Intermittent left bundle branch block in the athletic heart syndrome

Area of Science:

• Cardiology
• Exercise Physiology
• Autonomic Neuroscience

Background:

• Athletic heart syndrome is characterized by cardiac adaptations to prolonged endurance exercise.
• Intraventricular conduction abnormalities are uncommon but can occur in athletes.
• Left bundle branch block (LBBB) is a rare finding in the context of athletic heart syndrome.

Observation:

• A 30-year-old male athlete presented with intermittent left bundle branch block.
• Electrocardiographic (ECG) monitoring was performed during right atrial pacing and exercise.
• The patient exhibited typical echocardiographic findings consistent with athletic heart syndrome.

Findings:

• The intermittent left bundle branch block resolved during periods of increased adrenergic stimulation (exercise) and reappeared with cholinergic influence.
• Right atrial pacing demonstrated alterations in intraventricular conduction patterns.
• These observations suggest a significant role for autonomic nervous system modulation in the manifestation of LBBB in this athlete.

Implications:

• This case highlights the potential for autonomic dysregulation to unmask or influence conduction abnormalities in athletes.
• Understanding the interplay between autonomic control and cardiac conduction is crucial for accurate diagnosis and management of athletes.
• Further research into the specific mechanisms of autonomic control on intraventricular conduction in athletic populations is warranted.