Michio Odake

Single-beat estimation of the slope of the end-systolic pressure-volume relation in the human left ventricle.

This study assessed a new method of estimating the slope (Ees) of the end-systolic pressurevolume relation (ESPVR) from a single beat of the human heart. Left ventricular pressure was recorded with a high-fidelity micromanometer in patients with heart disease during left ventriculography. Peak isovolumic pressure at the end-disastolic volume was estimated by a curve-fitting technique from an isovolumic left ventricular pressure curve. The ESPVR line was drawn from the estimated peak isovolumic pressure-volume point tangential to the left upper corner of the pressure-volume loop. The slope of this estimated ESPVR line from single-beat analysis was compared with the slope of the ESPVR line obtained from three pressure-volume loops in 16 patients given angiotensin II or nitroglycerin infusion. The estimated Ees was 5.0 ± 2.2 mm Hg/m1/m2, and the conventional Ees was 4.9 ± 2.7 mm Hg/mlm2. The estimated Ees showed a positive correlation with the conventional Ees (r = 0.91, p < 0.001, SEE= 1.2 mm Hg/ml/m2). In the other 13 patients, after dobutamine infusion (5, μg/kg/min i.v.) the estimated Ees increased significantly from 5.6 ± 1.4 to 7.4 ± 2.0 mm Hg/ml/m2 (p < 0.01). Thus, the estimated Ees approximated the conventional Ees and was sensitive to a positive inotropic intervention. We conclude that this single-beat analysis method facilitates assessment of the beat-by-beat ESPVR of the human heart.

Comparison of hemodynamic determinants for myocardial oxygen consumption under different contractile states in human ventricle.

BackgroundRecently, several indexes such as tension-time index (TII), tension-time or force-time integral (FfM), rate-pressure product (RPP), pressure-work index (PWI), and systolic pressure-volume area (PVA) have been developed as predictors of myocardial oxygen consumption in experimental and clinical studies. However, it is still unclear whether these indexes are reliable predictors of myocardial oxygen consumption under various contractile states in human hearts. Methods and ResultsWe assessed the relation between TTI, FTI, RPP, PWI, and PVA and myocardial oxygen consumption per beat (&OV0622;O2) in 13 patients with heart disease during volume loading. Left ventricular (LV) volume and pressure were measured simultaneously by the conductance catheter with the tipped micromanometer technique. &OV0622;O2 was calculated from arterial coronary sinus oxygen content difference, and coronary sinus blood flow was measured by the thermodilution method. After z transformation of the correlation coefficients, mean z value for the &OV0622;O2-PVA relation (1.83±0.60) was greater than those for the &OV0622;O2-TII relation (1.22±O.66; p<0.005), &OV0622;O2-FTI] relation (1.18±O.61;p <0.05), &OV0622;O2-RPP relation (0.95±0.65; p<0.05), and &OV0622;O2-PWI relation (1.24±0.58;p<0.05). During dobutamine infusion (5 μ·kg−1·min−1) in five of the 13 patients, &OV0622;O2 also correlated best with PVA (z=1.70±0.89) compared with TII (z=1.43±0.86), FTI (z=1.48±0.95), RPP (z=1.00±0.53), and PWI (z=0.88±0.80). The contractile efficiency (38±14% to 38±20%), the reciprocal of the slope of the &OV0622;O2-PVA relation, remained unchanged, whereas the &OV0622;O2, PVA 0.8 (&OV0622;O2 at PVA=0.8 J per beat/100 g LV) increased from 1.48±1.16 to 2.06±1.13 J per beat/100 g LV (p<0.05). These results show the parallel upward shift of the &OV0622;O2-PVA relation during dobutamine infusion. Because increases in the &OV0622;O2-intercept represent the &OV0622;O2 for the increased excitation-contraction (E-C) coupling associated with the augmented contractile state, the parallelism of the &OV0622;O2-PVA relation could discriminate between &OV0622;O2 for mechanical work (PVA-dependent &OV0622;O2) and &OV0622;O2 for E-C coupling (PVA-independent &OV0622;O2). ConclusionsThe results of the present study indicate that PVA is a reliable and valuable predictor of myocardial oxygen consumption under different contractile states in human hearts. The &OV0622;O2-PVA relation could provide useful information about mechanoenergetics in diseased human hearts.

Comparison of the effects on arterial-ventricular coupling between phosphodiesterase inhibitor and dobutamine in the diseased human heart

OBJECTIVES The aim of this study was to compare the effects of a phosphodiesterase inhibitor and catecholamine on arterial-ventricular coupling and myocardial energetics in the diseases human heart. BACKGROUND Recent experimental studies have indicated that the arterial-ventricular coupling analysis using the time-varying elastance model could discriminate between inotropic and vasoactive effects of the two agents. METHODS With the use of a conductance catheter, left ventricular contractility and arterial afterload were measured from the slope of the end-systolic pressure-volume relation, Emax, and the slope of the end-systolic pressure-stroke volume relation, Ea. Arterial-ventricular coupling was assessed by Ea/Emax before and after administration of a new phosphodiesterase inhibitor, E-1020 (0.3 microgram/kg per min), and a beta 1-stimulant, dobutamine (5 micrograms/kg per min), in 20 patients with heart disease. Left ventricular mechanical efficiency was assessed as the ratio of stroke work to myocardial oxygen consumption per beat measured by the thermodilution method. RESULTS The slope of the end-systolic pressure-volume relation increased comparably with both E-1020 (39%, p < 0.01) and dobutamine (47%, p < 0.01), but Ea/Emax decreased with E-1020 (1.25 to 0.78, -37%, p < 0.01) more than with dobutamine (1.23 to 0.99, -16%, p < 0.05). Although stroke work index increased with both agents, myocardial oxygen consumption remained unchanged with E-1020 but increased with dobutamine (p < 0.05). Consequently, left ventricular mechanical efficiency increased with E-1020 (0.30 to 0.36, p < 0.05) but remained unchanged with dobutamine (0.27 to 0.29, p = NS). CONCLUSIONS The phosphodiesterase inhibitor E-1020 improved arterial-ventricular coupling more than did dobutamine, with a resultant increase in mechanical efficiency. These data were in accordance with the theoretic prediction of the coupling analysis in the diseases human heart.