Combined liver-kidney transplantation in patients with cirrhosis and renal failure: effect of a positive cross-match and benefits of combined transplantation

Patients with renal failure after liver transplantation have a particularly poor prognosis. Therefore, in the setting of end-stage renal disease requiring dialysis or severe renal insufficiency that will not improve after liver replacement, combined liver-kidney transplantation (LKT) is the preferred approach. We have adopted a policy of LKT in patients with end-stage liver disease and renal insufficiency undergoing dialysis or with a creatinine clearance less than 35 mL/min and evidence of chronic renal dysfunction. Since 1991, we have performed 208 orthotopic liver transplantations. Fourteen patients (8%) have undergone combined LKT, including 6 patients undergoing hemodialysis. Cytotoxic cross-matches (modified Amos technique and antihuman globulin method) were performed on 13 of 14 patients and were positive in 3 patients. Two patients died less than 4 months after LKT and 12 patients are alive and well. Graft survival censored for patient death was 100% for liver allografts and 93% for renal allografts, with a mean follow-up of 39 +/- 24 months. The most recent serum creatinine level in the patients with the 11 functioning grafts was 1.1 +/- 0.6 mg/dL. Biopsy-proven acute rejection occurred in 50% of simultaneous liver allografts. By contrast, only a single episode (6%) of renal allograft dysfunction was attributable to acute rejection. All rejection episodes occurred in the first 90 days after transplantation and were steroid sensitive. Three of 14 combined procedures were performed in the setting of a positive cytotoxic cross-match. In 2 recent patients, the results were confirmed by positive cross-matches to the donor's T and B cells by flow cytometry. Flow cytometric cross-matches reverted to negative 1 hour after liver transplantation and several hours before the administration of antithymocyte globulin. The cross-matches remained negative on postoperative days 1 and 7. Presently, all 3 patients with a positive cross-match enjoy normal hepatic and renal function at 631, 706, and 2275 days follow-up. Renal scans were performed in 4 LKT recipients not previously undergoing hemodialysis and indicated varying and unpredictable degrees of function in the native and transplanted kidneys. In conclusion, combined LKT can be performed safely and is associated with a low rate of acute rejection, even in the setting of a positive cross-match. Predicting which patients with renal insufficiency will benefit from LKT remains challenging; however, these results suggest that LKT should be encouraged in patients with evidence of irreversible renal insufficiency who require liver transplantation.

Two hundred one consecutive living-donor nephrectomies

OBJECTIVE

To assess donor morbidity, recipient outcome, and changing trends during the past decade in donor nephrectomy for living-donor kidney transplantation.

DESIGN AND SETTING

Retrospective review at an academic tertiary care referral center.

PATIENTS

We reviewed 201 consecutive living-donor kidney transplantations performed between January 1988 and June 1997.

INTERVENTION

Donor nephrectomy and living-donor kidney transplantation.

MAIN OUTCOME MEASURES

Donor surgical complications, correlation of preoperative imaging of donor vascular anatomy and operative findings, and donor lengths of stay in the hospital were analyzed. Recipient delayed graft function and actuarial 1- and 5-year patient and graft survival rates were also analyzed.

RESULTS

Major donor postoperative complications were bleeding (0.5%), pneumothorax requiring a chest tube (1%), wound infection (1%), and pneumonia (1%). Minor postoperative complications were asymptomatic pneumothorax resolving spontaneously (10%), urinary retention (6%), and urinary tract infection (0.5%). Preoperative imaging failed to detect small accessory renal arteries in 12% of donors. The mean donor length of stay in the hospital was 5.0 days but decreased from 6.2 to 4.0 days during the study. Twenty donors (10%) were unrelated (ie, spouse or friend). Three (1.5%) cases of delayed graft function occurred. Overall recipient patient survival at 1 and 5 years was 97% and 90%, and graft survival was 95% and 83%, with no difference between related and unrelated living donors.

CONCLUSIONS

Living-donor nephrectomy is associated with low surgical morbidity. Recent trends include shortened lengths of stay in the hospital, the use of computed tomographic angiography instead of digital subtraction angiography for preoperative imaging of donor vascular anatomy, and an expanded use of unrelated living donors.

Peripheral vascular disease after kidney-pancreas transplantation in diabetic patients with end-stage renal disease

OBJECTIVE

To determine the long-term effect of a functioning pancreas transplant on peripheral vasculopathy.

