September 21, 2008 Leave a comment
Tumor thrombus extending from the renal vein into the vena cava has been reported to occur in 4% to 10% of patients with renal cell carcinoma.5 The extent of tumor thrombus involving the inferior vena cava can vary from involvement of the renal vein only to extension into the right atrium, which occurs in some of these patients. The majority of patients with vena caval tumors have right-sided renal primaries because of the short right renal vein. In the absence of metastatic disease, numerous centers have demonstrated long-term cancer-specific survival rates comparable to early-stage renal cell carcinoma following complete surgical excision.
Improvements in surgical technique have allowed the surgeon to safely perform a radical nephrectomy and vena cavotomy. Several centers have documented reduced morbidity and mortality associated with these procedures. We have removed tumor from both renal veins, lumbar veins, hepatic veins, the right atrium, and the right ventricle. Technical difficulties and complications (excessive bleeding, coagulopathy, and postoperative renal failure) can accompany these procedures, especially with extensive intra- or suprahepatic caval neoplastic extension.
Today, the majority of patients presenting with a renal mass and intracaval tumor extension are diagnosed with computerized tomography (CT). In the past, patients presenting with advanced disease had clinical signs and symptoms related to vena caval occlusion including bilateral lower extremity edema, a recently enlarging varicocele, or dilated abdominal wall veins. Patients may also present with proteinuria, hepatic dysfunction with hepatomegaly, or pulmonary embolus.
Patients should have a thorough evaluation for metastatic disease because, if present, we do not typically recommend proceeding with surgery. Further radiologic imaging typically includes CT of the chest and abdomen and a bone scan if applicable. The renal vein and vena cava can be noninvasively imaged using magnetic resonance imaging (MRI). The MRI can usually define the superior limit of the caval thrombus unless the distal thrombus is mobile, thus limiting its accuracy. The MRI is also effective when total caval occlusion is present. Vena cavography can be used to define a caval tumor; however, its invasive nature, its false-positive and -negative results, and a decreased ability to define the superior extent of the tumor limit its use. To fully delineate the extent of a large caval tumor, the combination of MRI and intraoperative transesophageal sonography provides the best results.8 All patients should have a complete medical evaluation and be deemed candidates to withstand an extensive surgery.
The primary indication for nephrectomy and vena cavotomy is a renal mass with intracaval tumor extension in the absence of metastatic disease. The patient should also be medically able to tolerate an extensive surgical procedure.
To date, complete surgical excision of tumor is the only curative treatment. Expectant therapy or systemic protocols may be applicable if the patient is a candidate.
In addition to a general anesthetic, a thoracic epidural can be utilized and is often effective with postoperative pain management with most flank incisions. For the majority of tumors, standard intraoperative monitoring includes central venous pressure, arterial pressure tracings, electrocardiography, and urinary output. Additional monitoring is used for extensive vena cava tumors, including a Swan–Ganz catheter, esophageal and rectal temperature probes, oxygen and carbon dioxide measurements, and transesophageal sonography. A hypothermic blanket is used to maintain body temperature. Elastic stockings and sequential compression devices are placed to prevent lower extremity venous stasis. An intravenous cephalosporin is generally sufficient as prophylactic antibiotic coverage.
The patient’s body habitus and extent of both the primary and intracaval tumor direct the surgical approach. For renal tumors with neoplasm extending minimally into the inferior vena cava, a supra-11th-rib or standard thoracoabdominal approach with rib excision is ideal, especially in obese patients. For left-sided tumors and more extensive caval tumors, an anterior incision will provide good exposure. We have used a thoracoabdominal incision extending from the tip of the scapula across the costal margin to the midline halfway between the umbilicus and the xyphoid process for right-sided tumors with intrahepatic and supradiaphragmatic intracaval tumor extension. In this approach, the patient should be positioned with the right shoulder rotated toward the contralateral side; the hips remain in the supine position, and the table is slightly extended. Although this incision provides both intra-abdominal and intrathoracic exposure, the infradiaphragmatic dissection is easier for the urologist while cannulating the aortic arch for cardiopulmonary bypass is more difficult.
We typically use a median sternotomy extending into either a midline abdominal or a chevron incision when the intracaval neoplasm extends into or beyond the liver and cardiopulmonary bypass is considered (Fig. 8-1).2 The chevron incision is useful in patients with a wide abdominal girth. Although these extensive incisions provide excellent exposure, allowing for additional operations to be performed, we recommend limiting the procedure to nephrectomy and caval thrombectomy.
