Carotid intima-media thickness after pediatric renal or liver transplantation at high-resolution B-mode ultrasonography

Current applications for measuring pediatric intima-media thickness

Intima-media thickness is a known subclinical radiologic marker of the early manifestations of atherosclerotic disease. It is the thickness of the vessel wall, most often the carotid artery. Intima-media thickness is measured on conventional US manually or automatically. Other measurement techniques include radiofrequency US. Because there is variation in its measurement, especially in children, several recommendations have been set to increase the measurement's validity and comparability among studies. Despite these recommendations, several pitfalls should be avoided, and quality control should be performed to avoid erroneous interpretation. This article summarizes current literature in relation to the clinical applications for intima-media thickness measurement in children with known risk factors such as obesity, liver steatosis, hypercholesterolemia, diabetes, hypertension, systemic inflammatory diseases, cancer survival, kidney and liver transplant, and sickle cell disease or beta thalassemia major. Most potential indications for intima-media thickness measurement remain in the research domain and should be interpreted combined with other markers. The objective of diagnosing an increased intima-media thickness is to start a multidisciplinary treatment approach to prevent disease progression and its sequelae in adulthood.

Cardiovascular involvement after liver transplantation: role of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

Patients submitted to liver transplantation (LT) are exposed to high risk of cardiovascular (CV) complications which are the main determinants of both short-term and long-term morbidity and mortality in LT. Non-alcoholic fatty liver disease (NAFLD) is a very frequent condition in general population and is associated with a high risk of cardiovascular disease (CVD) which represents the first cause of death of these patients. NAFLD is predicted to become the first indication to LT and nowadays is also frequently detected in patients submitted to LT for other indications. Thus, the risk of CVD in patients submitted to LT is forecasted to increase in the next years. In this review the extent of CV involvement in patients submitted to LT and the role of NAFLD, either recurring after transplantation or as de novo presentation, in increasing CV risk is analysed. The risk of developing metabolic alterations, including diabetes, hypertension, dyslipidemia and weight gain, all manifestations of metabolic syndrome, occurring in the first months after LT, is depicted. The different presentations of cardiac involvement, represented by early atherosclerosis, coronary artery disease, heart failure and arrhythmias in patients with NAFLD submitted to LT is described. In addition, the tools to detect cardiac alterations either before or after LT is reported providing the possibility for an early diagnosis of CVD and an early therapy able to reduce morbidity and mortality for these diseases. The need for long-term concerted multidisciplinary activity with dietary counseling and exercise combined with drug treatment of all manifestations of metabolic syndrome is emphasized.

High Burden of Subclinical Cardiovascular Target Organ Damage After Pediatric Liver Transplantation

Cardiovascular (CV) events account for 8%-13% of deaths after liver transplantation (LT) in adulthood. Although CV risk factors (RFs) are present, little is known about the prevalence of subclinical CV target organ damage (TOD) in children after LT. The aim of this prospective observational study was to assess the prevalence of subclinical CV TOD in children after LT and to identify RFs contributing to CV damage as potential targets for clinical intervention. In this study, 104 children after LT (54% female, 46% male; aged 11.5 ± 3.8 years) underwent cross-sectional assessment of subclinical TOD by carotid-femoral pulse wave velocity (PWV), carotid intima-media thickness (IMT), and left ventricular mass index (LVMI). Results were correlated with the presence of CV RFs (obesity, hypertension, dyslipidemia, renal impairment, anemia, and microinflammation). Of the patients, 22% were exposed to 2 CV RFs, and 36% displayed 3 or more CV RFs. Pathological results for PWV, IMT, and LVMI were found in 21.9%, 57.0%, and 11.1% of patients, respectively. In the multivariate analysis, diastolic blood pressure (P = 0.01) and estimated glomerular filtration rate (eGFR; P = 0.03) were independently associated with PWV, eGFR (P = 0.005), and age at LT (P = 0.048) with IMT and body mass index with LVMI (P = 0.004). In conclusion, patients after pediatric LT carry a substantial burden of subclinical CV TOD. Identification of modifiable CV RFs opens opportunities for targeted intervention in order to reduce CV morbidity and mortality in the future.

