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Regional wall motion during pacing for hypertrophic obstructive cardiomyopathy
1Department of Medicine, University Hospital, Lausanne, Switzerland.
Insights
Dual chamber pacing in hypertrophic obstructive cardiomyopathy (HOCM) significantly reduces the pressure gradient by altering septal wall motion. This change in left ventricular (LV) contraction may alleviate outflow tract obstruction.
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.
Abstract:
In order to assess the influence of right ventricular stimulation on LV contraction sequence in hypertrophic obstructive cardiomyopathy (HOCM), we performed a regional wall-motion analysis of the left ventricle by comparing normal His-Purkinje activation to pacing from the right ventricular apex. In 9 patients (5 males and 4 females, mean age 61 +/- 9 years) assessed after a mean pacing period of 12 weeks (range 7-24 weeks), AV sequential pacing induced a 52% reduction in maximal pressure gradient from 76 +/- 36 to 40 +/- 28 mmHg (P < 0.01) as determined by Doppler examination. Regional wall-motion analysis of the left ventricle was computed from digitized two-dimensional echocardiographic images by means of the area shrinking method. Pacing induced a significant reduction of total septal area shrinking from 25% +/- 17% to 12% +/- 17% (P < 0.005). A tendency toward paradoxical septal motion was observed in one patient only. The apex showed no significant variation. A 6% increase in area shrinking was observed at the posterior wall and lateral free wall, from 38% +/- 13% to 43% +/- 10% (P < 0.05). Pacing did not significantly alter the global ejection fraction. A direct correlation between the magnitude of subaortic pressure gradient reduction and that of septal motion changes was found in a majority of patients. In conclusion, dual chamber pacing reduces septal wall motion in patients with HOCM obstructive cardiomyopathy. This might be one of the mechanisms involved in the reduction of LV outflow tract obstruction.