Diagnosis of a unicuspid aortic valve using transesophageal echocardiography

NICUSPID AORTIC VALVE is a rare condition. It is often discovered during surgery or autopsy and can easily be mistaken for a bicuspid aortic valve. Morphologic similarities between unicuspid and bicuspid valves can often make echocardiographic differentiation difficult. However, multiplane transesophageal echocardiography (TEE) has been shown to be superior to transthoracic echocardiography for the diagnosis of aortic valve abnormalities. 1 CASE REPORT The patient was a 38-year-old white man with a history of congenital bicuspid aortic valve and aortic regurgitation. He presented with a 4- to 5-month history of shortness of breath with dyspnea on exertion and a 5-week history of chest pain and dizziness. Cardiac auscultation revealed a regular cardiac rate and rhythm with a 4 over 6 systolic ejection murmur heard best at the right upper sternal border, with radiation to the carotid arteries bilaterally. The remainder of the examination, including the pulmonary examination, was normal. Cardiac catheterization was significant for presumed bicuspid aortic valve with aortic regurgitation. The patient was scheduled for an aortic valve replacement with a pulmonary valve autograft (Ross procedure) versus placement of an aortic homograft. The patient was taken to the operating room where an intra-arterial catheter was placed, and general anesthesia was induced with sodium thiopental and sufentanil and muscle relaxation was initiated with pancuronium. After induction of anesthesia, a 5-MHz Hewlett Packard omniplane transesophageal probe (Hewlett-Packard, Andover, MA) was inserted orally and advanced to the level of the stomach. A full TEE examination was performed including 2-D (two-dimensional), M-mode, color, and Doppler modalities. The 2-D examination revealed mildly reduced left ventricular function with an estimated ejection fraction of 45% to 50%. No segmental wall motion abnormalities were appreciated. In the midesophageal short-axis view, the aortic valve appeared unicuspid as evidenced by a small, eccentric, and posteriorly located orifice (Fig 1). The possibility of a bicuspid valve remained, however, as a fused raphe seemed to appear intermittently during diastole in an anteriorly oriented position (at the 7 o’clock position). In the midesophageal long-axis view, the aortic annulus and aortic root were noted to be severely dilated measuring 35 mm and 56 mm, respectively. The ascending aorta was moderately dilated, and the descending thoracic aorta showed mild atherosclerotic disease. Color Doppler findings were significant for moderateto-severe aortic insufficiency. After commencement of cardiopulmonary bypass, the diagnosis of a unicuspid aortic valve was confirmed on aortotomy. On direct inspection, the valve was found to be unicuspid, markedly redundant, and severely insufficient (Fig 2). The ascending aorta and aortic root were replaced under deep hypothermic circulatory arrest with a composite 29-mm Hemashield Dacron (Boston Scientific, Boston, USA) graft and cryopreserved aortic allograft. The remainder of the surgical procedure was uneventful, and the patient was separated from cardiopulmonary bypass without inotropic support. The postpump TEE revealed a trileaflet, normal functioning aortic allograft with trace regurgitation and a peak valve gradient of 5 mmHg. A follow-up transthoracic echocardiography examination on postoperative day 4 revealed mild left ventricular dilatation and concentric left ventricular hypertrophy, with trace aortic regurgitation. The aortic peak gradient was 5 mmHg with a mean gradient of 3 mmHg. The remainder of the hospital course was uncomplicated, and the patient was discharged home on postoperative day 4 in satisfactory condition. DISCUSSION Unicuspid aortic valve is rare and is often confused with a bicuspid valve, a more common congenital abnormality. In adults undergoing surgical intervention for aortic valve disease, unicuspid valve accounts for 5% of the cases, whereas a bicuspid valve accounts for nearly 36% of the cases. 2-4 Both are usually asymptomatic at birth and in childhood, although they can cause symptoms of stenosis or regurgitation. In early adulthood, when degenerative fibrosis and calcification result in aortic stenosis and, less commonly, regurgitation, the symptomatology between the 2 valvular lesions remains indistinguishable. Syncope, angina, and shortness of breath are common manifestations of outflow obstructive lesions, which include bicuspid and unicuspid aortic valves, subaortic membranes, and idiopathic hypertrophic cardiomyopathy. Accordingly, TEE may be an effective diagnostic tool to distinguish