Key result
Supine bicycle exercise increased right ventricular metabolic rate of oxygen from 0.16 to 0.30 mL/min/g, which was significantly lower than the 0.44 mL/min/g observed in the left ventricle.
Why the study?
Simultaneously measuring RV and LV MBF, OEF, and MVO2 non-invasively in humans would provide new opportunities to understand cardiac physiology and pathophysiological states.
Can myocardial blood flow, oxygen extraction fraction, and oxygen consumption be assessed simultaneously in the right and left ventricles at rest and during exercise using 15O-labeled compounds and PET?
Cross-Sectional (n=15)
No
Can myocardial blood flow, oxygen extraction fraction, and oxygen consumption be assessed simultaneously in the right and left ventricles at rest and during exercise using 15O-labeled compounds and PET?
Absolute Event Rate: 0.3% vs 0.16%
p-value: p=<0.001
A novel PET method using 15O-labeled compounds can simultaneously assess MBF, OEF, and MVO2 in the right and left ventricles at rest and during exercise, revealing lower MVO2 in the RV during exercise.
Supports simultaneous PET assessment of RV and LV oxygen use at rest and exercise; hypothesis-generating pending validation.
Aims Simultaneous measurement of right (RV) and left ventricle (LV) myocardial blood flow (MBF), oxygen extraction fraction (OEF), and oxygen consumption (MVO2) non-invasively in humans would provide new possibilities to understand cardiac physiology and different patho-physiological states. Methods We developed and tested an optimized novel method to measure MBF, OEF, and MVO2 simultaneously both in the RV and LV free wall (FW) using positron emission tomography in healthy young men at rest and during supine bicycle exercise. Results Resting MBF was not significantly different between the three myocardial regions. Exercise increased MBF in the LVFW and septum, but MBF was lower in the RV compared to septum and LVFW during exercise. Resting OEF was similar between the three different myocardial regions (~70%) and increased in response to exercise similarly in all regions. MVO2 increased approximately two to three times from rest to exercise in all myocardial regions, but was significantly lower in the RV during exercise as compared to septum LVFW. Conclusion MBF, OEF and MVO2 can be assessed simultaneously in the RV and LV myocardia at rest and during exercise. Although there are no major differences in the MBF and OEF between LV and RV myocardial regions in the resting myocardium, MVO2 per gram of myocardium appears to be lower the RV in the exercising healthy human heart due to lower mean blood flow. The presented method may provide valuable insights for the assessment of MBF, OEF and MVO2 in hearts in different pathophysiological states.
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Kudomi et al. (2019) conducted a cross-sectional in Healthy (n=15). Supine bicycle exercise vs. Rest was evaluated on Right ventricular metabolic rate of oxygen (MVO2) (p=<0.001). Supine bicycle exercise increased right ventricular metabolic rate of oxygen from 0.16 to 0.30 mL/min/g, which was significantly lower than the 0.44 mL/min/g observed in the left ventricle.
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