DESIGN

We compared the progression of peripheral vascular disease in 39 recipients of successful kidney-pancreas transplants (KPT) with 65 consecutive diabetic patients who received cadaver kidney transplants alone (KTA) during the same period in a nonrandomized, retrospective control study. The mean duration of follow-up was more than 4 years in both groups.

SETTING

Academic subspecialty referral practice.

PATIENTS

A consecutive sample of all KPT recipients with more than 6 months of pancreas allograft function performed between May 1, 1988, and April 30, 1995. All patients who received cadaver renal transplants for diabetic nephropathy during the same period and who maintained a functioning renal allograft for more than 6 months were included as controls.

INTERVENTION

Kidney-pancreas transplantation.

MAIN OUTCOME MEASURE

Progression of peripheral vascular complications (PVC) defined as any midfoot or limb amputation (AMP), any ischemic ulceration requiring treatment (ULCER), and lower-extremity bypass surgery or angioplasty (LEBP). Ulcers leading to amputation were considered as single events (AMP only).

RESULTS

Thirty-five (90%) of 39 KPT recipients are insulin-free. The KTA recipients had more atherosclerotic risk factors, including a higher incidence of coronary artery disease (P = .008), higher serum cholesterol levels (P = .03), and higher triglyceride levels (P = .04) than KPT recipients. Peripheral vascular complications before transplantation were comparable (P = .94) between groups. After transplantation, there were 35 new PVC (9 AMP, 11 ulcers, and 15 LEBP) in 18 of 39 KPT recipients vs 32 PVC (10 AMP, 8 ulcers, and 14 LEBP) in 20 of 65 KTA recipients (P = .005), indicating that KPT recipients had more PVC than did KTA recipients, despite a functioning pancreas. Seven bypass grafts failed after KPT, resulting in 6 limb amputations. In contrast, only 3 limb amputations were performed in 14 patients undergoing lower-extremity bypass procedures after KTA.

CONCLUSIONS

Despite fewer risk factors for peripheral vasculopathy and the presence of insulin independence, KPT recipients had a higher incidence of PVC than a cohort of uremic diabetic patients undergoing KTA during the same period. These data show that a functioning pancreas allograft performed with a renal transplantation not only does not alter the progression of peripheral vascular disease in patients with renal failure secondary to diabetic nephropathy but also may accelerate PVC.

Correlation of clinical outcomes after tacrolimus conversion for resistant kidney rejection or cyclosporine toxicity with pathologic staging by the Banff criteria

BACKGROUND

Refractory rejection and cyclosporine (CsA)-induced nephropathy remain important causes of renal allograft loss. Previous studies demonstrated that 70-85% of the episodes of refractory acute rejection (AR) occurring in renal allograft recipients on a CsA-based immunosuppressive regimen could be salvaged by conversion to tacrolimus. No data are available regarding the correlation between allograft histology at the time of conversion and the response to tacrolimus. We examined the response to tacrolimus conversion in relation to preconversion biopsies stratified by the Banff criteria.

METHODS

Since May 1992, we have converted 22 patients from CsA to tacrolimus as part of a rescue protocol. We report on 18 patients in whom 6-month follow-up was available after conversion for biopsy-proven AR (n=13) or CsA toxicity (n=5). Sixteen patients were recipients of renal allografts, including three second transplants, and two were recipients of kidney-pancreas transplants. All patients with AR were treated with one or more courses of methylprednisolone and OKT3 before conversion. Renal allograft biopsies were interpreted by a transplant pathologist blinded to the clinical history, and graded according to the Banff criteria. Responses to tacrolimus were scored as improved (creatinine returned to within 150% of baseline), stabilized (creatinine rise arrested), or failed (returned to dialysis). RESULTS; Mean follow-up was 17.3+/-8 months. Fourteen of 18 patients (78%) showed improvement or stabilization in renal function as assessed by creatinine at 6 months or 1 year (when available). Of the 13 patients with histological AR, nine (69%) improved, including five of six with borderline AR, two of three with grade I AR, and two of four with grade II AR. Of the four other patients with AR, two stabilized and two failed. Three of five patients with severe clinical rejection requiring dialysis (range 2-16 weeks) recovered renal function after conversion. Of five patients with CsA toxicity, two (40%) improved. Seven of eight patients who were converted to tacrolimus less than 90 days after transplantation improved, compared with only 4 of 10 who were converted more than 90 days after transplantation. No grafts were lost in patients with a creatinine <3.0 mg/dl at the time of conversion versus two of seven grafts lost when the creatinine was 3.1-5.0 mg/dl and two of eight grafts lost when the creatinine was >5.0 mg/dl.

