Twenty-four-hour ambulatory blood pressure profiles in liver transplant recipients

Etiology, risk factors and management of hypertension post liver transplantation

BACKGROUND

Cardiovascular events are one of the most important causes of morbidity and mortality in the long-term follow-up of liver transplant recipients. Hypertension is a significant cardiovascular risk factor that occurs frequently after pediatric liver transplantation. Chronic use of immunosuppressants - mainly calcineurin inhibitors - plays a major role in the development of post-transplant hypertension and circadian disturbances such as flattening of the nocturnal blood pressure dip. This requires special attention in children given the long timeframe during which immunosuppressive therapy is necessary. Careful and structured blood pressure monitoring and adequate treatment of hypertension are essential to optimize the quality of life and life expectancy of pediatric liver transplant patients. However, evidence-based guidelines for monitoring and management of post-transplant hypertension and its complications are lacking.

METHODS

We conducted a comprehensive review of the current knowledge and practices concerning post-transplant hypertension. The databases Pubmed, Embase, Web of Science and Google Scholar were scanned with the following keywords: pediatric liver transplantation, immunosuppression, tacrolimus, cardiovascular effects, hypertension, heart function, kidney function, circadian rhythm, mechanism, monitoring, and management.

RESULTS

In this review, we describe the incidence and etiology of hypertension in pediatric liver transplant recipients, the underlying mechanisms and characteristics of calcineurin inhibitor-induced hypertension, and the consequences of and risk factors for post-transplant hypertension. We hereby present an overview of the current practices in blood pressure monitoring and antihypertensive treatment as well as an algorithm for the evaluation and management of hypertension post liver transplantation. Finally, we discuss knowledge gaps and suggestions for future research.

Evaluation of arterial hypertension by ambulatory blood pressure monitoring in pediatric liver transplant recipients

OBJECTIVE

Many cardiovascular complications, including hypertension, are seen in pediatric liver transplantation. The purpose of this study was to analyze the frequency of arterial hypertension of pediatric liver transplant recipients and also to determine the related risk factors.

METHODS

Thirty-six pediatric liver transplant recipients aged 8-17 years were prospectively studied by manual and ambulatory blood pressure measurement (ABPM) technique.

RESULTS

The mean age of patients was 12.42 ± 2.74 years and the mean ABPM measurement time after transplantation was 2 years (3 months-5.9 years). Only one (2.7%) patient was detected as hypertensive by casual measurement, but 17 (47.2%) patients were found to be hypertensive when measured through ABPM. Of children that were found to be hypertensive as a result of ABPM, 64.7% were observed to have a nondipper pattern. Considering the time passed after the transplantation, patients were found to be more hypertensive in the first 2 years posttransplant although it was not found statistically significant.

CONCLUSIONS

In this study, it has been shown that it is possible to diagnose hypertension at an earlier period of transplantation using ABPM in pediatric liver transplant patients. ABPM is needed to detect masked hypertension that may develop following liver transplantation.

Promoting cardiovascular health post-transplant through early diagnosis and adequate management of hypertension and dyslipidemia

Despite correction of underlying solid organ failure by transplantation, pediatric transplant recipients still have increased mortality rates compared to the general pediatric population, in part due to increased cardiovascular risk. In particular, pediatric kidney and non-kidney transplant recipients with chronic kidney disease have significant cardiovascular risk that worsens with declining kidney function. Biomarkers associated with future cardiovascular risk such as casual and ambulatory hypertension, dyslipidemia, vascular stiffness and calcification, and left ventricular hypertrophy can be detected throughout the post-transplant period and in patients with stable kidney function. Among these, hypertension and dyslipidemia are two potentially modifiable cardiovascular risk factors that are highly prevalent in kidney and non-kidney pediatric transplant recipients. Standardized approaches to appropriate BP measurement and lipid monitoring are needed to detect and address these risk factors in a timely fashion. To achieve sustained improvement in cardiovascular health, clinicians should partner with patients and their caregivers to address these and other risk factors with a combined approach that integrates pharmacologic with non-pharmacologic approaches. This review outlines the scope and impact of hypertension and dyslipidemia in pediatric transplant recipients, with a particular focus on pediatric kidney transplantation given the high burden of chronic kidney disease-associated cardiovascular risk. We also review the current published guidelines for monitoring and managing abnormalities in blood pressure and lipids, highlighting the important role of therapeutic lifestyle changes in concert with antihypertensive and lipid-lowering medications.

