Posterior Leaflet Mitral Valve Repair with Septal Myectomy For Hypertrophic Cardiomyopathy

Abstract

Hypertrophic cardiomyopathy (HCM) is the most common heritable cardiomyopathy, and presents with left ventricular hypertrophy resulting in left ventricular outflow tract (LVOT) obstruction in 60% of patients. Standard surgical therapy for the relief of outflow tract obstruction is septal myectomy which can effectively reduce the outflow tract gradient to normal levels.Several challenges exist when performing septal myectomy, especially in the cases of less basilar septal hypertrophy and elongated mitral leaflets. These include creation of a ventricular septal defect, injury to the conduction system requiring a permanent pacemaker, and failure to completely relieve the obstruction. In patients with elongated mitral leaflets, as is common in HCM, septal myectomy alone may be ineffective in completely relieving outflow tract obstruction. Mitral valve repair may be necessary to effectively eliminate any residual outflow tract gradient. Shortening the posterior leaflet with neochords is a repair technique that can move the mitral valve coaptation line posteriorly away from the septum and prevent anterior leaflet systolic motion into the outflow tract, thus relieving the outflow tract gradient. This can be achieved simply by placing neochords to the posterior leaflet through the aortic root and securing them to half the length of the existing cords. The posterior leaflet height is reduced, allowing the coaptation line to move away from the septum, and prevent systolic anterior motion of the anterior leaflet of the mitral valve. The obstruction is prevented, and normal mitral valve function is achieved. This repair technique is especially helpful when the basil ventricular septal thickness is less than 2 cm and the mitral valve leaflets are elongated.