Junctional rhythm in hypertrophic cardiomyopathy: a case report

Area of Science:

• Cardiology
• Electrophysiology
• Cardiovascular Physiology

Background:

• Hypertrophic cardiomyopathy (HCM) is a genetic heart muscle disease often associated with sudden cardiac death.
• Understanding dynamic left ventricular outflow tract (LVOT) obstruction mechanisms is crucial for patient management.

Observation:

• A 47-year-old male with HCM and a family history of sudden death experienced intermittent atrioventricular junctional rhythm during cardiac catheterization.
• During junctional rhythm, a significant left ventricular-aorta gradient emerged, absent during sinus rhythm.
• Premature ventricular beats potentiated the gradient, which resolved with return to sinus rhythm.

Findings:

• The study observed that the absence of effective atrial systole during junctional rhythm reduced left ventricular (LV) end-diastolic volume.
• This reduction in LV volume, or preload, was directly linked to the induction and potentiation of the LV-aorta gradient.
• The findings suggest preload reduction, not altered heart rate or contractility, is the primary driver of gradient increase in this context.

Implications:

• This case highlights the critical role of preload in modulating LVOT obstruction in HCM.
• It suggests that interventions aimed at optimizing LV filling may be beneficial in managing dynamic gradients.
• Further research into the interplay between atrial function and LV hemodynamics in HCM is warranted.