Alcohol septal ablation for obstructive hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic disease occurring in approximately one in 500–1000 of the general population. HCM is often undiagnosed or misdiagnosed, and asymptomatic cases are often unrecognized. Asymmetric left ventricular (LV) hypertrophy (LVH) most often develops during the period of rapid body growth of adolescence, but it may be present in childhood or, rarely, before birth. Progressive LVH after age 20 is uncommon, but initial diagnosis even in old age is not. The hypertrophy predominantly involves the LV, and is often more marked than in any other cardiac disease. Hypertrophy may involve the right ventricle (RV), and an atrial myopathy may be progressive (left atrial enlargement [LA) and increased risks of atrial fibrillation [AF]). RV and LA involvement may be secondary to the LV disease, and/or a primary consequence of the basic molecular defect. The LVH represents hypertrophy and hyperplasia of several cell types, including cardiac myocytes, fibroblasts, and smooth muscle cells, along with excessive collagen and matrix deposition, and abnormalities of the microvasculature. The normal parallel arrangement of myocytes is often disturbed (fibre disarray). Clinical practice addresses three needs: 1) assessing and treating the symptomatic patient; 2) assessing and addressing prognostic risks; and 3) genetic counselling, family screening, and mutation detection (genetic testing). Symptoms due to HCM will often have a striking variation in severity when patients may describe good and bad days, exacerbation of symptoms following large meals and an intolerance of dehydration or a hot climate. Chest pain, with a quality similar to angina pectoris but often developing at rest, dyspnoea, palpitations, dizziness, pre/syncope, and fatigue are the common complaints. Although the relief of LV outflow obstruction (LVOTO) by alcohol septal ablation (ASA) for the management of symptomatic HCM is the focus of this chapter, we will first describe some of the more important features of HCM in order that this procedure can be placed in the context of a complex cardiac condition.