Mechanisms of posttransplant hypertension

A holistic review of sodium intake in kidney transplant patients: More questions than answers

Kidney transplantation (KT) is the best treatment option for end-stage kidney disease (ESKD). Acute rejection rates have decreased drastically in recent years but chronic kidney allograft disease (CKAD) is still an important cause of allograft failure and return to dialysis. Thus, there is unmet need to identify and reverse the cause of CKAD. Additionally, cardiovascular events after KT are still leading causes of morbidity and mortality. One overlooked potential contributor to CKAD and adverse cardiovascular events is increased sodium/salt intake in kidney transplant recipients (KTRs). In general population, the adverse effects of high sodium intake are well known but in KTRs, there is a paucity of evidence despite decades of experience with KT. Limited research showed that sodium intake is high in most KTRs. Moreover, excess sodium intake is associated with elevated blood pressure and albuminuria in some studies involving KTRs. There is also experimental evidence suggesting that increased sodium intake is associated with histologic graft damage. Critical knowledge gaps still remain, including the exact amount of sodium restriction needed in KTRs to optimize outcomes and allograft survival. Additionally, best methods to measure sodium intake and practices to follow-up are not clarified in KTRs. To meet these deficits, prospective long term studies are warranted in KTRs. Moreover, preventive measures must be determined and implemented both at individual and societal levels to achieve sodium restriction in KTRs.

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.

Fatores de risco cardiovascular em pacientes pediátricos após um ano de transplante renal

OBJETIVO: Identificar a frequência de diabetes mellitus e a presença de fatores de risco cardiovascular em pacientes pediátricos após um ano de transplante renal. MÉTODOS: Estudo retrospectivo, de cunho documental e exploratório, realizado de janeiro de 2000 a janeiro de 2006, abrangendo 111 prontuários de pacientes pediátricos (0 a 18 anos incompletos) submetidos a transplante renal no Hospital do Rim e Hipertensão e no Hospital São Paulo da Universidade Federal de São Paulo. RESULTADOS: Foram analisados 111 pacientes, 50,5% utilizavam anti-hipertensivos antes do transplante renal. Um ano após este número caiu para 28%. No pré-transplante 13,5% pacientes apresentaram sobrepeso e após um ano não houve alteração importante (12,6%). O número de pacientes obesos aumentou 50% após um ano de transplante renal. Aproximadamente 1% das crianças desenvolveram diabetes mellitus pós-tranplante renal. CONCLUSÃO: A presença de excesso de peso (sobrepeso e obesidade), hipertensão arterial e diabetes mellitus são freqüentes em pacientes pediátricos pós-tranplante renal.

Risk factors for hypertension 3 years after renal transplantation in children

We performed a case-control study in renal transplant patients between 1998 and 2003 to identify risk factors for arterial hypertension over the medium term in pediatric patients undergoing renal transplantation. Three years after transplant, patients were classified into hypertensive or control groups. The following risk factors were analyzed: hypertension before transplant, glomerular filtration rate at sixth posttransplant month, acute rejection episodes, renal artery stenosis, accumulated prednisone and calcineurin inhibitor doses, presence of native kidneys, donor type (living or cadaver), body mass index at 1 year posttransplant, and glomerular disease as renal insufficiency etiology. Of 161 transplants, 124 fulfilled the inclusion criteria; 63 were hypertensive, and 61 were controls. Univariate analysis showed hypertension before transplant (52/63 vs. 27/61, p < 0.001), glomerulopathies (23/63 vs. 12/61, p = 0.001), glomerular filtration rate at 6 months (71 +/- 18 vs, 80 +/- 18 ml/min per 1.73 m(2), p = 0.003) as risk factors. A tendency to statistical significance was observed with regard to body mass index (SDS) in the first year (0.40 +/- 1.10 vs, 0.04 +/- 1.10, p = 0.072). Multivariate analysis showed statistical significance concerning previous hypertension and glomerular filtration rate at 6 months. Hypertension before transplant and early graft function are the major risk factors for hypertension in the medium term following renal transplant.

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.

