Transaortic Extended Left Ventricular Septal Myectomy in an Adult With Hypertrophic Obstructive Cardiomyopathy

This is a 52-year-old man with hypertrophic obstructive cardiomyopathy (HOCM). He has been on maximal medical therapy with combination of Beta blockers and calcium channel blockers with progression of his symptoms especially during exertion. Preoperative evaluation included transthoracic echocardiography and cardiac MRI for risk stratification. Studies showed severe septal hypertrophy especially at the basal levels. At rest, the the peak gradient across the left ventricular outflow tract was 59 mm Hg which increased to 115 mm Hg with Valsalva maneuver. There was systolic anterior motion (SAM) of the anterior mitral valve leaflet and posteriorly directed mitral regurgitation jet.
He was referred for extended left ventricular septal myectomy. Through a median sternotomy, direct pressure measurement prior to initiation of cardiopulmonary bypass with positive Brockenbrough-Braunwald-Morrow maneuver.
Cardiopulmonary bypass was initiated via an aortic and right atrial cannulation. Through a transaortic approach, an extended left ventricular septal myectomy was performed starting below the nadir of the right coronary cusp and was directed in an anticlockwise direction towards the commissure between the left and non-coronary cusps. Further resection was performed down in the midventricle to ensure complete elimination of the gradient. The anterolateral papillary muscle of the mitral valve was mobilized as it was fused to the interventricular septum.
Post bypass repeat pressure measurement revealed no LVOT gradient and negative Brockenbrough maneuver. The patient tolerated the procedure well and was extubated in the operating room, received no transfusions. He was discharged on the sixth postoperative day.
Pre-discharge echocardiography showed no LVOT obstruction, both at rest and with Valsalva’s maneuver. The aortic and mitral valves were competent and ventricular function was preserved. He was one much smaller dose of beta blocker therapy compared to preoperative period, with expectation to be weaned off completely in 3 months.
In conclusion, extended left ventricular septal myectomy is the gold standard for adults with obstructive pattern of HCM and failed to respond to maximal medical therapy.

References

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