Available online 8 September 2022

Donor to recipient size matching for heart transplantation typically involves comparing donor and recipient body weight, however weight is not linearly related to cardiac size. Attention has shifted toward use of computed tomography (CT) derived Total Cardiac Volume (TCV), i.e., CT-TCV, to compare donor and recipient heart organ size. At this time, TCV size matching is near-impossible for most centers due to logistical limitations. To overcome this impediment, echocardiography-derived TCV (ECHO-TCV) is an attractive, alternative option to estimate CT-TCV. The goal of this work is to test whether ECHO-TCV is an accurate and reliable surrogate for TCV measurement compared with the gold standard CT-TCV.

ECHO-TCV and CT-TCV were measured in a cohort spanning the neonatal to young adult age range intended to simulate the pediatric heart transplant donor pool. ECHO-TCV was measured using a modified Simpson’s summation of discs method from the apical 4 chamber (A4C) view. The gold standard of CT-TCV was measured from CT scans using 3D reconstruction software. The relationship between ECHO-TCV and CT-TCV was evaluated and compared with other anthropometric and image-based markers that may predict CT-TCV. Inter-rater reliability of ECHO-TCV was tested among 4 independent observers. Sub-analyses were performed to identify imaging views and timing that enable greater accuracy of ECHO-TCV.

Banked imaging data of 136 subjects with both echocardiogram and CT were identified. ECHO-TCV demonstrated a linear relationship to CT-TCV with Pearson correlation coefficient of r=0.96 (95% CI 0.95 – 0.97, p<0.0001) and mean absolute percent error (MAPE) of 8.6%. ECHO-TCV correlated most strongly with CT-TCV in the subset of subjects <4 years of age (n=33, r= 0.98, 95% CI 0.96-0.99, p<0.0001). The single-score intraclass correlation coefficient across all 4 raters is 0.96 (IQR 0.93 – 0.98). ECHO-TCV measured from a standard A4C view at end-diastole with the atria in the plane-of-view had the strongest correlation to CT-TCV.

ECHO-TCV by A4C view was found to be both an accurate and reliable alternative measurement of CT-TCV and is derived from readily available donor ECHO images. The ECHO-TCV findings in this study make the ECHO method an attractive means of direct donor to recipient TCV size matching in pediatric heart transplantation.

2022 Published by Elsevier Inc. on behalf of the American Society of Echocardiography.