CONCLUSION

The majority of steroid and antilymphocyte antibody (OKT3 or ATGAM) unresponsive rejections in patients on CsA-based immunosuppression will improve or stabilize after conversion to tacrolimus. There was no correlation with allograft histology stratified by the Banff criteria and the response to tacrolimus. Although there was a trend toward a poorer response with more severe histological rejection, higher serum creatinine at the time of conversion, and longer time from transplantation to conversion, favorable responses were noted in all groups. This indicates that a trial of conversion is warranted, irrespective of the histological severity of injury.

A single-center experience with six-antigen-matched kidney transplants

OBJECTIVES

To review our center's experience with the United Network of Organ Sharing six-antigen-matched (6-AgM) kidney program. Specifically, to determine whether recipients of 6-AgM cadaver kidney transplants have less perioperative and short-term (< 1 year) morbidity in comparison with living-related donor (LRD) recipients and a control group of immunologically less well-matched cadaver recipients.

DESIGN

A retrospective review of all solitary kidney transplantations performed over a 24-month period, from 1992 to 1993.

SETTING

A large urban tertiary care referral center with a long history of renal and extrarenal transplantation.

PATIENTS

Adult patients receiving a solitary kidney transplant from either a cadaver or a living donor.

MAIN OUTCOME MEASURES

Mortality, morbidity, and patient and graft survival. Other variables measured included rejection episodes, length of stay, readmissions, postoperative complications, waiting time, and delayed postoperative graft function.

RESULTS

Recipients of 6-AgM kidney transplants were at higher risk than the control groups of cadaver and LRD recipients, with more retransplantations, higher sensitization, and more with diabetes. There were fewer rejection episodes in the 6-AgM group, and these were more steroid responsive. They had fewer hospital days (22.6 days) in the first year following transplantation, compared with the remaining cadaver group (28 days). The delayed postoperative graft function rate was also significantly lower than that of the cadaver control group. Graft and patient survival were excellent for all groups. Analysis of these factors showed similar results when comparing the LRD and 6-AgM groups and a marked improvement over the cadaver control group.

CONCLUSIONS

Identical HLA matching for cadaver recipients provides superior results for graft and patient survival. There is much less perioperative morbidity in comparison with the less well-matched cadaver recipients. The effect of HLA matching is reflected in the perioperative courses of these patients, in addition to the long-term benefits of graft survival. Allograft survival is superior for this select group of cadaver recipients. The 6-AgM recipients behave similarly to LRD recipients in this cohort of patients. Our results would support the continued sharing of 6-AgM kidneys to optimize outcome and best use the limited resources available to the patients undergoing transplantation.

Kidney transplantation in diabetic patients using cyclosporine. Five-year follow-up

OBJECTIVE

To review our center's experience with kidney transplantation in diabetic recipients; specifically, to compare long-term (5-year) patient and graft survival rates between diabetic and nondiabetic recipients overall and according to donor source using cyclosporine-based immunosuppression.

DESIGN

A retrospective review of all kidney transplants performed over the 7-year period from 1987 to 1993.

SETTING

A large urban tertiary care referral center with a long history of kidney transplantation and care of the diabetic patient.

PATIENTS

All patients receiving a kidney transplant, either alone or simultaneously with a pancreas transplant, were reviewed.

MAIN OUTCOME MEASURES

Actuarial patient and graft survival, serum creatinine levels, and causes of late graft loss.

RESULTS

There was no significant difference in actuarial 5-year patient or kidney graft survival between diabetic and nondiabetic recipients overall or when analyzed by donor source. There was no significant difference in mean serum creatinine levels at 5 years between diabetic and nondiabetic recipients overall or between diabetic and nondiabetic cadaveric recipients. While chronic rejection was the major cause of late graft loss in nondiabetic recipients, death with a functioning graft, principally due to cardiovascular disease, was the major cause of graft loss in diabetic recipients.

CONCLUSIONS

With cyclosporine-based immunosuppression, diabetic kidney transplant recipients have 5-year patient and graft survival rates and allograft function comparable to nondiabetic recipients. Given the high mortality of diabetic patients receiving dialysis, kidney transplantation is the treatment of choice for end-stage diabetic renal disease.

