Liver Procurement

According to the degree of preliminary dissection, liver procurement can be classified into standard and rapid perfusion techniques.5 In the standard technique, preliminary dissections of the hepatic artery, celiac axis and portal vein are carried out before aortic and portal flushing with preservation solutions. Standard technique allows the dissection of vascular structures to an extent that anatomy is clarified.6 The rest of the dissection is then completed easily and safely after reperfusion of the liver. This technique tends to be time consuming and sometimes is associated with excessive blood loss during dissection.

The rapid perfusion technique minimizes dissection before flushing with preservation solutions.7 The preparatory steps include cannulation of the aorta and portal vein. The entire hilar dissection is performed after aortic cross-clamping. In this way donor hepatectomy can be completed in a nearly bloodless field. This technique requires dissection of asanguinous blood vessels, making them more difficult to identify, and may be associated with vascular injury. The rapid perfusion technique is mainly suitable for the hemodynamically unstable donor.

The method of procurement procedure principally depends on the preference and experience of the surgeon. Either of these techniques can be used for retrieval of organs without functional or anatomical damage.

Standard Technique

We currently use this technique for liver procurement. The procedure begins with a midline incision with electrocautery from the suprasternal notch to sym-physis pubis. A midline sternal splitting is performed with a bone cutting saw or a Lebsche knife. This allows maximum exposure, intrapericardial division of su-prahepatic vena cava, and provides immediate access to the heart in case of instability. Hemostasis of the cut surface of the sternum is achieved with electrocau-tery and bone wax. A self-retaining sternal retractor is placed and spread laterally. A large Balfour retractor is used for the abdomen. Upon entering the abdomen rapid intra-abdominal exploration is made for suitability of organs to be harvested. Intra-abdominal malignancy, peritonitis and ischemic bowel are the main intraoperative findings that preclude organ procurement.

The liver is inspected and palpated to assess color, size, consistency and any injury. Usually small lacerations or hematomas do not preclude the use of the liver.

A normal liver is red-brown in color with sharp edges. A large, brown-yellow soft liver with round edges is consistent with steatosis. Yellow color during blanching following the release of fingertip pressure on the liver surface is also a sign of steatosis. If gross appearance of the liver suggests steatosis a frozen section biopsy should be performed. The degree of steatosis is best determined by an experienced pathologist. For this reason we recommend frozen section biopsies to be examined by the hepatopathologist at the transplantation center. Livers that contain more than 40-50% macrovesicular fat on frozen section should be used very cautiously as we believe that they carry a higher risk of primary nonfunction.

A swollen liver with round edges may be seen in the presence of high central venous pressure. This appearance improves with intraoperative administration of diuretics. A swollen liver in the presence of low or normal central venous pressure is usually a sign of ischemic injury. Capillary perfusion can be assessed by pressing on the liver with fingertips and observing reperfusion after release.

Any lesion of the liver which is suspicious for malignancy should be biopsied. Livers from hepatitis-C antibody positive donors should undergo histopathologic examination regardless of their macroscopic appearance. Their use in transplantation is acceptable under special circumstance.

Mobilization of the liver begins with division of the round ligament between ligatures. Left triangular and falciform ligaments are divided with electrocautery. Then attention is turned to the distal aorta. We prefer to carry out aortic dissection early in the operation so that in the event of cardiovascular collapse, the aorta can be cannulated immediately and the rest of the dissection completed after aortic and portal flush as in the rapid flush technique.

The entire right colon and small bowel mesentery are mobilized by dividing retroperitoneal attachments and the intestines are swept up. An extended Kocher maneuver is then performed exposing the vena cava. The distal aorta is identified and dissected free. The inferior mesenteric artery is divided between ligatures. The aorta at the level of inferior mesenteric artery is encircled with two umbilical tapes. Care should be taken in encircling the aorta as lumbar arteries may be injured.

Table 8.1. Incidence of variations of the hepatic artery (%)

Variation

Suzuki et al (200 cases)20

Emre et al 496 cases4

Common hepatic artery originating from left gastric artery Left hepatic artery originating from left gastric artery Right hepatic artery originating from superior mesenteric artery Entire hepatic artery trunk originating from superior mesenteric artery Combination of left hepatic artery originating from left gastric artery and right hepatic artery from superior mesenteric artery Others

12.5

14 10

Next attention is directed to the supraceliac aorta. The gastrohepatic ligament is divided with electrocautery. If a left hepatic artery arising from the left gastric artery is palpated and/or visualized in the gastrohepatic ligament, it should be preserved by dissecting the artery back to its origin from the main left gastric artery (Table 8.1).8 The gastric branches of the left gastric artery are divided between ligatures and the continuity of the left hepatic artery with the left gastric artery is preserved. The diaphragmatic muscle fibers overlying the supraceliac aorta are separated longitudinally and divided with electrocautery. During this dissection the stomach is retracted laterally and the left lateral segment of the liver is retracted medially. After exposing the aorta, the preaortic fascia is incised and the aorta is encircled with an umbilical tape. Intercostal or lumbar aortic branches are usually not encountered in this location.

