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Effect of intrathoracic pressure on left ventricular performance
The New England Journal of Medicine
|August 30, 1979
Summary
Intrathoracic pressure significantly impacts left ventricular function, especially in lung diseases. Negative pressure increases afterload, affecting cardiac performance and ejection fraction.
Area of Science:
- Cardiology
- Pulmonary Medicine
- Physiology
Background:
- Left ventricular dysfunction is prevalent in respiratory conditions like asthma and obstructive lung disease.
- The role of intrathoracic pressure in this dysfunction requires further elucidation.
Purpose of the Study:
- To investigate the effects of intrathoracic pressure variations on left ventricular function.
- To determine the relationship between intrathoracic pressure, arterial pressure, and left ventricular volumes.
Main Methods:
- Studied eight patients undergoing Valsalva and Müller maneuvers.
- Utilized intramyocardial markers for beat-by-beat measurement of velocity of fiber shortening (VCF) and left ventricular volume.
- Measured arterial pressure and left ventricular end-systolic volumes.
Main Results:
- Müller maneuver decreased VCF and ejection fraction, increased left ventricular volume, and lowered arterial pressure.
- Corrected arterial pressure (adjusted for intrapleural pressure) correlated better with left ventricular end-systolic volumes than uncorrected pressure.
- Negative intrathoracic pressure increased left ventricular transmural pressures, thereby increasing afterload.
Conclusions:
- Negative intrathoracic pressure adversely affects left ventricular function by increasing afterload.
- Significant intrathoracic pressure changes, common in acute pulmonary disease, can impair cardiac performance.