Combined kidney and pancreas transplantation. A 3-year experience

Between May 1988 and September 1991, we performed 26 simultaneous kidney and pancreas transplants and one pancreas transplant after a kidney transplant. All transplants consisted of bladder drainage via a duodenal segment. Actuarial patient, kidney, and pancreas graft survival rates at 12 months were 96%, 88%, and 85%, respectively, and at 24 months were 96%, 88%, and 81%, respectively, and were not significantly different from those of diabetic recipients of cadaver kidney transplants alone. Excellent long-term glycemic control was obtained as monitored by fasting blood glucose and glycosylated hemoglobin levels and by oral glucose tolerance tests. The mean period of hospitalization and number of hospital admissions in the first year posttransplant were significantly greater for patients who received combined kidney and pancreas transplants than for those who received cadaver kidney transplants alone. Combined kidney and pancreas transplants can be performed with patient and graft survival comparable to those of kidney transplants alone, with excellent long-term glycemic control, but result in increased morbidity in the first postoperative year.

Bioavailability and patient acceptance of cyclosporine soft gelatin capsules in renal allograft recipients

OBJECTIVE

To evaluate the relative bioavailability and patient acceptance of cyclosporine (CSA) soft gelatin capsule versus oral solution in renal allograft recipients.

DESIGN, SETTING, AND PATIENTS

The bioavailability of CSA capsules was compared with that of CSA solution with crossover study design in the outpatient clinic setting. Nine renal allograft recipients with stable renal function participated in this study.

METHODS

CSA dose was switched from solution to capsule in each patient for seven days. At steady-state, nine blood samples were obtained over a 12-hour period from each patient on day 7 for CSA solution and on day 14 for CSA capsules. CSA blood samples were analyzed by HPLC and fluorescence polarization immunoassay (FPIA) methods. Time to peak concentration (Tmax), peak concentration (Cmax), and area under the curve (AUC) were calculated on days 7 and 14, and compared using the matched Student's t-test. Patient acceptance was evaluated by patient preference on the questionnaire.

RESULTS

For CSA blood concentrations measured by HPLC assay, the Tmax, Cmax, and AUC were 3.4 +/- 1.3 h, 569 +/- 240 nmol/L, and 4659 +/- 2144 h.nmol/L (mean +/- SD), respectively, with solution and 4.2 +/- 2.1 h, 560 +/- 257 nmol/L, and 4765 +/- 1799 h.nmol/L (mean +/- SD), respectively, with capsules. These differences were not significant (p greater than 0.1). The bioavailability was not significantly different between capsules and solutions when it was measured by PFIA assay (p greater than 0.1). The mean (+/- SD) relative bioavailability of capsules compared with solution was 109 +/- 29 percent AUC (0-12 h) measured by HPLC and 111 +/- 27 percent AUC (0-12 h) measured by FPIA. All patients expressed preference for capsules over the solution.

CONCLUSIONS

CSA oral soft gelatin capsule is bioequivalent to CSA oral solution and most patients preferred the capsule to the oral solution.

Use of Dacron cuffed silicone catheters as long-term hemodialysis access

Sixty-five Dacron cuffed, dual lumen, silicone central venous dialysis catheters (Quinton PermCath, Seattle, WA) were inserted in 51 patients as the sole form of permanent access for chronic hemodialysis. Six and 12 month actuarial survival rates of patients for all catheters were 53% and 35%, respectively. When calculations included revisions, 6 and 12 month actuarial catheter survival rates were 61% and 43%, respectively. The major limiting factors in survival using long-term catheters remain infection and thrombosis. Dacron cuffed, dual lumen, central venous, dialysis catheters can provide long-term vascular access for hemodialysis in high risk patients.

Immunologic heterogeneity among potential transplant recipients. Prospects for predicting immune responses to allografts with in vitro tests

The ability to accurately predict the response of a specific patient to a specific organ allograft has long been a goal of organ transplantation. The role of histocompatibility antigens in determining the acceptance or rejection of an allograft-recipient combination has been thoroughly investigated, but is being reevaluated as improved immunosuppressive agents become available. Early efforts at immunologic monitoring are reviewed in addition to more recent efforts that focus on the cellular and molecular mediators of immunity. The authors' own experience with lymphokine measurements in clinical transplantation is also reviewed, with emphasis on the role of interleukin-2 (IL-2) and its soluble receptor (IL-2R) in various transplant-associated conditions. The authors conclude that information useful in the management of transplant patients may be derived from serial measurements of IL-2 and IL-2R, but that infections, especially CMV, may not be ruled out with certainty by these measurements alone. The available data suggest that study of additional lymphokines such as interferon-gamma (IFN-gamma) and tumor necrosis factor (TNF) may be useful in discriminating rejection from infections in transplant patients.