Next attention is directed to hepatoduodenal ligament. First, the hepatic artery is dissected out. The peritoneum overlying the superior border of the pancreas is incised. The common hepatic artery usually lies in the groove between the pancreas and the common hepatic lymph node. Following identification of the common hepatic artery, gastroduodenal and right gastric arteries are divided between ligatures. By retracting the pancreas caudally, the left gastric and splenic branches of the celiac axis are identified, ligated and then divided. If there is a left hepatic artery coming from the left gastric artery, it is preserved as described previously. Further dissection of the celiac axis is not required at this point. The liga-tion of all branches is always performed away from the main artery to prevent intimal dissection. An adequate length of splenic artery cuff should be provided for possible anastomosis of right hepatic artery originating from superior mesen-teric artery.

The peritoneum overlying the distal part of hepatoduodenal ligament is incised. The common bile duct is identified and mobilized to a level as low as possible to have adequate length for later reconstruction of the biliary tract. The bile

duct is then transected after distal ligation. To preserve the blood supply of the common bile duct, dissection is kept to a minimum. The gallbladder fundus is opened with the electrocautery and bile is washed out with saline by a catheter-tipped syringe to prevent autolysis of the biliary mucosa. After the division of common bile duct, the presence of an anomalous replaced right hepatic artery arising from superior mesenteric artery is assessed.9 A finger is inserted into the foramen of Winslow to identify the replaced right hepatic artery. It can be located by its pulsation lateral to the portal vein and posterior to the common duct. Its origin from the superior mesenteric artery is usually found beneath the splenic vein near its junction with the portal vein. If a replaced right hepatic artery is present its further dissection all the way to its origin from superior mesenteric artery is usually performed after cold perfusion.

The portal vein which typically lies under the gastroduodenal artery is identified by dividing the areolar tissue. Then it is isolated by dividing the connective tissue and lymph nodes surrounding the vein. Dividing the lymph nodes between ligatures may facilitate a bloodless dissection. The coronary vein is ligated and divided. The portal vein is cleaned inferiorly to the junction of splenic and superior mesenteric veins.

The next step is the identification of superior mesenteric artery. The intestines are elevated from the retroperitoneum and areolar tissue over the aorta and vena cava cleaned until the left renal vein is exposed. The superior mesenteric artery is located at the base of the small bowel mesentery just above the renal vein. The connective tissue surrounding the superior mesenteric artery is divided and it is encircled with a heavy tie. The superior mesenteric artery is not tied at this point to prevent intestinal ischemia.

Following this preliminary dissection, the next step is cannulation of the aorta and portal vein for cold perfusion. Either the splenic or inferior mesenteric vein can be cannulated for portal perfusion. Inferior mesenteric vein cannulation is easier and less time consuming. After isolating proximally in the mesentery of the left colon, the inferior mesenteric vein is ligated and cannulated. The cannula is advanced until the tip is felt just entering the portal vein. If the splenic vein is chosen for cannulation, it is dissected free at least 1 cm and encircled. If necessary for exposure, the neck of the pancreas can be divided between ligatures. Then the splenic vein is ligated and through its central side a cannula is placed. The splenic vein is divided behind the cannula. The superior mesenteric vein is also encircled with a ligature to be tied off later. Some surgeons infuse a total of 1-2 liters of chilled lactated Ringer's solution through the portal vein for liver precooling before aortic cross-clamping. This step probably is not necessary. If precooling is used, close monitoring of temperature and blood pressure is crucial not to compromise the heart.

After all teams have completed their dissections, the donor is heparinized with 20,000-30,000 U (300 U/kg). The previously encircled aorta is ligated distally with umbilical tape and cannulated with a cardiovascular cannula. The cannula is secured to the aorta with the second umbilical tape. If there is a thoracic team, both teams coordinate the cardiopulmonary arrest and the supraceliac aorta is clamped.

Then vena caval decompression is performed by incising the inferior vena cava at its junction with the right atrium. We favor right chest venting of the vena cava as optimal. Sufficient length of supradiaphragmatic inferior vena cava should be obtained for adequate recipient anastomosis. The length of inferior vena cava staying on the liver graft is decided between heart and liver teams. The effluent is drained by a Poole suction tip through the transected vena cava. If lungs are not to be retrieved, the right pleura can be opened to keep the warm effluent away from the heart.

If the heart and/or lung team favors intra-abdominal caval decompression to keep the warm blood and effluent away from the thorax, the inferior vena cava can be cannulated just above the iliac bifurcation. This allows distal drainage of blood with perfusion fluids. In this case effluent is collected into a drainage bag. Intra-abdominal vena caval decompression needs extra dissection and may not be as effective in keeping the liver decompressed as supradiaphragmatic caval decompression.

During donor exsanguination, aorta and portal vein flushing with cold University of Wisconsin (UW) solution, the abdominal and thoracic cavities are filled with slushed-ice saline for topical cooling. With aortic and portal perfusion the liver and kidneys become cold and bloodless. We prefer to use 2 liters of infusate through each of the cannulas (aortic and portal). Perfusion volumes for children are 50 mL/kg for aorta and 30-50 mL/kg for portal vein. After starting cold perfusion the previously encircled superior mesenteric artery and superior mesenteric vein are ligated.

