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

Because of the close anatomic connections, the volume in 1 ventricle can directly influence the volume in the other ventricle. We examined this ventricular mechanical coupling at elevated pericardial pressures in 6 mongrel dogs. The animals were anesthetized and were mechanically ventilated with intermittent positive-pressure ventilation. Right and left ventricular volumes and pressures and pericardial pressure were simultaneously measured during control and after infusing 25, 50, and 75 ml of saline with dextran into the pericardial cavity. The ventricular volumes were calculated from cine-radiographic positions of endocardial, radiopaque markers. In the control state, right ventricular end-diastolic volume (RVEDV) increased 9.2 +/- 0.9 ml (p less than 0.05) during expiration, whereas left ventricular end-diastolic pressure (LVEDP) increased 0.6 +/- 0.7 mmHg and left ventricular end-diastolic volume (LVEDV) decreased 0.6 +/- 0.4 ml. The increased transmural LVEDP with a decreased LVEDV indicates an apparent left ventricular distensibility decrease as right ventricular diastolic volume increased, possibly because of ventricular interdependence. At the highest pericardial pressure, RVEDV increased 6.7 +/- 1.4 ml (p less than 0.05) during expiration as LVEDP increased 1.2 +/- 0.6 mm Hg and LVEDV decreased 2.0 +/- 0.6 ml (p less than 0.05). Thus, at the higher pericardial pressures, smaller changes in RVEDV produced significantly greater changes in LVEDV. This coupling between the ventricles was further examined in 5 hearts studied postmortem. The hearts were placed in cold cardioplegic solution and balloons were inserted into both ventricles.(ABSTRACT TRUNCATED AT 250 WORDS)