Median sternotomy is the preferred approach because it provides easy access to the SVC, both brachiocephalic veins, the aorta, and both atria. Right thoracotomy may be an option if the primary tumor is located in the right chest and involvement of the SVC and heart is limited. The aorta and both venae cavae can be reached through the fourth or fifth intercostal spaces by right thoracotomy. A hemiclamshell approach is another good alternative, and an upper hemisternotomy may be an option.
An upper hemisternotomy incision is made (Fig. 140-1). The sternum is divided from the sternal notch down to the fourth intercostal space using a regular sternal saw and then divided transversely to the right fourth intercostal space using an oscillating saw. This approach provides easy access to the SVC, left brachiocephalic vein, right atrial appendage, and aorta. When CPB is required, the ascending aorta is cannulated directly through the incision, and the right atrium is cannulated directly through the incision or percutaneously through the femoral vein. Because access to the free right atrial wall and right pleural space is limited, this approach is suitable only for small benign tumors or palliative bypass procedures.
Management of the Venous Circulation
If the collateral circulation is well developed, resection and reconstruction of the SVC can be performed with simple clamping after heparin administration. If the collateral circulation is poorly developed, simple clamping should be avoided because the cardiac output will be reduced secondary to the reduced venous return. It may be possible to manage the patient's hemodynamic status with fluid and vasoactive agents. However, if fluids and medication are ineffective, the venous circulation returning to the heart must be maintained by using an intraluminal shunt, other venous bypass, or CPB.
The left brachiocephalic vein to right atrial appendage is a common bypass technique used in this setting. A large vascular clamp is placed on the right appendage, which is opened. After excising some trabecular muscle, a graft is anastomosed to the appendage by using continuous 4-0 polypropylene sutures. Removing a portion of the trabecular muscle prevents obstructed flow gradient. The left brachiocephalic vein is clamped proximally and distally and divided. The graft is anastomosed in end-to-end fashion using continuous 5-0 or 6-0 polypropylene sutures. After replacing the venous return from the left brachiocephalic vein, the SVC or right brachiocephalic vein can be clamped for resection and reconstruction.
CPB is used when there is involvement of the heart or aorta necessitating resection. Although CPB increases the invasiveness of the surgery and can cause adverse effects on various organs, it provides safe hemodynamic control in an environment that is conducive to complete resection. The availability of CPB also provides a safety net in the event of injury to cardiovascular structures during tumor resection.14
Strategy for Cardiopulmonary Bypass
Portions of the tumor that can be resected safely without CPB should be removed before bypass is instituted to minimize blood loss and overall duration of CPB. If the situation warrants, however, CPB may be established before dissection of the tumor to ensure safe manipulation. After adequate heparinization, the ascending aorta is cannulated in standard fashion. When the aorta is invaded by the tumor, the cannula is placed distally to create a sufficient margin between the aortic cross-clamp and the tumor. The SVC and inferior vena cava are cannulated. If the cannula does not fit in the SVC, the left brachiocephalic vein is cannulated instead. We use a 24F single-stage flexible cannula for the SVC, inferior vena cava, and left brachiocephalic vein. When the left and right brachiocephalic veins are separately reconstructed, the cannula in the left brachiocephalic vein is snared with a tourniquet, and the right brachiocephalic vein is clamped. Unilateral clamping is usually tolerated well in patients with chronic obstruction. If the right brachiocephalic vein is prominently distended or CPB flow significantly decreases, placing a small cardiotomy suction tube (12–16F) in the right brachiocephalic vein is a useful technique to establish the venous return. When the ascending aorta is resected, the aortic cross-clamp is applied, and the antegrade cardioplegia is administered to obtain diastolic arrest of the heart. When the distal ascending aorta or aortic arch is resected, deep hypothermic circulatory arrest may be required. The patient is weaned from CPB in standard fashion after the resection and reconstruction is complete. Protamine is administered to reverse heparin after the patient has been weaned.
For limited reconstructions, the SVC can be sutured directly or a pericardial patch angioplasty can be performed. Otherwise, the SVC is reconstructed using one of a variety of vascular grafts and one of several methods. The method used for reconstruction is based on the location of venous involvement, collateral circulation, and intraoperative circulation management. In principle, the grafts should be short and straight to avoid kinking and thrombosis, and an end-to-end anastomosis generally is preferred over an end-to-side anastomosis. When only the SVC is reconstructed, a graft is anastomosed to the distal end of the remaining SVC and superior cavoatrial junction or right atrial appendage. When the right and left brachiocephalic veins are reconstructed separately, several reconstruction patterns are possible: a single right brachiocephalic graft, a single left brachiocephalic graft, two separate grafts to the right atrium, or a Y-graft (Fig. 140-2). It is usually unnecessary to reconstruct the azygos vein, but when this is necessary, it is anastomosed to the SVC graft in an end-to-side fashion with or without interposition of a short 6- or 8-mm ringed expanded polytetrafluoroethylene (ePTFE) graft.
A. Right brachiocephalic vein graft. B. Left brachiocephalic vein graft. C. Two separate grafts to the right atrium. D. Y-graft.
