Inferior vena cava (IVC) thrombus is found in approximately 4–10% of cases of RCC [1]. Complete resection by radical nephrectomy and IVC thrombectomy improves 5-year survival from 17% to 68% in patients with non-metastatic RCC [2]. In these patients embolism of tumour thrombus into the pulmonary vasculature is found in 4.4% of patients preoperatively [3]. Intraoperative embolism occurs rarely (1.5% of cases) [4] and is associated with a high mortality of 60–75% [4]. Here we present a case of intraoperative embolism and subsequent pulmonary embolectomy. A 77-year-old man with a 12 cm locally advanced renal cancer with Level IV IVC thrombus as shown on MRI (Fig. 1) underwent elective right nephrectomy and IVC thrombectomy following multidisciplinary team assessment. With the patient supine, via a 'reverse-L' abdominal incision extending to sternotomy, the IVC and both renal veins were exposed. At the start of the case tumour thrombus was noted to be present in the right atrium on transoesophageal doppler ultrasound. The kidney was completely mobilised on the renal vein and the patient was placed on normothermic cardiopulmonary bypass. At the time of IVC venotomy with clamps placed on the left renal vein, porta hepatis and the infra-renal IVC, no tumour thrombus was noted in the IVC on direct inspection. Transoesophageal echocardiography (TOE) also confirmed absent right atrial thrombus. The right atrium was opened, and no tumour thrombus was noted. The right kidney was removed with thrombus visible in the renal vein. It was apparent that the thrombus had dislodged during surgery and migrated into the pulmonary circulation. However, as the patient remained stable with no new evidence of right heart strain or thrombus in the right atrium or common pulmonary arterial trunk on TOE the decision was made to complete the surgery and perform a CT-pulmonary angiography (CT-PA) prior to considering any further intervention. Postoperatively the patient remained stable and had a CT-PA the following day. The CT-PA (Fig. 2) showed a non-obstructing saddle embolus extending across the pulmonary trunk bifurcation with some extension into lobar branches. There were no features of pulmonary hypertension or right heart strain. The case was discussed with the national pulmonary endarterectomy centre and a decision was made to proceed with pulmonary embolectomy on normothermic bypass, as opposed to attempting interventional radiological thrombus aspiration. Open pulmonary embolectomy was performed on normothermic cardiopulmonary bypass via ascending aortic, and bicaval cannulation. The aorta was cross-clamped and antegrade cold blood cardioplegia given. The pulmonary trunk was opened longitudinally. The embolised IVC tumour thrombus was sitting in the bifurcation, extending into both pulmonary arteries. This was removed, in its entirety as shown in Fig. 3. Deep suctioning of both pulmonary arteries was followed by visual inspection with a flexible Ambuscope (Ambu, Ballerup, Denmark) and complete clearance of the thrombus was confirmed. The patient made a slow recovery complicated by an L3 lumbar artery bleed requiring embolisation on Day 14, and the need for a pacemaker to treat new first-degree heart block on a background of new atrial fibrillation. Additionally, he developed Stage IV chronic kidney disease with a discharge estimated GFR of 20 mL/min/1.73 m2 from a preoperative baseline of 84 mL/min/1.73 m2. This confirmed a clear cell RCC, International Society of Urological Pathology Grade 4 with necrosis present. Rhabdoid and giant cell elements were noted. The Leibovich score was 8. TNM grading was pT3c. Preoperatively diagnosed caval tumour embolus into the pulmonary arteries has been successfully managed by surgical embolectomy as first described in 1977 [5]. More recently Serena et al. [6] describe three approaches to preoperatively known embolus in seven patients, with conservative management of small unresectable emboli in four, pulmonary lobectomy for one patient and pulmonary embolectomy for two patients. Another unit reported nine cases of tumour embolism in a series of 290 cases in 6 years [7]. Elective pulmonary embolectomy at the time of nephrectomy was successfully complete in each of these patients with a poor survival rate of 25% survival at 3 years. However, embolisation of tumour thrombus during planned IVC thrombectomy presents a different challenge during high-risk surgery requiring quick decisions to manage both haemodynamic and oncological sequelae. The incidence of intraoperative tumour embolisation is ~1.5% of cases (12/803 cases) and is associated with a high operative mortality of 75% [4]. With regards to the oncological issues, it appears only 1% of tumour cells may remain viable on transit through the lung and may not survive in the lung environment [8]. Risk factors for intraoperative embolisation of the caval tumour thrombus may include extensive mobilisation of advanced kidney tumour, long non-occlusive and non-adherent tumour to the wall of the cava (as noted in our case), bland fragile thrombus, and a porridge consistency of the thrombus. The strategies for management of acute intraoperative embolism are limited in the literature. They include open pulmonary embolectomy, pulmonary lobectomy, delayed interventional aspiration thrombectomy [9] and conservative management. Factors that may influence the choice of strategy include the patient's stability and the available skillset such as the presence of cardiac surgeons familiar with pulmonary embolectomy. As in our case, it is not always clear where the thrombus has migrated to, and an unplanned pulmonary embolectomy would add significant time and morbidity to the operation. In a stable patient, Gayed et al. [9] describe the successful aspiration of large volumes of tumour thrombus via a 24-F aspiration catheter. Delayed open pulmonary embolectomy following CT-PA was utilised by Wang [10] in a case where embolisation was not immediately recognised. Planning using CT-PA may enable unilateral surgery in select cases. What is not described in the literature is taking the patient off bypass and proceeding to immediate CT under general anaesthesia to plan immediate intervention. Equally, few operating theatres have suitable radiological facilities to provide detailed interventional angiography on-table. This was the first such case in our unit despite a long history of performing Level IV IVC thrombectomy on cardiac bypass. The key to a successful outcome is early recognition, continuous monitoring of the location and size of the thrombus via TOE, localisation of the tumour embolus by CT, and timely cardiothoracic intervention. This case also highlights that massive embolus may not always cause immediate cardiovascular instability and right heart strain. There has been a debate on the role of preoperative, or intraoperative, placement of IVC filters [4]. However, insertion is associated with a 27% rate of complications [4] and clearly in cases of Level IV tumours filters have no role. Intraoperative placement of an occluding balloon above the thrombus has been used successfully; however, this introduces the problems of impaired venous return earlier in the operation and runs the risk of inducing an emobolic event during placement, but prior to deployment of the balloon. Strategies to reduce IVC venous return such a reverse Trendelenburg positioning in combination with positive pressure ventilation could be considered. Intraoperative tumour thrombus embolism remains rare, but awareness of the risk is crucial in managing this potential hazard. TOE remains the mainstay of intraoperative monitoring in these cases. Finally, the presence of a cardiac surgical skillset to provide pulmonary embolectomy is the most widely reported safety net for stable and unstable patients with tumour embolism. We are grateful for the patient's consent to publish their case. None declared.
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