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Exercise-induced complete heart block in a patient with chronic bifascicular block
J M Byrne1, H J Marais, G A Cheek
1Department of Medicine, Loma Linda University School of Medicine, California.
Journal of Electrocardiology
|October 1, 1994
Summary
Exercise can trigger high-grade atrioventricular (AV) block in patients with chronic bifascicular block, potentially leading to sudden death. This case highlights distal AV nodal block as a cause, emphasizing diagnostic and therapeutic strategies.
Area of Science:
- Cardiology
- Electrophysiology
- Internal Medicine
Background:
- Chronic bifascicular block poses a risk for developing high-grade atrioventricular (AV) block.
- Exercise-induced arrhythmias, including AV block, can lead to serious cardiovascular events and sudden death.
Observation:
- A case study detailing exercise-induced AV block in a patient with pre-existing chronic bifascicular block.
- Ventricular asystole lasting 30 seconds was recorded during exercise treadmill testing.
Findings:
- Myocardial ischemia was excluded as the cause of the observed asystole.
- The event was attributed to distal AV nodal block, a specific type of heart block.
Implications:
- This case underscores the importance of considering distal AV nodal block in patients with bifascicular block experiencing exertional symptoms.
- Exercise treadmill testing and electrophysiologic studies are crucial for diagnosing and managing distal AV block.
- Understanding the pathophysiology of exercise-induced AV block can inform preventative and therapeutic strategies to reduce the risk of sudden cardiac death.
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