Possible causes and consequences of hypertension in stable renal transplant patients

Role of hypertension in kidney transplant recipients

Cardiovascular events are one of the leading causes of mortality in kidney transplant recipients. Hypertension is the most common comorbidity accompanying chronic kidney disease, with prevalence remaining as high as 90% even after kidney transplantation. It is often poorly controlled. Abnormal blood pressure profiles, such as masked or white-coat hypertension, are also extremely common in these patients. The pathophysiology of blood pressure elevation in kidney transplant recipients is complex and includes transplantation-specific risk factors, which are added to the traditional or chronic kidney disease-related factors. Despite these observations, hypertension management has been an under-researched area in kidney transplantation. Thus, relevant evidence derives either from studies in the general population or from small trials in kidney transplant recipients. Based on the relevant guidelines in the general population, lifestyle modifications should probably be applied as the first step of hypertension management in kidney transplant recipients. The optimal pharmacological management of hypertension in kidney transplant recipients is also not clear. Dihydropyridine calcium channel blockers are commonly used as first line agents because of their lack of adverse effects on the kidney, while other antihypertensive drug classes are under-utilised due to fear of the possible haemodynamic consequences on renal function. This review summarizes the existing data on the pathophysiology, diagnosis, prognostic significance and management of hypertension in kidney transplantation.

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.

The Relationship between Sleep-Disordered Breathing and Hypertension in a Nationally Representative Sample

Sleep-disordered breathing (SDB), characterized by abnormal respiratory patterns or inadequate quantity of ventilation, is common in adults. A positive association between SDB and hypertension has been established, in both cross-sectional and longitudinal studies. One void in the literature concerns the role of race/ethnicity in the association between SDB and hypertension. In this context, a cross-sectional study was performed on 6,783 participants in the National Health and Nutrition Examination Survey 2005–2008. Participants were ≥age 20 and free from cardiovascular disease. The outcome of interest was hypertension, defined as ≥140 mmHg systolic blood pressure (BP), and/or ≥90 mmHg diastolic BP or antihypertensive medication use. Self-reported SDB was positively associated with hypertension, independent of confounders such as depression, diabetes, cholesterol levels, and body mass index, among others. The association persisted in subgroup analyses by gender, with a stronger association among males than females, as well as by race/ethnicity, with non-Hispanic blacks displaying the strongest association. In the multivariable-adjusted model, compared to a sleep summary score of zero (referent), the OR (95% CI) of hypertension for non-Hispanic blacks was 1.34 (0.98–1.83) for a sleep summary score of 1, 1.44 (1.06–1.97) for a score of 2 and 3.72 (1.98–7.00) for a score of >3; p-trend < 0.0001. SDB was positively associated with hypertension in a large, nationally representative sample of US adults. Along with being prevalent, SDB is also treatable. Therefore, our results are important for minority race/ethnic groups who typically experience a higher baseline for negative health outcomes.

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.

Progression of macrovascular diseases is reduced in type 1 diabetic patients after more than 5 years successful combined pancreas-kidney transplantation in comparison to kidney transplantation alone

Recent reports have demonstrated an improved cardiovascular outcome after simultaneous pancreas-kidney transplantation (SPKT) compared with kidney transplantation alone (KTA) in type 1 diabetic patients with end-stage renal disease. The purpose of this study was to determine the impact of SKPT and KTA on the progression of cerebrovascular disease (CVD), coronary heart disease (CHD) and peripheral vascular disease (PVD) 5 and 10 years after transplantation. Only patients with graft survival more than 5 years, were included in this study. In summary, 12 type 1 diabetic patients with SPKT and 10 diabetic subjects with KTA were evaluated. The immunosuppressive therapy was similar in both patient groups. The mean observation period was 124 (72-184) months in the SPKT group and 122 (64-216) months in the group with KTA. To investigate the vascular risk profile we examined mean HbA1c, blood pressure and lipid levels in both patient groups during the first 5 years (period I) and the second 5 years (period II) after transplantation (measurements at least at 3-month intervals). Additionally, we evaluated the prevalence of moderate (stage I-II) and severe (stage III-IV) macrovascular diseases prior as well as 5 and 10 years after transplantation. During period I the mean HbA1c-value was 5.7+/-0.4% in the group with SPKT versus 7.4+/-0.8% in the KTA group, and in period II 5.8+/-0.4% in the SPKT group versus 7.6+/-0.9% (P<0.001) in the patients with KTA. The cholesterol levels were approximately the same in both groups, the triglycerides were lower in the patients with SPKT than in the subjects with KTA with 1.3+/-0.4 vs. 2.2+/-0.9 mmol/l in period I, and 1.4+/-0.5 vs. 2.3+/-0.6 mmol/l in period II (P<0.05). The BP-values were similar in both groups. Five years after transplantation the prevalence of vascular diseases was not significantly different between both groups. During the following 5 years the prevalence of macrovascular diseases increased more in the KTA than in the SKPT group. After a mean observation period of 10 years the SKPT group showed a lower prevalence of vascular diseases (stage I-IV) with 41% CVD, 50% CHD and 50% PAV in comparison to the KTA group with a prevalence of 80% CVD, 90% CHD and 80% PAV), the difference was not statistically significant because of the small patient groups. The frequency of the vascular complications myocardial infarction (16% vs. 50%), stroke (16% vs. 40%) and amputations (16% vs. 30%) was in summary significant lower in the patients with SPKT than in the patients with KTA (P<0.05). In conclusion, while for the first 5 years after transplantation the progression of macroangiopathy in patients with SPKT and KTA was not significantly different, after a mean 10-year observation period the progression of macrovascular diseases was significantly lower in recipients with a functioning SPKT compared to patients with a KTA; this can be explained by a better vascular risk profile after SPKT. The 10-year patient survival was 83% in the SPKT group and 70% in patients with KTA.

