One of the consequences of the conventional cava technique is hemodynamic instability as the blood flow through the IVC is completely interrupted. In this situation the blood return to the heart is entirely from the superior vena cava. Combined with portal vein clamping during the hepatectomy, the result is massive sequestration of blood volume in the mesenteric and lower body venous circulation. In addition to systemic hypotension, this obstruction of systemic and splanchnic venous return causes renal venous hypertension, which can lead to renal dysfunction, diffuse edema of the gastrointestinal tract, and exacerbation of hemorrhage from thin-walled venous collaterals and varices. Cardiovascular instability requires volume preloading which can then result in volume overload and pulmonary edema after liver revascularization [5]. Moreover the high potassium and acidity of the stagnant blood can result in hemodynamic collapse when returned to the systemic circulation.

Venovenous bypass was developed to prevent these undesirable effects by providing an alternate route for blood flow back to the heart [6–8]. The bypass mechanism facilitates hemodynamic stability during the anhepatic phase of the operation and avoids the consequences of systemic and splanchnic venous sequestration.

Venovenous bypass can be performed as single bypass using the femoral vein with return through either the internal jugular or axillary vein or as double bypass in which the portal system is also decompressed via a cannula in circuit. A cannula is placed into the greater saphenous vein either percutaneously or via open technique and advanced through the saphenofemoral junction to near the confluence of the common iliac veins. A portal cannula is placed into the transected portal vein and these two cannulae are joined together via a Y connection. The blood flows through heparin-bonded shunt tubing to a centrifugal pump and is returned to the patient via the axillary or jugular vein (Fig. 11.2). Flow rates are generally maintained at 1–4 L/min, but can be higher [5]. Alternatively, the portal system can be cannulated through the inferior mesenteric vein. This variation is particularly useful in cases of abnormalities of the extrahepatic portal vein such as thrombosis, friability, short length, and retransplantation.

The use of venovenous bypass in liver transplantation has allowed for a safer and easier operation and has also facilitated the training of surgeons while keeping the patient stable. It is, however, not without risks such as air emboli, venous thromboemboli, vascular injury, and bleeding complications from cannula placement. It is therefore not recommended for universal use, but rather on an individual basis. It is most often used in hemodynamically labile patients, those with decreased cardiac reserve, those with poorly developed venous collaterals (fulminant liver failure, prior portocaval shunt, TIPS, etc.), and those who otherwise do not tolerate test clamping of the IVC.

The technique of vena cava-sparing hepatectomy in liver transplantation was first described in dogs by Fonkalsrud in 1966 [9]. The method was further developed and refined in humans over the next several decades [10–12]. The feasibility of maintaining continuity of the recipient IVC remedies the hemodynamic instability encountered with the conventional method and generally obviates the need for venovenous bypass. The technique is accomplished by first freeing the falciform, left and right triangular ligaments to mobilize the liver as with conventional hepatectomy. The short hepatic veins are then individually ligated and divided, generally inferiorly to superiorly and either right to left or left to right (Fig. 11.3). The isthmus of the caudate must be divided as well to completely free the liver and to allow skeletonization and clamping of the right, middle, and left hepatic veins. Once these veins are controlled at their base with clamps, they are divided inside the liver to ensure adequate length and the hepatectomy is completed. A large vein cuff for the anastomosis is then created by placing a large curved vascular clamp behind the confluence of the hepatic veins with the IVC and joining the orifices of the three hepatic veins. As opposed to conventional technique, the upper cava is only partially clamped for a short interval, minimizing physiologic disturbance of the circulation. After the suprahepatic anastomosis is complete, another clamp can be placed on the donor side of the anastomosis and the first clamp removed to restore unimpeded blood flow through the IVC while the portal vein anastomosis is being performed. Additionally the time to revascularization of the liver is reduced as only one caval anastomosis is required. The liver can be flushed of preservation solution via the portal vein as described above and the effluent removed via the infrahepatic IVC before it is ligated. Alternatively the liver can be flushed with blood via the completed portal vein anastomosis and vented from the infrahepatic IVC before it is ligated. The subsequent portal vein, hepatic artery, and bile duct anastomoses are performed in an identical manner as with the conventional technique (Fig. 11.4).

Less retroperitoneal dissection is an additional advantage of IVC preservation as it creates less raw surface area and less bleeding. Preservation of the native IVC also allows transplantation using smaller donor grafts despite IVC size discrepancy [10]. In these cases of small grafts, two rather than three suprahepatic veins are joined to provide the appropriate-sized outflow of the graft. The routine use of only two hepatic veins for outflow reconstruction is discouraged, however, because it has been associated with a higher incidence of outflow obstruction [13]. The piggyback hepatectomy is feasible in most cases [14, 15]. Technical difficulty can be encountered in the presence of a circumferential caudate lobe and in cases of notable recipient hepatomegaly such as polycystic liver disease.

