Immunologic considerations in renovascular hypertension

Transplant Renal Artery Stenosis: Association With Acute Vascular Rejection

BACKGROUND

Transplant renal artery stenosis, the prevalence of which varies from 2% to 12%, is an important cause of hypertension and allograft dysfunction. We sought to determine the clinical characteristics of this disorder, assessing, predisposing factors, establishing treatment options, and examining patient outcomes.

PATIENTS AND METHODS

Among 321 renal allograft recipients between November 1996 and December 2004, six patients were identified with this finding. We analyzed their clinical data before and after treatment compared with the 315 recipients face of the disorder.

RESULTS

The six patients with the disorder were diagnosed within the first year (2 to 8 months; median 5.5 months). All patients displayed renal dysfunction, peripheral edema, and new-onset or uncontrolled hypertension at presentation. Abnormal Doppler findings were observed in 5 (83.3%) patients. The hemodynamically significant stenosis was successfully treated with percutaneous transluminal angioplasty (PTA) in all six. However, 3 (50%) patients displayed recurrent stenosis requiring a second PTA. The mean serum creatinine level decreased from a pre-PTA value of 4.4 +/- 1.8 mg/dL to a 1-month post-PTA value of 2.2 +/- 0.5 mg/dL (P = .027). Patients had no significant improvement in mean systolic and diastolic pressure. Vascular acute rejection episodes were more frequent among the affected than the control group (3/6; 50% vs 18/315; 5.7%; P < .001). No differences were found in age, sex, donor type, etiology of renal disease, immunosuppression, acute tubular necrosis, acute cellular rejection, cold ischemia time, or HLA matching.

CONCLUSION

Transplant renal artery stenosis is a common cause of hypertension and renal allograft dysfunction. Acute vascular rejection is associated with this disorder.

Hypertension and facial palsy in middle aortic syndrome

A female infant presented with facial palsy and was found to be severely hypertensive. Plasma renin activity was raised and an angiogram showed middle aortic syndrome. This condition is of unknown aetiology, but positive antineutrophil cytoplasmic antibodies may indicate a vasculitis which heals by intimal fibrosis, causing the observed findings.

Transplant renal artery stenosis: potential role of ischemia/reperfusion injury and long-term outcome following angioplasty

PURPOSE

We assess long-term arterial pressure, renal function, and patient and graft survival in recipients of cadaveric kidney transplant with or without transplant renal artery stenosis. We also evaluate the risk factors for transplant renal artery stenosis.

MATERIALS AND METHODS

We reviewed and analyzed baseline clinical, immunological and outcome data for 26 patients with transplant renal artery stenosis before and after angioplasty, and 72 without stenosis on angiography. We also analyzed graft and patient survival in 304 cases in which angiography was not performed.

RESULTS

The incidence of transplant renal artery stenosis was 6.6% (26 of 402 patients). Acute rejection episodes (42 versus 22%, p <0.05) and delayed graft function (50 versus 32%, p <0.10) were more frequent, and mean cold ischemia time plus or minus standard error (29.2+/-1.7 versus 24.8+/-1.3 hours, p <0.01) was longer in patients with than without transplant renal artery stenosis. The technical success of angioplasty was 92.3%. Restenosis was documented in 6 of 26 patients (23.1%). Revascularization resulted in a decrease in arterial pressure and better renal function. The 8-year patient (100, 98.6 and 95.7%, respectively) and graft (88.1, 88.9 and 89.3%, respectively) actuarial survival rates were similar among patients with or without transplant renal artery stenosis, and those who did not undergo angiography.

CONCLUSIONS

Transplant renal artery stenosis had no detectable influence on long-term arterial pressure control, renal function, and patient and graft survival rates, which were similar to those in patients without stenosis. Long cold ischemia time may have a role in the development of transplant renal artery stenosis through ischemia/reperfusion injury.

Transplant renal artery stenosis in 77 patients--does it have an immunological cause?

