Related Experiment Videos
Restoring forces assessed with left atrial pressure clamps
S P Bell1, J Fabian, A Higashiyama
1Cardiology Unit, University of Vermont College of Medicine, Burlington 05405, USA.
The American Journal of Physiology
|March 1, 1996
Summary
Restoring forces in the left ventricle (LV) are present at low physiological filling pressures but diminish at higher pressures. Ventricular filling slows the rate of pressure decline, aiding mitral valve opening.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
Background:
- Negative pressure in the fully relaxed left ventricle (LV) signifies restoring forces generated during contraction.
- Understanding these forces is crucial for comprehending diastolic function and ventricular mechanics.
Purpose of the Study:
- To assess left ventricular (LV) restoring forces under physiological filling conditions in an intact heart model.
- To investigate the impact of ventricular filling on the rate of LV pressure fall and mitral valve (MV) dynamics.
Main Methods:
- Anesthetized open-chest dogs (n=8) were studied using a servomotor system to induce nonfilling diastoles via left atrial pressure (LAP) clamping.
- Left ventricular end-diastolic pressure (EDP) was manipulated through volume infusion.
- Two-dimensional echocardiography was employed to assess mitral valve (MV) leaflet displacement.
Main Results:
- Fully relaxed LV pressures increased significantly with rising EDP.
- LAP clamping accelerated the rate of LV pressure fall.
- Substantial downward displacement of MV leaflets occurred despite reversed atrial-LV gradient and absence of filling.
Conclusions:
- LV restoring forces are present at low physiological EDP but absent at high physiological EDP.
- Ventricular filling retards the rate of LV pressure fall.
- LV relaxation facilitates MV opening even without ventricular filling.