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.

Pathomechanisms and the diagnosis of arterial hypertension in pediatric renal allograft recipients

Arterial hypertension is common in pediatric renal allograft recipients. While the causes are multifactorial, including chronic graft rejection, immunosuppressive therapy, and renal vascular disorders, the effect of hypertension on renal allograft function is detrimental. As in adults, if not treated early and aggressively, hypertension may lead to cardiovascular damage and graft failure. Pathophysiological changes in the arteries and kidney af-ter renal transplantation and the impact of receptor regulation have not been studied extensively in children. For identifying children with hypertension following renal transplantation casual blood pressure measurements do not accurately reflect average arterial blood pressure and circadian blood pressure rhythm. Ambulatory 24-h blood pressure monitoring should regularly be applied in trans-plant patients. The purpose of this review is to analyze pathophysiological aspects of risk factors for arterial hypertension and underline the importance of regular blood pressure monitoring and early therapeutic intervention.

Blood pressure management in the kidney transplant recipient

Hypertension is extremely common after kidney transplantation. It has been observed in up to 80% to 90% of patients. The etiologies are multifactorial but, in large part, rest with the native kidneys, concomitant immunosuppressant drugs, and behavioral factors that promote the development of higher levels of blood pressure, including obesity, salt intake, smoking, and alcohol consumption. There is a direct relationship between kidney allograft failure and level of systolic blood pressure during follow-up. Patients with a systolic blood pressure greater than 180 mmHg have 2-fold greater risk of loss of graft function compared with patients with systolics of less than 140 mmHg. A similar pattern exists for diastolic blood pressure. Some investigators have also demonstrated that higher levels of blood pressure also correlate with an increased risk of acute graft rejection, particularly in African Americans. What is not known is whether more effective control of arterial pressure in the transplant patient will reduce the likelihood of graft loss and improve survival. No prospective outcome trials have ever been performed. However, it is likely, given the marked success of better control of blood pressure in nontransplant patients in reducing cardiovascular death and the rate of progression of kidney disease, that similar benefits will be appreciated in the transplant patient. Given the greater cardiovascular burden in the kidney transplant recipient because of the presence, in many cases, of diabetes and hypertension, perhaps even more risk reduction may be realized with incremental reductions in blood pressure. Preferred treatment strategies for lowering blood pressure depends on the mechanism of action and medical comorbidity. Drugs that block the renin-angiotensin system should be preferentially considered because they may have similar advantages in delaying progressive loss of allograft function, much in the same way they have proven benefits in protecting native kidney function. Treating blood pressure in the kidney transplant recipient is a complicated process because patients are already on multiple medications and many will need 3 to 5 antihypertensive drugs to achieve optimal control of blood pressure, which should preferably be below 130/80 mmHg.

Early posttransplantation hypertension and poor long-term renal allograft survival in pediatric patients

OBJECTIVE

To evaluate the effect of early hypertension on long-term allograft survival in children with kidney transplantation.

STUDY DESIGN

Data from a total of 159 patients (mean age, 12.8+/-4.8 years) who underwent kidney transplantation between 1978 and 1998 and whose allograft was functioning for at least 1 year were analyzed retrospectively. Patients were divided according to the presence of hypertension within the first year after transplantation. Primary outcome was time of allograft failure (death, return to dialysis, or retransplantation).

RESULTS

Kaplan-Meier analysis showed that systolic (P<.0001) and diastolic (P=.016) hypertension was associated with overall worse allograft survival. Children with systolic hypertension had a significantly higher graft failure rate regardless of the type of donor, cause of kidney failure, presence or absence of acute rejection, and allograft function at 1 year after transplantation. The multivariate Cox regression model proved that systolic hypertension was a significant and independent risk factor for poor graft survival (hazard ratio [HR], 1.79; P<.0001). Other predictors included allograft function at 1 year after transplantation (HR, 0.97; P<.0001), acquired cause of end-stage kidney disease (HR, 1.96; P=.01) and age <6 years (HR, 2.61; P=.045).

CONCLUSIONS

Early posttransplantation systolic hypertension strongly and independently predicts poor long-term graft survival in pediatric patients.

Insulin resistance as putative cause of chronic renal transplant dysfunction

Transplantation is the preferred organ replacement therapy for most patients with end-stage renal disease. Despite impressive improvements over recent years in the treatment of acute rejection, approximately half of all grafts will loose function within 10 years after transplantation. Chronic renal transplant dysfunction, also known as transplant atherosclerosis, is a leading cause of late allograft loss. To date, no specific treatment for chronic renal transplant dysfunction is available. Although its precise pathophysiology remains unknown, it is believed that it involves a multifactorial process of alloantigen-dependent and alloantigen-independent risk factors. Obesity, posttransplant diabetes mellitus, dyslipidemia, hypertension, and proteinuria have all been identified as alloantigen-independent risk factors. Notably, these recipient-related risk factors are well-known risk factors for cardiovascular disease, which cluster within the insulin resistance syndrome in the general population. Insulin resistance is considered the central pathophysiologic feature of this syndrome. It is therefore tempting to speculate that it is insulin resistance that underlies the recipient-related risk factors for chronic renal transplant dysfunction. Recognition of insulin resistance as a central feature underlying many, if not all, recipient-related risk factors would not only improve our understanding of the pathophysiology of chronic renal transplant dysfunction, but also stimulate development of new treatment and prevention strategies.

