Pancreas Transplantation Nicolas Demartines, Hans Sollinger

Pancreas Transplantation

Nicolas Demartines, Hans Sollinger

Introduction

The aim of pancreas transplantation is to restore normal glycemia in diabetics and to attempt to stop the vascular pathophysiology of diabetes, i.e., microangiopathy and, whenever possible, to reverse established renal, ophthalmologic, and neurologic compli- cations of microangiopathy. Pancreas transplantation can be performed either simulta- neously with or sometimes after a previous kidney transplant, or less commonly as a primary procedure alone.

The operative technique of the pancreas transplantation has evolved from a segmental organ transplantation to a complete (pancreatoduodenal) transplantation.

Similarly, the original method of drainage of the exocrine pancreas into the bladder has also evolved into enteric drainage. In many centers, enteric drainage has been shown to be safe and efficient and has largely replaced bladder drainage.

The question about the benefit of portal venous drainage versus caval (systemic) drainage remains unresolved, and both techniques will be described.

Indications and Contraindications

Indications Indications for Pancreas Transplantation

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Type 1 diabetes mellitus

Indications for Simultaneous Pancreas and Kidney Transplantation

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Diabetic nephropathy

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End-stage renal disease

Indication for Pancreas Transplantation After Kidney Transplantation

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Functioning kidney graft

Indication for Pancreas Transplantation Alone (Severe Complications of Diabetes)

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Instability of glycemia – unstable,“brittle”, insulin-dependent diabetes

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Progressive retinopathy

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Progressive neuropathy

Contraindications

Coexistent cancer (excluding squamous or basal cell carcinoma of skin)

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Severe infection

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Psychiatric disease (psychosis)

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Peripheral arteriopathy with infection

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Symptomatic coronary artery disease

Preoperative Investigations and Preparation for the Procedure

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Routine evaluation for transplantation with appropriate serum cross-match

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Evaluation of renal function unless on preoperative hemodialysis

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Clinical cardiovascular evaluation, further cardiac workup if clinically indicated

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Clinical exclusion of concurrent infection

Procedure

STEP 1

Back-table preparation

We prefer to completely prepare the pancreas for transplantation during cold ischemia.

All connective tissues around the pancreas are divided with 2-0 or 4-0 silk ligatures

placed close to the pancreas. The spleen is resected and the splenic vessels carefully

ligated with 0 silk. The superior mesenteric artery and vein distal to the pancreatic

vessels are divided in one of two ways: either with a vascular stapler close to the

pancreas or by ligating the vessels with 0 silk and oversewing them with polypropylene

running sutures. A 12-cm segment of the second portion of the duodenum containing

the entrance of the pancreatic duct is isolated using a gastrointestinal stapler. The staple

lines are oversewn for hemostasis with a running suture of resorbable suture. The portal

vein is usually left short at the procurement; this permits a very short portal anasto-

mosis, which decreases the risk of venous thrombosis. The mesenteric and splenic

arteries are connected with use of a Y-graft from the donor iliac bifurcation with

running sutures of 6-0 polypropylene. The graft is now ready for implantation.

STEP 2

(A-1,

Access to the retroperitoneum for portocaval anastomosis is obtained with a midline incision. An Omnitract or Octopus retractor aids exposure. The cecum and right colon are mobilized medially to expose the vena cava. Care should be taken to avoid injury to the right ureter that may cross the iliac vessels on the right side at several different levels, either at the caval bifurcation or more laterally. The ureter is retracted laterally.

During preparation of the vena cava for anastomosis (~5cm needed), the surgeon must

remember the sacral vein located posteriorly, usually just cephalad to the iliac bifurca-

tion. The right common iliac artery is prepared similarly. Lymphatic vessels should be

ligated to avoid formation of a lymphocele.

STEP 3

Venous anastomosis (A-1,

A Satinsky vascular clamp is placed on the vena cava for the venous anastomosis.

The type of clamp used on the common iliac artery depends on the site for anastomosis and the presence/absence of arteriosclerosis, either a Satinsky clamp or two right angle vascular clamps.

For the posterior aspect of the venous anastomosis, the cava is opened longitudinally for 20–30mm, corresponding to the size of the portal vein of the graft. A stay suture on the left side of the opened vena cava maximizes exposure. After irrigating the lumen with a heparin/saline solution, a 6-0 polypropylene running suture starts on the right side of the cava and is carried around the posterior circumference. The technique for the vascular anastomosis is also used for a portomesenteric venous anastomosis.