Transplant renal artery stenosis (TRAS) is a common complication after transplantation and is an important cause of graft dysfunction. Damage from graft rejection, trauma, and atherosclerosis have been implicated as possible causes. We reviewed all 917 patients transplanted in our unit since 1978 to study the prevalence, clinical features, and possible causes of TRAS. Seventy-seven patients with TRAS were identified. The detected incidence was 2.4% before the introduction of color doppler ultrasonography (CDU) and rose to 12.4% after CDU was introduced in 1985, giving an overall incidence of 8.4% during a mean follow-up period of 6.9 years. The TRAS group was compared with a control group of 77 transplanted patients matched for age, year of transplant, sex, and number of previous grafts. Mean ages for the study and control groups were 43.6 +/- 15 and 44.8 +/- 13.7 yr. A total of 25% of cases of TRAS were diagnosed within the first 8 wk of transplantation and in 60% within the first 30 wk (median = 23 wk). All patients were treated with angioplasty, 28 patients had recurrence of TRAS requiring multiple angioplasties (maximum 5) and 1 went on to have surgery. Angioplasty resulted in a significant fall in plasma creatinine. Patient and graft survival were significantly worse in the TRAS group: 69% vs. 83% (P < 0.05) and 56% vs. 74% (P < 0.05) (TRAS vs. Control), respectively. There was a significantly higher incidence of rejection, especially cellular rejection in the TRAS group, 0.67 vs. 0.35 episodes per patient (P < 0.01) (TRAS vs. Control). Recurrence but not occurrence of TRAS was associated with the use of cyclosporine.

Post-transplant renal artery stenosis: a possible immunological phenomenon

A retrospective review of 110 consecutive kidney transplants performed during 4 years revealed the development of renal artery stenosis in 9 patients (8.18%). A comparison of this group with a control group similar in patient age and interval elapsed since transplantation revealed no significant differences in donor and recipient ages, degree of HLA compatibility or serum creatinine levels. However, there was a significant difference in the number of acute rejection episodes. In our series only male patients were affected. A sizable proportion of the patients (50%) had no detectable murmur over the graft area despite high blood pressure and increased creatinine levels. The absence of surgical injury during extraction and implantation of the grafts, together with the anatomical site of the stenosis and correlation with the degree of immunological intolerance suggest an immunological factor as the underlying cause in post-transplant renal artery stenosis.

Renal artery stenosis in pediatric transplant recipients

From 1967 through 1985, 400 cadaveric transplants were performed at Children Hospital of Los Angeles. Of these 400, 31 were later identified as having renal artery stenosis. No live related graft developed RAS. Of the 31 grafts, 11 were from donors less than 2 years of age. The major feature suggesting stenosis was hypertension; either persistent or a sudden exacerbation often associated with hypertensive encephalopathy. In individuals with hypertension without obvious cause, renal angiography should be promptly conducted under controlled conditions to avoid complications. The stenotic lesion involved 13 end-to-end and 19 end-to-side arterial anastomoses. Surgery for revascularization of RAS was performed in 21 of 31 with success or improvement in 14, no change in 2, and graft loss in 5. Percutaneous transluminal angioplasty was performed in 4. Two were unsuccessful, 1 was successful and 1 graft was lost. The 7 remaining patients were treated medically.

Surgical treatment of renovascular hypertension in children: the roile of renal autotransplantation

We describe 2 children with renovascular hypertension treated successfully by autotransplantation, as well as an additional child in whom ex vivo microsurgical repair was attempted. The literature is reviewed and all patients within the pediatric age group with renovascular hypertension who were treated surgically are reported. The different types of vascular reconstructive techniques and, particularly, the previous use of autotransplantation are discussed.

Reversible renal artery stenosis in renal transplantation

Spontaneous regression of an arterial stenosis in a renal transplant recipient is documented. Implications of this observation and possible pathogenic mechanisms are discussed.

Renovascular hypertension after kidney transplantation

The development of hypertension after kidney transplantation was examined in a consecutive series of 83 transplantations (79 patients) with a graft survival of more than 30 days. After transplantation, 50% of the normotensive recipients developed mild or severe hypertension, while 74% of the hypertensive recipients remained hypertensive. Stenosis of the graft artery with a narrowing of the diameter of more than 50% was found in 13 patients and in 3 patients a minor or peripheral stenosis was found. Significantly more stenoses were seen in the presence of two donor arteries, whereas no other etiological factors could be shown. In arterial stenosis, severe hypertension was established within a few months after transplantation, but in spite of satisfactory controlled blood pressure and good graft function, hypertensive crises could arise. It is therefore concluded that arteriography and renin analysis should be considered in all cases of severe hypertension, and surgical correction should be considered when arterial stenosis is present.