Arterial hypertension following renal transplantation in children-a short-term study

Systemic arterial hypertension is a common complication among transplanted patients. The objective of this study was to investigate the risk factors for arterial hypertension after kidney transplantation in children. A retrospective study was carried out of 70 kidney transplants performed on patients under 18 years of age at the Hospital do Rim and Hipertensão, from January 1998 to June 2001. At the end of 6 months post transplant, the patients were classified into either normotensive ( n=31) or hypertensive ( n=39) groups. The following potential risk factors for arterial hypertension were studied: (1) hypertension before transplantation; (2) the glomerular filtration rate (GFR) at 1, 3, and 6 months post transplant; (3) acute rejection episodes; (4) cumulative dose of corticosteroids; (5) the presence of native kidneys; (6) symptomatic renal artery stenosis; (7) cold ischemia time greater than 24 h; (8) age and sex of the donor; (9) age of the recipient; (10) transplant type (living related or cadaveric donor); (11) the body mass index of recipients at the end of the follow-up period; and (12) delayed graft function. The two groups were comparable in terms of the etiology of renal insufficiency, age, gender, and immunosuppressive drugs. Among the risk factors studied, the sole factor showing a statistically significant association with arterial hypertension was the GFR at 3 and 6 months after transplantation. In the group of normotensive patients, GFRs were 92+/-29 and 83+/-20 ml/min per 1.73 m(2) at 3 and 6 months, respectively, whereas in the hypertensive patients, GFRs were 74+/-23 and 70+/-21 ml/min per 1.73 m(2) respectively. Hence, only the lower GFR can be considered a risk factor for hypertension in children within our sample. However, arterial hypertension might be a risk factor for the early onset of chronic allograft nephropathy; in this case, hypertension should be considered the cause of lower glomerular filtration. Our data do not permit us to distinguish between these two hypotheses. The known risk factors for hypertension following renal transplantation in adults were not confirmed in the present study. It remains unclear to us as to whether this means the etiology of hypertension differs in children, or if this is the result of a bias in patient selection.

A case of renal artery stenosis after transplantation: can losartan be more accurate than captopril renography?

Hypertension is a common complication observed after renal transplantation. If the hypertension is of renovascular origin, transluminal angioplasty or surgery of the renal artery stenosis can lead help cure the hypertension. The blood pressure of a 31-year-old man who underwent renal transplantation 2 years earlier gradually increased. Arteriography showed stenosis (>80%) in the two branches of the renal artery. To help confirm the presence of renovascular hypertension, captopril renography was performed but showed no significant changes compared with baseline renography. Renography was performed again after losartan administration and showed impaired renal function. In this case, losartan renography was more useful than captopril in suggesting renovascular hypertension.

Triple immunosuppression with subsequent prednisolone withdrawal: 6 years' experience in paediatric renal allograft recipients

Thirty-four children (< or = 15 years of age) with end-stage renal failure received 39 renal allografts between 1985 and 1991 and were treated with cyclosporin A (CyA), azathioprine and low-dose prednisolone (PNL). We aimed to withdraw PNL by 6 months after transplantation. Median duration of follow-up was 2 years 4 months (range 0.1 month to 6 years 4 months). There were no deaths. Crude graft survival for living-related grafts (n = 9) was 100%, although only 1 patient has been followed for > 2 years. For cadaveric grafts (n = 30), 1- and 5-year actuarial graft survivals were 90% and 79% respectively. At 12 months posttransplant, the median (range) glomerular filtration rate for all patients was 63 (19-109) ml/min per 1.73 m2 (n = 25) and at 5 years was 48 (17-64) ml/min per 1.73 m2 (n = 9). Complications observed included rejection episodes which occurred after discontinuation of PNL. Long-term (after 12 months), 28% of patients remain on PNL. Hypertension was present in more than 50% of patients. Severe CyA nephrotoxicity was not seen. Catch-up growth as determined by the change (delta) in mean height standard deviation score (Ht-SDS) was noted at 1 year [delta SDS/year = +0.60; P < 0.001 (n = 18)] and at 2 years [delta SDS/year = +0.27; P < 0.01 (n = 16)] in pre-pubertal patients. The median Ht-SDS at 2 years for pre-pubertal children was -0.71 SD and growth velocity did not improve thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Distinguishing the causes of post-transplantation hypertension