Routine renin-angiotensin system blockade in renal transplantation?

There is ample evidence to support the recommendation of renin-angiotensin system blockade therapy as the standard of care for strategies aimed at preserving renal function in chronic renal disease. Nevertheless, despite the well established antihypertensive effects of these drugs, the use of renin-angiotensin system blockers in renal transplantation has been quite limited so far, nephrologists being afraid of the possibility of inducing renal insufficiency in patients with a single kidney transplant. However, current knowledge of the ability of these agents to control blood pressure and urinary protein excretion, as well as post-transplant erythrocytosis, effectively in kidney transplant recipients suggests that it is now time to apply renin-angiotensin system blockers to the field of renal transplantation.

Syndrome X following renal transplantation

The cardiovascular risk factors that accompany postrenal transplantation include an atherogenic lipid profile, hypertension, new-onset diabetes mellitus, and a chronic prothrombotic state. This picture describes the dysmetabolic syndrome or syndrome X, which can significantly aggravate not only the risk of cardiovascular disease and death in this population, but also the progression of allograft dysfunction. The recognition and aggressive management of the dysmetabolic syndrome in postrenal allograft recipients may have a favorable impact on the incidence of cardiovascular morbidity and mortality in these patients and prolong allograft function.

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

BACKGROUND

Acute rejection (AR) is a strong predictor of renal allograft survival. Recent advances in immunosuppression have reduced considerably the incidence of AR. Still, approximately 25% of patients have AR early post-transplant, and the factors that predispose to AR have not been fully clarified.

METHODS

The study includes 1641 adults, recipients of first cadaveric (CAD, N = 1195) or living related renal grafts (LRD, N = 446), transplanted in one institution. The variables associated with the occurrence of AR during the first year post-transplant were identified.

RESULTS

By univariate analyses, AR was associated with the following variables: younger (P < 0.001); heavier (P = 0.003); and African American recipients (P = 0.002); CAD transplants (P = 0.001); higher number of HLA mismatches (P = 0.001); delayed graft function (DGF, P = 0.001); higher levels of serum creatinine post-transplant (P = 0.003); and higher levels of systolic and/or diastolic blood pressure (BP) post-transplant (P < 0.001). Higher BP levels were also associated with earlier AR episodes (P < 0.0001). By multivariable analysis AR was significantly associated with recipient age, number of HLA mismatches, DGF, pre-PRA and systolic BP. Analysis of BP measured weekly post-transplant indicated that elevated BP levels, even three weeks prior to the AR episode, were significantly associated with AR. For every level of BP, the use of BP medications was associated with a lower incidence of AR (P < 0.0001). Furthermore, the use of calcium channel blockers was also associated with lower incidence of AR (P = 0.001). Of note, 81% of recipients whose BP increased after the transplant had AR. In contrast, 22% of patients whose BP declined post-transplant had AR.

CONCLUSIONS

Elevated BP levels post-transplant identify patients at high risk of AR independently of graft function. Treatment of BP and reduction of BP levels appears to be associated with a decreased risk of AR. We hypothesize that high BP may be an indicator of a particular type of allograft damage, perhaps ischemic, that may predispose to AR.

Recommendations for the outpatient surveillance of renal transplant recipients. American Society of Transplantation

Many complications after renal transplantation can be prevented if they are detected early. Guidelines have been developed for the prevention of diseases in the general population, but there are no comprehensive guidelines for the prevention of diseases and complications after renal transplantation. Therefore, the Clinical Practice Guidelines Committee of the American Society of Transplantation developed these guidelines to help physicians and other health care workers provide optimal care for renal transplant recipients. The guidelines are also intended to indirectly help patients receive the access to care that they need to ensure long-term allograft survival, by attempting to systematically define what that care encompasses. The guidelines are applicable to all adult and pediatric renal transplant recipients, and they cover the outpatient screening for and prevention of diseases and complications that commonly occur after renal transplantation. They do not cover the diagnosis and treatment of diseases and complications after they become manifest, and they do not cover the pretransplant evaluation of renal transplant candidates. The guidelines are comprehensive, but they do not pretend to cover every aspect of care. As much as possible, the guidelines are evidence-based, and each recommendation has been given a subjective grade to indicate the strength of evidence that supports the recommendation. It is hoped that these guidelines will provide a framework for additional discussion and research that will improve the care of renal transplant recipients.

Prospective analysis of the value of 24-hour ambulatory blood pressure on renal function after kidney transplantation

BACKGROUND

No prospective study has been performed to determine the prognostic value of 24-hr ambulatory blood pressure (24-hr ABP) versus casual blood pressure (CBP) in patients after kidney transplantation. We have addressed this issue by analyzing renal graft function in patients for the first 5 years after transplantation.

METHODS

The 24-hr ABP (SpaceLabs 90207) was monitored 6 and 18 months after transplantation in 46 renal transplant recipients without any acute episodes of rejection. Combined study endpoints were death of patients, need for dialysis, second transplantation, and doubling of serum creatinine.

