Intrapericardial, Intrapleural, and Intracardiac Pressures during Acute Heart Failure in Dogs Studied without Thoracotomy

Pressures at multiple sites in the thorax of supine anesthetized dogs were recorded simultaneously with fluid-filled catheters inserted percutaneously. Pleural and pericardial pressures were corrected to the level of their respective recording catheter tips as determined by roentgenograms. Intracardiac pressures were referred to the midthoracic coronal plane or to the vertical level of the pericardial catheter tip. Pericardial pressures at end-expiration averaged -5.0 cm H 2 O (range 0 to - 13) and varied with the vertical position of the catheter tip, becoming less negative as the height above the midthoracic coronal plane diminished. Acute right heart failure was produced by partial obstruction of the pulmonary artery by a catheter-tip balloon. Although mean right atrial pressure increased by an average of 26 cm H 2 O, consistent increases in pericardial pressure did not occur. Similarly, during acute obstruction to left ventricular outflow by inflation of a balloon within the thoracic aorta, left atrial end-diastolic pressure increased by an average of 14.5 cm H 2 O, but no consistent increase in pericardial pressure was recorded. No systematic changes in pleural pressure were detected in either case. Thus there was no evidence of pericardial restriction of cardiac dilatation during acute heart failure under these experimental conditions.