Ambulatory Blood Pressure Monitoring in Pediatrics

PURPOSE OF REVIEW

This is a review of ambulatory blood pressure monitoring (ABPM) use in pediatrics, summarizing current knowledge and uses of ABPM.

RECENT FINDINGS

Updated guidelines from the American Academy of Pediatrics have emphasized the value of ABPM. ABPM is necessary to diagnose white coat hypertension, masked hypertension, and nocturnal hypertension associated with specific conditions. There is growing evidence that ABPM may be useful in these populations. ABPM has been demonstrated to be more predictive of end-organ damage in pediatric hypertension compared to office blood pressure. ABPM is an important tool in the diagnosis and management of pediatric hypertension. Routine use of ABPM could potentially prevent early cardiovascular morbidity and mortality in a wide variety of populations.

The Use of Ambulatory Blood Pressure Monitoring As Standard of Care in Pediatrics

Hypertension (HTN) is a significant global health problem, responsible for 7.5 million deaths each year worldwide. The prevalence of HTN is increasing in the pediatric population likely attributed to the increase in childhood obesity. Recent work has also shown that blood pressure (BP) tends to track from childhood to adulthood including BP-related target organ damage. In the last 25-30 years, pediatric use of ambulatory blood pressure monitoring (ABPM) has been expanding mainly in the setting of initial elevated BP measurement evaluation, HTN therapy efficacy follow-up, and renal disease. However, there are many clinical areas where ABPM could potentially be used but is currently underutilized. This review summarizes the current knowledge and the uses of pediatric ABPM and explores clinical areas where it can be very useful both to detect HTN and its longitudinal follow-up. And thus, ABPM could serve as a critical tool to potentially prevent early cardiovascular mortality and morbidity in wide variety of populations. With solid data to support ABPM's superiority over clinic BP measurements and these clinical areas for its expansion, ABPM should now be part of standard of care in BP evaluation and management in pediatrics.

Tacrolimus Predose Concentration Is Associated With Hypertension in Pediatric Liver Transplant Recipients

BACKGROUND

The aim of the study was to analyze the incidence of hypertension in pediatric liver transplantation (LT) recipients using ambulatory blood pressure measurements (ABPM) and to identify factors associated with hypertension. We also investigated whether hypertension or tacrolimus predose concentration (TAC C0) was associated with increased left ventricular (LV) wall thickness.

PATIENTS AND METHODS

On a retrospective longitudinal base, we included 39 pediatric LT recipients. Median time since transplantation was 65 months (range: 11-183). Two consecutive ABPM were analyzed with a median time interval of 13 months. Data from echocardiographic evaluation parallel to the baseline ABPM were analyzed. All patients except 1 were prescribed tacrolimus. The median TAC C0 was 4 ng/mL (range 0.9-11.2). Univariate and multivariate logistic regression models were fitted to identify factors associated with systolic and diastolic hypertension and LV wall thickness.

RESULTS

Twenty-two of 39 children were hypertensive at baseline and 19 of 32 were hypertensive at follow-up. At baseline 10 (26%) children had masked systolic hypertension. TAC C0 was associated with systolic (P = 0.007, Exp(B) 2.02, 95% CI 1.2-3.3) and diastolic (P = 0.044, Exp(B) 1.48, 95% CI 1.0-2.2) hypertension. LV wall thickness was increased in children after LT compared with healthy population, but it was not associated with hypertension or TAC C0.

CONCLUSIONS

Given the high prevalence of masked hypertension, ABPM should be performed in all pediatric LT recipients. Systolic and diastolic hypertension is associated with TAC C0; therefore, children with a higher target TAC C0 require a more intensive blood pressure surveillance.