Sequential interleukin 2 and interleukin 2 receptor levels distinguish rejection from cyclosporine toxicity in liver allograft recipients

Previous studies of renal transplant recipients have demonstrated that allograft rejection is accompanied by an increase in plasma and urinary levels of interleukin 2 and its soluble receptor before the development of clinical symptoms. After measuring interleukin 2 and interleukin 2 receptor levels in the plasma, bile, and urine of liver transplant recipients, we found that rejection is preceded by elevation of plasma and biliary levels of both substances, that cyclosporine toxicity did not affect either of these levels, and that urinary levels of the substances are unaffected in either condition. Levels of interleukin 2 and interleukin 2 receptors increased in bile earlier than in plasma, and interleukin 2 levels did not overlap among stable patients and those experiencing rejection, whereas levels of interleukin 2 receptors did. Serial measurements of interleukin 2 levels, particularly in the product of the transplanted organ, provide a reliable assessment of the immunologic status of the allograft.

Acute aortic thrombosis presenting as painless paraplegia

Two patients with acute aortic thrombosis presented with painless paraplegia secondary to spinal cord infarction. In one case, the initial symptom was unilateral leg weakness, leading to the misdiagnosis of stroke. In the other case, a patient with a large, painful vulvar abscess, experienced spontaneous relief of pain. In the complete absence of pain, both patients slept undisturbed and awoke with complete paraplegia, incontinence, and cadaveric extremities. Aortic reconstruction was advised to obviate thigh or hindquarter amputation, not to restore limb function. One patient died on the second postoperative day; the second remains well but paraplegic two years later.

Sequential determinations of urinary cytology and plasma and urinary lymphokines in the management of renal allograft recipients

Urine cytology, plasma (P), and urinary (U) interleukin-2 (IL-2)* and IL-2 receptor (IL-2R) levels were evaluated as immunological monitoring techniques in 65 renal allograft recipients. Normal individuals showed normal urine cytology, IL-2(U) = 0, IL-2(P) = 0.4 +/- 0.1 ng/ml (mean +/- SEM) and IL-2R(P) = 318 +/- 26 U/ml. Stable transplants also showed normal urine cytology, no IL-2(U), IL-2(P) = 0.8 +/- 0.2 ng/ml, and IL-2R(P) = 326 +/- 29 U/ml. Rejection episodes (n = 21) were accompanied by cytologic changes, including lymphocyturia, exfoliation of immature tubular cells, platelet aggregates, and fibrin deposits. The corresponding lymphokine changes were IL-2(U) = 39.6 +/- 1.4 ng/ml, IL-2(P) = 79 +/- 21 ng/ml, and IL-2R = 1884 +/- 202 U/ml, all markedly increased. Successful treatment was associated with return of all parameters to normal; treatment failure was associated with continued abnormalities. Fourteen rejections unresponsive to Solumedrol (500 mg x 5 days) required OKT3 rescue (5 mg x 14 days). In the 11 that were reversed, onset of OKT3 therapy was characterized by markedly increased exfoliation of necrotic cellular debris, lymphocytes, and collecting duct cells. Interestingly, serum creatinine increases of 57.2 +/- 18.9% (range 25-90%) over pre-OKT3 levels were noted. Maximal changes occurred 48-72 hr after the first dose, followed by gradual return to normal. Rejections unresponsive to OKT3 (n = 3) showed no cytologic changes from the pretreatment mean creatinine increase of 13.2 +/- 2.7% (range 9-15%), and maximum change occurred 24 hr after the first dose. Rejections responsive to Solumedrol only (n = 4) showed gradual improvement of all parameters. Rejections treated with Solumedrol following failed OKT3 prophylaxis (n = 3) did not reverse and continued to show rejection associated cytologic changes and abnormal creatinines. Patients experiencing CsA toxicity (n = 12) showed mild creatinine elevations, normal or negative IL-2(P) and IL-2R(P) levels, and no IL-2(U). They showed distinctive cytologic changes consisting of swollen convoluted tubular cells with nuclear pyknosis and cytoplasmic vacuoles. Pretransplant IL-2(P) levels of patients who subsequently rejected were elevated, with 19/21 patients with preoperative IL-2 levels greater than 15 ng/ml having subsequent rejections. In contrast, pretransplant creatinine, urine cytology, and IL-2(U) levels showed no correlation to subsequent clinical course.(ABSTRACT TRUNCATED AT 400 WORDS)

Does non-invasive carotid testing influence the selection of patients for carotid surgery?