Several types of grafts are available for SVC reconstruction. Each graft has specific advantages and disadvantages. Grafts should be chosen based on multiple factors, including anatomy, primary disease characteristics, prognosis, and graft availability. Careful selection of appropriate diameter and length is critical. Diameter mismatch can cause residual obstructive flow and symptoms and, secondarily, graft thrombosis. Length mismatch can cause excessive tension or kinking.
Ringed Expanded Polytetrafluoroethylene Graft
The ringed ePTFE graft is the most common prosthetic material used for reconstruction of large veins. The advantages are availability, ease of use, and wide range of sizes. Using a prosthetic graft also saves time because there is no need for advance preparation. Furthermore, this ring-supported material is less likely to kink or succumb to extrinsic compression than other biologic materials. Generally, prosthetic grafts have inferior patency to biologic grafts for veins. However, long-term patency has been shown to be favorable when it is used for SVC reconstruction.15,16 This graft is not as well suited for reconstruction of small peripheral veins because of the high incidence of thrombosis. The ePTFE graft is used most commonly for malignant SVC obstruction. A graft diameter of 12-14 mm is used for the SVC, and 8- to 12-mm grafts are used for its tributaries in most cases. Anticoagulation is required to prevent graft thrombosis.
Autologous and bovine pericardium is often used for patch angioplasty,31 but a pericardial tube graft is also used for reconstructing the SVC in benign and malignant disease.17,18 Long-term patency in a human study has not been systematically reported. Anticoagulation is not required, but temporary use may be helpful to reduce the risk of thrombosis. The disadvantage of using autologous pericardial graft is its limited availability. Bovine pericardium, on the other hand, is widely available in a range of sizes. The pericardial tube is constructed by wrapping the pericardial graft around a chest tube or plastic syringe of appropriate diameter and approximating the edges with continuous 4-0 or 5-0 polypropylene sutures. Using metal staples instead of sutures is a helpful time-saving technique.18
Spiral Saphenous Venous Graft
Spiral saphenous vein graft has been reported to have an excellent long-term patency rate that is superior to that of other graft materials.19,20 This may be the best option in terms of its tissue compatibility, low thrombogenicity, and long-term patency. However, it requires additional operative time and incisions to harvest the graft. The length of graft is limited by the available segment of the saphenous vein. Varicose vein is not a favorable material. The required length of saphenous vein is determined by the desired graft diameter and length and the average diameter of the saphenous vein.20 To make a 10-cm spiral vein graft, the saphenous vein needs to be harvested roughly from the groin to the knee. The saphenous vein is harvested with classic open technique or endoscopic technique. Endoscopic vein harvest provides smaller incisions and less frequent incidence of wound infection.18 After harvesting the required length of saphenous vein, the vein is opened longitudinally, and the valves are excised. The opened vein is wrapped around a chest tube of appropriate size (usually 28–36F), and the edges of the saphenous vein are sutured with running 6-0 or 7-0 polypropylene sutures.
Use of the superficial femoral vein for the SVC reconstruction has been reported.21 The tailoring process used for saphenous vein graft is not required because its size is compatible with that of the SVC. Cryopreserved aortic homograft also may be a good alternative22 because it has a large caliber and low thrombogenicity. Aortic arch homograft can be used as a natural branched graft for the reconstruction of both brachiocephalic veins.22
Surgical Technique of Resection and Reconstruction of the SVC and Right Atrium
A median sternotomy is performed. The pericardium is opened in the midline, and the mediastinum is inspected to rule out unresectable tumor. The right atrium and SVC are exposed (Fig. 140-3). The left and right brachiocephalic veins are also exposed and taped, if necessary. After adequate heparinization, the ascending aorta, SVC, and inferior vena cava are cannulated as described earlier, after which CPB is initiated. After both venae cavae are snared with a tourniquet, the cardiotomy suction tube is placed in the right atrium (Fig. 140-4). The SVC and right atrium are resected with adequate margins from the edge of tumor. When the atrial wall defect is large, reconstruction with an autologous or bovine pericardial patch is required (Fig. 140-5). Otherwise, direct closure can be performed. After reconstruction of the right atrium, the selected graft is anastomosed to the cavoatrial junction of the right atrium with continuous 5-0 polypropylene sutures. The distal anastomosis is performed with continuous 5-0 polypropylene sutures. The azygos vein is closed with continuous 6-0 polypropylene sutures. The snares are released, and the cardiotomy suction tube is removed from the right atrium. The patient is weaned from CPB, heparinization is reversed with protamine, and all cannulas are removed. Temporary atrial and ventricular pacing wires should be placed when the heart is manipulated because temporary or permanent dysrhythmia requiring pacing could occur after surgery, and placement of transvenous pacing leads should be avoided in the immediate postoperative period. Chest tubes are placed, and the chest is closed in standard fashion.
Exposure of right atrium and SVC before resection and reconstruction.
Operative setup for cardiopulmonary bypass.
Large atrial wall defects are reconstructed with autologous or bovine pericardial patch. The SVC is reconstructed with a ringed ePTFE graft that is anastomosed to the cavoatrial junction of the right atrium.