Isovolumic Contraction relaxation

Heart sounds Sound Si occurs at the beginning of systole as the mitral and tricuspid valves close S2 occurs at the beginning of diastole as the aortic and pulmonary valves close. These points should be in line with the beginning of electrical depolarization (QRS) and the end of repolarization (T), respectively, on the ECG trace. The duration of Si matches the duration of isovolumic contraction (IVC) and that of S2 matches that of isovolumic relaxation (IVR). Mark the vertical lines on the plot to demonstrate this fact. 

Other new echocardiographic methods have been employed in evaluation of PAH. One of them is strain imaging, which measures deformation over time it has been used in concert with TAPSE and RV Tei index (isovolumic contraction time and relaxation time/ejec-tion time [TVt - RVt]/RVt), and has been shown to be reduced in patients with acute pulmonary embolus and improved after stabilization (37). Using parameters of the eccentricity index, which highlight RV/LV interdependence, it was shown that an eccentricity index less than median was associated with improved survival and freedom from a composite endpoint (38). Lastly, the newer technique of vector velocity imaging applied to the right ventricle is promising as a quantitative assessment of RV function and reserve. 

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