The purpose of this article is to elucidate the causes of hypertension following kidney transplantation. In the months and years that follow their operation, most recipients of renal transplants develop or maintain blood pressures that are high. This complication has become more prominent since the widespread use of cyclosporine for immunosuppression. Children seem especially prone to hypertension after kidney transplantation. Absence of hypertension is a favorable long-term prognostic sign. It's presence suggests that allograft function is impaired. Impaired allograft function may be due to either lesions intrinsic to the allograft, or lesions that are extrinsic to the allograft but alter its function. Many transplant patients have more than one possible explanation for hypertension. This multifactorial nature of hypertension after transplantation complicates the management of patients.

Hypertension after renal transplantation in patients treated with cyclosporin and azathioprine

The incidence of hypertension was sought in 102 children who had undergone renal transplantation. Fifty five were being treated with cyclosporin and 47 with azathioprine, and they were followed up for a maximum of five years. After one year 35 of those receiving cyclosporin (64%) and 34 of those receiving azathioprine (72%) were hypertensive; after five years the figures were 5/6 (83%) and 25/35 (71%), respectively. Recipients of grafts from living related donors had a lower incidence of hypertension than recipients of cadaveric grafts. The incidence of hypertension was higher in patients with acquired original kidney disease than in children with congenital or familial diseases. In both groups creatinine clearance and the frequency of acute rejection episodes did not differ between normotensive and hypertensive patients. When the lowest concentrations of cyclosporin in whole blood were more than 400 ng/ml the incidence of hypertension one year after transplantation was higher. The incidence of hypertension after renal transplantation in children is higher than that reported in adults. Acquired original disease, transplantation of cadaveric grafts, and nephrotoxicity of cyclosporin are all contributory factors.

Hypertension in cyclosporine-treated renal transplant recipients is sodium dependent

PURPOSE

Physicians increasingly prescribe cyclosporine as an immunosuppressive agent for both organ-transplant and non-organ-transplant recipients. Investigators have reported a high incidence of drug-induced hypertension even when clinical nephrotoxicity was not present. We wanted to determine the reason.

PATIENTS AND METHODS

A comparison was made of hypertension in 15 cyclosporine-treated transplant recipients with that in a similar group of 15 azathioprine-treated transplant recipients.

RESULTS

Hypertension in the cyclosporine group responded differently from that seen in the azathioprine group and from previously described forms of post-transplantation hypertension. Hypertensive cyclosporine-treated patients show a sodium acquisitive renal state that responds to sodium restriction. Unlike rat models, which suggest cyclosporine-induced stimulation of the renin-angiotensin system, or previous forms of post-transplant hypertension in humans, plasma renin levels were not elevated and blood pressure did not respond to a test dose of captopril.

CONCLUSION

Hypertension in cyclosporine-treated patients is an iatrogenic form of hypertension that may be associated with an early, subtle, renal defect in sodium excretion, a genesis of hypertension that is consistent with Guyton's view of essential hypertension.

Blood pressure determinants in living-related renal allograft donors and their recipients

We studied 99 living related allograft donors with follow-up information of at least 10 years and the 50 recipients who had successful outcomes. Recipients were younger and had significantly lower blood pressures at follow-up than their donors. Borderline and definite hypertension were present in 22.2% and 4.0% of donors prior to donation, in 14.4% and 21.1% of donors at follow-up, and in 2.0% and 18.0% of the 50 recipients at follow-up. Age, relative weight, and mean arterial pressure (MAP) prior to donation were the key variables in predicting the follow-up ranked MAP of the donors. CPAH prior to donation was inversely correlated with the age of the donors and, indirectly, with the follow-up MAP. Donor CPAH prior to donation was significantly correlated with the renal allograft function of the recipients but not with the recipient ranked MAP at follow-up. No correlation of the ranked MAP or blood pressure outcome categories between donors and recipients was found. We conclude that donation of one kidney can accelerate the development of hypertension in those donors with predisposition to develop hypertension. In addition, the predisposition of the donors to develop hypertension and their age, within the range observed in the study, does not significantly influence the long-term blood pressure status of the recipient.