Geert Kleinnibbelink

Exercise-Induced Cardiac Function under Hypoxia 2 43 that the region of interest (ROI) incorporated all of the wall thickness while avoiding the pericardium. 35, 36 The region of interest was divided into six myocardial segments, providing segmental strain curves and a longitudinal strain curve as an average of all six segments for the LV views and as an average of the 3 segments of the RV freewall. LV global longitudinal strain (LVGLS) was obtained by averaging the single strain measurements of the three separate apical LV views. If inappropriate tracking of segments was observed visually or detected by the system, retracing was performed until all segments were considered acceptable. RV strain-area loops . The longitudinal strain-area relationship (detailed methods of derivation see, Supplemental 1, Oxborough et al. 5 and Hulshof et al. 37 ) was assessed using the following parameters ( Figure 2 ): (I) the linear strain-area slope (Sslope) and early strain-area slope during first 5% of volume ejection in systole (ESslope); (II) end-systolic peak longitudinal strain (peak strain); (III) the early linear strain-area slope during first 5% (EDslope) and late linear strain-area slope (LDslope) during last 5% of volume increase in diastole; and (IV) diastolic uncoupling (i.e. difference in strain between systole and diastole at any given area), divided into uncoupling during early (Uncoupling ED) and late diastole (Uncoupling LD). 5, 28 Based on previous work from our laboratory, we found that PAH patients with higher PVR have a lower Sslope and a decreased Uncoupling LD. Therefore, these may serve as markers of an increased PVR and consequently PAP. 28