There is a subset of patients with severely symptomatic hypertrophic obstructive cardiomyopathy who are intolerant of or do not respond to medical therapy. Surgical myectomy has been performed, which provides relief of gradient and improvement of symptoms. Recently, dual-chamber pacing has been proposed as an alternative to surgical myectomy. Dual-chamber pacing can decrease the left ventricular outflow tract gradient, improve symptoms, and perhaps even cause regression of hypertrophy in a subset of patients. This 62-year-old woman with severely symptomatic hypertrophic obstructive cardiomyopathy underwent an acute hemodynamic pacing study in the cardiac catheterization laboratory. Her initial left ventricular outflow tract gradient was 90 mm Hg. During dual-chamber atrial synchronous pacing at an atrial ventricular delay of 60 ms, the outflow tract gradient fell dramatically to 5 mm Hg. There was a loss of the “spike and dome” pattern on the ascending aortic pressure trace. There was a mild decrease in the left atrial pressure.
The mechanism of a decrease in the severity of the left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy by dual-chamber pacing is multifactorial. Acutely, the decrease in gradient may be related to an alteration of ventricular activation, which decreases projection of the basal septum into the left ventricular outflow tract. There may be a long-term effect on ventricular remodeling. Results of large-scale multicenter trials are required to determine the ultimate role of dual-chamber pacing in these patients with severely symptomatic hypertrophic obstructive cardiomyopathy.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
- Copyright © 1997 by American Heart Association