AST-to-platelet ratio index in non-invasive assessment of long-term graft fibrosis following pediatric liver transplantation

Long-term graft fibrosis occurs in the majority of pediatric liver transplant recipients. Serial biopsies to monitor graft health are impractical and invasive. The APRI has been evaluated in pediatric liver disease, but not in the context of post-transplantation fibrosis. We aimed to investigate the validity of APRI as a predictor of long-term graft fibrosis in pediatric liver transplant recipients. This was a retrospective, observational study of a cohort of children who underwent liver transplantation at King's College Hospital between 1989 and 2003, with a relevant dataset available. Protocol liver biopsies were performed at 10-yr follow-up and fibrosis was graded using the Ishak scoring system, with S3-6 denoting "significant fibrosis." APRI was calculated concurrently with biopsy. A total of 39 asymptomatic patients (20 males; median age at transplant, 1.43 yr) underwent protocol liver biopsies at a median of 10.39 yr post-transplantation. APRI was associated with significant fibrosis (p = 0.012). AUROC for APRI as a predictor of significant fibrosis was 0.74 (p = 0.013). The optimal cutoff APRI value for significant fibrosis was 0.45 (sensitivity = 0.67; specificity = 0.79; PPV = 0.67; NPV = 0.79). APRI appears to be a useful non-invasive adjunct in the assessment of significant graft fibrosis in the long-term follow-up of pediatric liver transplant survivors.

Blood pressure profiles 5 to 10 years after transplant in pediatric solid organ recipients

Arterial hypertension is a major risk factor for cardiovascular disease after solid organ transplantation, emphasizing the need for blood pressure (BP) monitoring. The authors studied 24-hour ambulatory BP monitoring (ABPM) parameters (index, load, dipping) and their predictive value with regard to hypertension as well as correlations with graft function and metabolic parameters such as obesity and dyslipidemias. The ABPM profiles of 111 renal, 29 heart, and 13 liver transplant recipients were retrospectively analyzed 5 to 10 years after transplant (median 5.1 years). The BP profiles among the different transplant groups were similar. The BP index and load were abnormal especially at nighttime and the nocturnal BP dipping was often blunted (in 49% to 83% of the patients). The BP variables were found to be equally valued when assessing hypertension. BP load of 50% instead of 25% seems to be a more adequate cutoff value. The BP variables correlated poorly with the metabolic parameters and kidney function. Antihypertensive medication did not notably change the ABPM profile in renal transplant recipients. Hypertension, including nocturnal hypertension, is present in children receiving solid organ transplant, underlining the importance of use of ABPM in the follow-up of these patients.

The kidney in pediatric liver transplantation: an updated perspective

CKD continues to detract from the success of improved survival in pediatric liver transplantation, and its presence is likely under recognized. Here we review the literature regarding the prevalence, etiology, and management of renal dysfunction in pediatric liver transplant recipients. Long-term studies suggest the prevalence of CKD to be 25-38% by 5-10 yr post-transplant. While important, sole use of serum creatinine overestimates renal function in this population. Screening for and treatment of persistent proteinuria and hypertension as well as minimization of nephrotoxic insults are the mainstays to delay or prevent CKD progression. Office-based blood pressure measures are less sensitive than ABPM, which is specifically recommended by the American Heart Association for its ability to diagnose masked hypertension in pediatric liver transplant recipients. Long-term risk of CKD is predominantly secondary to CNI toxicity. CNI minimization protocols have shown promise in slowing progression of CKD while maintaining graft function, but large-scale randomized control trials with long-term follow-up are needed.

Posttransplant metabolic syndrome in children and adolescents after liver transplantation: a systematic review

During long-term follow-up, 18% to 67% of pediatric liver transplant recipients are overweight or obese, with rates varying by age and pretransplant weight status. A similar prevalence of posttransplant obesity has been seen in adults. Adults also develop posttransplant metabolic syndrome and, consequently, cardiovascular disease at rates that exceed the rates in age- and sex-matched populations. Posttransplant metabolic syndrome has never been studied in pediatric liver transplant recipients, and this population is growing as transplant outcomes continue to improve. Here we systematically review the literature for each component of metabolic syndrome-obesity, hypertension, dyslipidemia, and glucose intolerance-in pediatric liver transplant recipients. Their rates of obesity are similar to the rates in children in the general U.S. population. However, hypertension, dyslipidemia, and diabetes are more common than would be expected in transplant recipients according to age, sex, and obesity severity. Immunosuppressive medications are major contributors. The limitations of previous studies, including heterogeneous methods of diagnosis, follow-up times, and immunosuppressive regimens, hinder the analysis of risk factors. Importantly, no studies have reported graft or patient outcomes associated with components of metabolic syndrome after pediatric liver transplantation. However, if the trends in children are similar to the trends seen in adults, these conditions may lead to significant long-term morbidity. Further research on the prevalence, causes, and consequences of posttransplant metabolic syndrome in pediatric liver transplant recipients is needed and will ultimately help to improve long-term outcomes.

