Subaortic Membrane Excision: Mid-Term Results.

Background: Subaortic membrane (SAM) is a form of fixed subaortic obstruction in which a fibrous membrane is located below the aortic valve. Aim: To determine the role of surgical treatment for patients with a discrete SAM. Patients and Methods: The hospital records of 45 patients (age range: 2–23 years; median 8 years) undergoing surgery for SAM between 1990 and 1998 at the All India Institute of Medical Sciences, New Delhi, India, were analysed. Preoperative echocardiographically calculated gradients across the left ventricular outflow tract ranged from 50 to 154 mmHg (mean: 86.5 ± 33.2 mmHg). Nine patients had trivial aortic regurgitation (AR), 10 had mild AR and five had moderate–severe AR. The left ventricular ejection fraction (LVEF) ranged from 20 to 68% (mean 48 ± 15%). Nineteen patients had significant left ventricular dysfunction (LVEF <50%). Transaortic resection of SAM was done in all patients along with excision of a wedge-shaped segment of septal muscle underlying the membrane. Results: There were no early or late postoperative deaths. On follow up (up to 113 months), only four patients had gradients >30 mmHg. LVEF improved to 45–70% (mean 58 ± 7.7%). AR reduced to mild in four patients and trivial in four patients, and did not progress further. Conclusion: Resection of SAM carries long-term benefits. Routine septal myectomy appears to be associated with a low risk of recurrence. (Heart, Lung and Circulation 2001; 10: 130–135). [ABSTRACT FROM AUTHOR]