Hypertension following cadaveric renal transplantation

Thoracic endovascular aortic repair for type B aortic dissection after renal transplantation

Thoracic endovascular repair (TEVAR) is an effective treatment for type B aortic dissection (TBAD). Here, we evaluated the early-midterm effectiveness and safety of TEVAR for treating TBAD patients after renal transplantation. Six patients with TBAD treated with TEVAR after renal transplantation were recruited between February 2012 and December 2016. They were then followed up with clinical examinations and computed tomography angiography (CTA). TEVAR was successfully performed in all patients (100%), and the primary tear sites were well covered by stents with or without coverage of the left subclavian artery. No severe complications occurred in any patient during perioperative period. The one-year survival rate was 100%, one patient died of renal graft failure and heart failure four years after TEVAR; the remaining five patients (83.3%) survived and exhibited no severe complications. Our findings show that TEVAR provides satisfactory short-midterm results for TBAD patients after renal transplantation. Moreover, our experience shows that it need relative longer proximal landing zone to prevent the endoleak and recurrence. However, regular hematodialysis, long-term immunosuppressive therapy, and blood pressure control remain crucial factors to prolong survival. Long-term follow-up studies are needed to evaluate the long-term prognosis in these patients.

Masked hypertension in renal transplant recipients

PURPOSE

Arterial hypertension is a risk factor affecting graft function in renal transplant recipients (RTRs). In pediatric RTRs, high prevalence of masked and nocturnal hypertension was reported. Most of the RTRs had a history of hypertension and some of them were normotensive at outpatient visits whereas home blood pressure (BP) levels were higher. Masked hypertension (MHT) is defined as a normal office BP but an elevated ambulatory BP. Previous reports have demonstrated the detrimental role of MHT in clinical outcomes in hypertensive patients. However, the true prevalence of MHT in RTRs is yet to be defined.

METHODS

A total of 113 RTRs (mean age 44 ± 16 years, 72 males, 41 females) with normal office BP (< 140/90 mmHg) were enrolled to the study from the outpatient renal transplantation clinic. Ambulatory BP monitoring (ABPM) was performed in all participants for a 24-h period. Average daytime BP values above 135 mmHg systolic and 85 mmHg diastolic were defined as MHT.

RESULTS

The prevalence of MHT in our cohort was 39% (n = 45). Fasting glucose and C-reactive protein levels were higher in patients with MHT compared with normal BP group (p = 0.02 and p = 0.04, respectively). RTRs with deceased donor type had higher prevalence of MHT than RTRs with living donor (40% vs 19%, p = 0.003). In multivariate analysis, deceased donor type could predict the MHT independent of age, gender, office systolic BP level, diabetes mellitus, serum creatinine, C-reactive protein, and glucose levels (OR = 3.62, 95% CI 1.16-11.31, p = 0.03).

CONCLUSION

We demonstrated an increased prevalence of MHT in a typical renal transplant cohort. In addition, transplantation from a deceased donor may be a predictor of MHT. The prevalence of MHT may help to explain high rate of cardiovascular events in RTRs. Therefore, routine application of ABPM in RTRs may be plausible, particularly in RTRs with deceased donor type.

The renin-aldosterone system and renal hemodynamics in patients with posttransplant hypertension

Plasma renin concentration (PRC), plasma aldosterone concentration (PAC), renal plasma flow (RPF) and glomerular filtration rate (GFR) have been studied in 19 patients who had received a renal allotransplant. Group 1 consisted of 7 normotensive and group 2 of 12 hypertensive patients. Bilateral nephrectomy was performed in all patients; all were on a fixed daily sodium intake, and no antihypertensive agents were given. No significant differences were found between the groups in age, time after transplantation or dosages of prednisone. PRC and PAC were normal in all but one patient in group 1 and two in group 2. In these three patients a slight elevation of PRC was measured. After one hour in the erect position, a significant increase was measured in PAC, but not in PRC in both groups. After 6 days on a 10 mEq sodium diet, PRC and PAC increased significantly in both groups. After a further 6 days on the diet plus 150 mEq sodium daily, significant decreases in PRC and PAC were measured in both groups. No differences were detected in PRC or PAC between groups 1 and 2 either before or after the two dietary periods. RPF was significantly lower in the hypertensive group, whereas no significant difference was found in GFR between the groups. No significant relationship could be demonstrated between blood pressure (BP) and PRC or PAC, and PRC and PAC were not correlated to each other. RPF was significantly correlated to mean BP and PRC in the normotensive group but not in the hypertensive. It is concluded that PRC and PAC are normal in most patients with posttransplant hypertension, whereas the RPF is decreased. It is suggested that an abnormal regulation of renin secretion plays a role in the sustained elevation of BP after renal allotransplantation.

