Elevated blood pressure predicts the risk of acute rejection in renal allograft recipients

Hypertension in kidney transplant recipients

Kidney transplantation is considered the treatment of choice for end-stage kidney disease patients. However, the residual cardiovascular risk remains significantly higher in kidney transplant recipients (KTRs) than in the general population. Hypertension is highly prevalent in KTRs and represents a major modifiable risk factor associated with adverse cardiovascular outcomes and reduced patient and graft survival. Proper definition of hypertension and recognition of special phenotypes and abnormal diurnal blood pressure (BP) patterns is crucial for adequate BP control. Misclassification by office BP is commonly encountered in these patients, and a high proportion of masked and uncontrolled hypertension, as well as of white-coat hypertension, has been revealed in these patients with the use of ambulatory BP monitoring. The pathophysiology of hypertension in KTRs is multifactorial, involving traditional risk factors, factors related to chronic kidney disease and factors related to the transplantation procedure. In the absence of evidence from large-scale randomized controlled trials in this population, BP targets for hypertension management in KTR have been extrapolated from chronic kidney disease populations. The most recent Kidney Disease Improving Global Outcomes 2021 guidelines recommend lowering BP to less than 130/80 mmHg using standardized BP office measurements. Dihydropyridine calcium channel blockers and angiotensin-converting enzyme inhibitors/angiotensin-II receptor blockers have been established as the preferred first-line agents, on the basis of emphasis placed on their favorable outcomes on graft survival. The aim of this review is to provide previous and recent evidence on prevalence, accurate diagnosis, pathophysiology and treatment of hypertension in KTRs.

Hypertension in kidney transplantation: a consensus statement of the 'hypertension and the kidney' working group of the European Society of Hypertension

Hypertension is common in kidney transplantation recipients and may be difficult to treat. Factors present before kidney transplantation, related to the transplantation procedure itself and factors developing after transplantation may contribute to blood pressure (BP) elevation in kidney transplant recipients. The present consensus is based on the results of three recent systematic reviews, the latest guidelines and the current literature. The current transplant guidelines, which recommend only office BP assessments for risk stratification in kidney transplant patients should be reconsidered, given the presence of white-coat hypertension and masked hypertension in this population and the better prediction of adverse outcomes by 24-h ambulatory BP monitoring as indicated in recent systematic reviews. Hypertension is associated with adverse kidney and cardiovascular outcomes and decreased survival in kidney transplant recipients. Current evidence suggests calcium channel blockers could be the preferred first-step antihypertensive agents in kidney transplant patients, as they improve graft function and reduce graft loss, whereas no clear benefit is documented for renin-angiotensin system inhibitor use over conventional treatment in the current literature. Randomized control trials demonstrating the clinical benefits of BP lowering on kidney and major cardiovascular events and recording patient-related outcomes are still needed. These trials should define optimal BP targets for kidney transplant recipients. In the absence of kidney transplant-specific evidence, BP targets in kidney transplant recipients should be similar to those in the wider chronic kidney disease population.

Hypertension, living kidney donors, and transplantation: where are we today?

Hypertension is a prevalent problem in kidney transplant recipients that is known to be a "traditional" risk factor for atherosclerotic cardiovascular disease leading to premature allograft failure and death. Donor, peritransplant, and recipient factors affect hypertension risk. Blood pressure control after transplantation is inversely associated with glomerular filtration rate (GFR). Calcineurin inhibitors, the most commonly used class of immunosuppressives, cause endothelial dysfunction, increase vascular tone, and sodium retention via the renin-angiotensin-aldosterone system resulting in systemic hypertension. Steroid withdrawal seems to have little impact on blood pressure control. Newer agents like belatacept appear to be associated with less hypertension. Transplant renal artery stenosis is an important, potentially treatable cause of hypertension. Dihydropyridine calcium channel blockers mitigate calcineurin inhibitor nephrotoxicity and may be associated with improved estimated GFR. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are not recommended in the first 3 to 6 months given their effects on reduced estimated GFR, anemia, and hyperkalemia. The use of ß-blockers may be associated with improved patient survival, even for patients without cardiovascular disease. Living donation may increase blood pressure by 5 mm Hg or more. Some transplant centers accept Caucasian living donors with well-controlled hypertension on a single agent if they agree to close follow-up.

