Preload-Adjusted 2 Wave-Intensity Peaks Reflect Simultaneous Assessment of Left Ventricular Contractility and Relaxation

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Background The magnitudes of the first (WI_1) and the second wave-intensity peak (WI_2) during the ejection period can be used as indices of left ventricular (LV) contractility and relaxation, respectively. However, use of WI to characterize LV dp/dt and the end-diastolic volume (V_<ed>) relationship may be more problematic, as WI may be affected by changes in preload. Methods and Results The LV pressure-volume data sets, consisting of 23 recordings obtained by the conductance method from 12 heart disease patients, were studied. End-systolic elastance (E_<es>) and volume-axisintercept (V_0) were calculated with varying preload. Time constant of LV relaxation (τ), V_<ed>, and WI were calculated from steady-state averaged data. The E_<es> showed a weak correlation with WI_1 (r=0.46, p<0.05) but a better correlation with preload-adjusted WI_1 [WI_1/V_<ed>; r=0.86, WI_1/V_<ed>^2; r=0.92, WI_1/(V_<ed>-V_0)^2; r=0.89, all p<0.01]. Similarly, τ did not correlate with WI_2 but did correlate with preload-adjusted WI_2 [WI_2/V_<ed>; r=-0.73, WI_2/V_<ed>^2; r=-0.63, WI_2/(V_<ed>-V_0)^2; r=-0.78, all p<0.01]. Conclusions These data demonstrate the importance of preload-adjustment when using the WI index for simultaneous assessment of LV contractility and relaxation.
社団法人日本循環器学会の論文
2005-05-20