Longer Ischemic Time is Associated with Increased Ventricular Stiffness as Measured by Pressure-Volume Loop Analysis in Pediatric Heart Transplant Recipients.

Abstract

The purpose of this study was to investigate the associations between clinical factors and cardiac function as measured by pressure-volume loops (PVLs) in a pediatric heart transplant cohort. Patients (age<20years) who underwent heart transplantation presenting for a clinically indicated catheterization were enrolled. PVLs were recorded using microconductance catheters (CD Leycom®, Zoetermeer, Netherlands). Demographic data, serum B-type natriuretic peptide (BNP), time from transplant, ischemic time, presence of transplant coronary artery disease, donor-specific antibodies, and history of rejection were recorded at the time of catheterization. PVL data included contractility indices: end-systolic elastance and preload recruitable stroke work; ventricular-arterial coupling index; ventricular stiffness constant, Beta; and isovolumic relaxation time constant, tau. Associations between PVL measures and clinical data were investigated using non-parametric statistical tests. A total of 18 patients were enrolled. Median age was 8.7years (IQR 5-14years). There were ten males and eight females. Six patients had a history of rejection and ten had positive donor-specific antibodies. There was no transplant coronary artery disease. Median BNP was 100pg/mL (IQR 46-140). Time from transplant to PVL obtained during catheterization procedure was 4.1years (IQR 1.7-7.8year). No single clinical characteristic was statistically significant when correlated with PVL data. However, longer ischemic time was associated with worse Beta (r=0.49, p=0.05). Our study found that longer ischemic times are associated with increased left ventricular stiffness. No other single clinical variable is associated with cardiac dysfunction as determined by PVL analysis.