To help define the role of non-invasive carotid testing, all patients undergoing carotid endarterectomy between January 1/1978 and December 31/1983 were reviewed. In late 1979, non-invasive carotid tests became available. No significant changes in the indications for carotid endarterectomy occurred in this interval, and all carotid patients were investigated with arteriography prior to operation. In this setting, we investigated the role, if any, of the carotid laboratory. Within two years of introduction, 1200 carotid tests were performed annually, a level which remained stable. It was found that the percentage of patients with significant lesions at arteriography increased, and the proportion of patients progressing to surgery after arteriography went up by 50%. Remarkably, the number of arteriograms did not increase in this interval. The present ratio of non-invasive studies to angiograms is 12:1, but when this ratio was only 4.6:1 in 1980, the increased yield of surgery following angiography was already noted. These results indicate that the non-invasive tests increase the accuracy of clinical diagnosis, place relatively fewer patients at risk from angiography, and are readily accepted and used by clinical staff even when angiography is used to evaluate all possible operative candidates. The results suggest that these benefits can be realized when non-invasive tests are ordered when necessary after careful clinical evaluation, and that their use as a screening measure in all patients with possible cerebrovascular disease may not be necessary.

Binding of antihuman globulin by exfoliated renal tubular cells following kidney transplantation

Exfoliated renal tubular epithelial cells (RTCs) from kidney allograft recipients may bind antibody against human globular proteins. Urine from sixty consecutive transplant recipients was studied in the first month following transplantation to relate this binding to the clinical course and rejection. The spun, washed sediment was incubated with fluoresceinated goat antihuman globulin and examined under light and fluorescent microscopy for fluoresceinated RTCs. Of 28 patients who were never positive, 27 manifested no clinical rejection episodes. Of 22 total rejection episodes, 21 were preceded by the appearance of fluorescent RTCs. Five patients in this group did not revert to negative in this test, and all went on to loss of graft from acute rejection. Of 46 patients who were discharged from the hospital with negative RTCs, only four were readmitted within one month for treatment of rejection. In contrast, of the 11 patients who were positive at the time of discharge, 10 were readmitted in the first month. Graft survival was only 55% (6/11) in this latter group as compared with 91% (42/46) in the former. There were 11 patients with transiently positive tests who did not warrant a clinical diagnosis of rejection. In no case of acute tubular necrosis (ATN) alone or in obstructive uropathy was the assay positive. However, in some cases, in which the ATN merged imperceptibly into rejection, the RTCs started to fluoresce well in advance of the clinical suspicion of rejection. Information obtained from this examination may be used to assess the cause of renal failure in the early posttransplant period and to differentiate rejection from ATN and obstruction. This phenomenon of fluorescent RTCs may be an early manifestation of an immunological change occurring in a cell that is targeted by the host for rejection.

Conformational stress and anastomotic hyperplasia

Late failure of synthetic vascular grafts to small-diameter arteries (less than or equal to 4 mm) is commonly due to anastomotic hyperplasia. Theoretic analysis suggests that conformational changes at the anastomosis lead to high localized arterial wall stress caused by increases in radius of curvature of the artery (law of Laplace: tension = pressure X radius). Nine 3 kg rabbits had a plastic insert implanted into the infrarenal aorta. The insert was designed to recreate the conformational changes caused by the anastomosis of a synthetic graft to a small-diameter artery, without significantly altering blood flow. The increase in arterial wall tension created by the insert was calculated to be 80% to 100% over baseline values. Aortography, real-time ultrasound, and computed tomography (CT) scanning were done to confirm the absence of luminal thrombus formation or migration of the insert. Ultrasound and CT scans also confirmed the desired conformational changes in the aorta at the site of the insert. Aortas, with the inserts in place, were removed from 3 days to 6 months after implantation. Implantation times of 1 to 6 months resulted in a hyperplastic subintimal lesion characterized by fibrous tissue deposition, spindle cells (which may have been fibroblasts), and/or smooth muscle cells covered by endothelium. In contrast, two rabbits that had the insert placed and then removed at 1 minute and were allowed to survive for 37 and 72 days, respectively, demonstrated complete healing of the aorta without anastomotic hyperplasia. The arterial wall conformational changes induced in this experiment led to the formation of a lesion consistent with anastomotic hyperplasia. An increase in wall tension may have been the stimulus for this response. Prevention of anastomotic hyperplasia may require a means of uniting a graft to an artery without increasing wall tension.

