Regional wall motion during pacing for hypertrophic obstructive cardiomyopathy

Area of Science:

• Cardiology
• Cardiac Electrophysiology
• Cardiovascular Imaging

Background:

• Hypertrophic obstructive cardiomyopathy (HOCM) is characterized by left ventricular (LV) outflow tract obstruction.
• Right ventricular pacing is a potential therapeutic strategy for HOCM.
• Understanding the impact of pacing on LV mechanics is crucial for optimizing treatment.

Purpose of the Study:

• To evaluate the effect of right ventricular (RV) apical pacing on left ventricular (LV) contraction sequence in patients with HOCM.
• To assess changes in regional LV wall motion and their correlation with pressure gradient reduction.

Main Methods:

• Regional wall-motion analysis of the LV using 2D echocardiography and the area shrinking method.
• Comparison of His-Purkinje activation with RV apical pacing in 9 HOCM patients.
• Doppler echocardiography to measure maximal pressure gradient.

Main Results:

• AV sequential pacing reduced the maximal pressure gradient by 52% (P < 0.01).
• Pacing significantly reduced septal area shrinking (25% to 12%, P < 0.005).
• Increased area shrinking was noted in the posterior and lateral walls (38% to 43%, P < 0.05).

Conclusions:

• Dual chamber pacing effectively reduces septal wall motion in HOCM patients.
• Altered septal motion is a potential mechanism contributing to the reduction of LV outflow tract obstruction.
• RV pacing may be a valuable therapeutic approach for managing HOCM symptoms.