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Introduction: The objective of this study was to develop echocardiographic parameters that could be used to distinguish RV (Right ventricle) volume overload and RV pressure overload. The necessity of the study was evaluating RV contractility in a non invasive way & understanding more about regional RV function in these two conditions.Material & Methods: The RV pressure overload group consisted of 16 patients with pulmonary stenosis & 18 patients with pulmonary hypertension. They should have RVSP>60 mmHg. The RV volume overload group consisted of 35 patients with unrepaired ASD or PAPVC that had a significant left to right shunt and RVSP was no more than 35mmHg. Exclusion criteria included: left heart valvular involvement more than mild to moderate, systolic LV dysfunction, any rhythm other than sinus rhythm, complete bundle branch block, right to left shunt or eisenmenger. We used global (MPI & RVFAC) & regional (strain & strain rate) indices of RV function. All patient underwent echocardiographic study (standard, tissue Doppler imaging & strain imaging). RV IVRT & IVCT & RV MPI were obtained from tricuspid lateral annulus tissue Doppler. RV end systolic area (ESA), RV end diastolic area (EDA )& RV fractional area change (FAC )were obtained from 2D images. Systolic velocity, strain & strain rate were obtained from tissue Doppler of RV free wall basal, mid & apical segments.Results: RV MPI in RV pressure overload group was more than RV MPI in RV volume overload group (0.55 versus 0.32, P<0.001). RV IVRT in RV pressure overload group was more than that in RV volume overload group. (84 versus 25, P<0.001) which showed that diastolic function was also impaired in RV pressure overload group.RV FAC in RV pressure overload group was less than that in RV volume overload group (P=0.035). Strain & strain rate in RV free wall segments in RV pressure overload group were significantly lower than those in RV volume overload group (P<0.001).Conclusions: We found good parameters which were different inRV pressure overload and RV volume overload; that included: RV MPI, RV IVRT, RV FAC, Strain & strain rate. These parameters showed that pressure overload was probably more harmful for RV than volume overload and that using this parameters can be important in early diagnosing pulmonary artery hypertension to prevent from progression to RV failure and also in patients with concomittant RV perssure and volume overload for distinguishing the dominant pathology.