Radioisotopic evaluation of renal transplants

Owing to the noninvasive nature, ready availability, and efficacy, radionuclide studies remain widely utilized following renal transplantation for monitoring changes in the functional status and detection of detrimental complications of the grafted kidney. Whereas surgical complications, including vascular occlusion, urine extravasation, drainage obstruction, hematoma, or lymphocele formation, can often be detected effectively, specification of other underlying causes of deterioration of parenchymal function, including acute tubular necrosis (ATN), various types of rejection, and cyclosporine A nephrotoxicity (CyA-NT), frequently cannot be derived independently from the findings of a study without clinical correlation. Besides imaging, plotting of renogram or time/activity curves, numerous quantitative methods have been introduced to provide objective measurements of the blood flow, as well as to gauge the capability of concentration and excretion of the transplanted kidneys. However, the findings whether qualitative or quantitative all have overlapping zones. There is no abnormal image, graphic, or numeric index absolutely specific for any of the possible posttransplant renal parenchymal complications. The differentiation of such conditions may best be achieved through chronologic association of the sequential changes, with or without quantification, detected in serial studies with the clinical presentation and findings.

Long-term outcome of renal transplantation in autosomal dominant polycystic kidney disease

This study was performed to determine the long-term outcome of renal transplantation in 54 patients with end-stage renal failure secondary to autosomal dominant polycystic kidney disease (ADPKD) and in 107 patients with renal diseases other than ADPKD or diabetes mellitus matched by gender, age, year of transplantation, and source of the allograft. The overall patient survival and patient survival with a functioning first renal allograft were similar in both groups. Infection and cardiovascular accidents were the leading causes of early and late death in both groups. No cause of death was greatly overrepresented in the ADPKD group. Serious complications from extrarenal manifestations of ADPKD following renal transplantation included a ruptured intracranial aneurysm in one patient, a dissection of the ascending thoracic aorta in one patient, and infected hepatic cysts in two patients. Neoplasia (other than skin or cervical) occurred in four ADPKD patients and in one control patient and included one lymphoma in each group. Two ADPKD and one control patient had monoclonal gammopathies of undetermined significance. No complications related to the retention of native kidneys were detected in 12 ADPKD patients with a mean follow-up of 3 years. Cysts were observed in the renal allografts of some patients in both groups at autopsy and in a prospective computed tomography (CT) study of the allograft. However, we failed to detect a significant difference in the occurrence and number of the cysts between ADPKD and control patients.

Percutaneous transluminal angioplasty for transplant renal artery stenosis in children

Severe hypertension developed secondary to renal artery stenosis in 11 of 229 children who received a renal allograft. Renal artery stenosis was suspected because of de novo development of hypertension or exacerbation of pre-existing hypertension, which was detected 1 to 24 months after transplantation. Selective renal angiography was performed 2 to 74 months after transplantation (mean 13 months). Follow-up was 1 to 8 years (mean 2.5 years). The stenosis involved the anastomosis in 5 patients and was distal to the anastomosis in 6. One graft had an arteriovenous malformation. Seven grafts were suitable for vessel dilation; percutaneous transluminal angioplasty was partially successful in 4 cases in which the stenosis occurred at the anastomosis. The remaining patients were treated with medical therapy alone and the grafts were not lost. Our findings suggest that strictures distal to the anastomosis rarely are amenable to percutaneous transluminal angioplasty and should be treated medically whenever possible. Strictures at the anastomosis respond to vessel dilation but antihypertensive medication also often is required. An operation should be reserved for patients who do not respond to these measures.

