Pressure-volume relationships in right ventricle.

• Recently, we have reported on the pressure developed in the left ventricle when that chamber was made to contract under conditions closely approaching that of being isovolumic.' 2 More recently, the use of a latex balloon to change the amount of effort of the right ventricle yielded data on the pressure developed in the right ventricle at different volumes under nearly isovolumic conditions. The method is described in detail in a report published in this issue. It is deemed appropriate to present the data obtained and to compare it with that found in the left ventricle. The curves (fig. 1) are similar to that seen in the isovolumic left ventricle,' except for scale values. The pressure curve increased slightly in duration, the steepness of the pressure rise and fall was augmented, and the early diastolic dip was exaggerated as the volume of the ventricle increased. The occurrence of spontaneous tachycardia with a concomitant rise of right intracardiac pressure is also illustrated in figure 1. A rise in aortic pressure occurs with the tachycardia, accompanied by a marked change in aortic pressure contour. The marked augmentation in the pressure pulse of the right ventricle is also evident, as is the augmentation of the gradient of pressure rise and fall. An earlj diastolic dip develops which brings the ventricular pressure below the zero level. This may represent suction (cf. reference 4),