As surgeons gained more experience with the piggyback approach, other variations of IVC reconstruction evolved [14, 16–18]. These were developed not only to allow preservation of the IVC but to decrease venous outflow complications. Alternate approaches include side-to-side cavocavostomy and end-to-side cavocavostomy. The hepatectomy for these techniques is similar to that described above for piggyback technique. A temporary portocaval shunt can be created [19] depending on the operating team’s preference and the patient’s clinical status (discussed below). To perform the side-to-side cavocavostomy, the liver is removed and the recipient hepatic veins are oversewn. A partially occluding clamp is placed on the IVC and a longitudinal cavotomy is created in the anterior wall of the recipient IVC. The suprahepatic and infrahepatic IVC of the donor are oversewn or stapled closed. A cavotomy is made in the posterior aspect of the retrohepatic donor IVC and the anastomosis is created between the donor and recipient IVC (Fig. 11.5a). For the end-to-side cavocavostomy, the recipient hepatic veins are oversewn, and the anastomosis is created between the donor suprahepatic IVC and a longitudinal cavotomy on the anterior wall of the recipient IVC (Fig. 11.5b). These techniques create a large and unimpeded outflow and can also be advantageous in gaining better exposure for the anastomosis. The resulting positioning of the liver more inferiorly can also facilitate a spatulated or side-to-side biliary anastomosis [20].

A variation on this approach is to combine the longitudinal cavotomy incision with the confluence of the hepatic veins on both the donor and recipient [21]. This has been referred to as a suprahepatic cavoplasty [22] or a triangulating cavocavostomy [23]. It is similar to the variant of the piggyback technique described above but creates a much larger cavotomy. This method requires full clamping of the IVC, and the hemodynamic changes are similar to the standard bicaval technique, potentially requiring the use of venovenous bypass. However, unlike the bicaval technique, there is no need for retroperitoneal dissection of the IVC, nor is there a need for the usual piggyback dissection ligating all the short hepatic veins. For this method, the recipient suprahepatic and infrahepatic IVC are clamped and the short hepatic veins are sharply divided with scissors up to the main hepatic veins. During this dissection a longitudinal patch of the recipient anterior IVC can be excised along with the short hepatic veins. Subsequently the main hepatic veins are transected creating a large “triangular” opening along the IVC including the orifices of the right, middle, and left hepatic veins. The short hepatic veins are either removed with the cavotomy, are excluded by the suture line, or are suture ligated. Extraneous tissue on the remnant hepatic veins is trimmed in preparation for the anastomosis. For the donor liver, a cavotomy is made in the posterior aspect of the IVC starting from and incorporating the suprahepatic IVC opening. This cavotomy is created to match the opening of the recipient IVC (Fig. 11.5c). Using 3–0 polypropylene suture, the three corner sutures are placed. Care must be taken to avoid compromising the hepatic vein orifices on the donor liver. Initially the right lateral wall is created, followed by the left side, and finally the superior aspect. Sometimes it may be easier to perform the entire anastomosis from the left side of the table by approaching the right suture line intraluminally. The infrahepatic donor cava is stapled closed or ligated.

Although this modification requires full IVC clamping with potential need for venovenous bypass, it does have several advantages. It allows creation of the largest possible outflow. Additionally, in cases with difficult exposure, it allows excellent exposure during both the IVC reconstruction and after reperfusion for examination of the suture line. Since minimal dissection is required and short hepatic veins will be either removed with the patch of IVC or incorporated into the anastomoses, the hepatectomy is very fast. Furthermore, bleeding during the hepatectomy is minimized since there is full control of the IVC during mobilization of the liver. The technique can be done expeditiously and it may be possible to forego systemic and/or portal bypass. Any potential size mismatch between the donor and recipient IVC is also eliminated [22].

Another piggyback variant is the reverse piggyback or infrahepatic cavocavostomy [24]. In this case, the donor suprahepatic IVC is closed and the infrahepatic IVC is used for an end-to-side anastomosis (Fig. 11.6). This technique has been used as an alternative when either recipient or donor factors make using the suprahepatic cava inadvisable. Such examples include a short suprahepatic donor IVC or injury during organ recovery, Budd-Chiari syndrome, retransplantation, TIPS stent disrupting the hepatic vein, or significant size mismatch between the donor and recipient. It has also been used in domino transplantation and autotransplantation when the donor suprahepatic cuff is very short [25].

In cases where dissection of the suprahepatic IVC and development of a sufficient cuff are difficult, an anterior approach to the hepatectomy can be utilized. The native liver is devascularized and mobilized by techniques described above, including clamping of the infrahepatic IVC. The suprahepatic IVC is encircled and clamped, but the hepatic veins are not dissected. Instead an anterior vertical incision is made in the cirrhotic liver, and the anterior IVC is cleaned sharply (Fig. 11.7a, b). Working from within the split parenchyma, the left, middle, and right hepatic veins are dissected and clamped and the liver is removed. The IVC anastomosis can be created by any method described above. This intraparenchymal exposure is also useful in major hepatic resections. In certain patients the liver may be frozen into the hepatic fossa by previous operations to the extent that it cannot be safely and expediently removed by other methods [11, 26].

As previously discussed, the consequences of clamping the portal vein and IVC during the hepatectomy and anhepatic phase led to the development of venovenous bypass [6, 8]. Although the development of the piggyback technique allowed uninterrupted blood flow in the IVC, clamping of the portal vein must still occur. The use of a temporary portocaval shunt was described in order to minimize the effect of portal venous interruption [19, 27]. To construct the shunt, the hilar dissection proceeds as usual and the common bile duct and hepatic artery are divided. The portal vein is transected high into the liver beyond its bifurcation (Fig. 11.8a). The infrahepatic IVC is exposed and a side-biting vascular clamp is applied. A cavotomy is made, and the free end of the portal vein is sewn to the IVC in an end-to-side manner using continuous polypropylene suture (Fig. 11.8b). The remainder of the hepatectomy proceeds as usual. After the liver is brought in and the IVC anastomosis is completed, the shunt is ligated just proximal to the anastomosis, and the portal vein anastomosis is performed (Fig. 11.8c).