Physiologic role of the normal pericardium

Area of Science:

• Cardiovascular Physiology
• Cardiac Mechanics
• Pericardial Function

Background:

• The parietal pericardium has limited volume reserve, becoming non-compliant at high normal physiological heart volumes.
• Pericardial restraint functions as a contact force influencing cardiac filling dynamics.
• Pericardial contact pressure is likely lower than right atrial pressure.

Purpose of the Study:

• To investigate the functional impact of the pericardium on cardiac mechanics and filling.
• To understand how pericardial restraint affects ventricular diastolic properties.
• To explore the role of the pericardium in conditions of increased cardiac volume.

Main Methods:

• Measurement of pericardial contact pressure using flattened balloons.
• Analysis of diastolic pressure-volume relationships of the right and left ventricles.
• In vivo studies in dogs to assess the effect of pericardiectomy on cardiac output.

Main Results:

• Pericardiectomy shifts the diastolic pressure-volume relationship downward for both ventricles.
• The pericardium has been demonstrated to limit maximal cardiac output in canine models.
• Conditions like subacute mitral regurgitation and right ventricular infarction show increased pericardial influence on cardiac filling.

Conclusions:

• The pericardium significantly influences cardiac filling and diastolic function, particularly under conditions of increased heart volume.
• Pericardial restraint plays a critical role in limiting cardiac output and maintaining diastolic compliance.
• Understanding pericardial mechanics is crucial for managing diseases that affect cardiac volume.