EXPERIMENTAL AND CLINICAL TRANSPLANTATION

Key words : Deceased donor organ donation, Donation after brain death, Donation after cardiac death, Organ procurement

The present shortage of transplant organs has resulted in an increased use of extended criteria donor allografts.¹ One of the largest potential sources for these extended criteria allografts is the pool of organs procured from people who donate after cardiac death (DCD).^2-9 One of the limitations with this type of organ is the increased risk for biliary necrosis compared with standard criteria donor allografts, because bile ducts are particularly susceptible to perfusion/reperfusion injury.^10,11 Some of the identified risk factors for ischemic cholan-giopathy in this setting include prolonged warm ischemia (>30 minutes), prolonged cold ischemia (>8 hours), protracted intraoperative course during implant, and some demographic factors such as donor age >60 years or morbid obesity.^12-15 The risk for graft loss due to primary nonfunction seems only slightly elevated compared with other types of extended criteria allografts. There have been several attempts to improve outcomes of clinical liver transplants of DCD allografts, including administration of heparin, oxygen free-radical scavengers, and fibrinolytics.⁵ Also, rapid cannulation techniques have been the focus of recent research.¹⁶ Cold and warm machine perfusion are new exciting techniques and are in clinical use.^1,17 At least 1 study has proposed the use of a low-viscosity perfusion solution for aortic perfusion and University of Wisconsin (UW) solution to flush the graft via the portal vein.¹⁸ The noncolloidal histidine-tryptophan-ketoglutarate solution may have advantages over the highly viscous UW solution in these donors.^19-21

As a standard, most centers perform simultaneous aortic and portal perfusion; however, it is not clear if simultaneous portal perfusion is necessary.^9,22-24 For DCD liver allografts, recent data seem to favor simultaneous aortic and portal perfusion.^9,25,26 An alternative method is rapid aortic cannulation and perfusion followed by aortic cross-clamping and venous drainage with secondary cannulation of the portal system and perfusion within a few minutes. Aortic perfusion at the operating table followed by back-table portal perfusion is another option.

The most common approach for portal perfusion in situ is via the inferior mesenteric vein (IMV), which is easily accessible near the ligament of Treitz. Alternative routes include access via side branches of the superior mesenteric vein (SMV) at the root of the transverse mesocolon and direct portal vein access within the liver hilum. Portal perfusion through the splenic vein²⁷ was suggested by Starzl and colleagues in 1984 but this method has not been popularized.^28,29

We herein report a case series of organ pro-curements performed with cannulation of the splenic vein in the hilum of the spleen. In addition to 4 DCD donors, we report 2 donors after brain death for whom we used the same approach. The technical aspects of this easy-to-perform technique as well as the outcomes of the procured liver allografts are presented.

Materials and Methods

Study design and data collection
Operative reports of the 6 procurements were studied in detail. For grafts procedures in our center, recipient hospital charts were the guide for follow-up. If grafts were used at outside centers, then only baseline data could be obtained. The study was approved by the local ethics committee. Data are given as median values with minimum-maximum range or as percent of the collective.

Surgical transplant technique for donation after cardiac death
All ethical guidelines and local hospital policies were strictly followed.30-32 Consent for organ donation was obtained, and patients were disconnected from the ventilator in the intensive care unit or postanesthesia care unit depending on hospital protocol; in some hospitals this step could be done in the operating room. Cardiac arrest was awaited; death was declared 2 to 5 minutes after loss of circulation according to guidelines.

Donors were rapidly brought to the operating room (1-5 minutes, depending on each hospital), placed supine on the operating room table, and the chest and abdomen were prepared sterilely and draped. Administration of heparin varied according to the local hospital policies. The skin was incised from the sternal notch to the symphysis pubis, the sternum was divided, and the abdomen was opened. Self-retaining retractors were placed in the chest and abdomen, and the falciform ligament was divided. The aortic bifurcation was identified, and the aorta was encircled, opened, and cannulated (20-24F cannula). Flush was started with UW solution, and the cannula was secured with an umbilical tape. The right atrium was opened to vent blood and perfusion solution, the aorta was cross-clamped in the chest, and the abdomen was packed with ice.

