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Right and left ventricular adaptation to hypoxia: a tissue Doppler imaging study
Sandrine Huez1, Kathleen Retailleau, Philippe Unger
1Department of Physiology, Faculty of Medicine of the Free University of Brussels, Belgium.
Summary
Hypoxia alters diastolic function in both ventricles and improves left ventricular systolic function, while right ventricular systolic function remains preserved in healthy individuals. This study clarifies hypoxia's impact on cardiac performance.
Area of Science:
- Cardiovascular Physiology
- Respiratory Medicine
- Diagnostic Imaging
Background:
- Hypoxia is known to affect left ventricular (LV) diastolic function.
- The impact of hypoxia on right ventricular (RV) systolic and diastolic function is not fully understood.
Purpose of the Study:
- To investigate the effects of acute hypoxia on RV and LV systolic and diastolic function.
- To compare the effects of hypoxia with dobutamine, which mimics heart rate changes without altering pulmonary vascular tone.
Main Methods:
- Echocardiography and tissue Doppler imaging were used in 25 healthy volunteers.
- Participants underwent 90 minutes of hypoxic breathing (FiO2 of 0.12) or dobutamine infusion.
- Measurements included cardiac output, ejection fraction, and various systolic and diastolic indices.
Main Results:
- Both hypoxia and dobutamine increased cardiac output and LV systolic function indices.
- Hypoxia did not alter RV systolic function indices, whereas dobutamine did.
- Hypoxia impaired diastolic function in both ventricles, evidenced by increased isovolumic relaxation time and decreased E/A ratios.
Conclusions:
- Acute hypoxia in healthy subjects alters diastolic function in both ventricles.
- Hypoxia improves LV systolic function but preserves RV systolic function.
- Dobutamine enhances systolic function in both ventricles, unlike hypoxia.