Risk markers for later cardiovascular diseases in liver-transplanted children and adolescents

BACKGROUND

Increased risk of cardiovascular diseases is well described after adult liver transplantation, whereas the risk in the pediatric population still is discussed. The aim of this study was to investigate the prevalence of metabolic syndrome in pediatric liver transplant recipients and whether measurements of carotid intima media thickness and pulse wave velocity were increased compared to healthy controls.

METHODS

We included 42 pediatric liver transplantation recipients and examined them for markers of metabolic syndrome, liver fibrosis measured by shear wave velocity, body fat measured by DXA scans and carotid intima-media thickness, and pulse wave velocity (n = 41 for the carotid scans). The ultrasound measurements of carotid intima-media thickness and pulse wave velocity were also conducted on 82 healthy children and adolescents matched on height and age, respectively.

RESULTS

Participants had a median age of 13.03 years, and median time since transplantation was 8.54 years. Compared to healthy controls, liver-transplanted patients had significantly increased intima-media thickness measurements in both control groups whereas there was no significant difference with regard to pulse wave velocity. Two patients (6.25%) were diagnosed with metabolic syndrome. Within the group of liver-transplanted pediatric patients, only elevated body mass index was associated with elevated carotid intima-media thickness measurement. Elevated pulse wave velocity was only associated with abdominal obesity. Factors not significantly correlated with either were age, sex, metabolic syndrome, hyperglycemia, triglycerides, years since transplantation, fibrosis of the liver, body fat content, smoking habits, HDL cholesterol levels, hypertension, and mono-drug versus multi-drug therapies.

CONCLUSION

Pediatric liver transplant recipients do have an increased risk of increased carotid intima-media thickness.

Increased carotid intima-media thickness in African American pediatric kidney transplant recipients

Early signs of subclinical CV dysfunction can be detected by ultrasound for CIMT. Although A-A are at high risk for CV disease, CIMT of A-A kidney transplant recipients has not been previously investigated. The aim of this prospective, controlled, longitudinal study was to investigate determinants of CIMT in a multiracial pediatric kidney transplant population, with a focus on A-A. Transplant recipients (n = 42) had BMI, waist-to-height ratio, fasting glucose, lipid panel, HbA1c%, and CIMT measured at 1, 18, and 30 months post-transplant. Twenty-four healthy children (14 A-A) served as controls. CIMT of A-A transplant (0.49, 0.49, and 0.48 mm) was higher than non-AA transplant (0.43, 0.44, and 0.44 mm) at 1, 18, and 30 months and higher than A-A controls (0.47 mm). Hyperparathyroidism prior to transplant predicted high CIMT-for-race. A-A race was associated with 10% higher CIMT vs non-A-A transplant. Metabolic syndrome was associated with 0.03 ± 0.01 mm increase in CIMT among A-A transplant recipients only. In conclusion, A-A kidney transplant recipients have increased CIMT. Metabolic syndrome disproportionately affects CIMT of A-A children post-transplant. Identification of subclinical CV damage, detected by CIMT, may provide an opportunity for early detection of CV risk in this vulnerable population.

Subclinical Atherosclerosis in Pediatric Liver Transplant Recipients: Carotid and Aorta Intima-Media Thickness and Their Predictors

OBJECTIVE

To investigate prevalence and predictors of cardiovascular risk in pediatric liver transplant recipients using noninvasive markers of subclinical atherosclerosis: carotid intima-media thickness (cIMT) and aorta intima-media thickness (aIMT).

STUDY DESIGN

Cross-sectional study of 88 pediatric liver transplant recipients. The cIMT and aIMT were measured by ultrasound imaging using standardized protocol.

