At the highest exercise intensity, end-diastolic volume decreased from 163±38 ml to 143±47 ml while stroke work plateaued at 1.39±0.55 J in healthy volunteers.
Does a novel protocol using exercise MRI and computational modeling allow for the non-invasive calculation of cardiac energetics in healthy volunteers?
Exercise MRI combined with computational modeling is a feasible non-invasive method to recover cardiac energetics and stroke work in healthy volunteers.
Tasa de eventos absoluta: 0% vs 0%
Abstract Introduction Cardiac power would be an objective, quantitative, and clinically useful assessment of cardiac function but is not used because it requires simultaneous ventricular pressure and volume data. Furthermore, research studies of cardiac power neglect exercise, which is precisely when patients with cardiovascular disease experience symptoms and limitations. Purpose To develop a novel experimental and computational modelling methodology to quantify cardiac power during exercise MRI in healthy volunteers, establishing a baseline for patient assessments. Methods Seven healthy volunteers were recruited. Cardiac MRI images were acquired at rest and three incremental levels of exercise. Exercise levels were determined at a fixed interval of the max HR (220-age) minus resting HR. At each state, short-axis stack (SAX), coronary sinus (CS) flow and chamber views were acquired. Figure one shows the schematic of the planned exercise test. Non-invasive BP was taken from a brachial sphygmomanometer and the pressure reconstructed using an assumed elastance. Changes in energetics were compared to trends in literature. Results ESV decreased and ESP increased with exercise intensity, in line with relative changes from multigated blood pool studies (ESV: 59±17 ml, 61±18 ml, 50±18 ml, 37±14 ml*; ESP: 102±8 mmHg, 109±9 mmHg, 113±11 mmHg, 124±15 mmHg, *significant to P0.05 compared to level 1). End-diastolic volume increased at lower exercise intensities, but decreased relative to the resting state at the highest exercise intensity (EDV: 149±38 ml, 163±38 ml, 163±46 ml, 143±47 ml). This late decrease in EDV was associated with a plateau in stroke work at the highest exercise intensity (SW: 1.07±0.32 J, 1.30±0.36 J, 1.39±0.55 J, 1.39±0.50 J). Figure 2 shows the stroke work with increasing exercise intensity, relative to the resting value. Data points represent different cohorts presented in Chantler 2008 (circles: male normotensive, male hypertensive, female normotensive and female hypertensive) relative to our study (green crosses). The dashed blue lines represent ± 1 standard deviation for the Chantler data. Conclusion Exercise MRI is a feasible method to recover cardiac energetics from healthy volunteers. Further work will compare healthy individuals with patients with cardiovascular disease to determine how the cardiac exercise response differs in the context of cardiovascular pathophysiology.Figure 1:schematic of planned exercise Figure 2:stroke work with exercise
Faulkner et al. (Thu,) reported a other. At the highest exercise intensity, end-diastolic volume decreased from 163±38 ml to 143±47 ml while stroke work plateaued at 1.39±0.55 J in healthy volunteers.