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Influence of the pericardium and ventricular interdependence on left ventricular diastolic and systolic function in
1Cardiovascular Institute, Michael Reese Hospital, University of Chicago Pritzker School of Medicine, Illinois 60616.
Insights
The pericardium, a heart sac, can limit cardiac function by restricting stroke volume and altering pressure dynamics during exercise, especially in heart failure patients. This pericardial constraint impacts the heart's ability to pump efficiently under increased demand.
Area of Science:
- Cardiology
- Physiology
- Biophysics
Background:
- The pericardium's pressure-volume relationship influences cardiac pump function.
- Pericardial elasticity can limit ventricular dilation and stroke volume increase.
- Ventricular interdependence is amplified by pericardial properties.
Purpose of the Study:
- To investigate the role of pericardial constraint in limiting left ventricular diastolic and systolic function during exercise in heart failure patients.
- To characterize the hemodynamic changes associated with pericardial constraint during incremental exercise.
Main Methods:
- Evaluated 61 heart failure patients undergoing incremental upright exercise.
- Monitored stroke volume, right atrial pressure, and pulmonary capillary wedge pressure.
- Identified pericardial constraint by invariant stroke volume and equal pressure rises with increased workload.
Main Results:
- Pericardial constraint was observed in 31 of 61 patients.
- Constraint was characterized by stroke volume invariance and similar increases in right atrial and pulmonary capillary wedge pressures.
- The presence of pericardial constraint was independent of heart failure severity.
- Absence of constraint showed significantly greater increases in pulmonary capillary wedge pressure compared to right atrial pressure.
Conclusions:
- The pericardium plays a significant role in limiting left ventricular diastolic and systolic function.
- Pericardial constraint can be a limiting factor in cardiac performance during exercise in heart failure.
- Understanding pericardial influence is crucial for managing heart failure patients.
Abstract:
The pericardium, because of the nature of its pressure-volume relation, can influence left ventricular diastolic and systolic pump function. During an acute increase in heart size that results in the stretching of the pericardium, the elastic properties of the pericardium restrict further cardiac dilatation and curtail the ability of the ventricles to increase stroke volume. In addition, the pericardium enhances the degree to which increments in right ventricular volume would alter left ventricular diastolic distensibility. Ventricular interdependence is enhanced as a direct consequence of pericardial elastic properties. During the heightened venous return associated with marked muscular work, we found evidence of pericardial constraint in 31 of 61 patients with heart failure of varying severity and diverse etiology. The occurrence of pericardial constraint, which was characterized by stroke volume becoming invariant and an equivalent rise in right atrial and pulmonary capillary wedge pressures as work load was raised during incremental upright exercise, was independent of the degree to which maximum oxygen consumption was reduced or, equivalently, the severity of heart failure. In contrast, when pericardial constraint was not apparent during our exercise protocol, stroke volume did not become invariant, and the increments in pulmonary capillary wedge pressure were two- to threefold that of right atrial pressure. Thus, the pericardium can have a substantial role in determining the limits to left ventricular diastolic and systolic function.