The pathophysiology of endothelin in complications after solid organ transplantation: a potential novel therapeutic role for endothelin receptor antagonists

Although short-term allograft survival after solid organ transplantation has improved during the past two decades, improvement in long-term graft survival has been less pronounced. Common complications after transplantation include chronic allograft rejection, nephrotoxicity from calcineurin inhibitors (CNIs), and systemic hypertension, which all impact posttransplantation morbidity and mortality. Endothelin (ET)-1, a potent endogenous vasoconstrictor, inducer of fibrosis, and vascular smooth muscle cell proliferation, may play a key role in both the development of CNI-induced nephrotoxicity and endothelial vasculopathy in chronic allograft rejection. ET-1 levels increase after isograft implantation, and ET-1 plays a key role in CNI-induced renal vasoconstriction, sodium retention, and hypertension. Preclinical studies have demonstrated that endothelin receptor antagonists (ERAs) can reduce or prevent CNI-induced hypertension after renal transplantation. In addition, ERAs can ameliorate CNI-induced renal vasoconstriction and improve proteinuria and preserve renal function in animal models of renal transplantation. ET-1 may also play a significant role in cardiac allograft vasculopathy, and in animal models, ERAs improve pulmonary function and ischemic-reperfusion injury in lung transplantation and hepatic function and structure in liver transplantation. Emerging pharmacokinetic data suggest that the selective ERA ambrisentan may be used safely in conjunction with the most commonly used immunosuppressive agents tacrolimus and mycophenolate, albeit with appropriate dose adjustment. The weight of available evidence pointing toward a potential beneficial role of ERAs in ameliorating common complications after solid organ transplantation must be balanced with potential toxicities of ERAs but suggests that a randomized clinical trial of ERAs in transplant patients is warranted.

Hypertension in kidney transplant recipients

Arterial hypertension is frequently observed in renal transplant recipients. Its pathogenesis is multifactorial in most cases. Calcineurin inhibitors (CNI) can increase peripheral vascular resistance by inducing arteriolar vasoconstriction and can cause extracellular fluid expansion by reducing the glomerular filtration rate (GFR), activating the renin-angiotensin system (RAS), and by inactivating the atrial natriuretic peptide. Glucocorticoids can impair urinary water and salt excretion. Poor graft function can lead to increased extracellular volume and inappropriate production of renin. Native kidneys, older age of the donor and transplant renal artery stenosis (TRAS) may also contribute to the development of hypertension. Arterial hypertension not only can increases the risk for cardiovascular events but can also deteriorate renal allograft function. A number of studies have shown that the higher the levels of blood pressure are, the higher is the risk of graft failure. On the other hand, a good control of blood pressure may prevent many cardiovascular and renal complications. Appropriate lifestyle modification is the first step for treating hypertension. Calcium channel blockers (CCB) and renin-angiotensin system (RAS) inhibitors are the most frequently used antihypertensive agents, but in many cases, a combination of these and other drugs is required to obtain good control of hypertension.

Hypertension following kidney transplantation

The majority of patients become hypertensive following kidney transplantation. Its occurrence is associated not only with increased fatal and nonfatal cardiovascular events but also with decreased allograft survival. This review summarizes the current knowledge of the epidemiology, etiology, pathophysiology, and management of post-transplant hypertension.

Management of Hypertension in Renal Transplant Patients: A Comprehensive Review of Nonpharmacologic and Pharmacologic Treatment Strategies

Objective:

To review the guidelines and literature for the treatment of hypertension in renal transplant patients and to provide guidance to practitioners in the selection of appropriate nonpharmacologic and pharmacologic treatment options.

