Occult tumor embolization detected by intraoperative transesophageal echocardiography.

rior vena cava (IVC) in 4% to 10% of patients, and of these patients, further extension into the right atrium occurs in 2 to 16%. 2 The evaluation of tumor extension requires preoperative investigation with a chest computed tomography scan and, if intracardiac extension of tumor is suspected, transthoracic echocardiography. Because the presence of vena caval extension of the tumor has no impact on survival, complete resection of tumor at the time of surgery is the goal. 3 The Neves and Zincke classification of RCC tumors is based on tumor extension into the IVC, where a level IV tumor is indicated by extension into the right atrium. Transesophageal echocardiography (TEE) may be used as a surveillance tool during resection of RCC in patients with a level IV tumor because thrombus may embolize into the pulmonary circulation during surgery. Sudden pulmonary tumor embolus during surgical excision has been reported as a cause of intraoperative mortality. 4 In addition, TEE may be used to examine intracardiac tumor involvement and confirm complete removal of the tumor after resection. 5 In this report, the authors present a case in which TEE was instrumental in detecting clinically silent migration of a tumor embolus to the pulmonary artery during the resection of RCC with vena caval extension. CASE REPORT A 68-year-old man with a history of coronary artery disease and RCC presented for nephrectomy, tumor thrombectomy, and coronary artery bypass graft surgery. The preoperative workup included a chest computed tomography scan, which showed intracardiac extension of the RCC into the IVC and the right atrium, and a cardiac catheterization, which revealed a 70% stenosis of the left anterior descending coronary artery. Preoperative transthoracic echocardiography also revealed a large mass in the IVC entering the right atrium and passing through the tricuspid valve with moderate tricuspid regurgitation. A nephrectomy was planned via a midline laparotomy followed by median sternotomy, right atriotomy, tumor thrombectomy, and coronary artery bypass graft surgery on cardiopulmonary bypass without aortic cross-clamping. After the uneventful induction of general anesthesia, intraoperative TEE confirmed previous transthoracic echocardiography findings of an IVC tumor that extended into the right atrium and traversed the tricuspid valve into the right ventricle (Fig 1 and Video 1 [supplementary videos accompanying this article are available online]) and moderate tricuspid regurgitation (TR). Normal right and left ventricular size and function were seen, but no other valvular abnormalities, abnormalities of the main pulmonary artery or its branches, or patent foramen ovale were noted. During nephrectomy and IVC mobilization, the position of the IVC/right atrial tumor mass was continuously monitored by TEE, and its position was unchanged. Subsequently, a sternotomy was performed, and the left internal thoracic artery was harvested. At the time of harvesting of the left internal thoracic artery, a repeat TEE examination could no longer visualize the tumor in the right atrium or ventricle. Further inspection localized the tumor embolus to the main pulmonary artery (Fig 2 and Video 2). Hemodynamics were stable during tumor migration. No TEE signs of increased right ventricular (RV) afterload were seen. The TEE discovery required a revision of the surgical plan including initiation of cardiopulmonary bypass with aortic cross-clamping, cardioplegic-induced cardiac arrest, and an incision to the main pulmonary artery. Subsequently, a thrombus measuring 13 3 cm was removed from the pulmonary artery. After the anastomosis of the left internal thoracic artery, the patient was successfully weaned from cardiopulmonary bypass. TEE examination of the IVC, right atrium, and pulmonary artery showed complete removal of the tumor and resolution of the tricuspid valve incompetence. DISCUSSION Intraoperative TEE played an important role in determining surgical strategy in this report by confirming the tumor location and the degree of cardiac involvement, detecting tumor embolization despite the absence of clinical findings, and confirming complete tumor removal and resolution of tricuspid regurgitation. In addition, TEE functioned as an essential monitoring tool because insertion of a pulmonary artery catheter is contraindicated in the presence of a large intra-atrial tumor. In this report, TEE findings significantly impacted surgical management. Routine TEE monitoring of the tumor position during intraoperative IVC mobilization was uneventful. Unexpectedly, the tumor embolized to the main pulmonary artery during a period without IVC manipulation and without subsequent hemodynamic effect. Only the discovery by TEE alerted anesthesia and surgical teams to tumor migration. The decision to convert from a beating-heart atriotomy to cardioplegicinduced cardiac arrest on full cardiopulmonary bypass was made in order to reduce the possibility of the tumor embolus migrating further into the pulmonary circulation. After tumor removal, TEE was instrumental in confirming complete tumor removal and resolution of tricuspid valve incompetence so that surgical repair of this valve was unnecessary. An intracardiac tumor may cause diverse echocardiographic findings depending on its location. Tumors located in the region of the tricuspid valve may result in TR, intermittent RV inflow obstruction, and subsequent pulmonary thromboembolism. TR occurs if the tumor mass alters the geometry of the valve leaflets or interferes with their complete closure. This was shown echocardiographically by protrusion of the mass through the tricuspid valve annulus during diastole while inhibiting usual systolic closure of valve leaflets. The tumor may also cause RV inflow obstruction, which is detected by TEE findings of right atrial dilation, widened tricuspid orifice, failure of tricuspid valve leaflet coaptation, and an underfilled right ventricle. 6 Acute pulmonary embolus may occur and is detected by indirect consequences of a sudden increase in RV afterload. A 25% to 30% obstruction of the pulmonary vascular bed is