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Restraining effect of intact pericardium during acute volume loading
R J Applegate1, W E Johnston, J Vinten-Johansen
1Department of Medicine (Section of Cardiology), Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157.
The American Journal of Physiology
|June 1, 1992
Summary
The intact pericardium does not affect ventricular filling at low volumes. However, it restricts filling once ventricular pressures rise, influencing cardiac function during volume loading.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
Background:
- The pericardium, a sac surrounding the heart, plays a role in cardiac mechanics.
- Understanding its influence on ventricular pressures is crucial for diagnosing and managing cardiac conditions.
Purpose of the Study:
- To investigate the effect of the intact pericardium on ventricular end-diastolic pressures (EDP) during acute volume loading.
- To determine when the pericardium begins to exert a restrictive effect on cardiac filling.
Main Methods:
- Measurements of left ventricular (LV) and right ventricular (RV) micromanometer pressure and LV volume using a conductance catheter in anesthetized dogs.
- Comparison of ventricular pressures with the pericardium intact versus removed during intravascular volume expansion.
- Calculation of pericardial pressure (Pper) using static equilibrium analysis.
Main Results:
- At low cardiac volumes, pericardial pressure was not significantly different from zero, indicating no effect on LV filling.
- Pericardial restraint (Pper ≥ 0 mmHg) began when LVEDP reached approximately 9.1 mmHg.
- After the onset of restraint, RVEDP and Pper increased similarly, showing a direct relationship.
Conclusions:
- The intact pericardium functions in two distinct ways: it does not impede filling at low volumes but restricts it as volumes increase.
- The pericardium's influence on cardiac filling is volume-dependent, becoming significant at higher ventricular end-diastolic pressures.