Reduction in complement activation from biomaterials by removal of air nuclei from the surface roughness

The activation of the rabbit complement system by each of three different synthetic materials is reported. Samples of each type of material were subjected to one of two different priming procedures. One priming procedure was intended to remove the air nuclei from the surface roughness of the materials; the other procedure was just the normal one. It was found that the removal of the air nuclei during priming reduced the complement activation by each of the two materials of lower surface tension, but not by a statistically significant amount for the material of highest surface tension, cellophane. For the denucleated samples of the three materials, the amount of complement activation was found to correlate with the critical surface tension of the materials; if the samples of the materials were normally primed, there was no correlation of the amount of complement activation with the critical surface tension of the material.

Femoropopliteal bypass: saphenous vein and expanded polytetrafluoroethylene grafts

The patency of 181 saphenous vein and expanded polytetrafluoroethylene (PTFE) femoropopliteal bypass grafts was assessed during a follow-up that ranged from 1 to 53 months after operation. Significantly better patency (P less than 0.05) was noted with saphenous vein (70%) than with PTFE (56%). Life-table analysis at 30 months demonstrated a cumulative patency of 50% for saphenous vein grafts versus 39% for PTFE, while at 53 months the rates were 46% and 33% respectively. The PTFE grafts tended to occlude earlier than saphenous vein grafts but after the initial year, both types of graft failed at a rate of about 5% a year. Patency was similar in both groups when operation was performed for claudication, but for limb salvage operations saphenous vein patency was superior to PTFE. Although the groups were similar in constitution, a higher percentage of patients in the PTFE group had undergone previous vascular operations.

Aortoiliac reconstruction following renal transplantation

With better survival and extended indications for renal transplantation, it is anticipated that the problem of aortoiliac disease in the posttransplant patient will be seen with increasing frequency. Two patients requiring aortoiliac reconstruction were successfully managed with improvement in graft function after surgery. One patient manifested atheroembolism resulting from aortoiliac occlusive disease; the other had a 2 cm rupture in an aortic aneurysm, which resulted in a large retroperitoneal hematoma, but without frank shock. Perfusion of the transplanted kidney was maintained by the use of a temporary axillofemoral graft, which was removed following aortoiliac repair. The use of this technique involves minimal physiologic disturbance to the patient and the renal graft and allows conventional aortoiliac reconstruction.

Intra-arterial alprostadil for nonatherosclerotic vasculopathy

A 33-year-old man with a nonatherosclerotic vasculopathy of undetermined origin had progressive occlusive disease of the lower limb vessels. The resultant severe rest pain and ischemic ulceration of his foot were inoperable and unresponsive to conventional drug therapy. Treatment was begun with intra-arterially administered alprostadil (prostaglandin E1), a vasodilator and inhibitor of platelet aggregation. Although immediate benefit was equivocal, his rest pain had disappeared six weeks after infusion, and the ischemic ulcer almost healed completely. Blood flow studies showed increased flow to the feet, consistent with the subjective improvement. The beneficial effect of alprostadil suggests that further studies with this agent are warranted for patients with nonatherosclerotic vasculopathy.

Numerical simulation of blood and plasma flow through the Petschek flow chambers

The Stagnation Point Flow Experiment is a popular means for studying blood-surface interactions in a surface strain rate gradient. The strain rate distribution on the test surface of the flow chamber used in this experiment was originally assumed to be simply proportional to the radial distance from the stagnation point. A numerical simulation of the flows through the five most frequently used chambers shows that this is true only for one of the chambers, approximately so for another, and not true for the other three. An additional numerical simulation indicates the blood should purge the saline priming liquid within a few seconds at the beginning of the experiment.

