Mitral valve replacement (MVR) has been performed on 31 patients as primary or secondary treatment of resting and/or provokable left ventricular outflow tract obstruction (LVOT) secondary to idiopathic hytpertrophic subarotic stenosis (IHSS). Indications for MVT include: (1) septal thickness less than 18 mm; (2) persistent LVOT obstruction after an adequate left ventriculomyotomy andmyectomy; 3) atypical septal morphology; and (4) severe mitral regurgitation secondary to ruptured chordae tendineae or papillary muscle. Intraoperative echo has provided very useful images of the septal morphology which allows selection of patients for MVR. There has been 1 (3.2%) operative death secondary to hepatic and renal failure and no late deaths. Symptomatic improvement to functional class I or II has occurred in 92.8% of 16 patients returning for postoperative evaluation. Excellent hemodynamic relief of resting and provokable gradients have been demonstrated. Long-term follow-up of these patients will be necessary to assess moratality and morbidity compared to the well known results of left ventriculomyotomy and myectomy used to palliate patients in this intitution for 25 years.