Data Sources:

A PubMed search (January 1948–March 2010) was performed using the search terms hypertension, antihypertensive agents, blood pressure, and cardiovascular disease, in combination with renal transplant and kidney transplant. The search was limited to articles published in English. All relevant peer-reviewed original studies, meta-analyses, guidelines, consensus statements, and review articles were examined. In addition, reference citations from publications identified were reviewed.

Study Selection and Data Extraction:

All literature found was evaluated for inclusion. Review articles as well as prospective and retrospective original research articles were reviewed.

Data Synthesis:

Hypertension after solid organ transplantation is a problem commonly encountered in patients during their posttransplantation clinic visits. Effective management of these patients' hypertension is crucial, as hypertension left untreated may lead to increased morbidity and mortality as well as graft loss. The unique, multifactorial etiology of hypertension in this population makes treatment choices more challenging compared to treatment of a nontransplant patient. Therefore, to guide practitioners in this process, we developed a hypertension management protocol, taking into account the unique considerations faced in the adult renal transplant population. The review guides practitioners from the initial assessment of patients' hypertension through the evaluation and selection of nonpharmacologic and pharmacologic treatment options and provides information about the discontinuation of certain antihypertensive medications. It also provides a concise, but comprehensive review of the major antihypertensive drug classes and economic considerations.

Conclusions:

The management of hypertension in posttransplantation patients is challenging and complicated, yet necessary to prevent morbidity, mortality, and graft loss for these patients. Therapy should be individualized based on patient assessment, response to previous therapy, and economic considerations.

Hypertension in dialysis and kidney transplant patients

For the first time, the Canadian Hypertension Education Program has studied the evidence supporting blood pressure control in people requiring renal replacement therapy for end-stage kidney disease, including those on dialysis and with renal transplants. According to the Canadian Organ Replacement Registry's 2008 annual report, there were an estimated 33,832 people with end-stage renal disease in Canada at the end of 2006, an increase of 69.7% since 1997. Of these, 20,465 were on dialysis and 13,367 were living with a functioning kidney transplant. Thus, it is becoming more likely that primary care practitioners will be helping to care for these complex patients. With the lack of large controlled clinical trials, the consensus recommendation based on interpretation of the existing literature is that blood pressure should be lowered to below 140/90 mmHg in hypertensive patients on renal replacement therapy and to below 130/80 mmHg for renal transplant patients with diabetes or chronic kidney disease.

Enalapril/amlodipine combination in cyclosporine-treated renal transplant recipients: a prospective randomized trial

BACKGROUND

Most hypertensive renal transplant recipients require two or more antihypertensive medications to achieve blood pressure control. However, which medications must be combined is still a matter of debate.

METHODS

A prospective randomized open-label blinded evaluation trial comparing the six-month effects of the amlodipine-enalapril combination (n = 32) vs. enalapril alone (n = 33) and vs. amlodipine alone (n = 34) on arterial pressure, renal function, albuminuria and tolerability.

RESULTS

At six months, diastolic arterial pressure was more adequately controlled (i.e., <90 mmHg) in the combination group than in the amlodipine and enalapril groups (100% vs. 82.4% and 84.8%, respectively, p = 0.038). The same trend was observed for systolic arterial pressure (65.6% vs. 58.8% and 51.5%, NS). The six-month change in albuminuria was similar in the combination group and in the enalapril group (-64.7% vs. -59.5%); however, patients in the combination group exhibited a greater reduction in albuminuria than in the amlodipine group (-64.7% vs. -29.0%, p = 0.002). As compared with baseline values, serum creatinine and potassium remained unchanged in the combination group, whereas they increased by 9 +/- 12 micromol/L (p = 0.01) and by 0.2 +/- 0.4 mmol/L (p < 0.01), respectively, in the enalapril group. The cyclosporine trough levels remained unchanged in the combination group, but increased in the amlodipine group.