Once aortic perfusion was secured, the spleen was mobilized out of the retroperitoneum, and the short gastric vessels and the splenocolic ligament were divided. The spleen could now be used as a handle, and the tail of the pancreas was retracted anteriorly. The anterior serosa was incised, and the tissue covering the hilar vessels posteriorly was divided. The splenic artery and vein were dissected out, the vein was opened, and a 14F cannula was inserted. Portal flush was started with UW solution and the cannula was secured with a 2-0 silk tie. During the portal flush, the usual steps of organ procurement were performed. The retroperitoneum was completely mobilized, and the left and right triangular and the hepatogastric ligaments were divided. The left and right paracolic gutters were opened and packed with ice. The arterial anatomy of the liver was inspected, and the bile duct was dissected out, divided, and flushed with 60 mL of UW solution. The gallbladder was incised on the back-table and flushed with UW solution. After organ perfusion was complete, first the liver and thereafter the kidneys were procured in the standard fashion. Liver and kidneys were evaluated for surgical damage, anatomical variations, and pathology, and biopsies were taken. The liver was packed in ice and the kidneys were continuously pumped.

We analyzed 6 multiorgan procurements (including 4 DCDs) that were performed by access through the splenic vein for portal perfusion (see Table 1). We used this technique for the first time in a donor who had suffered a polytrauma with a massive retroperitoneal hematoma and pelvic fracture. He was treated with an open abdomen. During the procurement we noted that the IMV was disrupted. Aortic perfusion seemed inadequate, dissection of the SMV would have risked a longer duration of surgery, and access to the portal vein in the hilum would have carried the risk of injury to the hepatic artery or bile duct. We were familiar with the original technique published by Starzl and colleagues,²⁸ and so we decided to mobilize the spleen, dissect the splenic hilum, and access the splenic vein for cannulation. We used a 10F cannula that had been prepared for IMV access.

The organ showed excellent perfusion, the access was simple, and the graft had excellent initial function, so we used the technique of Starzl and colleagues for the next 3 DCD allografts and 2 additional allografts donated after brain death. In these 5 later cases we used a 14F cannula to facilitate rapid flow.

The first donor after brain death had a history of coronary artery bypass graft and multiple intra-abdominal procedures with lysis of adhesions and bowel resections as sequalae of a gunshot to his abdomen. During procurement significant intra-abdominal adhesions were found. The aorta was severely calcified, so we obtained arterial access through the right iliac artery. There were adhesions due to the gunshot trauma and multiple reoperations, so dissection of the IMV seemed unreasonable; therefore, in this case we also chose to perform portal perfusion through the splenic vein.

In 4 cases the splenic vein was accessed from the anterior aspect, and in 2 cases from a posterior access. Figure 1 shows the cannulas inserted in the splenic vein.

Five liver grafts were transplanted, 3 of these at our center, and 2 accepted at outside centers. One DCD liver from a morbidly obese donor with a body mass index (calculated as weight in kilograms divided by height in meters squared) >40 was declined because of the high fat content (>50%) and stage 2 fibrosis on liver biopsy.

Table 2 shows demographic and clinical data for the 5 recipients. All grafts showed good initial function, none was lost due to primary nonfunction or vascular thrombosis, and none had biliary complications.

We herein report an easy method of access for portal perfusion that may have some advantages compared with previously described techniques. This approach is particularly useful in DCD transplants but also in cases of intra-abdominal adhesions with difficult access to the IMV and/or SMV. Whereas for DCD organs and organs from donors after brain death with intra-abdominal adhesions, this technique was found to have advantages over cannulation of the IMV, which is our preferred access; however, for surgery in standard donors, no advantage has been observed. One graft was not used because the liver showed significant steatosis and fibrosis. All other organs were used and all showed good initial graft function.

The IMV can be a small vessel, and in the case of DCD, the IMV can be difficult to identify when the vein is collapsed. Mobilization of the spleen is an easy-to-perform procedure, and after division of the short gastric vessels and the splenocolic ligament, the spleen can be used as a handle to mobilize the tail of the pancreas anteriorly; by this method, optimal exposure of the hilum can be obtained. The splenic vein can be accessed from an anterior or posterior approach. This step has proved to be of short duration (no more than 5 minutes), similar to that of the IMV approach, with the additional advantage that hilar dissection to the portal vein is not needed and thus avoids the associated risk for graft injury. A major advantage of SMV versus IMV cannulation is the much larger diameter of the splenic vein, which allows easy insertion of a 14F cannula. This method facilitates rapid infusion and this may flush small thrombi out of the liver sinusoids. Our technique is not suitable if the pancreas is used, because there is a danger of damage to the pancreas during mobilization and cannulation.³³

Longer follow-up and additional cases are needed before this technique could be confirmed as an effective alternative to established methods. Nevertheless, the option to cannulate the splenic vein, as originally suggested by Starzl²⁸ and as has been used in some animal models,²⁷ should be considered as a suitable rescue procedure if the IMV or SMV are difficult to dissect out. This applies both for DCD organs and nonstandard operations with organs from donors after brain death, particularly in the case of intra-abdominal adhesions.

Volume: 19 Issue: 12 December 2021

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