RESULTS

Six months after transplantation systolic and diastolic 24-hr ABP correlated with serum creatinine (r=0.41, P=0.005 and r=0.37, P<0.01, respectively) although CBP did not. Divided into tertiles according to average 24-hr ABP (lower tertile: < or =91 mmHg; middle tertile: 92-97 mmHg; upper tertile: > or =98 mmHg) serum creatinine significantly differed between the three groups (1.26 +/- 0.38 vs. 1.32 +/- 0.25 vs. 1.65 +/- 0.39 mg/dl, respectively; analysis of variance, P< 0.01). Confounding factors of renal function such as age, body weight, cold and warm ischemic time, cytomegaly virus status, methylprednisone and cyclosporine dosages, cyclosporine concentrations, as well as concomitant antihypertensive medication did not differ among the three groups. In the long-term follow-up (5 years), combined endpoints were reached in 3 of 15 of the lower tertile group, in 3 of 15 of the median tertile group, and in 8 of 16 of the upper tertile group (log-rank test, P<0.01). No relation to long-term out come was found when patients were stratified according to their CBP.

CONCLUSION

In our small but homogenous study cohort 24-hr ABP was more closely related to renal function in patients after transplantation than CBP suggesting that 24-hr ABP is superior for evaluation of hypertension-related renal graft dysfunction.

Explained and unexplained ischemic heart disease risk after renal transplantation

Whether the high incidence of ischemic heart disease (IHD) among renal transplant patients can be attributed to the same risk factors that have been identified in the general population is unclear. The risk for major IHD events occurring >1 yr after transplantation among 1124 transplant recipients was estimated by using the risk calculated from the Framingham Heart Study (FHS). The FHS risk predicted IHD (relative risk, 1.28; 95% confidence interval, 1.20 to 1.40; P: < 0.001); however, the FHS risk tended to underestimate the risk of IHD for renal transplant recipients. This was largely attributable to increased risks associated with diabetes mellitus and, to a lesser extent, age and cigarette smoking for renal transplant recipients. For men, the relative risks for diabetes mellitus were 2.78 (1.73 to 4.49) and 1.53 for the transplant recipient and FHS populations, respectively; the relative risks for age (in years) were 1.06 (1.04 to 1.08) and 1.05, respectively, and those for smoking were 1.95 (1.20 to 3.19) and 1.69, respectively. For women, the relative risks for diabetes mellitus were 5.40 (2.73 to 10.66) and 1.82, respectively. There was a tendency for the risk associated with cholesterol levels to be higher for transplant recipients, compared with the FHS population, but the risks associated with high-density lipoprotein cholesterol levels and BP appeared to be comparable. Independent of these and other risk factors, the adjusted risk of IHD for the transplant recipient population has decreased. Compared with the era before 1986, transplantation between 1986 and 1992 was associated with a lower relative risk of 0.60 (0.39 to 0.92); transplantation after 1992 was associated with an even lower relative risk of 0.27 (0.11 to 0.63) for IHD. Of concern was the fact that dihydropyridine calcium channel antagonists were associated with an increased risk for IHD (relative risk, 2.26; 95% confidence interval, 1.24 to 4.12; P: = 0. 008), and this association was independent of other antihypertensive agents and risk factors. Therefore, although the FHS risk predicts IHD after renal transplantation, it tends to underestimate the risks, especially the risk associated with diabetes mellitus. The unexpected finding that dihydropyridine calcium channel antagonists were associated with an increased IHD risk merits further evaluation.

Hypertension after pancreas-kidney transplantation: role of bladder versus enteric pancreatic drainage

BACKGROUND

Recent reports suggest that hypertension may be less common after simultaneous pancreas-kidney transplantation than after kidney transplantation alone. However, the mechanisms for this beneficial effect have not been delineated. We hypothesize that lower blood pressures may result from chronic volume depletion in patients with bladder-drained pancreatic allografts.

METHODS

We compared the incidence and severity of hypertension 12 months after transplantation in 79 bladder-drained pancreas-kidney recipients and 46 diabetic kidney-only recipients. These two groups were compared with a smaller group of enterically drained pancreas-kidney recipients. Blood pressure was also compared before and after surgical conversion from bladder to enteric drainage in 10 patients.

RESULTS

Hypertension was significantly less common and less severe after pancreas-kidney transplantation than after kidney transplantation alone, but the benefit of the pancreas transplant was evident only in bladder-drained patients. Logistic regression analysis of the bladder-drained pancreas-kidney patients confirmed the independent impact of the pancreatic allograft on the presence of hypertension, indicated an independent association with serum creatinine concentration and donor age, but suggested no correlation with recipient age, race, or number of rejection episodes. A comparison of blood pressures before and after pancreatic conversion from bladder to enteric drainage indicated no significant change in the prevalence or severity of hypertension.

CONCLUSIONS

We conclude that the beneficial effect of a pancreas transplant on the prevalence and severity of hypertension after simultaneous pancreas-kidney transplantation is limited to bladder-drained patients. Although it is possible that the effect is mediated by chronic volume depletion, the observation that blood pressure does not increase after conversion from bladder to enteric drainage suggests that other factors may be involved.