CONCLUSION

Angiotensin-converting enzyme inhibitor (ACEI)-calcium-channel blocker (CCB) combination controls arterial pressure more adequately than ACEI alone or CCB alone, reduces albuminuria and may prevent the ACEI-induced initial rise in serum creatinine.

ABPM vs office blood pressure to define blood pressure control in treated hypertensive paediatric renal transplant recipients

While 24-h ambulatory blood pressure monitoring (ABPM) is an established tool for monitoring antihypertensive therapy in adults, data in children are scarce. We retrospectively analysed whether office blood pressure (BP) is reliable for the diagnosis of BP control in 26 treated hypertensive paediatric renal transplants. Controlled office BP was defined as the mean of three replicate systolic and diastolic BP recordings less than or equal to the 95th age-, sex- and height-matched percentile on the three-outpatient visits closest to ABPM. Controlled ABPM was defined as systolic and diastolic daytime BP < or =95th distribution adjusted height- and sex-related percentile of the adapted ABPM reference. Eight recipients (30%) with controlled office BP were in fact categorized as having non-controlled BP by ABPM criteria. Overall, when office BP and ABPM were compared using the Bland and Altman method, the 95% limits of agreement between office and daytime values ranged from -12.6 to 34.1 mmHg for systolic and -23.9 to 31.7 mmHg for diastolic BP, and the mean difference was 10.7 and 3.9 mmHg respectively. Office readings miss a substantial number of recipients who are hypertensive by ABPM criteria. Undertreatment of hypertension could be avoided if ABPM is applied as an adjunct to office readings.

Efficacy and Safety of Valsartan, an Angiotensin II Receptor Antagonist, in Hypertension After Renal Transplantation: A Randomized Multicenter Study

BACKGROUND

The prevalence of posttransplant hypertension is high, and it appears to be a major risk factor for graft and patient survival. The aim of this study was to assess the efficacy and safety of valsartan, an angiotensin-receptor blocker (ARB), in the treatment of posttransplant hypertension.

METHODS

A multinational, multicenter, prospective, randomized, double-blind, placebo-controlled study was performed on the treatment of hypertension (systolic blood pressure [BP] >/= 140 and/or diastolic BP >/= 90 mm Hg) in adult cyclosporin-treated renal transplant recipients randomized to receive either valsartan (80 mg once daily) or a matching placebo for 8 weeks. After the first 4 weeks, furosemide 20 mg twice daily was added on a open basis if systolic BP remained >/= 130 mm Hg and/or diastolic BP remained >/= 85 mm Hg.

RESULTS

One hundred fifteen (valsartan = 57, placebo = 58) uncontrolled hypertensive patients despite monotherapy for hypertension, other than angiotensin-converting enzyme inhibitor or ARB, were randomized. In the valsartan group, significant decreases were seen in systolic BP (from 153 +/- 11 to 140.9 +/- 18.35 mm Hg at 4 weeks, and 136.5 +/- 15 mm Hg at 8 weeks) and diastolic BP (from 93 +/- 9 to 85.2 +/- 11.28 mm Hg at 4 weeks, and 83.8 +/- 9.2 mm Hg at 8 weeks). There was no significant change in the placebo group. In the valsartan group, a statistically but not clinically significant reduction was observed in the mean hemoglobin concentration (12.9 +/- 1.6 g/dL versus 13.8 +/- 1.6 g/dL at 4 weeks, P < .01; and 12.3 +/- 1.6 versus 13.8 +/- 1.7 at 8 weeks; P < .001) as well as a significant increase in serum potassium (4.4 +/- 0.5 mmol/L versus 4.1 +/- 0.4 mmol/L at 4 weeks, P < .01) vs placebo.

CONCLUSIONS

Valsartan is effective in the treatment of posttransplant hypertension and is well tolerated.

