Feasibility and safety of quantitative adenosine stress perfusion cardiac magnetic resonance imaging in pediatric heart transplant patients with and without coronary allograft vasculopathy.

BACKGROUND: Pediatric heart transplant patients require cardiac catheterization to monitor for coronary allograft vasculopathy. Cardiac catheterization has no safe and consistent method for measuring microvascular disease. Stress perfusion cardiac magnetic resonance imaging (MRI) assessing microvascular disease has been performed in adults. OBJECTIVE: To investigate the feasibility and safety of performing cardiac MRI with quantitative adenosine stress perfusion testing in pediatric heart transplant patients with and without coronary allograft vasculopathy. MATERIALS AND METHODS: All pediatric heart transplant patients with coronary vasculopathy at our institution were asked to participate. Age- and gender-matched pediatric heart transplant patients without vasculopathy were recruited for comparison. Patients underwent cardiac MRI with adenosine stress perfusion testing. RESULTS: Sixteen pediatric heart transplant patients, ages 6-22 years, underwent testing. Nine patients had vasculopathy by angiography. No heart block or other complications occurred during the study. The myocardial perfusion reserve for patients with vasculopathy showed no significant difference with comparison patients (median: 1.43 vs. 1.48; P=0.49). Values for both groups were lower than expected values based on previous adult studies. The patients were also analyzed for time after transplant and the number of rejection episodes. Patients within 6 years of transplantation had a nonsignificant trend toward a higher myocardial perfusion reserve (median: 1.57) versus patients with older transplants (median: 1.47; P=0.46). Intra- and interobserver reproducibility were 97% and 92%, respectively. CONCLUSION: Myocardial perfusion reserve is a safe and feasible method for estimating myocardial perfusion in pediatric heart transplant patients. There is no reliable way to monitor microvascular disease in pediatric patients. This method shows potential and deserves investigation in a larger cohort.

The effect of transport on the physiologic stability of neonates with ductal-dependent single-ventricle lesions.

OBJECTIVE: To compare the status of infants with hypoplastic left heart syndrome (HLHS) or pulmonary atresia-hypoplastic right heart (PA-HRH) before and following transport using the validated Transport Risk Index of Physiologic Stability (TRIPS) score. METHODS: In this retrospective review of infants with HLHS or PA-HRH transported to a Children's Hospital by a pediatric transport team, an increase in TRIPS score (temperature, blood pressure, respiratory status, and response to stimuli) following transport was defined as deterioration. Statistical analyses included t-test (paired and independent), χ2, and McNemar's tests for comparisons between groups with and without deterioration and before and after transport. RESULTS: Our cohort [n = 64; 39 (61%) HLHS and 25 (39%) PA-HRH] was predominantly female (61%), black (56%), and diagnosed antenatally (78%). Median transport time was 20 (10-30) min and age was <12 h in 48 (75%) infants. TRIPS scores worsened after transport in 24 (37.5%) infants, due to temperature (n = 10) or respiratory (n = 7) dysregulation. Infants who deteriorated during transport had HLH more often (83 versus 48%) and lower pH [7.27 (0.12) versus 7.33 (0.07)]. HLH was significantly predictive of deterioration during transport [OR 5.60 (95% C.I. 1.18-26.62)]. CONCLUSIONS: The physiologic deterioration in a third of infants with single ventricle following short transports is intriguing and may have implications on their optimal place of birth.