Application of Multiple Novel Imaging Modalities for Guidance and Treatment of the Patient with Subaortic Stenosis

Abstract

Discrete Subvalvar Aortic Stenosis (DSS) is an uncommon acquired cause of left ventricular outflow tract obstruction (LVOT) and often found during Transthoracic Echocardiography (TTE). The membranes are located adjacent to the Aortic Valve (AV) or extended to the anterior leaflet of the mitral valve. The high-velocity systolic jet collides and damages the AV leaflets making the valve more likely to fail and more susceptible to clot and vegetation formation. There is an increased risk of moderate to severe Aortic Insufficiency (AI) when the peak LVOT gradient reaches >50mmHg. The clinical course of subvalvar aortic stenosis is generally progressive with increasing obstruction and progression of AI. Surgical resection of the fibrous ridge with myomectomy is the treatment of choice. The DSS was discovered unexpectedly in this 42 year-old white male with a past medical history of ascending aortic aneurysm, diabetes, hypertension and hyperlipidemia. He was admitted with chest pain, shortness of breath and syncope. TTE showed normal left ventricle with calcified and thickened AV. Peak LVOT gradient was 48mmHg. Due to poor acoustic window, Transesophageal Echocardiogram (TEE) with real time 3-dimensional imaging (RT3D-TEE) was performed. TEE revealed a membranous structure located in the LVOT below a severely calcified AV. Doppler study revealed peak LVOT gradient of 57mmHg with a mean gradient of 38mmHg. Severe AI was also noted. Patient received a #25mm porcine valve with resection of the subaortic membrane and septal myomectomy. Pathology report revealed rubbery, fibromembranous tissue, consistent with DSS. Patient did well after surgery and was discharged home in 4 days. Application of multiple novel imaging modalities, such as TEE and RT-3D-TEE allowed us to better characterize the structure of the DSS and provide guidance for better surgical outcome.