Overcoming Barriers to Long-Term Graft Survival

Although short-term kidney graft survival has improved in recent years, the focus has shifted to the challenge of improving long-term graft survival. Acute rejection, chronic allograft nephropathy, and cardiovascular disease are associated with graft loss and patient death. Reducing the potential for such posttransplantation complications may improve long-term graft survival. In addition, gaining a better understanding of the role that various immunosuppressive therapies have in decreasing the risk for graft injury will help clinicians make better-informed decisions about appropriate treatment regimens for individual kidney transplant recipients.

The effects of blood pressure and lipid control on kidney allograft outcome

Despite the improvement in short- and long-term kidney allograft survival in recent years, a significant number of grafts are lost because of chronic allograft nephropathy (CAN) or death secondary to cardiovascular disease (CVD). There is growing evidence that both hypertension and hyperlipidemia play important roles in the progression of CAN and CVD in kidney transplant recipients. Large, randomized, controlled studies to determine the optimal target levels for BP and serum lipids, as well as the choice of drug therapy, are lacking. However, based on the available data, we suggest that currently recommended target levels in non-transplant patients should also be used after transplantation. We believe that achieving these target levels for BP and serum lipids are of primary importance, and that the non-lipid-lowering effects of HMG-CoA reductase inhibitors might exert additional benefits in prolonging graft survival.

Hypertension in Kidney Transplantation

Arterial hypertension in renal transplant patients plays a major role in the progression to chronic allograft failure, and in morbidity and mortality associated with cardiovascular disease. Its cause is diverse, with contributions not only from donor and/or recipient factors, but it also is influenced strongly by the type of immunosuppressive regimen. Despite increased awareness of the adverse effects of hypertension in both graft and patient survival, long-term studies have shown that arterial hypertension in the transplant population has not been controlled adequately. Ambulatory blood pressure measurements provide the advantage of a better assessment of the diurnal blood pressure variation, a predictor of target organ damage and cardiovascular morbidity and mortality events. Although the available data do not support the recommendation of any class of antihypertensive medication as preferred agents for blood pressure management in the transplant population, angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers have shown beneficial effects beyond their antihypertensive effects. Clinical data in transplant recipients are emerging that suggest that applying interventions proven to be effective in reducing cardiovascular morbidity and mortality in the general population may be effective for the transplant population.

Hypertension after kidney transplantation

BACKGROUND

Few studies have examined the possible role of blood pressure (BP), independent of acute rejection and graft function, on outcomes after kidney transplantation.

METHODS

We investigated the prevalence, treatment, control, and clinical correlates of hypertension and its association with outcomes, using multivariate analyses with time-dependent covariates, in a retrospective cohort of 1,666 kidney transplant recipients.

RESULTS

Hypertension was common, and its control was poor. For example, at 1 year, only 55.5% had a BP less than 140 mm Hg. Control improved only slightly in 1993-2002 compared to 1976-2002, even as patients administered 2 or more antihypertensive medications at 1 year increased from 43.5% to 54.6%. Independent correlates of higher BP included male sex, age, donor age, diabetes, body mass index, the presence of native kidneys, and delayed graft function. Previous acute rejection was associated with higher BP at virtually all times after transplantation, and these associations were independent of estimated creatinine clearance (C(Cr)). Conversely, an association between BP and subsequent acute rejection was not statistically significant when differences in C(Cr) were taken into account. After adjusting for the effects of acute rejection, C(Cr), and other variables, each 10 mm Hg of systolic BP was associated with an increased relative risk for graft failure (1.12; 95% confidence interval, 1.08 to 1.15; P < 0.0001), death-censored graft failure (1.17; 1.12 to 1.22; P < 0.0001), and death (1.18; 1.12 to 1.23; P < 0.0001).

CONCLUSION

High BP is closely tied to graft function, but nevertheless is an independent risk factor for graft failure and mortality. Better strategies are needed to control BP after kidney transplantation.

