Morphologic abnormalities of the mitral valve are very common among patients with indications for operative treatment for hypertrophic cardiomyopathy (HCM) and left ventricular outflow tract (LVOT) obstruction, and in previous series 10% to 20% of patients undergoing septal myectomy have required concomitant procedures on the MV.

In a recent study, surgeons and cardiologists at the University of Maryland determined transmitral septal myectomy (TMSM) facilitates exposure of the ventricular septum for addressing concomitant mitral pathology and subvalvular apparatus. Benefits of the transmitral exposure include a wide view of the ventricular septum, absent risk of injury to the aortic valve cusps, and an enhanced ability to teach trainees to perform septal myectomy (both trainee and attending can see the procedure).


Twenty patients who underwent this procedure were identified (70% women; mean age 63 years). Mitral regurgitation was moderate in 55% and severe in 40%. Preoperative peak left ventricular outflow tract gradient was 92 ± 43 mm Hg. Mitral valve repair (n = 11) or replacement (n = 9) was performed. Pre-discharge transthoracic echocardiography demonstrated a left ventricular outflow tract gradient of 10 ± 5 mm Hg. There was no operative mortality. Follow-up was 100% complete and averaged 22 ± 25 months. No patient required reoperation, and there was no recurrence of left ventricular outflow tract obstruction or mitral regurgitation greater than mild.

View the Transmitral Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy article.

Learn more about the multidisciplinary Hypertrophic Cardiomyopathy program at the University of Maryland Heart and Vascular Center.

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