Transesophageal echocardiography and the intraoperative diagnosis of a right pulmonary artery aneurysm.

ULMONARY ARTERY ANEURYSM (PAA) is a rare clinical disorder in which the underlying etiology may be unclear. It can be either acquired or congenital in origin. The diagnosis may be difficult with chest radiography and pulmo- nary angiography. However, there has been improved recogni- tion with computed tomography (CT), magnetic resonance imaging, and transesophageal echocardiography (TEE). Previ- ously, cases of distal PAA have been reported in the setting of malignancy, immunologic disease, and other disease modali- ties. In this report, the authors present the rare finding of a right pulmonary artery aneurysm seen only with TEE in the setting of chronic pulmonary hypertension. With the presence of a chronic right pleural effusion and a mass-like lesion in the right lung as seen on the chest radiograph and CT, a repeat thoracentesis was done several weeks before surgery. A total of 2.6 L was drained, and the pleural effusion was found to be transudative. Cytology was again negative, as were cultures and acid-fast bacillus staining. Further preoperative studies included transthoracic echocar- diography (TTE), heart catheterization, and pulmonary angiogram. These studies confirmed the presence of severe right ventricular (RV) dysfunction and pulmonary hypertension with a pulmonary vascular resistance of 800 dynes/s/cm 5 . Pulmonary angiogram revealed only dilatation of the main PA and perfusion defects consistent with CTEPH. In light of the results and chronicity, with infection or malig- nancy being unlikely, chronic pulmonary thromboembolism was thought to be the most probable cause of his condition. Accordingly, he was scheduled to undergo a PTE. After radial arterial and peripheral intravenous catheter placement and anesthetic induction, a right internal jugular 9F cordis and pulmonary artery catheter (PAC) were placed. TEE findings were consistent with right-sided pressure and volume overload secondary to chronic pulmonary hypertension. These findings included re- duced left ventricular size secondary to leftward septal shift, normal left ventricular systolic function, a severely dilated RV with de- pressed systolic function, and mild tricuspid regurgitation. Also, the midesophageal aortic short-axis view revealed a large thrombus-lined PAA compressing the SVC (Fig 1). The aneurysm was approximately 6 cm in diameter, and the proximal portion of the feeding right PA was about 3 cm in diameter (measured from TEE). A view of the RV outflow tract showed no masses but showed dilatation of the outflow tract and main PA (Fig 2), as well as mild pulmonic regurgitation on color-flow Doppler (not shown). PTE involves complete endarterectomy of the pulmonary vascular tree. This is performed via median sternotomy with cardiopulmo- nary bypass. It requires deep hypothermia and 2 periods of complete circulatory arrest (one for each side). Circulatory arrest is necessary to prevent bronchial artery blood from entering the surgical field. For each PA, the surgeon makes a small proximal incision, raises an endarterectomy plane, and then uses a blunt dissector/suction device to complete the endarterectomy in each branch of the PA. It is technically demanding surgery, with much of it is performed distally with limited exposure. The presence of the right PAA in this case made the endarterectomy particularly difficult, and the surgeon limited the extent of the endarterectomy to avoid perforating the vessel wall. The specimen obtained is shown in Figure 3. After CPB, the patient's pulmonary vascular resistance had decreased from its starting value of 666 to 282 dyne/s/cm 5 . The patient did well postoperatively and was extubated the following day. Patho- logic examination of the endarterectomy specimen revealed only thrombus with no evidence of malignancy or infection. DISCUSSION