Blood pressure control in kidney transplantation: therapeutic implications

Post-transplant hypertension remains a significant risk factor for graft loss, but whether or not specific blood pressure (BP) medications affect graft outcome is still unknown. We assessed the interaction between BP control and antihypertensive drugs on graft outcome. We retrospectively examined clinic BP data for 1662 renal transplant (RTx) patients, transplanted between 1994 and 2000 at our centre. The analysis examined all patients who received central alpha-agonists and peripheral alpha-antagonists, beta-blockers, calcium channel blockers (CCBs), angiotensin-converting enzyme (ACE) inhibition (ACEI), angiotensin receptor blockers (ARBs). BP recordings during treatment were categorized for each agent. Thus, a particular BP could be categorized for multiple medications. A total of 1462 patients (pts) (88%) were Caucasian and 800 pts (46%) received cadaveric RTx. There were 10.6+/-6.8 BP measurements for each patient post-RTx. CCBs, alone among the classes of antihypertensive drugs evaluated, reduced the risk for graft loss (RR: 0.736; P=0.035) in the overall analysis. Interestingly, stratifying levels of BP control unmasked a beneficial effect on graft survival of ACEI/ARB therapy in individuals with higher levels of systolic (>152 mmHg) and diastolic blood pressure (>98 mmHg) treated with ACEI/ARBs compared to individuals treated with CCBs (P<0.01 for each). Thus, stabilizing BP is important post-RTx. CCBs are associated with improved rates of graft survival. Their role in a compromised RTx, however, deserves further study. ACEI/ARBs have clear benefits, improving graft survival in individuals with elevated systolic blood pressure and proteinuria. CCBs are not as efficacious in this setting.

Ambulatory blood pressure monitoring in renal transplantation: should ABPM be routinely performed in renal transplant patients?

In renal transplant recipients, hypertension is common and associated with increased cardiovascular and allograft rejection risks. Ambulatory blood pressure monitoring is required for its accurate diagnosis and adequate treatment, as it clearly offers several advantages over office or casual blood pressure measurements. First, it correlates better with target-organ damage and with cardiovascular mortality. Second, ambulatory blood pressure monitoring can eliminate "white coat" hypertension. Most important is the identification of nocturnal hypertension, an independent cardiovascular risk factor. A circadian nondipping pattern is often found in renal transplant recipients, most probably resulting from cyclosporine A and persistent fluid overload in the early posttransplant phase (approximately 70% prevalence), but reflecting an underlying renal (parenchymal or vascular) allograft disease when persistent (approximately 25% prevalence) beyond the first year posttransplant.

Perioperative blood pressure control, delayed graft function, and acute rejection after renal transplantation

BACKGROUND

Blood pressure (BP) control immediately after renal transplantation is poorly understood, with patients experiencing both high and low BP levels. Donor kidneys lack the ability to autoregulate their blood flow, meaning high pressures are directly translated to the graft endothelium, whereas reduced perfusion may augment ischemic injury. We hypothesize that early BP control may therefore influence the early alloimmune response.

METHODS

A total of 276 patients undergoing primary cadaveric renal transplantation who received cyclosporine-based therapy were followed; standard transplant variables were identified. BP was serially recorded before, during, and after reperfusion until 50 hr after surgery. Variables predicting acute rejection and delayed graft function were identified using Cox and logistic regression models.

RESULTS

The mean (SD) BP after surgery was 161(19) mm Hg systolic and 73(12) mm Hg diastolic. Forty-two percent had perioperative hypertension defined by conventional parameters. Increasing postoperative systolic BP, measured as standardized area-under-the-curve, was associated with an increased risk for acute rejection (hazard ratio [per mm Hg]=1.008), independent of other covariables including the preoperative BP level. Diastolic BP was inversely associated with the risk of delayed graft function (odds ratio [per mm Hg]=0.956).

CONCLUSIONS

Early hypertension is common after renal transplantation. Early BP control has the potential to influence the risk of allograft rejection and delayed graft function.

