise-induced myocardial ischaemia accompanied by complete atrioventricular block (CAVB). A 59-year-old man with major depression, treated with regular imipramine and lithium for 20 years, experienced syncope episodes during exercise. Exercise, testing initially, identified ST depression in the inferior leads, and later found CAVB resulting in syncope and seizure. The patient recovered completely after resuscitation. Myocardial ischaemic markers were negative, but 35% stenosis was detected in the distal left main coronary artery by angiography. The combined use of verapamil, nitrate and aspirin was treated as the possible coronary spasm. Repeat treadmill caused negative ischaemic study or exercise-induced arrhythmia, 7 days later. The pathophysiology of the very rare exercise-induced paroxysmal CAVB has been reviewed.