Central aortic stiffness, hypertension, and coronary allograft vasculopathy in children

Elevated Aortic Stiffness after Pediatric Heart Transplantation

In adults, arterial stiffness has been linked to the development of target end-organ damage, thought to be related to abnormal transmission of pulse pressure. Increased arterial stiffness and endothelial dysfunction have been hypothesized to contribute to the development of microvascular dysfunction and coronary allograft vasculopathy (CAV), an important comorbidity after heart transplantation. However, little data exists regarding arterial stiffness in pediatric heart transplantation and its influence on development of coronary allograft vasculopathy is not well understood. We sought to assess aortic stiffness and distensibility in pediatric post-heart transplant patients. A prospective, observational study analyzing the ascending (donor tissue) and descending aorta (recipient tissue) using transthoracic echocardiographic M-mode measurements in patients aged < 21 years was conducted. Descending and ascending aorta M-modes were obtained from the subcostal long axis view, and the parasternal long axis view 3-5mm above the sinotubular junction, respectively. Two independent reviewers averaged measurements over 2-3 cardiac cycles, and Aortic Distensibility (AD) and Aortic Stiffness Index (ASI) were calculated using previously validated methods. We recruited 39 heart transplant (HT) patients and 47 healthy controls. Median end diastolic dimension of the ascending aorta (donor tissue) was significantly larger in the transplant group than the control group (1.92 cm vs. 1.74 cm, p = 0.01). Ascending aortic distensibility in post-transplant patients was significantly lower than in the control group (4.87 vs. 10.53, p < 0.001). Ascending aortic stiffness index was higher in the transplant patients compared to the controls (4.63 vs. 2.21, p < 0.001). There is evidence of altered ascending aortic distensibility and stiffness parameters in post-heart transplant patients. Further studies are required to assess its influence on complications like development of coronary artery vasculopathy.

Risk factors for specific causes of death following pediatric heart transplant: An analysis of the registry of the International Society of Heart and Lung Transplantation

We sought to determine temporal changes in COD and identify COD-specific risk factors in pediatric primary HTx recipients. Using the ISHLT registry, time-dependent hazard of death after pediatric HTx, stratified by COD, was analyzed by multiphasic parametric hazard modeling with multivariable regression models for risk factor analysis. The proportion of pediatric HTx deaths from each of cardiovascular cause, allograft vasculopathy, and malignancy increased over time, while all other COD decreased post-HTx. Pre-HTx ECMO was associated with increased risk of death from graft failure (HR 2.43; p < 0.001), infection (HR 2.85; p < 0.001), and MOF (HR 2.22; p = 0.001), while post-HTx ECMO was associated with death from cerebrovascular events/bleed (HR 2.55; p = 0.001). CHD was associated with deaths due to pulmonary causes (HR 1.78; p = 0.007) or infection (HR 1.72; p < 0.001). Non-adherence was a significant risk factor for all cardiac COD, notably graft failure (HR 1.66; p = 0.001) and rejection (HR 1.89; p < 0.001). Risk factors related to specific COD are varied across different temporal phases post-HTx. Increased understanding of these factors will assist in risk stratification, guide anticipatory clinical decisions, and potentially improve patient survival.

Arterial Stiffness in Children: Pediatric Measurement and Considerations

BACKGROUND

Arterial stiffness is a natural consequence of aging, accelerated in certain chronic conditions, and predictive of cardiovascular events in adults. Emerging research suggests the importance of arterial stiffness in pediatric populations.

METHODS

There are different indices of arterial stiffness. The present manuscript focuses on carotid-femoral pulse wave velocity and pulse wave analysis, although other methodologies are discussed. Also reviewed are specific measurement considerations for pediatric populations and the literature describing arterial stiffness in children with certain chronic conditions (primary hypertension, obesity, diabetes, chronic kidney disease, hypercholesterolemia, genetic syndromes involving vasculopathy, and solid organ transplant recipients).

CONCLUSIONS

The measurement of arterial stiffness in children is feasible and, under controlled conditions, can give accurate information about the underlying state of the arteries. This potentially adds valuable information about the functionality of the cardiovascular system in children with a variety of chronic diseases well beyond that of the brachial artery blood pressure.