Hypertension increases expression of growth factors and MHC II in chronic allograft nephropathy

BACKGROUND

Hypertension of the recipient is strongly associated with chronic allograft nephropathy. It is unclear, however, whether hypertension is the cause or the consequence of chronic allograft nephropathy.

METHODS

The present study was performed in the Fisher to Lewis rat kidney transplant model. Transplanted rats (N = eight in each group) received either no treatment or were made hypertensive by administration of deoxycorticosteron acetate (DOCA) and salt. Proteinuria and systolic blood pressure was measured monthly, grafts were harvested at 3 and 6 months for semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and for immunohistology.

RESULTS

Systolic blood pressure was markedly elevated in rats receiving DOCA/salt. Allografts of hypertensive animals contained significantly more cells expressing the proliferating cell nuclear antigen compared to isografts and to allografts from normotensive animals (P < 0.05). Histologic staining and mRNA expression of major histocompatibility complex (MHC) II was markedly increased in allografts of hypertensive animals compared to all other groups (P < 0.05). Expression of mRNA for platelet-derived growth factor-B (PDGF-B), transforming growth factor-beta (TGF-beta) and collagen was higher in allografts than in isografts and was highest in hypertensive animals.

CONCLUSION

We conclude that hypertension augments the expression of growth factors in the allograft possibly aggravating the intimal hyperplasia observed in chronic allograft nephropathy. By increasing the expression of MHC II antigens, hypertension may render the allograft more susceptible to alloantigen-dependent damage. Hypertension and alloantigen-dependent factors appear to exert additive or synergistic effects on inflammatory pathways leading to graft injury.

A prospective study of the physician effect on blood pressure in renal-transplant recipients

BACKGROUND

Physician presence results in elevated blood pressure (BP) in the general population. The determinants of this phenomenon in renal-transplant recipients are not known.

METHODS

We prospectively evaluated BP changes with physician presence in 231 stable adults with graft survival > or =1 year. A nurse measured timed sitting BP by Korotkoff phase I and V sounds before physician entry, during physician presence and upon exit. The haemoglobin, creatinine, weight, immunosuppressive drug dosage and/or level, and anti-hypertensive medication profile were recorded. Paired Student's t-test with Bonferroni correction and multiple linear regression analysis were used to examine BP changes. Characteristics of patients with change in mean arterial BP > or =+10 mmHg (n=55, "high") were compared with those with change < or =+5 mmHg (n=132, "low") by chi-square or Wilcoxon rank sum test as appropriate. A group of 100 recipients served as controls in whom BP was measured thrice without physician presence on any occasion. A multivariate analysis was performed for the combined groups controlling for physician entry as a predictor variable.

RESULTS

In the study group, systolic BP (mean+/-SE) rose by 4.2+/-0.8, diastolic BP by 3.5+/-0.5 and mean arterial BP by 3.5+/-0.5 mmHg in physician presence. The BP returned to baseline with exit (P<0.001 for each). Higher haemoglobin and creatinine demonstrated a trend towards influencing the physician-induced rise in diastolic BP. The "high" sub-group demonstrated a shorter time to the second BP measurement in physician presence (P=0.03) and a trend towards morning measurements (P=0.08). In the control group, systolic BP declined by 3.2+/-0.9 mmHg from the first to the second measurement, with a further decline of 2.4+/-0.6 mmHg from the second to third measurements. Diastolic BP did not change. In the combined multivariate analysis, physician entry was an independent predictor of BP change (P=0.0001).

CONCLUSIONS

Renal-transplant recipients demonstrate a significant physician effect on BP despite adequate experience with post-transplant clinic visits and BP-altering medication. This population deserves further evaluation through ambulatory BP monitoring.

