Intraluminal shunt for the thoracic aorta: blood flow and function in chronic studies.

BACKGROUND: Aortic cross-clamping during operations on the thoracic aorta may result in paraplegia or kidney failure. METHODS: A nonshunting method of repair was compared with intraluminal shunting in two groups of young pigs: the no-shunt group, which received simple aortic cross-clamping at the ligamentum for 15 minutes; and the shunt group, which received an aortic graft with a temporary intraluminal shunt and balloon occlusion of the inferior vena cava only during shunt insertion and removal. Blood flow to the spinal cord and viscera was measured with radiolabeled microspheres on days 1, 3, 5, and 7 after operation. Renal and neurologic function and histology also were studied. RESULTS: In the no-shunt group, there was hyperemia of the lumbar cord compared with the shunt group. There were no significant differences in renal cortex blood flow or creatinine clearance. Seven of 10 animals in the no-shunt group had paraplegia, compared with none in the shunt group. Histologic studies of the lower lumbar cord showed bilateral central necrosis of gray matter in the no-shunt group, but no evidence of necrosis in the shunt group. CONCLUSIONS: An intraluminal shunt allowed thoracic aorta reconstruction without paraplegia.

Intraluminal shunt for the thoracic aorta: spinal cord and visceral blood flow in acute studies.

Aortic cross-clamping during surgery of the thoracic aorta may result in paraplegia or kidney failure. Difficulties associated with external shunts and bypasses have limited their use. Therefore we compared intraluminal shunting to the nonshunting method of repair in neonatal pigs. Blood flow to the spinal cord and viscera was measured with radiolabeled microspheres before, during, and after thoracic aortic cross-clamping or shunting. Two no-shunt groups were studied: One group was clamped distal to the left subclavian artery for 30 minutes and the other for 1 hour. In the intraluminal shunt group, a shunt was placed in the aorta just below the ligamentum arteriosum for 1 hour; it was then removed and the aorta repaired. In the no-shunt groups, there was virtually no blood flow to the lower cord and viscera during the cross-clamp period. Hyperemia of the lower thoracic and lumbar cord occurred in the no-shunt 30-minute group 15 minutes after clamp removal. In the no-shunt 60-minute group, flow initially returned to the lumbar cord but then declined; and after 1 hour of reperfusion it was significantly lower than baseline. Renal blood flow was even more severely affected in the no-shunt 60-minute group, with minimal recovery during the reperfusion period. In the intraluminal shunt group baseline spinal cord and visceral blood flow were maintained during thoracic aortic cross-clamping, without the problems associated with extracorporeal circulation.

Investigation of passive venovenous shunts during the anhepatic period of canine hepatic transplantation.

The anhepatic period of canine orthotopic hepatic transplantation is usually accompanied by cardiovascular instability due to occlusion of both the portal and inferior systemic venous systems. The present study was undertaken in order to determine some of the hemodynamic and renal alterations that occur during a 2 hour anhepatic period in the dog and to investigate the use of a passive endoportal, endocaval venovenous shunt that places both the portal and infrahepatic vena caval limbs of the shunt directly into the divided ends of these vessels. Three groups of experimental animals were studied. One group had hepatectomy without a shunt and was compared with two other groups which had hepatectomy with some form of venovenous shunting. Systemic arterial blood pressure, portal and inferior vena caval pressure, urinary output, and renal histology were all better maintained when a shunt was used.

Small bowel obstruction from an antacid bezoar: a ranitidine-antacid interaction?

A 63-year-old man had an acute small bowel obstruction while being treated with ranitidine and self-prescribed antacid. On exploration, a firm mass, chemically similar to the ingested antacid, was found impacted in the terminal ileum. We believe the effect of ranitidine on gastric secretory volume was the cause of the antacid concretion.

Autotransfusion in hepatic transplantation.

Hepatic transplantation is often accompanied by a large volume of intraoperative blood loss which may place extraordinary transfusion demands on a community blood bank. In an effort to conserve blood bank resources, intraoperative autotransfusion has recently been used in our adult patients undergoing orthotopic hepatic transplantation. A group of seven patients receiving autotransfusion was studied and compared to another group of five patients who did not receive autotransfusion. In spite of receiving more blood during the transplant procedure, the autotransfusion group required a mean of 7.9 units less banked blood. Post-transplant transfusion requirements and bleeding complications were similar in both groups. Hematocrit and total bilirubin were not adversely affected, while transient elevation of BUN and serum creatinine appeared to be unrelated to the salvage process. This procedure was found to be safe and cost-effective, while conserving blood bank resources.

Biopsy-directed immunosuppression following hepatic transplantation in man.

Patients undergoing orthotopic hepatic transplantation were studied with routinely available liver function studies and serial hepatic biopsies. Rejection was diagnosed only if confirmed histologically. Cyclosporine and a rapidly decreasing dose of corticosteroids were used for immunosuppression. Hepatic dysfunction suggesting rejection was seen in 22 instances, but acute rejection was diagnosed histologically in only 6 patients. The liver function studies used in these patients did not accurately distinguish rejection from other causes of hepatic dysfunction. We conclude that liver biopsy as performed in these patients is an accurate and safe means of assessing the adequacy of immunosuppression and minimizing the use of high dose corticosteroids.

Liver transplantation with cyclosporine and low-dose corticosteroids.

Twenty consecutive patients receiving 21 hepatic transplants were treated with cyclosporine and low-dose corticosteroids. Survival was 80 per cent at 30 days, 75 per cent at 6 months, and 65% in the 6-17 months follow-up period. Compared with earlier series, this improved survival using cyclosporine results from fewer infectious and sound healing complications. Reliance on hepatic biopsy to confirm the diagnosis of rejection may also reduce the corticosteroid exposure and help diminish the complications of excessive immunosuppression.