Effect of surrogate tolerogenesis on the vascular rejection of pig heart xenografts.

BACKGROUND: Organ xenografts are fulminantly rejected by antibody-mediated vascular rejection. Surrogate tolerogenesis (ST), the induction of tolerance within the donor, is effective with aorta xenografts. This preliminary study assesses the effect of ST on preformed antibodies and rejection of porcine heart xenografts. METHODS: Tolerance to the donor pig was induced by infusing recipient marrow into fetal pigs. Later, pig splenocytes were transfused and heterotopic pig hearts transplanted using chimeric or nonchimeric pigs. Anti-pig antibodies were assessed. RESULTS: With ST alone, xenografts developed cellular rejection at 4-6 days, whereas control grafts developed vascular rejection at 3-4 days (cellular vs. vascular, P<0.03). There was a reduction in preformed antibodies (P<0.03). ST combined with moderate cyclosporine prevented rejection at 9+ and 25 days in sensitized recipients compared with vascular rejection at 0.5-2 days for controls (P<0.07). CONCLUSIONS: ST seems to provide protection against vascular rejection. The cellular rejection seems sensitive to cyclosporine.

Biliary strictures in liver transplant recipients: treatment with metal stents.

PURPOSE: To determine initial and long-term results of metal stent placement in biliary strictures that failed to respond to balloon dilation. MATERIALS AND METHODS: Sixty-one metal stents were placed in 36 liver transplant recipients (age range, 3 months to 71 years) with biliary strictures that failed to respond to balloon dilation. Patients were followed up for up to 5 years. RESULTS: Initial stent placement was successful in all patients. Primary patency was 44% at 3 years and was 0% at 5 years; secondary patency was maintained at 88% at those intervals. Patency associated with the Gianturco Z stent was superior to that with the Palmaz stent. Stents located at anastomotic sites had higher patency rates than those at nonanastomotic sites. Major stent-related complications occurred in eight patients and included two pediatric deaths. CONCLUSION: Metal stents can be useful in the short term but have limited patency, often require repeat intervention, and have substantial complications. Long-term success depends heavily on repeat interventions or stent removal.

Complications and technical limitations of hepatic arterial infusion catheter placement for chemotherapy.

PURPOSE: To determine the rate of complications associated with hepatic arterial infusion (HAI) catheter placement, as well as technical success related to liver perfusion. MATERIALS AND METHODS: The authors reviewed 44 patients who underwent 106 HAI catheter placements, including 15 men and 29 women with an average age of 55 years (range, 32-82 years). One to nine placements were performed per patient with 61 (58%) via the left brachial artery, 40 (38%) via the right femoral artery, and five (4%) via the left femoral artery. Chemoinfusion lasted 4 days, with initial catheter placement assessed on technetium-99m macroaggregated albumin (MAA) perfusion scans, as well as daily abdominal radiographs. RESULTS: One hundred attempted hepatic arterial catheter placements were completed. Liver perfusion was global in 66 (66%) cases, in the right lobe only in 28 (28%) cases, and in the left lobe only in six (6%) cases. Eight (8%) had gastrointestinal (GI) tract perfusion; this was eliminated in seven cases (7%) after catheter repositioning. Forty-six (43%) placement attempts required embolization of 62 GI vessels to preclude GI chemoinfusion. Complications included one cerebrovascular accident (related to removal of a left brachial catheter), eight brachial artery thromboses (four that required emergent thrombectomy), six hepatic arterial dissections, four hepatic arterial thromboses, and four catheter malfunctions. CONCLUSIONS: HAI catheter placement via the left brachial artery has increased complications. Nearly one-half of placements required embolization of GI vessels to preclude GI perfusion. Global perfusion is possible in two-thirds of cases.

Cardiac perforation and tamponade during transjugular intrahepatic portosystemic shunt placement.

A patient developed acute severe hemodynamic compromise during a transjugular intrahepatic portosystemic shunt (TIPS) procedure for intractable ascites. Rapid clinical and radiographic evaluation of the patient disclosed pericardial blood and cardiac tamponade as the cause, probably due to right heart perforation from guidewire and catheter manipulation. The tamponade was successfully treated percutaneously, and the patient survived. Cardiac tamponade should be considered in the differential diagnosis of patients who develop hypotension during TIPS placement.

An unopened titanium Greenfield IVC filter: intravascular ultrasound to reveal associated thrombus and aid in filter opening.

