Surgical treatment for obstructive hypertrophic cardiomyopathy

Abstract

Keywords Hypertrophic cardiomyopathy Mitral valvereplacement Septal myectomyHypertrophic cardiomyopathy (HCM) is one of the mostcommon genetic diseases affecting myocardium with widevariety of clinical manifestation, hemodynamic character-istics, anatomic morphology, and natural history. Patientswith HCM may develop limiting symptoms due to dynamicleft ventricular outflow tract obstruction (LVOTO) andassociated mitral regurgitation (MR) due to systolic ante-rior motion (SAM) of the anterior mitral leaflet [1]. Forthose who have severe symptoms unresponsive to maxi-mum medical therapy including beta-blockers and antiar-rhythmic drugs such as disopyramide or cibenzoline,surgical left ventricular septal myectomy has been thestandard option. It has been shown that septal myectomysignificantly decreases LVOT gradient and associated MRand provides excellent long-term outcomes.Although the basic transaortic approach for performinga septal myectomy has been known for over 40 years, theoperation remains technically challenging and results areoperator dependent to a high degree [2]. This procedurecarries many tips and pitfalls. Incisions or excisions madetoo deep may create ventricular septal defects or ventric-ular perforations, both of which increase surgical mortalitysignificantly. Poor visualization of the anatomy below theaortic valve can result in injury to mitral leaflets or chor-dae. Incorrect placement of incisions or excessive tractioncan produce complete heart block, requiring permanentpacemakers. Inadequate myocardial protection of thehypertrophied heart can cause difficulty in defibrillationand low cardiac output, which may require mechanicalcirculatory support. The aortic valve is always at risk forinjury from instruments passed through the valve andmanipulated within the ventricle. Therefore, it is under-standable that overly conservative surgical attitudes maysometimes prevail, resulting in limited myocardial resec-tion and consequent incomplete relief or early return ofLVOTO and symptoms. Even if adequate resection issurgically obtained at the level of the basal septum, mid-ventricular obstruction and/or MR associated with abnor-mal papillary muscles and/or chordae, and other musclebundles may persist, and additional procedures maybecome necessary [3].As Furukawa et al. [4] reported their surgical case in thisissue of the GTCS, in which mitral valve replacement(MVR) was required because of residual LVOTO and MRafter standard septal myectomy, surgeons performing thisprocedure should always think about options for residualLVOTO and MR. Because SAM plays an essential role forLVOTO and MR, additional procedures such as mitralvalve plasty including Alfieri’s stitch or MVR with low-profile prosthesis can be effective alternatives. It was firstreported by Cooley et al. that MVR using mechanicalvalves eliminate MR and can relief LVOTO and symptomsin patients with obstructive HCM [5]. Because MVR is asimple and highly reproducible procedure, it can be anattractive option for those who have residual LVOTO andMR even after standard septal myectomy although thoseundergoing MVR with mechanical valve require life-longanticoagulation therapy.