Post-renal-transplant hypertension. Urine volume, free water clearance and plasma concentrations of arginine vasopressin, angiotensin II and aldosterone before and after oral water loading in hypertensive and normotensive renal transplant recipients

Urine volume (V), free water clearance (CH2O) and plasma concentrations of arginine vasopressin (AVP), angiotensin II (A II) and aldosterone (Aldo) were determined before and three times during the first 5 h after an oral water load of 20 ml/kg body wt in 19 patients with post-renal-transplant hypertension (group I), in 13 normotensive renal transplant recipients (group II) and in 20 control subjects (group III). Both V and CH2O increased significantly in all groups, but considerably less in groups I and II than in group III. When CH2O was related to glomerular filtration rate no differences existed between patients and control subjects. Basal AVP was the same in groups I (3.3 pmol/l, median) and II (3.0 pmol/l), but significantly (p less than 0.01) higher than in group III (1.9 pmol/l). Basal A II was significantly (p less than 0.01) elevated in group I (18 pmol/l) when compared to both groups II (10 pmol/l) and III (11 pmol/l), and the level was independent of the presence of native kidneys. Basal Aldo was the same in all groups. During loading, AVP was reduced in all groups, A II was almost unchanged, and Aldo was increased in groups I and II and reduced in group III depending on alterations in serum potassium. Thus urinary diluting ability is reduced in renal transplant recipients due to a reduced glomerular filtration rate. The enhanced A II in hypertensive renal transplant recipients gives further evidence for the point of view that hypertension is angiotensin-dependent in most of these patients.

Control of hypertension after renal transplantation by embolisation of host kidneys

A percutaneous embolisation technique was used for host kidney ablation in 13 patients with renal allografts and hypertension. Markedly improved blood pressure control was achieved in 9 of them, and morbidity was minimal. All patients have been followed from 12 to 25 months. Embolisation of the host kidneys appears to be a simple, effective, and less hazardous alternative to surgery in the treatment of drug-resistant hypertension after renal transplantation in some patients.

Screening for transplant renal artery stenosis in hypertensive recipients using digital subtraction angiography

Digital subtraction angiography was used in 10 renal allograft recipients with sustained hypertension after transplantation to detect transplant renal artery stenosis. Recipients with end-to-end vascular anastomoses were visualized adequately in the anteroposterior projection. Two cases of transplant renal artery stenosis were identified by digital subtraction angiography and then verified by catheter angiography. Patients with end-to-side vascular anastomoses may require additional oblique projections. Digital subtraction angiography is a safe, noninvasive and cost-effective screening procedure to diagnose transplant renal artery stenosis in most recipients. Catheter angiography can be applied more selectively to those recipients with stenosis observed by digital subtraction angiography or when more detailed imaging is required.

Peripheral plasma renin activity (PRA) in recipients with allograft artery stenosis; its diagnostic value in acute stage hypertension

Peripheral PRA was examined in 11 patients with graft artery stenosis after the onset and throughout the course of hypertension. In the acute stage PRA was elevated in 9 patients and decreased to normal in the later stage of hypertension in all but 1 patient with malignant hypertension. The findings suggest that the determination of peripheral PRA is helpful in diagnosing graft artery stenosis only in the acute stage of hypertension, but it has no unequivocal value to the prognosis of hypertension or indication for operation.

Surgical correction of posttransplant renovascular hypertension

The incidence of renovascular hypertension in the transplanted kidney is reported to range between 5 and 15%. A review of 391 consecutive renal transplant patients revealed 16 patients (5.4%) with hypertension secondary to partial obstruction of renal arterial blood flow. The clinical course of this group of patients was marked by early normotension followed by progressive diastolic pressure elevation, with improving renal function and loss of accumulated excess volume. Five etiologic factors are responsible for impaired arterial flow in this group of patients. Indication for operation was based on hypertension and/or impaired renal function. Patch angioplasty using saphenous veins was the procedure of choice in most instances. The average blood pressure was 185 mmHg; systolic/125 mmHg; diastolic preoperatively, compared with 140 mmHg; systolic/90 mmHg: diastolic postoperatively. Twelve of 16 patients had good results, and improvement in renal function was observed in eight patients. Serum renin levels did not correlate well with the operative findings. The use of meticulous technique, combined with maximum use of autogenous tissue, is emphasized.

