Right and left ventricular pressure-volume response to elevated pericardial pressure

Area of Science:

• Cardiovascular Physiology
• Cardiac Mechanics
• Ventricular Interdependence

Background:

• The heart's two ventricles are anatomically connected, allowing volume changes in one to affect the other.
• Ventricular mechanical coupling is a crucial aspect of cardiac function, especially under varying physiological conditions.

Purpose of the Study:

• To investigate ventricular mechanical coupling under elevated pericardial pressures.
• To quantify the influence of right ventricular volume changes on left ventricular volume at increased pericardial pressures.

Main Methods:

• Utilized mongrel dogs (n=6) under anesthesia and mechanical ventilation.
• Measured right and left ventricular volumes and pressures, and pericardial pressure.
• Employed cine-radiography with radiopaque markers to determine ventricular volumes.
• Experimentally increased pericardial pressure by infusing saline-dextran into the pericardial cavity.

Main Results:

• In control conditions, increased right ventricular end-diastolic volume (RVEDV) during expiration correlated with decreased left ventricular end-diastolic volume (LVEDV).
• Elevated pericardial pressures amplified this effect, where smaller increases in RVEDV led to significantly larger decreases in LVEDV.
• At the highest pericardial pressures, RVEDV increased by 6.7 ml and LVEDV decreased by 2.0 ml (p < 0.05).

Conclusions:

• Ventricular mechanical coupling is significantly influenced by pericardial pressure.
• Increased pericardial pressure enhances ventricular interdependence, where right ventricular expansion constricts the left ventricle.
• Findings suggest that pericardial pressure plays a critical role in modulating the mechanical interaction between the cardiac ventricles.