[Response of cardiac patients to dynamic exercise: analysis with "systolic" pressure-volume area].
In the present study, we constructed a left ventricular pressure-volume loop from catheterization data and RN-angiocardiography. By connecting the point of origin of the plane, not the point of Vd, with the end-systolic point of the loop, we calculated a "systolic" pressure-volume area (PVA), elastic potential energy (EPE), and stroke work (SW). A cardiac output (CO)-pulmonary artery wedge (PAW) pressure plot was constructed at rest and during exercise, using a bicycle ergometer, to evaluate cardiac pump function. End-systolic volume (ESV) was obtained from the left ventricular P-V loop, and the response of ESV to exercise was investigated. Thirty-five patients with various cardiac diseases were categorized in two groups according to the delta CO/delta PAW obtained from the shift of the CO-PAW plot during exercise; group I (n = 28) with the properly functioning hearts having the ratio greater than 0.12 l/min/mmHg and group II (n = 7) with the poorly functioning hearts having the ratio less than or equal to 0.12 l/min/mmHg. Group I was subdivided further into two subsets according to the changing pattern of ESV during exercise; group I-A with decreased or unchanged ESV (n = 20) and group I-B with increased ESV in which end-diastolic volume (EDV) was increased during exercise (n = 8). During exercise, PVA and SW were unchanged but SW/PVA increased in group I-A, suggesting improvement of external mechanical efficiency. SW/PVA was unchanged in group I-B, despite the increase in PVA and SW. This suggested that external mechanical work increased as a result of increased cardiac oxygen consumption. In group II, PVA increased, SW was unchanged and SW/PVA decreased, which could be explained by the mechanism that external mechanical work during exercise decreased as compared with that at rest. It was suggested that a different mechanism may have been responsible for the production of external mechanical work among patients in group I-A and in group I-B with properly functioning hearts judged from the CO-PAW plot. Therefore, it seems useful to calculate PVA, SW and SW/PVA during exercise using the left ventricular pressure-volume loop for evaluating cardiac function.
Yagi
Y
Y
Second Department of Internal Medicine, Gifu University School of Medicine.
Goto
K
K
Ooshima
S
S
Takatsu
H
H
Tsukamoto
T
T
Iida
M
M
Yamamoto
N
N
Deguchi
F
F
Terashima
Y
Y
Hirakawa
S
S
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D002302:Cardiac Output; D002306:Cardiac Volume; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006331:Heart Diseases / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011669:Pulmonary Wedge Pressure; D013599:Systole