Abnormal circadian blood pressure regulation in liver transplanted children

HT is a frequent cardiovascular risk factor in liver transplant recipients. However, there are only few studies in the literature regarding the risk of HT in liver transplanted children. The aim of this study was to assess the 24 h BP profiles of liver transplanted patients and to compare the results with healthy children. ABPM was performed on 20 liver transplanted patients and 27 healthy children aged 7.1 ± 4.8 and 8.5 ± 2.9 yr, respectively. HT was defined as SDS > 1.64 (i.e., >95th percentile) adjusted for gender and height. The mean duration of post-transplant follow-up was 32 ± 19 months. Six (30%) patients were found to be hypertensive. The physiological nocturnal BP fall was attenuated significantly in the study group for diastolic BP (11.5 ± 6.1 mmHg vs. 17.7 ± 7.1 mmHg, p = 0.006). Specifically, the number of patients with high nighttime systolic and diastolic BP SDS (p = 0.02 and p = 0.004, respectively) as well as elevated nighttime systolic (p = 0.03) and diastolic (p = 0.003) BPLs was found to be significantly higher than those in the controls. Alteration of the "normal" circadian rhythm is very frequent in liver transplant recipients. Thus, it is recommended to perform ABPM on all liver transplanted children not to underdiagnose HT.

Arterial hypertension in liver transplant recipients

Hypertension is an important cardiovascular risk factor that influences patient survival. This study sought to evaluate hypertension incidence and circadian rhythms of blood pressure (BP) among liver transplant recipients during the first posttransplant month. We also compared hypertension incidence according to clinical and automated blood pressure monitoring methods. BP was determined by clinical blood pressure monitoring (CBPM) methods and by automated blood pressure monitoring (ABPM) using the SpaceLabs device. We also assessed blood biochemistry, particularly kidney function parameters and immunosuppressive drug blood trough levels, among 32 white subjects (10 women and 22 men) of average age 47.58±14.19 years. The leading cause for transplantation was liver insufficiency due to viral hepatitis B and/or C infection (43.75%). The majority (93.75%) of patients was prescribed immunosuppressive treatment with tacrolimus. Although we observed hypertension in 28 patients (87.5%) by ABPM measurements and in 25 (78.12%) using CBPM method, the difference did not reach statistical significance. However, BP control was inadequate in 28 patients (87.5%) by ABPM assessment versus 3 (9.38%) according to CBPM readings (P=.025). The BP circadian rhythm was altered in 30 patients (93.75%) including 15 with higher nighttime BP readings. There was no correlation between tacrolimus blood levels and BP values or with kidney function as assessed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. We concluded that prevalence of arterial hypertension among liver transplant recipients within 1 month after transplantation is high. The majority of the patients show disturbed circadian rhythms in the early period after liver transplantation with loss or even reversal of the normal nocturnal decrease in BP. Owing to the fact that ABPM enables more adequate daily assessment of BP values, it is an optimal method to adjust antihypertensive therapy to optimal levels.

