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Current status of nonsurgical septal reduction therapy in hypertrophic obstructive cardiomyopathy

RM Cooper, A Shahzad & RH Stables

Left ventricular outflow tract obstruction pathophysiology ▪ The critical process in left ventricular outflow tract obstruction is systolic anterior motion of the mitral valve (MV). The pathophysiology is a complex interplay of basal hypertrophy, anterior displacement of the anterior papillary muscle and long anterior MV leaflet. This results in systolic anterior motion and MV contact with the basal septum. The longer the MV is in contact with the septum, the greater the obstruction to flow, and therefore the higher the gradient. ▪ Removal of the hypertrophied basal segment opens the left ventricular outflow tract. This alters the hemodynamics and reduces obstruction and, therefore, gradient. Indications & patient selection ▪ Negatively inotropic medications improve symptoms and gradients in the majority of hypertrophic obstructive cardiomyopathy patients. ▪ Patients must have a subaortic gradient of >50 mmHg (at rest or with exercise), suffer from New York Heart Association class III dyspnea and have a septal width sufficient to perform septal reduction therapy without risk of causing a ventricular septal defect (usually >15 mm).