The heart and/or lungs are removed first. This allows time for perfusion and topical cooling. Liver recovery begins with an incision of the pericardium surrounding the intrapericardiac inferior vena cava. The suprahepatic vena cava is freed completely. This requires an incision of the diaphragm over the esophageal hiatus. Care should be taken not to enter the esophagus. The right diaphragm is incised with a wide margin away from the liver. During this dissection, pulling the liver or the right kidney forcefully can cause tears in the liver capsule. The peritoneum overlying the infrahepatic vena cava and right kidney is incised. The right kidney is retracted laterally and caudally to allow the surgeon to encircle the inferior vena cava with index finger. The left renal vein is identified and the inferior vena cava is transected above the left renal vein. The right adrenal gland is divided leaving half of the gland with the liver and the other half with the right kidney. Using the right adrenal gland as a point of division allows both the liver and kidney teams reassurance that neither organ is "shortchanged." The liver is lifted anteriorly and superiorly and the right diaphragm with retroperitoneal attachments is divided sharply.

The splenic and superior mesenteric veins are divided (if the inferior mesen-teric vein was cannulated for portal flush and the splenic vein was not previously divided). The portal vein is reflected superiorly and freed up to the level of the transected bile duct. The portal vein cannula is kept in for subsequent back table flush. Next, the celiac axis is dissected free. This requires division of the left diaphragmatic crus and the nerve fibers of the celiac trunk around the celiac axis.

The previously ligated superior mesenteric artery in the root of the small bowel mesentery is identified at its confluence with the aorta. The aorta is then divided between the celiac and superior mesenteric arteries. At this point care should be taken not to injure the left renal artery. The supraceliac aorta is divided distal to the previously placed aortic clamp. In this way a cylinder of aorta which includes the celiac axis can be obtained. This provides an aortic Carrel patch with the celiac axis for the recipient arterial anastomosis. Next the liver is lifted anteriorly. The remaining right diaphragmatic and retroperitoneal attachments are divided and the liver is removed.

In the presence of an anomalous right hepatic artery branching from superior mesenteric artery, the superior mesenteric artery is dissected clean from its beginning at the aorta to beyond the origin of the anomalous right hepatic artery branch. This requires retraction of the pancreas inferiorly and division of the connective tissue with nerve bundles around the superior mesenteric artery. Then a segment of the superior mesenteric artery including the origin of the right hepatic artery is excised. The anomalous right hepatic artery usually originates within the first 3 cm of the superior mesenteric artery.

After procurement of all organs, the iliac arteries and veins are recovered for possible vascular reconstruction in the recipient. In case of atherosclerotic iliac arteries which renders them unusable, the carotid arteries may be recovered.

A part of the spleen and mesenteric lymph nodes in the terminal ileum mesentery are removed for tissue typing. Usually 10-12 lymph nodes are sufficient. If there are not enough lymph nodes in the mesentery, as can be seen in the elderly donor, mediastinal lymph nodes are taken.

Rapid Perfusion Technique

In this technique minimal dissection is needed before cold perfusion. A mid-line incision from the suprasternal notch to the symphysis pubis is made. The left triangular ligament is incised. The diaphragmatic crura overlying the supraceliac aorta are separated and divided with electrocautery. The supraceliac aorta is encircled with an umbilical tape. Next, the distal aorta is dissected free and the inferior mesenteric artery is divided between ligatures. The distal aorta is encircled with two umbilical tapes at this level. The inferior mesenteric vein is isolated, ligated and cannulated. The tip of the cannula is advanced to the level of the portal vein entrance. The gall bladder fundus is opened and bile is washed out with saline irrigation. The distal aorta is cannulated after systemic heparinization. The supraceliac aorta is cross-clamped. The inferior vena cava is transected close to its junction with the right atrium. Cold perfusion and topical cooling are performed as described previously.

Hepatectomy is completed in the bloodless field. The suprahepatic inferior vena cava is freed from diaphragm and pericardium. The hepatic hilum is carefully dissected. The gastroduodenal, right gastric, splenic and left gastric arteries are ligated and divided. In the presence of a left hepatic artery originating from the left gastric artery, this artery is preserved by dividing gastric branches. The portal vein is encircled and splenic and superior mesenteric veins are divided

between ligatures. If present, the anomalous right hepatic artery originating from the superior mesenteric artery is preserved. Liver procurement is completed as described in the standard technique.

Back Table Preparation

The liver is placed in a plastic bag (typically a "bowel bag") and taken to an ice basin on the back table. The portal vein is perfused with 500 mL of cold UW solution through the previously placed cannula. The effluent is kept in the plastic bag. Next the hepatic artery is perfused with an additional 300-500 mL of UW solution. Less fluid is used for the perfusion of pediatric grafts. The common bile duct is flushed with 20-40 mL of UW solution through a baby feeding tube to clear bile ducts of bile.

The liver is completely immersed in UW solution and packed in two sterile plastic bags. One liter of cold lactated Ringer's solution is placed between two bags for protection from trauma. The packaged liver is placed in a cooler and covered with ice for transportation.

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