Hypertension after kidney transplantation: impact, pathogenesis and therapy

Hypertension (HTN) contributes to the high incidence of cardiovascular disease mortality as well as chronic allograft nephropathy (CAN) and late graft failure in renal transplant recipients. The mechanisms are complex and may involve pathogenic factors attributable to the host, allograft, and immunosuppressive drugs. Calcium channel blockers should be used to ameliorate the nephrotoxicity of calcineurin inhibitors in the early years after transplantation. Angiotensin-converting enzyme inhibitors and angiotensin-2 type-1 receptor blockers are safe and effective, have antiproteinuric effects, slow the progression of CAN, and may provide survival benefits. Diuretics and/or beta-adrenergic receptor blockers are frequently added in combination regimen. Appropriate adjustment of the immunosuppressive drugs should also be considered for the long-term care of kidney recipients with HTN.

The relationship between donor age and cadaveric renal allograft survival is modified by the recipient's blood pressure

Increasing donor age correlates with reduced renal allograft survival. In this study we analyzed variables that may modify this relationship. The study included 1285 cadaveric kidney allograft recipients followed for 7.2 + 4.5 years. By Cox, increasing donor age beyond 30 years was associated with significant increases in the hazard ratio for graft loss [age 31-46, hazard ratio (HR) = 1.4, p = 0.02; 46-60, HR = 1.55, p = 0.008; > 60, HR = 1.68, p = 0.03]. Increasing donor age was significantly associated with: older and heavier recipients; higher creatinine and blood pressure (BP) 6 months post-transplant; and lower total cyclosporine dose during the first year. Of interest, the 6-month serum creatinine and the BP level modified significantly the relationship between age and survival. Thus, increasing donor age was significantly related to reduced graft survival only in patients with a 6-month creatinine < 2 mg/dL. Furthermore, donor age related significantly to graft survival only among patients with higher BP levels 6 month post transplant. It is concluded that increasing donor age is associated with reduced cadaveric graft survival, but that relationship is significantly modified by graft function and BP. These data suggest that poorly functioning kidneys have reduced survival irrespective of age. Furthermore, elevated BP levels may have a particularly negative effect on the survival of older grafts.

Recipient hypertension potentiates chronic functional and structural injury of rat renal allografts

BACKGROUND

Systemic hypertension affects many allograft recipients, is an important risk factor for chronic graft dysfunction, and is linked to reduced graft survival. The condition may up-regulate the expression of inflammatory host cells and their products. These, in turn, may significantly injure vascular endothelium and other components of allografted kidneys.

METHODS

Lewis rats received orthotopic F344 renal allografts, a standard model of chronic rejection. Renovascular hypertension was produced by placing a silver clip (0.25 mm) on the renal artery of the retained contralateral native kidney 4 weeks after transplantation. Sham-clipped rats served as normotensive controls. Four recipient groups (Gp) were studied: Gp 1, rats with an allograft plus a clipped native kidney; Gp 2, those with an allograft and a sham-clipped native kidney; Gp 3, isografted animals with a clipped native kidney; and Gp 4, those bearing an isograft and a sham-clipped native kidney. Systolic blood pressure and proteinuria were measured every 2 weeks for 24 weeks. Grafts were assessed serially for morphologic and immunohistologic changes.

RESULTS

Systemic blood pressure rose to hypertensive levels in Gps 1 and 3 within a week of clipping but never increased in Gps 2 and 4. Proteinuria developed in hypertensive animals but remained at baseline in normotensive controls. Intimal thickening of allograft arteries progressed to luminal obliteration with extensive perivascular and interstitial fibrosis by 24 weeks. In contrast, vascular changes in isografts of hypertensive hosts were restricted to medial hypertrophy. Tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, platelet derived growth factor (PDGF), endothelin, Il-6, major histocompatibility complex (MHC) class II, and B7 were up-regulated in allografts in hypertensive hosts. Vascular deposition of immunoglobulin (IgG) was increased. These changes were markedly less pronounced in Gp 3 isografts and minimal in the kidneys of the normotensive animals of Gps 2 and 4.

CONCLUSIONS

An experimental model is presented that examines the influence of recipient hypertension in the pathogenesis of chronic dysfunction and injury developing in rat renal allografts over time.