Michael Lanuti
INDICATIONS/CONTRAINDICATIONS
Indications
The superior vena cava (SVC) is susceptible to invasion from tumors arising from the anterior mediastinal compartment, such as thymomas, thymic carcinoma, thyroid neoplasms, and germ cell tumors, as well as right-sided pulmonary neoplasms. Extended resection for SVC invasion (T4 disease) of nonsmall-cell lung cancer (NSCLC) and anterior mediastinal neoplasms often evokes controversy about its long-term benefit but has been associated more recently with acceptable morbidity and survival in published series. The surgeon should be familiar with the techniques used to resect and reconstruct the SVC in conjunction with the planned pulmonary resection. The most common pulmonary resection is right upper lobectomy.
Contraindications
There is little contention about SVC resection for anterior mediastinal tumors, but SVC resection in the context of NSCLC with nodal metastasis remains controversial. Staging mediastinoscopy should be performed prior to any planned resection of lung cancer to exclude N2 disease. Multistation N2 disease would be a relative contraindication to SVC resection and reconstruction by virtue of poor survival despite therapy.
PREOPERATIVE PLANNING
The feasibility and low morbidity of extended resection for pulmonary or mediastinal tumors infiltrating the SVC are well documented, but the selection of optimal candidates for aggressive resection is less well defined. Completeness of resection, extent of SVC involvement, and the presence of mediastinal lymph node metastases are all regarded as important in the evaluation of these select patients. Patients should be evaluated with noninvasive staging modalities such as contrast-enhanced computed tomography chest and positron emission tomography to rule out extraregional or M1 disease. Pathologic staging with mediastinoscopy, endobronchial ultrasound transbronchial lymph node biopsy, or thoracoscopy is paramount in determining a multimodality strategy in this heterogeneous population. Mediastinal MRI and sometimes cardiac-gated MRI can be considered when evaluating anterior mediastinal neoplasms to better define invasion into the great vessels or through pericardium.
SURGERY
Positioning
The majority of patients with right upper lobe tumors involving the SVC can be approached through a right posterolateral thoracotomy via the fourth or fifth intercostal space (Fig. 44.1A). In contrast, median sternotomy (Fig. 44.1B) is often preferred in patients with primary mediastinal tumors involving the SVC and is ideal in patients who may require brachiocephalic vein reconstruction to the right atrium. Cardiopulmonary bypass can be considered in these cases but it is usually not necessary. A thoracosternotomy (Fig. 44.1C) incision is used in right-sided tumors that may require significant posterior mediastinal dissection. This approach allows control of the SVC and associated vasculature, particularly the right subclavian, right jugular, and left brachiocephalic venous systems. This may be of benefit for those tumors that are large and require either a concomitant chest wall resection or lysis of extensive posterior adhesions following a course of induction therapy. Moreover, for those patients needing a right upper lobe sleeve resection or a right pneumonectomy, this approach may be preferable.
Technique
Upon completing the initial exploratory approach, one should palpate the tumor and assess the degree of invasion into the SVC. Vascular control should include placement of vascular loops around left and right brachiocephalic veins and around the SVC just above the azygos vein if feasible. If the right pulmonary artery is involved, intrapericardial control of the right main pulmonary artery can be obtained between the SVC and aorta. The degree of SVC infiltration will dictate the type of resection. Primary repair should only be considered in patients when <50% of caval circumference is resected. Primary suture repair is conducted with a running nonabsorbable monofilament (polypropylene) suture usually by tangential placement of a partial occlusion clamp (Fig. 44.2). The clamp is placed from an inferior to superior direction and should include a cuff of SVC wall to permit suture placement. No systemic anticoagulation is necessary for such a limited repair where there is still flow through part of the SVC. Larger defects (where primary repair may narrow the SVC) require a patch repair (Fig. 44.3A,B). Options include bovine or autologous pericardium. Patch repair avoids narrowing of the SVC lumen and should be the preferred approach unless the defect is very small. The surgeon should plan ahead for this and have harvested autologous pericardium or retrieved a biologic or synthetic patch to reduce the amount of time that SVC flow is disrupted. Patches can be sewn with running 4-0 (polypropylene) sutures.
Figure 44.1 Surgical incisions used to approach SVC resection and reconstruction. A: Standard posterolateral thoracotomy, (B) median sternotomy often used for anterior mediastinal tumors or right carinal pneumonectomy, (C) thoracosternotomy “hemiclamshell” incision used for tumors that extend posteriorly on the right.
