The relationship between left and right pericardial pressures in humans: an intraoperative study.

Background: The purpose of this study was to show the similarity between the pericardial constraint over the right and left ventricles of humans at various levels of central venous pressure (CVP) using flat Silastic balloons in the pericardial space during elective cardiac surgery.

Methods: Six subjects (aged 19-76 years) were instrumented with flat, liquid-containing Silastic balloons in the pericardial space during elective cardiac surgery. No subject had valvular disease or right ventricular (RV) hypertrophy. These balloons were positioned to lie over the RV and left ventricular (LV) free walls to measure RV and LV pericardial pressure (P(prv) and P(plv), respectively). Volume loading was achieved by an intravenous infusion of 1 to 2 L of Ringer's lactate or normal saline. Depending on the patient's status during the operative procedure, the mean CVP was increased by 5-10 mm Hg from the baseline postinduction levels. RV and LV pericardial pressures were measured continuously throughout the volume loading.

Results: The pooled data from all subjects demonstrate that RV pericardial pressure is equal to LV pericardial pressure over central venous pressures ranging from 4 to 18 mm Hg and that the RV late-diastolic (pre-a-wave) cavitary pressure (P(rv)) correlates with LV pericardial pressure.

Conclusions: Changes in LV pericardial pressure are approximately equal to changes in RV pericardial pressure and RV late-diastolic (pre-a-wave) cavitary pressure is a good predictor of LV pericardial pressure.