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Changes in left ventricular contractility with the phase of respiration
K Karlocai1, G Jokkel, M Kollai
1Department of Cardiology, National Koranyi Institute, Semmelweis Medical University, Budapest, Hungary.
Journal of the Autonomic Nervous System
|December 23, 1998
Summary
This study introduces a noninvasive method to measure left ventricular contractility using the end-systolic wall stress-velocity of circumferential fiber shortening relation during breathing. Contractility varied with respiration, suggesting reduced function during expiration.
Area of Science:
- Cardiology
- Physiology
Background:
- Assessing left ventricular contractility noninvasively is crucial for cardiovascular health.
- The respiratory cycle influences cardiac function, but its effect on contractility requires further elucidation.
Purpose of the Study:
- To establish a noninvasive method for measuring left ventricular contractility.
- To investigate the relationship between end-systolic wall stress and velocity of circumferential fiber shortening during the respiratory cycle.
Main Methods:
- Studied eight healthy subjects performing slow-paced breathing.
- Utilized echocardiography and calibrated carotid pulse tracings.
- Determined the left ventricular end-systolic wall stress-velocity of circumferential fiber shortening relation via linear regression analysis.
Main Results:
- End-systolic wall stress and velocity of circumferential fiber shortening showed significant changes during respiration.
- Velocity of circumferential fiber shortening was higher during expiration than inspiration at similar stress levels.
- The relationship remained significant and inverse during both inspiration and expiration.
Conclusions:
- The end-systolic wall stress-velocity of circumferential fiber shortening relation provides a noninvasive measure of left ventricular contractility.
- Ventricular contractility appears reduced during the expiratory phase, potentially due to increased vagal influence.