RESULTS

Participants were 15.4 ± 4.8 years of age, and 11.2 ± 5.6 years post-transplantation. The cIMT and aIMT were both higher in males than females. In analyses adjusted for sex, age, and height, the cIMT was higher in subjects transplanted for chronic/cirrhotic liver disease and lower in subjects on cyclosporine (n = 9) than tacrolimus (n = 71). The cIMT was not associated with rejection history or current corticosteroid use. The cIMT increased with increasing diastolic blood pressure and triglycerides. The aIMT (n = 83) also increased with age, and its rate of increase post-transplant varied by age at transplantation. In adjusted analyses, aIMT was higher in subjects with glucose intolerance. In analysis of patients ≤20 years of age for whom blood pressure percentiles could be calculated (n = 66), aIMT increased with increasing diastolic blood pressure percentile (0.010 mm per 5-percentile; 95% CI, 0.000-0.021; P = 0.05). Neither the cIMT nor the aIMT was associated with obesity, systolic hypertension, or other dyslipidemia at study visit.

CONCLUSION

Measures of long-term cardiovascular risk were associated with conditions that are more common in pediatric liver transplant recipients than nontransplanted peers, namely, diastolic hypertension and glucose intolerance. Larger, longitudinal studies are warranted to investigate whether cIMT could be useful for stratifying these patients' cardiovascular risk-and potential need for proactive intervention-during long-term follow-up.

Cardiovascular effects of metabolic syndrome after transplantation: convergence of obesity and transplant-related factors

Children are at increased risk of developing metabolic syndrome (MS) after kidney transplantation, which contributes to long-term cardiovascular (CV) morbidities and decline in allograft function. While MS in the general population occurs due to excess caloric intake and physical inactivity, additional chronic kidney disease and transplant-related factors contribute to the development of MS in transplant recipients. Despite its significant health consequences, the interplay of the individual components in CV morbidity in pediatric transplant recipients is not well understood. Additionally, the optimal methods to detect early CV dysfunction are not well defined in this unique population. The quest to establish clear guidelines for diagnosis is further complicated by genetic differences among ethnic groups that necessitate the development of race-specific criteria, particularly with regard to individuals of African descent who carry the apolipoprotein L1 variant. In children, since major CV events are rare and traditional echocardiographic measures of systolic function, such as ejection fraction, are typically well preserved, the presence of CV disease often goes undetected in the early stages. Recently, new noninvasive imaging techniques have become available that offer the opportunity for early detection. Carotid intima-media thickness and impaired myocardial strain detected by speckle tracking echocardiography or cardiac magnetic resonance are emerging as early and sensitive markers of subclinical CV dysfunction. These highly sensitive tools may offer the opportunity to elucidate subtle CV effects of MS in children after transplantation. Current knowledge and future directions are explored in this review.

Cardiovascular risk after orthotopic liver transplantation, a review of the literature and preliminary results of a prospective study

Improved surgical techniques and greater efficacy of new anti-rejection drugs have significantly improved the survival of patients undergoing orthotopic liver transplantation (OLT). This has led to an increased incidence of metabolic disorders as well as cardiovascular and cerebrovascular diseases as causes of morbidity and mortality in OLT patients. In the last decade, several studies have examined which predisposing factors lead to increased cardiovascular risk (i.e., age, ethnicity, diabetes, NASH, atrial fibrillation, and some echocardiographic parameters) as well as which factors after OLT (i.e., weight gain, metabolic syndrome, immunosuppressive therapy, and renal failure) are linked to increased cardiovascular mortality. However, currently, there are no available data that evaluate the development of atherosclerotic damage after OLT. The awareness of high cardiovascular risk after OLT has not only lead to the definition of new but generally not accepted screening of high risk patients before transplantation, but also to the need for careful patient follow up and treatment to control metabolic and cardiovascular pathologies after transplant. Prospective studies are needed to better define the predisposing factors for recurrence and de novo occurrence of metabolic alterations responsible for cardiovascular damage after OLT. Moreover, such studies will help to identify the timing of disease progression and damage, which in turn may help to prevent morbidity and mortality for cardiovascular diseases. Our preliminary results show early occurrence of atherosclerotic damage, which is already present a few weeks following OLT, suggesting that specific, patient-tailored therapies should be started immediately post OLT.

