Surgical myectomy resection that focuses just on the subaortic septum, to increase the size of the outflow tract to reduce Venturi forces, may be inadequate to abolish systolic anterior motion (SAM) of the anterior leaflet of the mitral valve. With this limited resection, the residual mid-septal bulge still redirects flow posteriorly; SAM persists because flow still gets behind the mitral valve. It is only when the deeper portion of the septal bulge is resected that flow is redirected anteriorly away from the mitral valve, abolishing SAM. With this in mind, a modification of the Morrow myectomy termed extended myectomy, mobilization and partial excision of the papillary muscles has become the excision of choice. In people with particularly large redundant mitral valves, anterior leaflet plication may be added to complete separation of the mitral valve and outflow. Complications of septal myectomy surgery include possible death, arrhythmias, infection, incessant bleeding, septal perforation/defect, and stroke. Alcohol septal ablation
Alcohol septal ablation, introduced by Ulrich Sigwart in 1994, is a percutaneous technique that involves injection of alcohol into one or more septal branches of the left anterior descending artery. This is a catheter technique with results similar to the surgical septal myectomy procedure but is less invasive, since it does not involve general anaesthesia and opening of the chest wall and pericardium (which are done in a septal myectomy). In a select population with symptoms secondary to a high outflow tract gradient, alcohol septal ablation can reduce the symptoms of HCM.
These medications also decrease the heart rate, though their use in people with severe outflow obstruction, elevated pulmonary artery wedge pressure, and low blood pressures should be done with caution. Dihydropyridine calcium channel blockers should be avoided in people with evidence of obstruction. For people whose symptoms are not relieved by the above treatments, disopyramide can be considered for further symptom relief. Diuretics can be considered for people with evidence of fluid overload, though cautiously used in those with evidence of obstruction. People who continue to have symptoms despite drug therapy can consider more invasive therapies. Intravenous phenylephrine (or another pure vasoconstricting agent) can be used in the acute setting of low blood pressure in those with obstructive hypertrophic cardiomyopathy who do not respond to fluid administration.Mavacamten was approved for medical use in the United States in April 2022. Surgical septal myectomy
Surgical septal myectomy is an open-heart operation done to relieve symptoms in people who remain severely symptomatic despite medical therapy. It has been performed successfully since the early 1960s. Surgical septal myectomy uniformly decreases left ventricular outflow tract obstruction and improves symptoms, and in experienced centers has a surgical mortality of less than 1%, as well as 85% success rate. It involves a median sternotomy (general anesthesia, opening the chest, and cardiopulmonary bypass) and removing a portion of the interventricular septum.