Surgery for Hypertrophic Obstructive Cardiomyopathy

Hypertrophic obstructive cardiomyopathy (HOCM) is an inherited disorder with variable expressivity, resulting in asymmetric septal hypertrophy and left ventricular outflow tract obstruction (LVOTO). Symptoms are similar to those of aortic stenosis and are due to LV diastolic dysfunction and myocardial ischemia in the absence of epicardial coronary narrowing. Goals of treatment include symptomatic control, resolution of hemodynamic abnormalities and their sequelae, reduction of sudden cardiac death risk and screening of family members. Left ventricular outflow tract obstruction at rest is a predictor of severe symptoms, heart failure, and death. The majority of patients are managed medically, predominantly with b-blockers and calcium channel blockade. Disopyramide, a negative inotrope, can be used in cases with persistently high resting gradients. To prevent sudden cardiac death, implantable cardioverterdefibrillators are used aggressively [1]. Surgical treatment has been limited to patients with refractory symptoms and high resting gradients. Results of surgical intervention are well documented, with 5% of patients being asymptomatic with accompanying dramatic reduction in outflow tract gradient. Transcoronary ablation of septal hypertrophy with alcohol – TASH procedure is a newer percutaneous technique. It is designed to ablate hypertrophied cardiac septal muscle through localized infarction, but its efficacy compared with that of surgical myectomy is uncertain. Surgery is not indicated in the absence of significant left ventricular outflow tract obstruction. Only those patients with symptoms refractory to medication and obstruction either at rest or with provocation are generally referred for surgery [2]. Several techniques for relief of obstruction in hypertrophic obstructive cardiomyopathy (HOCM) have been described ever since Cleland in 1 58 started with transaortic myotomy, a procedure known better as Bigelow technique. Septal myectomy rather than simple myotomy was introduced by Morrow in 1 61 and advanced over the years to the standard operation known as Morrow procedure. It was based on the assumption that the asymmetric septal hypertrophy was solely responsible for the left ventricular outflow tract obstruction [3]. Surgery for obstructive HCM has evolved over the past four decades, from ventricular septal myotomy (i.e., without muscular resection), to the classic Morrow myectomy. More recently, an extended and more extensive myectomy (up to about 7 cm long compared with 3 cm for the standard Morrow resection), combined with repair of mitral valve and submitral abnormalities, is practiced by some surgeons. Septal myectomy is performed through an aortotomy. A rectangular trough is created by first making two parallel longitudinal incisions in the basal septum near the nadir of the right coronary aortic cusp (RCC); septum beneath the commissure of the RCC and LCC. Incisions are extended distally and then connected transversely proximally below the aortic valve and distally just beyond the level of mitral-septal contact and AtHENs cArDIOLOGY UPDAtE 2008