Episodic hypertension caused by recurrent renal artery lesions following transplantation: a case report

A kidney transplant patient developed recurrent hypertension on two successive occasions associated with lesions of the renal artery. The first episode of hypertension was caused by renal artery stenosis and was surgically corrected; the second was caused by a sizable pseudoaneurysm at the site of arterial anastomosis which was resected, and arterial continuity was successfully re-established.

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.

Role of the renin-angiotensin system in post-transplantation hypertension in patients with multiple kidneys

To define the role of the renin-angiotensin system in post-transplantation hypertension we studied 12 hypertensive recipients of renal transplants. The patients received saralasin acetate, an angiotensin II antagonist, while on a normal sodium diet and again after seven days of sodium restriction. In six patients with only one kidney, saralasin did not lower blood pressure on either diet; salt depletion did not lower systolic or diastolic blood pressures. In six patients with more than one kidney, salt depletion also did not lower blood pressure; however, salt depletion plus saralasin lowered their systolic pressures from a mean (+/- S.E.M.) of 146 +/- 9 to 128 +/- 8 mm Hg, and mean diastolic pressures fell from 103 +/- 5 to 89 +/- 5 (P less than 0.001). In four of five patients renal-vein renin activity was greater in one or more host kidneys than in the transplant kidney (or kidneys). Although pre-transplant blood pressure was the same in both groups, post-transplantation hypertension is more likely to be angiotensin II-dependent in patients with more than one kidney.

[Arterial stenoses after kidney transplantation]

After 268 kidney allotransplants, 7 cases of renal artery stenosis were observed. An additional 3 patients were referred to use from another center. The outstanding symptom of all 10 patients was hypertension refractory to medical treatment, beginning not later then 10 months after transplantation. In 9 cases there was a murmur over the transplant. In 6 patients hypertension was accompanied by a deterioration of renal function which was resistant to antirejection therapy. The tentative diagnosis was confirmed by selective renal arteriography of the transplant. Two main types of stenoses could be diagnosed: Segmental stenoses, 0.5-2 cm distal to the anastomosis, which were due to intimal lesions caused during removal of the kidney or by the perfusion canula; and kinking stenoses due to a technically inadequate implantation. Hypertension was controlled in all but 1 patient with reconstruction of the artery. Therefore, hypertension after kidney transplantation refractory to medical treatment should be further investigated with selective renal arteriography of the transplant. Stenoses with clinical symptoms which are confirmed by arteriography should be surgically corrected.

Diagnosis and management of arterial stenosis causing hypertension after successful renal transplantation

Renal artery stenosis causing hypertension has been noted in 11 patients after successful renal transplantations. We believe that all patients with moderate to severe post-transplant hypertension should be evaluated with angiography and selective renin determinations. However, because of definite risk to the graft we believe that operative intervention should be undertaken only if hypertension is uncontrolled or if declining renal function is present and attributable to the stenosis.

Hypertension after renal transplantation in children

Hypertension persisted for longer than 6 mo or developed de novo after the first month following transplantation in seven of 77 pediatric recipients of renal allografts; concomitantly there were an elevation of PRA and renal angiographic abnormalities. In two of the four patients who developed RAS there was evidence of diminished allograft function. Successful correction of the stenotic lesion in these two recipients resulted in a return of the blood pressure, PRA, and biochemical function of the allograft to normal. Unsuccessful attempts at surgical repair led to loss of the allograft in the other two patients with RAS. Intrarenal vascular and/or parenchymal lesions were evident in the other three recipients with hypertension. Although an explanation was not apparent, subclinical rejection was hypothesized. Treatment effected reduction of the hypertension in these three patients and no deterioration of allograft function was observed for periods of 5, 34, and 38 mo, respectively. Renal angiographic studies and determinations of PRA are recommended in any pediatric recipient of an allograft who develops hypertension after the first month following transplantation or has hypertension which persists for longer than 6 mo after transplantation.