Comparisons Between the Effects of Right Ventricular Pressure and Volume Overload on Ventricular-Arterial Coupling

In congenital heart disease, the right ventricle (RV) has been the forgotten chamber for many decades. Congenital atrial septal defect (ASD) leads to volume overload on the RV, while pulmonary hypertension (PH) results in pressure overload. Three-dimensional echocardiography is noninvasive and has become a readily available method for assessing the RV-PA coupling ratio through the division of the RV stroke volume (SV) by RV end-systolic volume (ESV), correlating with RV function. We sought to compare this ratio between ASD (RV volume overload) and PH (RV pressure overload) groups.
 
Ninety patients were divided into 3 equal groups: congenital ASD, PH, and control. Electrocardiography-gated 2D and 3D echocardiographic studies were performed on the study population.
 
The ASD and PH groups showed statistically significant differences regarding RV volume and the RV-PA coupling ratio compared with the control group.  However, the PH group was affected more than the ASD group concerning the RV-PA coupling ratio, with the mean coupling ratio being 1.14 in the ASD group, 0.77 in the PH group, and 1.25 in the control group. The P value between the ASD and control groups was 0.054, while the P value between the PH and control groups was below 0.0001.
 
The RV-PA coupling ratio, measured by 3D echocardiography (RVSV/RVESV), was markedly reduced (uncoupling) in the PH group and to a lesser extent in the ASD group compared with the control group. (Iranian Heart Journal 2023; 24(3): 54-61)