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Updated: Aug 11, 2026
11:40
Quantitative Autonomic Testing
Published on: July 19, 2011
Changes in pulmonary venous return during head-up tilting in man
M Guazzi1, G Tamborini, A Maltagliati
1Istituto di Cardiologia dell'Università degli Studi, Milan, Italy.
Clinical Science (London, England : 1979)
|July 1, 1997
Summary
Head-up tilting causes blood redistribution from lungs to the heart, increasing pericardial compliance. This mechanism compensates for reduced venous return by enhancing cardiac filling during head-up tilt.
Area of Science:
- Cardiovascular Physiology
- Respiratory Physiology
- Biophysics
Background:
- The pericardium normally constrains cardiac filling in the supine position.
- During head-up tilting, reduced venous return challenges cardiac output.
Purpose of the Study:
- To investigate blood redistribution from lungs to the left heart during vertical displacement.
- To elucidate the mechanisms compensating for reduced venous return during head-up tilt.
Main Methods:
- Doppler-echocardiography in 16 healthy volunteers during 20, 40, and 60 degrees head-up tilting.
- Measurements included pulmonary venous flow velocity and ventricular dimensions.
- Tilting duration varied (10 min vs. 45 min) in two subject groups.
Main Results:
- Head-up tilting reduced right and left ventricular dimensions.
- Pulmonary venous flow velocity showed characteristic changes (decreased systolic, increased diastolic).
- These changes intensified with increasing tilt angles and were consistent over time.
Conclusions:
- Reduced ventricular dimensions and lung underfilling increase pericardial compliance.
- This facilitates blood redistribution from lungs to the heart.
- The heart-lung interaction during head-up tilt sustains compensation for reduced venous return.
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