Significance of exercise-induced second degree atrioventricular block

Sudden cardiac death: the finish line as a beginning: a true endurance race in a case report

Background

The benefits of exercise are well documented. Intensive exercise for more than 4 h per week is associated with cardiovascular remodelling, including increases in ventricular dimensions, wall thickness, and left ventricular mass. These changes are influenced by sex, ethnicity, and type and duration of exercise. In highly trained endurance athletes, exercise is often associated with electrocardiographic changes at rest.

Case summary

A well-trained endurance athlete underwent cardiac investigation after his 33-year-old brother died while jogging. A resting 12-lead electrocardiogram showed significant first degree atrioventricular block (AVB), and longer monitoring revealed advanced AVB. This led to further testing and exercise restrictions.

Discussion

Although most electrocardiographic changes are related to athletic performance, the distinction between normal variants, often exaggerated by the physiology of the conditioned athlete, and myocardial or electrical disease may be challenging. Athletes should undergo comprehensive cardiovascular evaluation, with management based on these results.

Exercise-induced Atrioventricular Block with Coronary Artery Stenosis that Appeared Five Years after Bypass Surgery

A 68-year-old man with a history of coronary artery bypass surgery was referred to our hospital because of pre-syncope on effort. During a treadmill exercise electrocardiogram test, the patient developed advanced atrioventricular block associated with dizziness. Coronary angiography revealed significant stenosis of the right coronary artery, which had not existed at the time of the bypass surgery. We implanted drug-eluting stents in the stenotic lesion, and an exercise test showed resolution of the atrioventricular block. Exercise-induced atrioventricular block is rare, and it is necessary to distinguish it from ischemic heart disease, especially in patients with a history of coronary artery disease.

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 atrioventricular block with gap phenomenon in atrioventricular conduction

A 54-year-old man with normal atrioventricular (AV) conduction at rest gave a 4-year history of presyncope during exercise. Treadmill testing showed exercise induced AV block. Electrophysiological study demonstrated rate dependent infranodal AV block and abnormal refractory period of the His-Purkinje system. The gap phenomenon in AV conduction occurred during the programmed stimulation. Supernormal conduction could be considered as the mechanism of the gap phenomenon in this patient.

[Exercise-induced atrioventricular block. Significance of the ischemic component. Report of 4 new cases]

We report four new cases of exercise-induced atrio-ventricular block (appearing during treadmill exercise testing). The mechanism was ischemia in two patients and the conduction disturbance disappeared after coronary artery bypass grafting. The literature on this matter is reviewed. Also the etiology, the natural history and management are discussed in these cases.

Exercise-induced second-degree atrioventricular block

In this report we describe 2 patients with exercise-induced, second-degree atrioventricular (AV) block. Case 1 was a 49-year-old man with normal AV conduction at rest but who developed dyspnea on exertion. Treadmill testing showed an exercise-induced 2:1 AV block. Electrophysiologic study (EPS) demonstrated rate-dependent, presumably intrahissian, AV block. Case 2 was a 31-year-old woman with first-degree AV block and complete right bundle branch block with dyspnea on exertion and occasional syncope. She had twice undergone surgical patch closure of an ostium primum atrial septal defect. Exercise testing induced type II second-degree AV block. Atrial pacing during EPS did not disclose rate-dependent type II AV block, but disopyramide induced second-degree AV block.

Exercise-induced complete heart block in a patient with chronic bifascicular block

Heart block induced by exercise or associated with symptomatic, chronic bifascicular block can progress to high-grade atrioventricular (AV) block and sudden death. The authors describe a case of exercise-induced AV block in a patient with chronic bifascicular block. Thirty seconds of ventricular asystole were observed during exercise treadmill testing. Myocardial ischemia was ruled out, and the cause was determined to be distal AV nodal block. The pathophysiology, diagnosis, and treatment of distal AV nodal block are reviewed. The role of exercise treadmill testing and electrophysiologic studies in distal AV block are outlined in a diagnostic and therapeutic strategy.

Orthostatic and exercise-induced advanced nodal atrioventricular block

A 69-year-old woman was referred for asthenia and dizziness when walking in the last two months. No clinical abnormalities were found, and sinus rhythm was present when lying down. On orthostatism and walking, advanced AV block developed. Atropine and isoproterenol ameliorated the AV conduction abnormality, suggesting a nodal block. The patient remained asymptomatic after pacemaker implantation.

Tachycardia-dependent second degree AV-block in a patient with right bundle branch block

A 55-year old male patient, with dizzy spells during everyday activity and a complete right bundle branch block as the sole electrocardiographic abnormality, reproducibly demonstrated tachycardia-dependent Mobitz Type II- and 2:1 second degree atrioventricular block. An electrophysiologic study revealed a provocable block within the distal portion of the bundle of His without evidence of a split His potential. Because of the truly tachycardia-dependent AV-block, beta-blocker medication was initiated to prevent high sinus rates during everyday activity. This therapy abolished symptoms totally.

Progressive atrioventricular block during exercise in univentricular heart

Two patients who had univentricular heart presented with complaints of recurrent nausea and vomiting during exertion. Exercise study revealed 1:1 atrioventricular conduction and no symptoms at rest; at peak exercise, both patients experienced progressive, high grade, second degree atrioventricular block and nausea. Both patients underwent permanent pacemaker implantation, with relief of symptoms. Exercise testing is important in evaluating patients who are at increased risk of spontaneous atrioventricular block, and exertion-induced nausea may be a clue to its presence.

Exercise induced "Mobitz type II" second degree AV block in a patient with chronic bifascicular block (right bundle branch block and left anterior hemiblock)

A 55 year old healthy man with chronic bifascicular block (right bundle branch block and left anterior hemiblock) had a near syncopal episode. A treadmill test showed exercise induced Mobitz type II AV block manifested clinically by paradoxical slowing of the heart rate and decreased blood pressure. True His Purkinje block and pseudo AV block due to His extrasystoles were documented by an electrophysiological study.

Exercise-induced distal atrioventricular block

Three patients with 1:1 atrioventricular (AV) conduction at rest developed fixed 2:1 or 3:1 AV block during treadmill exercise testing. Electrophysiologic study documented block distal to the AV node in all three patients, and suggested that the exercise-induced block occurred because of increased atrial rate and abnormal refractoriness of the His-Purkinje conduction system. The findings in these three patients suggest that high grade AV block appearing during exercise reflects conduction disease of the His-Purkinje system rather than of the AV node, even in the absence of bundle branch block. Patients with this diagnosis should be considered for permanent cardiac pacing.