Abnormal 24-hour blood pressure patterns in children after renal transplantation

Hypertension after renal transplantation occurs commonly and is associated with decreased allograft survival. Hypertension is usually diagnosed by casual blood pressure (BP) measurements in the outpatient clinic that may not reflect the overall 24-hour BP pattern. To better describe the pattern of BP in children after renal transplantation, 24-hour ambulatory BP monitoring (APBM) was performed in 42 patients with stable renal function. BP was measured every 20 minutes during the daytime and every 30 minutes at night. Mean patient age was 12.8 +/- 5.2 years, and mean time after transplantation was 34 +/- 36 months. Seventy-six percent of the patients were administered antihypertensive medications. Twenty-four-hour mean systolic BP (SBP) was 127 +/- 11 mm Hg, and diastolic BP (DBP) was 80 +/- 11 mm Hg. Mean 24-hour BP load values (percentage of BP readings > 95th percentile based on Task Force criteria) were 59% for SBP and 50% for DBP, which were significantly elevated compared with healthy children (P < 0.001). An attenuated decline in sleep BP (nondipping) was found in 78% of the patients for SBP and 50% for DBP. Sleep BP exceeded awake BP in 24% of the patients for SBP and 17% for DBP. Boys had a greater SBP load (66% versus 45%; P = 0.03) and DBP load (57% versus 38%; P = 0.04) than girls. These results confirm in children the high prevalence of hypertension by ABPM criteria after renal transplantation and show attenuation of normal sleep BP decreases. These BP disturbances may shorten renal allograft survival and predispose children to long-term hypertensive end-organ damage.

Use of anti-hypertensive medications and post-transplant renal allograft function in children

Post-transplant hypertension is a common occurrence in children. The relative effect of this hypertension on renal allograft function is uncertain. Examining the accumulated data for pediatric renal transplant recipients at our institution from monthly visits for up to three years, we determined whether the use of anti-hypertensive medications (anti-HTN medications) was associated with allograft dysfunction. Monthly clinical data included height, weight, serum creatinine, cyclosporin A (CsA) trough levels, number of acute rejection episodes, and number of anti-HTN medications. Estimated glomerular filtration rate (eGFR) was calculated monthly for each patient using the Schwartz formula. Time post-transplant was grouped into 6-month intervals. One thousand three hundred and sixty-three monthly data sets from 6 months (n = 76 patients) to 3 yr post-transplant (n = 47 patients) were analyzed. Overall mean eGFR was 75 mL/min/1.73 m2 at 6 months and 54 mL/min/1.73 m2 at 3 yr. A lower eGFR was found at all post-transplant time intervals for patients receiving anti-HTN medications compared with those who were not (p < 0.01). This lower eGFR was found at some but not all times post-transplant when patients were grouped by donor type or history of acute rejection episodes and analyzed separately. Mean CsA trough levels were higher at all post-transplant time intervals in patients receiving anti-HTN medications (p < 0.05). While a causal relationship between post-transplant hypertension and graft dysfunction cannot be established from this study, we conclude that the need for anti-HTN medications is associated with worse allograft function.

The best way to manage hypertension after renal transplantation

Hypertension in renal allograft recipients is a common problem arising from multiple factors, including peripheral vascular damage caused by pretransplant hypertension, side effects of immunosuppressive medications, allograft dysfunction, renal artery stenosis, recurrent glomerulonephritis, synthesis of vasoconstrictive hormones by the native kidneys, and excessive dietary salt intake. Identification of modifiable factors causing hypertension and concurrent medical conditions, and measurement of glomerular filtration rate, cyclosporine/tacrolimus blood levels, and magnitude of proteinuria are essential to tailor treatment for an individual patient. Lifestyles that exacerbate hypertension should be modified. For pharmacological therapy, diuretics and calcium channel blockers are first-line agents in patients on cyclosporine shortly after transplant. Angiotensin-converting enzyme inhibitors are good choices for patients with significant proteinuria. Reduction of immunosuppression will improve hypertension in some patients, but entails a potential risk of rejection or graft loss. Angioplasty is necessary in patients with a functionally significant stenosis of the allograft renal artery. Other patients on maximal medical therapy may benefit from native nephrectomy.

Use of calcium-channel blockers in pediatric renal transplant recipients

Hypertension (HTN) is a significant problem in pediatric renal transplant (TP) recipients, predisposing the individuals to the development of cardiovascular disease and graft dysfunction. Calcium channel blockers (CCB) are considered excellent agents to treat post-TP HTN. We compared the efficacy and adverse effects of the two most commonly prescribed CCBs in our pediatric renal TP population: nifedipine (Procardia, or P) and amlodipine (Norvasc, or N). All patients (n = 24) had been started on a CCB for systolic (SBP) and/or diastolic BP (DBP) > 95%. There were no other changes in adjunctive antihypertensive medications or doses during the cross-over period. Post-TP, pretreatment (pretx) SBP was 137.6 +/- 10.9 mmHg. The post-treatment SBP were (in mmHg): 128.5 +/- 11.9 (all patients, n = 24) (p = 0.009 vs. pretx); 126.4 +/- 10.0 (P alone, n = 15) (p = 0.007 vs. pretx); 132.8 +/- 14.4 (P + other antihypertensive(s), n = 9) (p = 0.331, NS vs. pretx). The post-TP, pretreatment DBP was 88.2 +/- 11.1 mmHg. The post-treatment DBP were (in mmHg): 78.5 +/- 6.9 (all patients, n = 24) (p = 0.03 vs. pretx); 77.2 +/- 7.4 (P alone, n = 15) (p = 0.008 vs. pretx); 80.7 +/- 6.1 (P + other antihypertensive(s), n = 9) (p = 0.063, NS vs. pretx). P and N were equally effective in reducing SBP (p = 0.843, NS) and DBP (p = 0.612, NS). Cyclosporin A (CyA) dose (p = 0.81) and trough levels (p = 0.19) were similar in P- and N-treated patients. Calculated GFR was virtually identical in P- and N-treated patients (p = 0.89). Patients (or parents of) reported a higher incidence of various side-effects while receiving P, including headache, flushing, dizziness and leg cramps. Furthermore, 22/24 (91.7%) reported some degree of gingival hyperplasia during treatment with P, and all these patients reported a stabilization or reduction of hypertrophy after the switch from P to N. We conclude that CCBs (N) are efficacious drugs for the purpose of BP control and renal protection in pediatric renal TP recipients.

