A 38-year-old female with severe mitral regurgitation, severe aortic regurgitation, and moderate pulmonary hypertension was taken up for double-valve replacement surgery. After induction of anesthesia, transesophageal echocardiography (TEE) probe (Philips X7-2t, iE33 system) was inserted. Comprehensive TEE examination revealed an abnormal continuous color flow signal arising from the ascending aorta to the right pulmonary artery (RPA) [Figures 1 and 2, Video 1]. The direction of the color flow jet was perpendicular to the blood flow in the main PA. There was no history of a prior cardiac intervention except coronary angiography to rule out coronary artery disease. Suspecting a left to right shunt, blood samples from the right ventricle and RPA were taken for oximetry study, which showed a 7.3% step-up of oxygen saturation (73.3% vs. 80.6%). During surgery, excision of the pericardium superiorly showed a vascular structure extending from the left posterolateral aspect of the ascending aorta to the RPA. The vessel was doubly ligated with clips which resulted in cessation of its flow on TEE examination, as well as equalization of saturations in the right ventricle and RPA. The rest of the surgical procedure and postoperative course were uneventful.
The most likely diagnosis of this communication is an aortopulmonary window or fistula. Aortopulmonary fistula is generally congenital in origin and may be associated with other congenital cardiac anomalies including patent ductus arteriosus, interrupted aortic arch, coarctation of the aorta, atrial septal defect, or coronary artery anomalies in about half of the patients. Acquired aortopulmonary fistulae have either prior aortotomy, percutaneous endovascular procedure, or acute aortic dissection as the underlying pathology.[2,3] Aortopulmonary fistulae have also been described in chronic diseases of the aortic wall, such as aneurysm, giant cell aortitis, syphilitic or mycotic disease, or endocarditis. After accurate delineation of the anatomy, location, and size of the fistula is achieved, the patient can be treated by either open surgery, hybrid procedure, or endovascular stenting. The risks of pulmonary hypertension, Eisenmenger syndrome, and congestive heart failure remain high in patients with large aortopulmonary fistulae. Patients with very small shunt lesions, such as this patient, may remain asymptomatic, however. The case also highlights the importance of a comprehensive TEE examination to detect abnormal blood flow.
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