Subclinical cardiovascular changes in pediatric solid organ transplant recipients: A systematic review and meta-analysis

CV disease is a major cause of morbidity and mortality following solid organ transplantation in adults. While the prevalence of multiple cardiometabolic risk factors is increased in pediatric solid organ transplant recipients, it is not clear whether they have subclinical CV changes. cIMT, central pWV, and CAC are indicative of subclinical CV disease, and, in adults, predict future CV events. The objective of this systematic review and meta-analysis was to investigate the prevalence of subclinical CV changes, as measured by cIMT, pWV, and CAC among pediatric solid organ transplant recipients. We searched MEDLINE(®) and EMBASE and conducted meta-analysis for studies that evaluated cIMT, central pWV, and CAC among pediatric solid organ transplant recipients (kidney, lung, intestine and liver). The search identified nine eligible studies that included a total of 259 patients and 685 healthy controls. Eight studies reported on kidney transplant recipients and one study on a combined cohort of kidney and liver transplant recipients. The mean cIMT of transplant recipients was significantly higher than that of healthy controls (mean difference = 0.05 mm, 95% CI 0.02-0.07; p < 0.0001) with an estimated pooled prevalence of elevated cIMT of 56.0% (95% CI 17.0-95.0). The one study that assessed pWV showed increased vascular stiffness in transplant recipients compared to healthy controls. No studies assessing for CAC were found. There were limited data regarding subclinical CV disease following pediatric solid organ transplantation. In conclusion, kidney transplantation in childhood is associated with a higher prevalence of subclinical CV changes compared to healthy children. Longitudinal studies are needed to determine whether children have increased CV morbidity and mortality after transplantation.

Outcomes in pediatric solid-organ transplantation

LaR Pediatric solid-organ transplantation is an increasingly successful treatment for organ failure. Five- and 10-yr patient survival rates have dramatically improved over the last couple of decades, and currently, over 80% of pediatric patients survive into adolescence and young adulthood. Waiting list mortality has been a concern for liver, heart, and intestinal transplantation, illustrating the importance of transplant as a life-saving therapy. Unfortunately, the success of pediatric transplantation comes at the cost of long-term or late complications that arise as a result of allograft rejection or injury, immunosuppression-related morbidity, or both. As transplant recipients enter adolescence treatment, non-adherence becomes a significant issue, and the medical and psychosocial impacts transition to adulthood not only with regard to healthcare but also in terms of functional outcomes, economic potential, and overall QoL. This review addresses the clinical and psychosocial challenges encountered by pediatric transplant recipients in the current era. A better understanding of pediatric transplant outcomes and adult morbidity and mortality requires further ongoing assessment.

CKD-MBD after kidney transplantation

Successful kidney transplantation corrects many of the metabolic abnormalities associated with chronic kidney disease (CKD); however, skeletal and cardiovascular morbidity remain prevalent in pediatric kidney transplant recipients and current recommendations from the Kidney Disease Improving Global Outcomes (KDIGO) working group suggest that bone disease-including turnover, mineralization, volume, linear growth, and strength-as well as cardiovascular disease be evaluated in all patients with CKD. Although few studies have examined bone histology after renal transplantation, current data suggest that bone turnover and mineralization are altered in the majority of patients and that biochemical parameters are poor predictors of bone histology in this population. Dual energy X-ray absorptiometry (DXA) scanning, although widely performed, has significant limitations in the pediatric transplant population and values have not been shown to correlate with fracture risk; thus, DXA is not recommended as a tool for the assessment of bone density. Newer imaging techniques, including computed tomography (quantitative CT (QCT), peripheral QCT (pQCT), high resolution pQCT (HR-pQCT) and magnetic resonance imaging (MRI)), which provide volumetric assessments of bone density and are able to discriminate bone microarchitecture, show promise in the assessment of bone strength; however, future studies are needed to define the value of these techniques in the diagnosis and treatment of renal osteodystrophy in pediatric renal transplant recipients.