Cardiology specialty research intern Colorado State University Fort Collins, CO, United States
Abstract:
Background: Reference intervals (RIs) for simple bodyweight-independent measurements of right atrial (RA), right ventricular (RV) minor chamber dimension, and RV wall thickness (RVWT) are limited. Hypothesis/
Objectives: We sought to generate reference intervals for measurements of right heart size indexed to the right parasternal long-axis aortic diameter (AoD) and the corresponding left heart structure. Additionally, we sought to describe the reproducibility of these measurements. Animals: Ninety healthy adult dogs of varying body size.
Methods: Prospective study. All dogs underwent an echocardiogram performed by the same operator using a right parasternal long-axis 4-chamber (RPLx) view and a left apical 4-chamber (Ap4Ch) view. Eight dogs underwent repeated echocardiograms by 3 different operators (intra-day) and the same operator performed echocardiograms on these 8 dogs on 3 different days. 95% RIs were generated (Clinical Laboratory Standards Institute methodology). Measurement variability was quantitated using coefficients of variation.
Results: Reference intervals for RA_RPLx/AoD, RV_RPLx/AoD, and RVWT_RPLx/AoD were 1.08-1.95, 0.67-1.57, and 0.25-0.49, respectively, and for RA_RPLx /left atrium (LA)_RPLx, RV_RPLx /left ventricle (LV)_RPLx, and RVWT_RPLx/left ventricular wall thickness (LVWT)_RPLx were 0.53-0.95, 0.33-0.68, and 0.45-0.78, respectively. Reference intervals for RA_Ap4Ch/AoD and RV_Ap4Ch/AoD were 0.89-1.90 and 0.83-0.1.76, respectively, and for RA_Ap4Ch/LA_Ap4Ch, RV_Ap4Ch/LV_Ap4Ch were 0.51-1.07 and 0.37-0.76, respectively. The RVWT could not be reliably measured from the Ap4Ch view. All intra-operator (between-day) and inter-operator (intra-day) coefficients of variation were < 16.4%. Conclusions and clinical importance: Simple bodyweight-independent RIs for assessment of right heart size are available for clinical use. Reproducibility appears sufficient for serial evaluations.