Antihypertensive medication and renal allograft failure: a North American Pediatric Renal Transplant Cooperative Study report

Hypertension after renal transplantation occurs commonly and, in adults, is associated with decreased graft survival. The North American Pediatric Renal Transplant Cooperative Study database was analyzed to determine: (1) the percent use of antihypertensive (anti-HTN) medication based on donor type, race, age, and acute rejection status; and (2) whether use of anti-HTN medication is associated with higher rates of subsequent graft failure. Data regarding anti-HTN medication use was available in 5251 renal allografts (4821 patients) with >30 d graft function. Posttransplant follow-up data were collected at 30 d, 6 mo, 12 mo, and then annually for 5 yr. At each follow-up, patients were selected for further analysis if the graft was functioning at that visit and subsequent follow-up data were available. Overall, anti-HTN medication use was 79% on day 30 and 58% at 5 yr. At each follow-up, anti-HTN medication use was higher (P < 0.01) for cadaveric donor versus living related donor, blacks versus whites, age >12 versus <12 yr, and > or = 1 versus 0 acute rejection episodes. Anti-HTN medication use at each annual follow-up was associated with significantly higher rates of subsequent graft failure. Multiple regression analysis controlling for all factors associated with increased use of anti-HTN medications revealed a relative risk of graft failure for use of anti-HTN medication of greater than 1.4 (P < 0.001). In recipients of cadaveric allografts, only acute rejection status predicted subsequent graft failure more strongly than use of anti-HTN medications. These data suggest that hypertension after renal transplantation in children, as evidenced by use of anti-HTN medications, is associated with increased rates of subsequent graft failure.

Treatment of posttransplant hypertension by laparoscopic bilateral nephrectomy?

BACKGROUND

Hypertension is an important risk factor for the development of chronic graft failure and decreased graft and patient survival after renal transplantation.

METHODS

Between September 1994 and August 1996, 14 patients underwent laparoscopic bilateral nephrectomy for treatment of drug-resistant hypertension after successful renal transplantation. Common causes of hypertension were largely excluded before bilateral nephrectomy. A scoring system was developed for comparison of different antihypertensive regimes. In this system, points were given according to type and dosage of each antihypertensive drug.

RESULTS

At 6-month follow-up, all patients showed well-controlled blood pressure (median of mean arterial pressure: 104 vs. 130 mmHg preoperatively, P<0.001, n=14), and significantly fewer antihypertensive drugs were needed according to the scoring system (48.9+/-20.9 points vs. 105.9+/-23.5 points preoperatively, P<0.001, n=14). During laparoscopy, three conversions to open surgery were necessary. Postoperatively, four complications occurred. After laparoscopy, immunosuppression and other oral medication were given continuously. The hospital stay ranged between 3 and 6 days (median: 5 days).

CONCLUSIONS

The results indicate that bilateral nephrectomy using the laparoscopic technique can be an effective alternative method for a selected group of patients with severe hypertension, which is unresponsive to conservative management after successful renal transplantation with regard to improving the long-term graft survival.

Relationships between arterial hypertension and renal allograft survival in African-American patients

In previous studies, we showed that in African-American patients arterial hypertension during the first 6 months after transplantation is associated with a high risk of renal allograft loss. In this study, we sought to examine the relationships between pretransplant blood pressure (preBP), blood pressure early after transplantation (postBP), and allograft function and survival. The study included 116 African-American recipients of first cadaveric renal allografts followed for 64 +/- 40 months. Prior to transplantation, 78% of the patients required antihypertensive medications and 59% had poorly controlled BP (average mean arterial pressure, > or =107 mm Hg). Blood pressure levels increased significantly during the first month posttransplant, particularly in patients with poorly controlled preBP. During the first 6 months posttransplant, 95% of patients required antihypertensive drugs; after the transplant, patients required significantly more and higher doses of antihypertensives compared with pretransplant. In 38% of the patients, postBP remained high despite therapy. The level of postBP correlated with the patient's weight pretransplant and with the level of preBP. Pretransplant BP correlated with postBP 1 month after transplantation (r = 0.4, P < 0.0001), and 70% of the patients with poorly controlled postBP had uncontrolled preBP. Patients with poorly controlled preBP had worse graft survival than patients with well-controlled preBP (P = 0.03 by Cox regression). Furthermore, compared with patients with well-controlled postBP, patients with high postBP had higher serum creatinine at 10 days (P = 0.04) and at 6 months (P = 0.0004) posttransplant; these patients had reduced graft survival (P = 0.0006 by Cox). We found no objective evidence of differences in patient compliance between individuals with high postBP and those with well-controlled postBP. This study confirms the association between high postBP and reduced renal allograft survival in African-American patients. In addition, these results show that the level of preBP can be used to identify patients at high risk of developing severe hypertension immediately after transplantation and those at risk for renal allograft failure.

Laparoscopic bilateral nephrectomy: results in 11 renal transplant patients

PURPOSE

We report our experience with bilateral laparoscopic nephrectomy after renal transplantation.

