The evaluation of eccentric cardiac hypertrophy due to volume overload using radiographic cardiac indices in rats

Abstract

The purpose of this study was to determine the diagnostic values of the vertebral heart score (VHS), radiographic left atrial dimension (RLAD) and vertebral left atrial size (VLAS) in the radiographic evaluation of eccentric cardiac hypertrophy due to volume overload (VO) in rats. Rats underwent either needle aortocaval shunting or sham operations. Six weeks later, VHS, RLAD, and VLAS were measured from radiographs of all surviving rats (20 control and 54 VO). Measurements were performed by two observers blinded to the study data. Heart weight (HW) and HW: body weight (HBW) ratio were determined for all rats after sacrifice. Correlations between HBW and VHS, RLAD and VLAS values were estimated, as well as their sensitivity and specificity for detecting cardiomegaly and left atrial (LA) enlargement. Receiver operating characteristic (ROC) curves were used to estimate the optimal decision criteria for each radiographic index. A strong positive correlation was observed between these indices and both HW and HBW. The sensitivity and specificity of these indices for detecting cardiomegaly and LA enlargement when evaluated at the optimal cut-off values were 100% and 95%, respectively, at 8.7 vertebrae (v) for RL-VHS, 98.4% and 96.6% at 8.8v for DV-VHS, 97.6% and 90% at 1.6v for RLAD and 92.7% and 89.1% at 2.1v for VLAS. Both intra- and inter-observer measurements revealed good to excellent agreement for these indices. The study results indicate that VHS, RLAD and VLAS are simple, repeatable and useful radiographic measurements for predicting cardiomegaly and LA enlargement in rats with eccentric cardiac hypertrophy.