Stable long-term renal function after pediatric liver transplantation

Long-term exposure to calcineurin inhibitors increases the risk of CKD in children after LT. The aims of this study were to study renal function by measuring GFRm before and yearly after LT, to describe the prevalence of CKD (stage III: GFR 30-60 mL/min/1.73 m(2)) and to investigate if age and underlying liver disease had an impact on long-term renal function. Thirty-six patients with a median age of 2.9 years (0.1-16 yr) were studied. Median follow-up was 6.5 (2-14 yr). GFRm decreased significantly during the first six months post-transplantation with 23% (p < 0.001). Thereafter renal function stabilized. At six months, 17% (n = 5) of the children presented CKD stage III and at five yr the prevalence of CKD III was 18% in 29 children. However, in 13 children with a 10-year follow-up it was 0%. None of the children required renal replacement therapy after LT. When analyzing renal function of those children younger than two yr (n = 14) and older than two yr (n = 17) at the time of transplantation, we found that in both cohorts the filtration rate remained remarkably stable during the five-yr observational period. However, there was a statistically significant (p < 0.05) difference in the percentual decrease in GFRm between the groups during the first six months after LT 13% and 31%, respectively. Baseline GFRm according to diagnosis did not differ between the groups. During the first six months after LT, patients transplanted for hepatic malignancy (n = 6) and those with metabolic liver disease (n = 4) had a percentage loss of GFRm of 32% and 35%, respectively. The corresponding loss of GFRm in patients with other diseases was 10-19%. Six months post-transplantation mean GFRm in the group with malignant liver disease was 65 +/- 15 mL/min/1.73 m(2) and in the group with other diseases (n = 24) 82 +/- 17 mL/min/1.73 m(2) (p < 0.05). At one, three and five yr post-transplantation there was no longer a statistically significant difference between these cohorts. Our findings suggest that there can be a long-term recovery of renal function after LT in children.

Long-term management of immunosuppression after pediatric liver transplantation: is minimization or withdrawal desirable or possible or both?

PURPOSE OF REVIEW

The aim is to review available data regarding the risks and benefits of indefinite immunosuppression against attempted immunosuppression withdrawal for children who have undergone liver transplantation.

RECENT FINDINGS

Emerging data suggest that conventional immunosuppression practices may well be responsible for a substantial proportion of the long-term mortality and morbidity burden borne by pediatric liver transplant recipients. The cumulative risk of chronic kidney disease, infection, malignancy, and cardiovascular risk factors such as hypertension, diabetes, and hyperlipidemia appear to threaten the health and well being of children more than that of acute or chronic allograft rejection. In parallel, single-center experiences have suggested that gradual immunosuppression withdrawal can be done safely with higher success rates in pediatric compared with adult liver transplant recipients. The coalescence of these two data streams has engendered substantial interest in systematic exploration of the safety and efficacy of immunosuppression withdrawal in conjunction with a vigorous scientific effort to elucidate an immunologic signature predictive of successful withdrawal.

SUMMARY

There is a concerted effort within the transplant community to identify biomarkers that can accurately predict the success of immunosuppression withdrawal after liver transplantation. Freedom from lifelong immunosuppression is likely to yield considerable benefit, particularly for children who face the longest lifetime horizons.

Ambulatory blood pressure monitoring: what a pediatrician should know

PURPOSE OF REVIEW

Ambulatory blood pressure monitoring is a useful tool for the evaluation and management of hypertension in children and adolescents. This review provides a basic overview of ambulatory blood pressure monitoring and summarizes the most recent available knowledge regarding its use in the pediatric population.

RECENT FINDINGS

Evaluation and validation of ambulatory blood pressure monitoring equipment in children remains limited, although advances in the interpretation of results for this age group have been reported specifically in the area of circadian (24 h) and ultradian (<24 h) variability. Blood pressure is a dynamic phenomenon that varies not only with time but also with changing patient and environmental circumstances. Growing evidence regarding conditions identified when this variability is considered, specifically white coat and masked hypertension, suggests that office blood pressure measurement may not be a sufficient screening test for hypertension-related target-organ damage.

SUMMARY

Information regarding ambulatory blood pressure monitoring use in children is increasing, although due to its limitations and expense, it remains a tool primarily utilized by the pediatric sub-specialist.

Is ABPM clinically useful after pediatric solid organ transplantation?

When ambulatory blood pressure monitoring (ABPM) is performed in populations with a high risk for secondary hypertension, such as solid organ transplant recipients, hypertension or abnormalities in circadian blood pressure variability are often discovered even in patients with normal office blood pressure (BP). To discuss whether ABPM should be routinely assessed in pediatric solid organ recipients, the available information on pathological findings, association of ABPM abnormalities with outcome parameters, and treatment options is reviewed. ABPM is a useful tool to optimize therapy in the large proportion of transplant recipients with confirmed hypertension. Whether the use of ABPM on a routine basis should be recommended for pediatric transplantation patients without office hypertension remains to be determined.