[Clinical application of a right ventricular pressure-volume loop determined by gated blood-pool imaging and simultaneously measured right ventricular pressure].

The data obtained by ECG-gated radionuclide angiography were collected simultaneously with right ventricular pressure and thermal cardiac output (CO) obtained by a Swan-Ganz catheter in Scintipac 1200 ( Shimazu Co) in order to create a right ventricular pressure-volume (RV P-V) loop. Subjects consisted of 15 patients with old myocardial infarction (MI group), seven with angina pectoris (AP group), six with congestive cardiomyopathy (CCM group) and five with neurocirculatory asthenia (NCA group). Right ventricular end-diastolic volume ( RVEDV ) was calculated as RVEDV = CO/(EF X HR) (CO = cardiac output; HR = heart rate). Systolic work (Ws), diastolic work (WD) and net work (WN) were calculated from a RV P-V loop by Simpson's method. The measurements were performed before and 5 min after sublingual administration of nitroglycerin (NG) (0.3 mg). The results were as follows: RV P-V loops shifted towards the left lower part of the P-V plane after sublingual administration of nitroglycerin, indicating the reduction of pressure and volume of the right ventricle. Right ventricular ejection fraction (RVEF) in the MI, AP and CCM groups showed smaller values than that of the NCA group. The CCM group presented a significantly smaller value than the NCA group (p less than 0.005). RVEF of each group increased after NG. In the AP and CCM groups, it increased significantly (p less than 0.005). Right ventricular end-diastolic volume index ( RVEDVI ) showed a converse relation with RVEF. The MI and CCM groups demonstrated significantly higher values (p less than 0.05). After NG, RVEDVI of each group decreased significantly (p less than 0.001 in the MI and NCA groups, and p less than 0.005 in the AP and CCM groups). Cardiac index in all groups decreased after NG and a statistical significance was seen in the MI, AP and NCA groups (p less than 0.05). RV Ws, RV WD and RV WN showed no difference among each group in the control state, and significantly decreased after NG. This was due to the reduction of RV pressure and volume. It was indicated that the principal cause was the systemic volume reduction. We conclude that the present method using RV P-V loop might be useful as a noninvasive bedside monitoring and permits the evaluation of RV function in a clinical setting.