Transmural Ventricular Pressures and Pulsus Paradoxus in Experimental Cardiac Tamponade

¹ The Cardiac Laboratory, Cincinnati General Hospital and the Department of Medicine, University of Cincinnati.

Transmural pressures were measured from both cardiac ventricles before, during and after experimental cardiac tamponade in open chest dogs. During the control and recovery periods, the transmural pressures were positive in both ventricles. During tamponade, the transmural diastolic pressures became negative in both ventricles.

In a series of closed chest dogs, subatmospheric transmural pressures were measured during cardiac tamponade from both atria and both ventricles. With severe tamponade, the intrapericardial pressure exceeded the right ventricular systolic pressure, and with very severe tamponade, even the left ventricular transmural systolic pressure was negative.

In the control and recovery tracings, inspiration was accompanied by an increase in the pulmonary arterial pulse pressure and a simultaneous decrease in the aortic pressure pulse. This phenomenon was exaggerated during cardiac tamponade. The implications of this finding regarding the genesis of pulsus paradoxus were discussed.