MATERIALS AND METHODS

Between August 1994 and October 1995, 11 patients who had previously undergone renal transplantation underwent bilateral laparoscopic nephrectomy at our hospital due to poorly controlled hypertension. The records of 10 patients undergoing bilateral open nephrectomy were reviewed for comparison.

RESULTS

Mean operative time in the laparoscopy group was 195 minutes (range 125 to 270). Mean blood loss was 345 ml. and 1 patient required conversion to an open operation. Oral intake and mobilization were begun 1 day postoperatively. Mean postoperative morphine equivalent consumption was 14 mg., mean hospital stay was 4.2 days (range 3 to 6) and mean return to normal activities was 14 days. At a mean followup of 10.4 months blood pressure had improved significantly in 8 patients (73%). Mean operative time in the open surgery group was 145 minutes (range 115 to 170) and mean postoperative morphine equivalent required was 44 mg. Compared to the laparoscopy group the interval to resumption of oral intake (3.5 days), duration of hospital stay (10.7 days) and return to normal activities (36 days) were prolonged in the open surgery group.

CONCLUSIONS

According to our results, bilateral laparoscopic nephrectomy could be an effective alternative for the treatment of severe hypertension after renal transplantation. Compared to open nephrectomy most patients benefit from the laparoscopic approach.

Secondary hypertension: evaluation and treatment

Most patients with hypertension in the United States have essential (primary) hypertension (95%), the cause of which is unknown. The remaining 5% of adults with hypertension have the secondary form of hypertension, the cause and pathophysiologic process of which are known. Internists and other primary care physicians refer to this as treatable or curable hypertension, because the hypertension can be managed or even controlled with medications. Similarly, the condition is called surgical hypertension by surgeons in the belief that once the cause is determined and identified, surgical intervention will result in cure of hypertension. Secondary causes of hypertension include renal parenchymal disease, renovascular diseases, coarctation of the aorta, Cushing's syndrome, primary hyperaldosteronism, pheochromocytoma, hyperthyroidism, and hyperparathyroidism. Occasionally included in this category are alcohol- and oral contraceptive-induced hypertension and hypothyroidism, but these conditions are not discussed herein. The evaluation of secondary hypertension is of interest and can bring together different facets of anatomy, physiology, pharmacology, and radiology in the medical and surgical treatment of these disorders. Despite enthusiasm that can be generated in the evaluation of these conditions, evaluation can be expensive and should not be conducted for all patients with hypertension. Features that aid in the diagnosis of secondary hypertension include the following: 1. Onset of hypertension before the age of 20 or after the age of 50 years. The presence of hypertension at a young age may suggest coarctation of the aorta, fibromuscular dysplasia, or an endocrine disorder. Hypertension found for the first time after the age of 50 years may suggest the presence of renovascular hypertension caused by atherosclerosis. 2. Markedly elevated blood pressure or hypertension with severe end-organ damage, as in grade III or IV retinopathy. These findings suggest the presence of renovascular hypertension or pheochromocytoma. 3. Specific body habitus and ancillary physical findings. For example, truncal obesity and purple striae occur with hypercortisolism, and exophthalmos is associated with hyperthyroidism. 4. Resistant or refractory hypertension (poor response to medical therapy usually necessitating use of more than three antihypertensive medications from three different classes). 5. Specific biochemical test that suggest the existence of certain disorders, such as hypercalcemia in hyperparathyroidism, hyperglycemia in Cushing's syndrome and pheochromocytoma, and unprovoked hypokalemia with renin-producing tumors, primary hyperaldosteronism, or renin-mediated renovascular hypertension. 6. Other characteristics that may suggest secondary hypertension such as abdominal diastolic bruits (renovascular hypertension), decreased femoral pulses (coarctation of the aorta), or bitemporal hemianopias (Cushing's disease). A combination of a good history and physical examination, astute observation, and accurate interpretation of available data usually are helpful in the diagnosis of a specific causation.

Outcome of renal transplant recipients in the ICU

OBJECTIVE

To determine the outcome of renal transplant recipients in an intensive care unit (ICU).

DESIGN

Prospective, cohort study.

SETTING

Surgical ICU in a tertiary care hospital.

PATIENTS

Consecutive adult renal transplant recipients admitted to an ICU.

MEASUREMENTS AND MAIN RESULTS

Demographic data, underlying diseases, indications for admission to the ICU, number of prior kidney transplantations, duration of immunosuppression, duration of mechanical ventilation, length of stay in ICU and hospital, and ICU and hospital mortality were recorded. Seventy-one patients were included in the study. Twenty-seven patients were admitted to the surgical ICU immediately after renal transplantation surgery for postoperative monitoring (group 1). One patient died in this group. The remaining 44 patients were renal transplant recipients admitted to the surgical ICU with various complications (group 2). The mean posttransplant time in group 2 was 23 +/- 30 months. Seven patients died in group 2. The overall ICU mortality in this study was 11% and hospital mortality was 14%. The hospital mortality for postoperative patients (3.7% in group 1) was below the rate predicted based on the acute physiology and chronic health evaluation (APACHE II) score (15%). APACHE II score, duration of mechanical ventilation, and ICU length of stay were significantly higher among nonsurvivors. The ICU mortality among renal transplant recipients was higher than that of other patients (6%) admitted to the surgical ICU during the study period.

CONCLUSION

The ICU mortality of renal transplant recipients was twice that of general surgical ICU patients. The hospital mortality rate for recipients admitted immediately postoperatively to the ICU (group 1) was less than predicted by APACHE II.