A titanium Greenfield filter did not open following placement in the infrarenal inferior vena cava (IVC). Abdominal radiograph and cavogram showed no definite reason for filter malfunction. Intravascular ultrasound (IVUS) demonstrated the unopened filter in the IVC with thrombus binding the legs. The thrombus was disrupted with a catheter, and the filter completely expanded with a balloon. IVUS documented full-filter opening in addition to residual thrombus in the filter following manipulation.

Microbubble potentiated ultrasound as a method of declotting thrombosed dialysis grafts: experimental study in dogs.

Intravenous perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles in the presence of low frequency ultrasound (LFUS) can lyse very small clots. We develop a similar method to declot full-size arteriovenous dialysis grafts. Dialysis grafts fashioned in three dogs were cannulated and ligated. After thrombosis, three declotting techniques were randomly applied: 1) direct injection of PESDA + LFUS; 2) direct injection of saline + LFUS; and 3) intravenous PESDA + LFUS. Declotting was graded by cine angiography scores of each third of the graft on a scale of 0-4 (maximum total score = 12). Twenty-six procedures showed mean patency scores of 11.1 for direct PESDA and 8.4 for i.v. PESDA, vs 4.9 for direct saline, p = <0.001. All eight direct PESDA injections achieved lysis and good flow, but none of 8 direct saline injections succeeded, p = <0.01. Intravenous PESDA succeeded in 4 of 10 procedures, p = <0.04 vs saline. Direct injection of PESDA with transcutaneous LFUS succeeds in lysing moderate-size clots and recanalizing thrombosed fistulas.

Aortic prosthetic graft infections: radiologic manifestations and implications for management.

Prosthetic graft infections are an uncommon complication of aortic bypass. These infections may have serious sequelae such as limb loss and can be lethal. They are hard to eradicate and, under certain circumstances, difficult to diagnose. Usually, computed tomography (CT) is the most efficacious imaging method for diagnosis of graft infections due to its quick availability. The sensitivity of magnetic resonance imaging in detection of perigraft infection has not been thoroughly investigated but is probably similar to that of CT. After the early postoperative period, persistent or expanding perigraft soft tissue, fluid, and gas are the CT findings of graft infection. Aortoenteric fistula should be considered a subset of aortic graft infection; however, perigraft air is more likely to be seen with an aortoenteric fistula. Other conditions associated with graft infection include pseudoaneurysm, hydronephrosis, and osteomyelitis. Adjunctive studies such as sinography, ultrasonography, gallium scanning, and labeled white blood cell scanning can be quite useful in diagnosis, determination of the extent of disease, and selection of the treatment modality. White blood cell scanning is an important complementary test to CT in ambiguous cases, such as in the early postoperative period, and may be more sensitive in detection of early graft infection.

Relative ultrasonographic echogenicity of standard, dimpled, and polymeric-coated needles.

PURPOSE: To use quantitative ultrasonographic measurements to compare the effect of a polymeric coating designed to increase needle echogenicity to commercially available needles. MATERIALS AND METHODS: Commercially available standard smooth and dimpled echogenic tip 21-gauge needles established reference levels of echogenicity in gelatin-based and turkey breast phantoms. Examples of both types of needles were coated with a thin polymeric film that utilizes entrapped microbubbles of air on its surface to increase echogenicity. Samples of each type in both coated and noncoated versions were placed in phantoms in matched positions and imaged with clinical ultrasound machines. Similar numbers of each category were evaluated at various angles of insonation for a total of 109 images. Similar numbers of each category were imaged at 5-minute intervals for up to 38 minutes for a total of 226 images. Images were recorded, digitized, and evaluated for relative echo strength in arbitrary echogenic brightness units. RESULTS: Coating increased peak echogenicity over the entire needle to a level that closely approximates the peak echogenicity of dimpled needle tips (means: dimpled = 834, coated smooth = 803, coated dimpled = 823; P = .54). Smooth is lower than this group at 468 (P = .0001). Representative area echogenicity increased with coating or dimpling (smooth = 377 vs coated smooth = 778, coated dimpled = 690, dimpled = 775; P = .0001). Coating increased peak values 74% and area values 95% compared to smooth. Decreased angles of insonation moderately reduced echogenicity on coated smooth, coated dimpled, and dimpled, while it decreased to below good visibility threshold on standard smooth needles. The echogenicity of the coated needles fades in saline with time (1%/min). CONCLUSION: Objective measurements show that this coating significantly increases echogenicity of entire needles to match that obtained with a dimpled tip.