The anterior part of the anastomosis is performed next with the same running suture, taking care not to include the posterior wall with the anterior suture layer.

Before completing the anastomosis by tying the two ends of the suture, a bulldog clamp

is placed on the portal vein and the anastomosis is tested by filling and distending the

cava and portal vein with a heparin/saline solution through a cannula. The bulldog

clamp should remain in place while the vascular clamp on the cava is removed.

STEP 4

Arterial anastomosis

The right common iliac artery is opened, and a patch corresponding to the diameter of the graft artery is resected. The vascular anastomosis is performed with two running sutures of 6-0 polypropylene. A bulldog vascular clamp is placed on the arterial graft, and the anastomosis is filled with heparin/saline solution.

After testing the arterial anastomosis for leak, the pancreas graft is ready to be

perfused. First, the venous clamp is removed and then the arterial one. The anesthesiolo-

gist should be warned about the possibility of cardiac dysrhythmias or hypotension

when the graft is first perfused. Also, it is not unusual for small vessels not ligated during

the back-table preparation to bleed during reperfusion; careful hemostasis is mandatory.

STEP 5

Portomesenteric anastomosis

Whenever possible, the venous anastomosis should be performed without an additional venous graft to decrease the risk of venous thrombosis. For this procedure, the colon is not mobilized. The small intestine is retracted to the left, and the superior mesenteric vein is located caudal to the transverse mesocolon. An incision is made about 20mm lateral of the vein to allow a better control of this vein while positioning the pancreas graft. The venous anastomosis is performed with the same technique described above.

For the arterial anastomosis, the common iliac artery is palpated medial to the ileocolic artery through the mesocolon, and the mesentery opened for 4–5cm to expose the common iliac artery. The anastomosis is performed through the mesentery using the same technique as above.

This approach speeds the procedure and avoids complete mobilization of the right

colon. The retroperitoneum is not opened, decreasing the risk of postoperative hemor-

rhage. Whether benefit is achieved through a portomesenteric versus systemic venous

drainage is still debated.

STEP 6

Duodenojejunostomy (A-1,

Exocrine drainage of the pancreas graft remains a major unsolved problem. The jejunum 40–50cm distal to the ligament of Treitz is selected for a side-to-side duodeno- jejunostomy. With portomesenteric venous drainage, the entire graft is intraperitoneal.

The anastomosis should be about 30–50mm in length. The anastomosis is performed in two layers with the inner layer as a running 4-0 absorbable suture, including all layers of the gut wall. The outer layer is performed with interrupted 0 silk seromuscular sutures.

Second layer of the duodenal anastomosis: Once the running suture is achieved, the second layer of interrupted stitches of silk is performed. As an alternative, the second layer may be a running suture.

A-1

STEP 7

Drainage and duodenal fixation

An 18-Fr. closed suction drain is placed alongside the pancreas graft. The cecum is usually pexed or reperitonealized with either running or interrupted polypropylene sutures to avoid later cecal volvulus. Such lateral refixation is not necessary for portomesenteric venous drainage.

If a simultaneous kidney transplant is to be done, the same intra-abdominal access

can be used to expose the iliac vessels transperitoneally or a separate contralateral

retroperitoneal approach is an alternative.

Postoperative Tests

The intraoperative glycemia monitoring shows usually normalization without additional insulin within 1–2h after the graft reperfusion.

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Close postoperative management in an intensive or immediate care unit

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Daily hemoglobin and kidney function

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Blood sugar determination every 4h

Local Postoperative Complications

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Short term:

– Postoperative bleeding – Duodenal anastomotic leak

– Ascites (R/O pancreatic ascites/anastomotic leak) – Portal vein graft thrombosis

– Hypoglycemia – Acute rejection – Mild pancreatitis

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Long term:

– Chronic pancreas rejection – Adhesive small bowel obstruction

Tricks of the Senior Surgeon

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Whenever possible, avoid the use of a venous graft on the donor portal vein.

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Meticulous hemostasis at the end of the procedure is imperative to prevent delayed hemorrhage up to 2h after reperfusion.

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The exocrine drainage must be tension-free, and the drainage catheter kept

away from the anastomosis to avoid catheter erosion.