The role of hypertension as a damaging factor for kidney grafts under cyclosporine therapy

The relative importance of glomerular filtration rate (GFR) and hypertension (permanent need for antihypertensive drugs) for the prognosis of kidney grafts was studied in 135 cyclosporine-treated primary cadaver kidney transplant recipients whose grafts lasted more than 1 year. The start point of 1 year after transplantation was chosen because hypertension developed within the first year in all our hypertensive patients. Graft prognosis in hypertensive patients was not significantly worse than that of normotensive patients; moreover at multivariate analysis, age at transplantation and GFR at 1 year (P = 0.014), but not hypertension, were significant prognostic factors for the graft. At logistic regression, GFR was a significant variable for hypertension (P = 0.009), but hypertension was not a significant variable for renal failure at 1 year (GFR < or = 0.83 mL/sec [50 mL n]; P, NS). Accordingly, hypertension per se resulted much more as a consequence of reduced renal function than as a direct cause of graft damage. However, when hypertensive patients were divided into controlled and uncontrolled, uncontrolled hypertensive patients had the worst prognosis (P = 0.03), and blood pressure control proved a strong prognostic factor for the graft, even after GFR was considered (P = value of the model considering blood pressure control, GFR, and age at transplantation: 0.007). Our data suggest that, apart from being an expression of reduced renal function, hypertension is also a direct kidney graft damaging agent, a role that can be controlled by strict reduction of blood pressure levels.

Hypertension after renal transplantation

In 212 cyclosporine-treated renal transplant recipients with stable graft function at 1 year and with potential follow-up of 5 years the prevalence of arterial hypertension was 81.6% at 1 year and 81.2% at 5 years. The logistic regression analysis showed that the presence of hypertension before transplantation (P = 0.0001; odds ratio 3.5), a plasma creatinine level higher than 2 mg/dL at 1 year (P = 0.0001; odds ratio 3.8), and a maintenance therapy with corticosteroids (P = 0.008; odds ratio 3.3) were positively associated with hypertension at 1 year after transplantation. The mean number of graft failures between 1 and 5 years was significantly higher and the mean reciprocal of plasma creatinine was significantly worse at 1 and 5 years in patients with noncontrolled hypertension than in normotensive patients or in patients with hypertension well controlled by drugs. We also investigated the potential protective role of nifedipine. The episodes of acute tubular necrosis (four versus three), of acute rejections (28 versus 29), the mean arterial pressure at 1 year (105 +/- 9 versus 104 +/- 9 mm Hg) and 5 years (105 +/- 10 versus 108 +/- 12 mm Hg), and the mean plasma creatinine level at 1 year (1.4 +/- 0.4 versus 1.6 +/- 0.4 mg/dL) and 5 years (1.8 +/- 1 versus 1.9 +/- 1 mg/dL) were similar in 52 patients who were given nifedipine for at least 4 years and 58 hypertensive patients who never took calcium channel blockers.(ABSTRACT TRUNCATED AT 250 WORDS)

Posttransplant renal artery stenosis--outpatient intraarterial DSA versus color aided duplex Doppler sonography

A prospective trial was conducted to assess the accuracy of color aided duplex Doppler (CADD) sonography to rule out transplant renal artery stenosis (TRAS) and to determine feasibility and safety of intraarterial digital subtraction angiography (DSA) in hypertensive renal allograft recipients on an outpatient basis. All patients were hypertensive (n = 18, mean age: 42 +/- 11 years) and underwent CADD and an i.a. DSA with 4F catheters. There was a 4 hour rest post DSA. Duplex Doppler measurements of maximum velocity were obtained. Absolute values of > or = 100 cm/s were considered indicative to suspect TRAS. DSA revealed severe TRAS in 4 patients (22%). The stenoses were located near the iliorenal anastomosis (n = 2) and at the bifurcation of the renal artery (n = 2). Duplex Doppler classified twelve (67%) renal artery pedicles normal (maximum velocity: 79 +/- 23 cm/s). TRAS was suspected in 6 patients with a maximum velocity of 159 +/- 48 cm/s (P < 0.01). False positive CADD diagnoses were due to tortuous graft vessels and a postbiopsy arteriovenous fistula. Sensitivity of CADD was 100%, specificity 86%. There were no DSA related complications. No impairment of graft function occurred. CADD allows renal angiography to be reserved to clarify an inconclusive ultrasound study and for definite diagnosis of angiomorphology and lesion classification. Intraarterial DSA of renal grafts in outpatients may be performed without an increased risk of procedure-related complications.

Risk factors for accelerated atherosclerosis in renal transplant recipients

The factors responsible for atherosclerosis in renal transplant recipients are not known. In the present study, cardiovascular disease was investigated in 403 patients who received 464 kidney transplants during a 10-year period. Among those who had no clinical evidence of vascular disease at the time of transplantation, atherosclerotic complications developed in 15.8 percent during the post-transplant follow-up period (46.1 +/- 36.2 months). Pre- and post-transplant vascular diseases were closely linked. However, after taking pre-transplant vascular disease into account, multivariate analysis showed that a number of known risk factors (age, sex, diabetes, cigarette smoking, hypertension, and serum cholesterol) were independently associated with post-transplant vascular disease. In addition, the number of acute rejection episodes (all treated with high doses of corticosteroids) was also independently linked to vascular disease. These results suggest that an increased prevalence of known risk factors, and events linked to allograft rejection, explain the high incidence of cardiovascular disease in renal transplant recipients.