Figure 44.2 Tangential superior vena cava (SVC) resection with primary repair. Tumor invasion is limited whereby primary closure can be achieved without narrowing the SVC. Before beginning the tangential resection, it is advisable to have proximal and distal control of the SVC with vascular loops or umbilical tape.
In patients in whom SVC infiltration encompasses more than 50% of the vessel (Fig. 44.4), the SVC can be replaced with ringed polytetrafluoroethylene (PTFE) graft, tubularized bovine or autologous pericardium, spiral saphenous vein graft, or cyropreserved arterial allograft. Each of these materials have limitations. PFTE grafts can be associated with infection or thrombosis and often require postoperative anticoagulation. Tubularized autologous pericardium and spiral vein grafts take time to construct and are subject to size limitations. Cryopreserved arterial allografts are resistant to infection and may avoid the need for anticoagulation but are expensive and various sizes would need to be stocked. Size matching of reconstruction grafts should be determined by extent of venous resection and the nature of the distal anastomosis to conform to native brachiocephalic vein or SVC.
Figure 44.3 A: Patch closure of the SVC defect can be performed with autologous or bovine pericardium. B: Completed patch closure with phrenic nerve preservation. Azygos vein can be preserved during repair to permit collateral venous return to the heart.
Temporary interruption of flow during prosthetic replacement with proximal and distal caval clamps should be managed with intravascular fluid expansion, lower extremity venous access, hyperventilation to reduce vasogenic cerebral edema, reverse Trendelenburg position, and vasoactive agents to elevate cerebral perfusion pressure. SVC resection and reconstruction is typically performed first, followed by right-sided bronchopulmonary resections, including pneumonectomy, carinal pneumonectomy, or resections with proximal pulmonary artery invasion. This sequence requires careful attention to avoid bacterial or tumor cell contamination of the prosthetic graft. In the setting of malignancy, an autotransfusion device is not recommended. Efforts should be made to clamp the SVC proximal to the azygous vein to preserve collateral circulation and reduce cerebral edema. Clamping at the cavoatrial junction should be avoided to reduce the risk of sinoatrial node injury. Patients should receive an intravenous heparin sodium bolus (50 to 100 units per kg) 5 to 10 minutes before vascular occlusion. Pharmacologic reversal of heparin is not necessary and should be avoided to reduce the risk of graft thrombosis. The graft of choice is brought onto the operative field. Employment of an SVC shunt can be considered during caval occlusion but is not absolutely necessary. The distal SVC anastomosis is performed first using 4-0 prolene suture. This anastomosis is then tested for any leak. The proximal venous anastomosis is subsequently performed, and air is removed from the conduit before tying down the last anastomotic suture. It is imperative that there be no tension on the graft. Torsion or kinking of the reconstruction can occur when there is graft redundancy. The surgeon should be very mindful of SVC clamp time since extending beyond 60 minutes can lead to complications. According to experimental data derived in 1989, 60 minutes of SVC occlusion was physiologically tolerated in a nonhuman primate model; however, Dartevelle et al. reported poor tolerance in humans when SVC clamping time exceeded 45 minutes. One strategy to reduce caval occlusion time is to perform the proximal anastomosis directly to the right atrial appendage by using a Satinsky clamp on the atrium. The distal venous anastomosis can be performed last, thereby reducing central venous clamp time to that necessary for the proximal anastomosis.
Figure 44.4 Extensive tumor invasion of the SVC. When tumors involve >50% circumference of the SVC, complete resection and reconstruction of the SVC is indicated. Clamping both proximally and distally requires careful planning.
Reconstructing only one of the brachiocephalic veins (Fig. 44.5A) can often be achieved by virtue of the presence of venous collaterals. Although the most common reconstruction following SVC resection is for the distal graft to be anastomosed to the right brachiocephalic vein (Fig. 44.5B), there are occasions when the distal venous anastomosis needs to be placed to the left brachiocephalic vein (Fig. 44.6A). Occlusion or thrombosis of the right jugular venous system would warrant such a reconstruction. The proximal anastomosis can be performed from either the transected proximal SVC or directly to the right atrial appendage. Reconstruction of both brachiocephalic venous systems can be considered (Fig. 44.6B) when there is no pre-existing venous collaterals. Some authors favor bilateral reconstruction due to a thrombosis rate exceeding 50% at 5 to 26 months, particularly with unilateral left venous reconstruction.