The operation is commenced by utilizing the entire incision including the median sternotomy, as this approach gives the best exposure. The abdomen is inspected for metastatic disease, and if discovered, the procedure is usually stopped, as cancer-specific survival has not been demonstrated to be improved in the long term. In the absence of overt metastasis, the renal tumor is approached first. For a right renal tumor, the right colon is mobilized along the line of Toldt and retracted medially to gain access to the retroperitoneum. For significant tumors via a midline approach, incision of the root of the mesentery up to the ligament of Trietz with placement of the bowel into an intestinal bag retracted onto the chest provides additional exposure. We use the OmniTract retractor (Minnesota Scientific Inc.), as it provides excellent superficial and deep exposure of the surgical field. The kidney and Gerota’s fascia are mobilized, first by a posterolateral approach developing the plane between the quadratus/psoas muscles and Gerota’s fascia. After the kidney has been mobilized posteriorly, the renal artery is ligated early to keep blood loss to a minimum. Anteriorly, the mesocolon is then reflected medially from the anterior surface of Gerota’s fascia until the vena cava is visualized. A Kocher maneuver provides additional medial exposure near the vena cava. Superiorly, dissection above the adrenal is undertaken with Ligaclips, and the adrenal vein is ligated. Inferiorly, the kidney is mobilized along with ligation of the gonadal vein and ureter. Mobilization of the primary tumor is complete when the kidney remains attached to the vena cava by the renal vein.
A left-sided renal tumor with caval thrombus requires dissection on both sides of the abdomen to access both the vena cava and the left kidney. A midline incision usually provides sufficient exposure. The descending colon is reflected medially by incising the line of Toldt. In a dissection similar to that for a right-sided tumor, the kidney and Gerota’s fascia is mobilized until only the left renal vein remains. The ascending colon is then mobilized medially by incising the line of Toldt, and the duodenum is reflected by the Kocher maneuver. Once adequate exposure to the vena cava is obtained, the remainder of the procedure is similar to that for a right-sided renal primary tumor.
The extent of the intracaval tumor dictates the length the vena caval needs to be isolated. Dissection should proceed directly on the vena cava with care taken to prevent potential dislodgment of caval tumor. If the intracaval tumor extends slightly beyond the ostium of the renal vein into the vena cava, a Statinsky vascular clamp can be placed on the caval sidewall beyond the tumor. This segment of caval wall can be excised with the nephrectomy specimen en bloc, and the cava can be oversewn with a 4-0 polypropylene on a cardiovascular needle.
With a more extensive infrahepatic intracaval tumor, control of the vena cava must be obtained above and below the extent of the caval tumor thrombus. During mobilization of the vena cava, one or more posterior lumbar veins may require ligation to prevent unexpected bleeding. Inferiorly, a Rummel tourniquet (umbilical tape passed through a 16-Fr red rubber catheter) is placed loosely below the tumor thrombus and both renal veins. For a right-sided tumor, a Rummel tourniquet is placed loosely around a segment of the left renal vein to secure control of this vessel. Additional exposure to the vena cava can be gained superiorly by dividing the posterior attachments of the liver and rotating the liver medially. Depending on the superior extent of the caval tumor, variable venous branches draining the caudate lobe of the liver may need to be ligated and divided (Fig. 8-2). If these veins are short, they can be controlled using suture ligatures placed into the liver parenchyma. Cardiopulmonary bypass can be obviated when vascular control using a vascular clamp or Rummel tourniquet can be gained above the superior extent of the tumor. Division of the diaphragm may aid in gaining vascular control above the superior extent of the tumor thrombus.
After adequate mobilization of the vena cava superior and inferior to the tumor thrombus with ligation of any lumbar veins, all vascular clamps or Rummel tourniquets are secured. A narrow elliptical incision circumscribing the ostium of the involved renal vein is made. If the tumor is inseparable from the caval endothelium superior to the renal veins, the involved cava is excised. The renal primary and caval tumor is removed en toto under direct vision. On occasion, we have used a dental mirror to inspect the hepatic veins or the flexible cystoscope to inspect the cava to ensure complete removal of tumor. If additional verification is necessary, transesophageal echography can be used to evaluate the superior extent of the cava, or direct intraoperative sonography can be used to evaluate the extent of the cava.8
To close the vena cava, a 4-0 or 5-0 cardiovascular polypropylene suture is used. Before the cavotomy closure is completed, the inferior tourniquet is released to allow trapped air to escape through the cavotomy site. If excision of the cava decreases the vascular diameter by more than 50%, reconstruction of the vena cava is recommended to prevent caval thrombosis (Fig. 8-3). We prefer to reconstruct the vena cava using pericardium because it is less thrombogenic, although prosthetic grafts can be employed.3 Venous drainage of the right kidney must always be preserved to prevent venous infarction. In some instances, the cava has been oversewn to prevent subsequent embolism if the thrombus below the renal veins is adherent to the caval endothelium.
