Hyp Obst Cardiomyopathy

Hypertrophic Obstructive Cardiomyopathy

Hypertrophic Obstructive cardiomyopathy (HOCM) is the most common genetic cardiomyopathy, heterogeneous in phenotype and clinical course. The genotype-phenotype relationship and associated molecular mechanisms are still incompletely understood. In the HOCM milieu, increased energy cost of force production, impairing performance and mitochondrial function, may be associated to patients' genotype and/or phenotype

Hypertrophic Obstructive cardiomyopathy (HOCM) is the most common genetic cardiomyopathy, heterogeneous in phenotype and clinical course. The genotype-phenotype relationship and associated molecular mechanisms are still incompletely understood. In the HOCM milieu, increased energy cost of force production, impairing performance and mitochondrial function, may be associated to patients' genotype and/or phenotype (1). Hypertrophic cardiomyopathy as a clinical entity was first described by Brock in 1957 (2). Hypertrophic cardiomyopathy is the most common cause of sudden cardiac death in young people, including competitive athletes (3). The characteristic pathologic features of hypertrophic cardiomyopathy are asymmetric hypertrophy, especially of the interventricular septum myocardial fiber hypertrophy and disorganisation of myocardial cells, abnormal thickened intramyocardial coronary vessels (small vessel disease) and interstitial fibrosis (4). In the majority of patients (approximately 90%), hypertrophy mainly involves the interventricular septum and anterolateral wall. In a minority of patients myocardial hypertrophy is confined to the apical part of the left ventricle (4). Myocardial hypertrophy is not the only hallmark of hypertrophic Obsructive cardiomyopathy. Klues et al. have described anatomic alterations in the mitral apparatus which may be present in this disorder: an increase of the mitral valve area, increase in length of the anterior leaflet, abnormal laxity and anterior displacement of the valve (5). Mitral valve (MV) leaflets have an important role in the pathophysiological process of left ventricular (LV) outflow tract obstruction in patients with hypertrophic obstructive cardiomyopathy (HOCM). Systolic anterior motion (SAM) of the mitral apparatus and contact of the leaflets with the hypertrophied septum narrow the LV outflow, leading to dynamic pressure gradients and in many patients, mitral regurgitation (MR) (6). Currently, surgery is the gold standard treatment for most drug refractory and severely symptomatic patients \[New York Heart Association (NYHA) class III or IV\] with obstructive HOCM \[7\]. The Septal myectomy is the preferred treatment of most patients with HOCM, and many studies have documented relief of symptoms and satisfactory late patient survival after relief of outflow tract gradients. valve repair or replacement may be necessary (7). However, adequate septal myectomy relieves outflow tract gradients, SAM of the MV, and MR in many patients (6). Nevertheless, several reports have described adjunctive techniques of mitral valvuloplasty aimed at eliminating SAM of the MV (8,9). Guidelines support decisions to select surgery for patients with mitral structural abnormalities. The 2011 American guidelines state: Additionally, specific abnormalities of the mitral valve and its support apparatus can contribute significantly to the generation of outflow tract obstruction, suggesting the potential value of additional surgical approaches (e.g., plication, valvuloplasty, and papillary muscle relocation) and making myectomy more appropriate than alcohol septal ablation in some patients (10) Finally, An appreciation of mitral abnormalities in HCM has accumulated over the past 20 years (11). There has been a natural response by surgeons to this greater understanding of the contribution of mitral pathology to SAM. At myectomy, they have tried to avoid leaving unrepaired pathology by repairing the mitral valve (12).

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