Figure 44.5 Complete SVC resection and reconstruction. A: Following SVC resection with negative histologic margins, a prosthetic graft can reestablish venous return. Frequently, the left brachiocephalic vein can be divided without reconstruction provided there are adequate venous collaterals. B: The proximal portion of the prosthetic graft is frequently performed first.
POSTOPERATIVE MANAGEMENT
Patients who undergo PTFE vascular reconstruction should be considered for an antiplatelet agent or Coumadin for a short interval (3 to 6 months) given the early prothrombotic property of this graft until it becomes endothelialized. If there are significant venous collaterals, the low flow state through the SVC reconstruction will increase the risk of graft thrombosis. If one of the brachiocephalic venous systems is ligated, the ipsilateral arm should be elevated with no intravenous infusions.
COMPLICATIONS
The overall thrombosis rate of PTFE reconstruction of the SVC has been reported to be 14% to 24% within 3 to 5 years. The thrombotic risk is higher when SVC revascularization occurs in the presence of venous collaterals. The operation can be associated with cerebrovascular complications by virtue of prolonged SVC clamp time.
Figure 44.6 Alternative SVC reconstruction techniques. A: If the right brachiocephalic vein is occluded, the SVC can be divided with venous reconstruction from left brachiocephalic vein to right atrium. B: Reconstruction of both right and left brachiocephalic venous systems can be employed when there is no pre-existing venous collaterals.
RESULTS
In appropriately selected patients SVC resection and reconstruction can provide prolonged survival for extended resection of lung cancer and anterior mediastinal neoplasms. Published results from single-center series are ∼30% and 54% 5-year survival for locally advanced lung cancer and anterior mediastinal neoplasms, respectively. These institutional experiences are associated with acceptable morbidity and mortality. The risk of major post-operative complications in one of these series has been associated with induction therapy and the risk of death has been associated with pneumonectomy and complete replacement of SVC.
CONCLUSIONS
SVC reconstruction should not be considered a contraindication for resection of a bronchopulmonary or mediastinal neoplasm in an otherwise potentially curable patient, provided a complete resection can be achieved. Preoperative staging and choice of incision are important aspects of approaching these tumors. Partial caval resection with patch reconstruction is the most common intervention for tumor infiltrating the SVC. Coumadin therapy must be employed postoperatively for 3 to 6 months when using PTFE for complete SVC resection and reconstruction. Antiplatelet therapy (i.e., aspirin or plavix) can be used for patch repairs of the SVC.
Recommended References and Readings
Dartevelle P, Macchiarini P, Chapelier A. Technique of superior vena cava resection and reconstruction. Chest Surg Clin N Am. 1995;5(2):345–358.
Garcia A, Flores RM. Surgical management of tumors invading the superior vena cava. Ann Thorac Surg. 2008;85(6):2144–2146.
Lanuti M, De Delva PE, Gaissert HA, et al. Review of superior vena cava resection in the management of benign disease and pulmonary or mediastinal malignancies. Ann Thorac Surg. 2009;88(2):392–397.
Shargall Y, de Perrot M, Keshavjee S, et al. 15 years single center experience with surgical resection of the superior vena cava for non-small cell lung cancer. Lung Cancer. 2004;45(3):357–363.
Shintani Y, Ohta M, Minami M, et al. Long-term graft patency after replacement of the brachiocephalic veins combined with resection of mediastinal tumors. J Thorac Cardiovasc Surg. 2005; 129(4):809–812.
Spaggiari L, Leo F, Veronesi G, et al. Superior vena cava resection for lung and mediastinal malignancies: A single-center experience with 70 cases. Ann Thorac Surg. 2007;83(1):223–229; discussion 229–230.
Spaggiari L, Magdeleinat P, Kondo H, et al. Results of superior vena cava resection for lung cancer. Analysis of prognostic factors. Lung Cancer. 2004;44(3):339–346.
Spaggiari L, Regnard JF, Magdeleinat P, et al. Extended resections for bronchogenic carcinoma invading the superior vena cava system. Ann Thorac Surg. 2000;69(1):233–236.
Suzuki K, Asamura H, Watanabe S, et al. Combined resection of superior vena cava for lung carcinoma: Prognostic significance of patterns of superior vena cava invasion. Ann Thorac Surg. 2004;78(4):1184–1189; discussion 1184–1189.