Cardiopulmonary Bypass, Hypothermia, and Temporary Cardiac Arrest
Cardiopulmonary bypass, hypothermia, and temporary cardiac arrest greatly facilitate the resection of a suprahepatic caval thrombus.4 It is best to dissect as much of the kidney and the vena cava as possible before cardiac bypass. Following isolation of the renal tumor, the pericardium is opened and retracted with stay sutures. Typically, the right atrial appendage is cannulated with a 32-Fr venous cannula, and the aorta is cannulated with a 22-Fr Bardic cannula. Heparin is then administered to maintain an activated clotting time greater than 450 seconds. The patient is placed on bypass with flow rates maintained between 2.5 and 3.5 liters/min. A core temperature of 18° to 20°C is attained within 30 minutes while an 8° to 10°C gradient is maintained between the perfusion and the patient’s core temperature. When a rectal temperature of 20°C is reached, the aorta is cross-clamped, and 500 cc of cardioplegic solution is administered. Once cardiac arrest is achieved, bypass is terminated, and the patient is temporarily exsanguinated into an oxygen reservoir. The patient’s brain is protected by placing ice bags around the head. At this point there is no anesthesia, ventilation, or circulation. To reduce the incidence of complications, circulatory arrest time is best limited to 45 minutes.
An elliptical incision is made around the ostium of the renal vein and carried superiorly along the length of the vena cava. The incision can extend into the right atrium or ventricle, depending on the superior extent of the thrombus. Cardiopulmonary bypass and deep hypothermic circulatory arrest permit the thrombus to be removed in a bloodless field and the interior of the vena cava and heart to be inspected under direct vision (Fig. 8-4). It is not uncommon to find some degree of adherence of the tumor to the endothelium. In this case, the tumor thrombus can be “endarterectomized” from the interior of the vena cava or atrium. Reconstruction of the vena cava is as previously described.
Following closure of the vena cavotomy, cardiopulmonary bypass is begun. The patient is slowly warmed using a 10°C gradient between the bypass machine and a warming blanket. Mannitol (12.5 g) is given along with 1 g of CaCl2 when core temperature reaches 25°C. Electrical defibrillation is necessary if the heart does not resume spontaneous beating. Following resumption of cardiac activity, blood is returned to the patient from the oxygen reservoir. Following the rewarming process, which can take up to 1 hour, heparin is neutralized with protamine. The patient is returned to the cardiac ICU intubated.
Intraoperative complications include excessive bleeding and coagulopathy. Coagulopathy is more common with prolonged cardiopulmonary bypass and cardiac arrest times. Intraoperatively, red blood cells, platelets, fresh frozen plasma, and calcium chloride are routinely administered. Furosemide and/or mannitol is given if urine output remains low. Transient hypotension can occur when the vena cava is clamped. This can be managed with volume expansion and is less of a problem if venous collaterals have developed with a completely occluded vena cava. Embolization of a segment of tumor thrombus can be a potentially lethal intraoperative complication, and extreme care should be taken when handling the vena cava to prevent such an occurrence.
Postoperatively, several complications can occur because of the magnitude of the surgical procedure or the use of cardiopulmonary bypass. Potential complications include caval thrombosis, deep venous thrombosis, pulmonary embolus, postoperative bleeding, or coagulopathy. Patients may also develop hepatic dysfunction, renal failure, sepsis, or myocardial infarction. Although the mortality rate associated with this procedure is tolerable, most patients who die of complications within the first postoperative month succumb to multisystem organ failure.
The 5-year survival rates in most reported large series vary from 14% to 68% following complete surgical removal of the renal tumor and caval extension.1,6,7 Differences in reported survival may reflect several factors, including local extension of the primary tumor, presence of lymphatic or visceral metastases, level of caval tumor extension, or invasion into the vascular wall. lt is generally agreed that patients with metastatic disease and significant perinephric fat involvement tend to have a poor prognosis. The majority of patients eventually dying of their disease succumb to metastases, which suggests that occult metastatic disease is frequently present at the time of surgery.6 We believe that patients with good performance status who have tumors confined to the renal capsule and are without evidence of metastatic disease are ideal candidates for this surgery and have improved long-term survival.