Portacaval shunt for familial heterozygous hypercholesterolemia

Two patients with heterozygous familial type 2 hypercholesterolemia are reported upon following treatment with end-to-side portacaval shunting. In both, the portacaval shunt decreased the cholesterol level by about 40 per cent. No adverse effects of the operation could be seen in either patient at 30 months, and no return of cardiovascular disease is evident in either patient. In one patient with large xanthelasmas, the lesions became a much duller yellow color and regressed from an elevated to flat appearance. However, the margins of the lesions did not change significantly. In young patients with heterozygous type 2 hypercholesterolemia in whom cardiovascular complications pose a major threat to life, a portacaval shunt is an effective means of reducing the cholesterol level. The benefits to the patient outweight the risks of operation. In one patient, an anxiety reaction developed which her psychiatrist related to a stressful situation. There were no clinical signs of encephalopathy, no response to protein restriction and a minimal elevation of the serum ammonia level, 86 versus 70 micrograms per cent as the upper limit of normal.

Enhancement of thrombus formation by vascular prostheses

The stagnation point flow experiment has been used to identify the microscopic events that occur in thrombus formation on foreign surfaces. In this investigation it was used to study the role of vascular grafts in preactivating blood, as well as the role of pretreatment of these grafts to remove the gas nuclei. The experiment was carried out under two conditions: (a) in which whole blood was led from the carotid artery of a dog to the undersurface of a microscope coverslip (control experiment) and (b) in which blood flowed from the left carotid artery of the dog through a 10-cm vascular graft to the right carotid artery and finally to the flow chamber for visualization. The thrombus morphology, time to thrombus formation and thrombus adhesiveness to the foreign surfaces were compared using knitted Dacron, woven Dacron, expanded polytetrafluoroethylene (PTFE) and saphenous vein grafts. Blood led through the vascular grafts showed a marked predisposition to thrombus formation, with no change in clotting times. Knitted Dacron most highly preactivated the blood, while PTFE showed a lesser degree of preactivation. Treating expanded PTFE so that it may be completely wetted eliminated any activation of blood and caused blood to behave as if it had not contacted a foreign surface. It was the only graft material, including autogenous vein to demonstrate this property. Therefore, of the materials tested, hydrophobic Teflon with no entrapped gas appears blood compatible.

The effect of Coumadin upon thrombus forming on foreign surfaces

Experience with the Stagnation Point Flow Experiment has revealed the earliest microscopic events surrounding thrombus inception and growth on foreign surfaces in a perfectly defined flow field. Using 40 and 80 X magnification, the effects of Coumadin upon these events was studied. These events include leukocyte adherence, fibrin deposition and platelet aggregation, deviation of flow streamlines around these aggregates, and subsequent downstream thrombus growth. Surface density of leukocytes was measured as a function of time and shear, and served as an index of the quantity of thrombus on the surface, which in turn, allowed direct comparisons of thrombus growth rate between experiments. Coumadin decreases the adhesive force between leukocytes or thrombi and the foreign surface. Emboli are more frequent with Coumadin, but are smaller. Thrombus inception is not altered. These results suggest that clinical benefit obtained from use of Coumadin derives from reduction in size of emboli.

Ascending aorta to bilateral femoral artery graft via a ventral subcutaneous route

Two patients were treated for grossly ischemic legs by a graft from the ascending aorta to both common femoral arteries. After leaving the mediastinum, the graft lay in the subcutaneous position throughout its course. In both patients, standard aorto-femoral repair was considered unduly hazardous because of gross obesity, large incisional hernias, previously unsuccessful vascular procedures, impaired renal function, emphysema, and complete occlusion of the abdominal aorta to the level of the renal arteries. Both patients had evidence of bilateral subclavian artery stenosis or occlusion. The technique of the operation is described and its assets and liabilities discussed. Within strict limitations, it is an alternative to axillo-femoral bypass.

Hemodynamic evaluation of intra-aortic balloon pumping in man

Intra-aortic balloon pumping is effective in reducing left ventricular peak systolic pressure and increasing cardiac output in patients with severe cardiogenic shock secondary to acute myocardial infarction. Associated with these effects is a reduction in intravenous catecholamine requirements and increased sensitivity to diuretics. Reduction in left ventricular end-diastolic pressure is implied by improvement in arterial blood gas saturation (reduced arterioalveolar gradient) and was shown directly in one patient. Total myocardial oxygen consumption is probably reduced by counterpulsation. Platelet levels have not fallen significantly with adequate heparinization and the slow infusion of low molecular weight dextran. No complications have occurred related to femoral artery cannulation, nor has there been significant damage to the aorta.

The findings suggest that this system is a safe means of assisting the failing left ventricle. The high mortality in this series (seven of eight patients) is related to the extent of irreversible myocardial damage which may be reduced by more aggressive, earlier application of counterpulsation.