Geert Kleinnibbelink

Chapter 2 42 stored cycles, was performed by a single observer with experience in echocardiography (GK) using commercially available software (EchoPac, version 203, GE Medical, Horton, Norway). The observer was blinded for the timing (pre vs . post) and condition (normoxia vs . hypoxia) under which echocardiography was performed. For stress echocardiography, low-to-moderate-intensity (target HR 110-120 bpm) exercise consisted of recumbent cycling at a cadence of ~60 revolutions per minute with watts manually adjusted to stabilise at target HR. Conventional measurements . Cardiac structural and functional measurements were made according to the current guidelines for cardiac chamber quantification. 34 Regarding the right heart, we examined the following structural and functional indices: basal and mid- cavity end-diastolic diameters, RV end-diastolic area (RVEDA), RV end-systolic area (RVESA), RV outflow tract (RVOT) diameter at the proximal level in the parasternal long-axis (PLAX) and parasternal short-axis (PSAX) view, right atrial (RA) area, RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), tissue Doppler imaging (TDI) of the tricuspid annulus (RV‘s, e’, a’) and pulmonary artery Doppler acceleration time (PAT). Tricuspid regurgitation velocity was not obtainable in the major part of the participants and therefore was unable to be utilized in this study. Regarding the left heart, the following structural and functional indices were determined: LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), LA diameter, LA volume, modified Simpson’s left ventricular ejection fraction (LVEF), tissue Doppler imaging (TDI) of the mitral annulus (LV ’, e’ and a’) and trans-mitral Doppler (E, A and E/A ratio). Doppler A and RV and LV TDI a’ were not measurable on account of e’/a’ and E/A fusion during stress echocardiography at higher heart rates. Mechanics . Images were acquired and optimized for STE. This involved maintaining frame rates between 40 and 90 frames s − 1 , depth to ensure adequate imaging of the chamber of interest and compression and reject to ensure endocardial delineation. The RV focused and the apical two-chamber, four-chamber and long-axis view were utilized for the RV and LV global longitudinal strain, respectively. Pulmonary and aortic valve closure times were determined from the respective pulsed wave Doppler signals. For both the RV and LV views the myocardium was manually traced to include the septum and adjusted so