Optimal preload adjustment of maximal ventricular power index varies with cardiac chamber size

Masaru Nakayama, Chen Huan Chen, Erez Nevo, Barry Fetics, Eddy Wong, David A. Kass*


研究成果: Article同行評審

24 引文 斯高帕斯(Scopus)


Background: Maximal left ventricular power (PWR(max)) can index contractile function and reserve; however, its marked preload dependence mandates load adjustment to yield a more cardiac-specific measurement. Prior studies have used varying methods, but supporting data have generally been lacking. We hypothesized that the optimal approach for preload adjustment varies with ventricular volume (particularly end-systolic volume) and is significantly different for dilated hearts with reduced left ventricular function compared with small to normal-sized hearts with normal systolic function. Methods: Left ventricular pressure-volume relations were measured by the conductance catheter method in 36 patients, with preload altered by inferior vena cava obstruction. Patients with normal ventricles (n = 16), hypertrophy or mitral stenosis (n = 12), and dilated cardiomyopathy (n = 8) were divided into three groups based on resting end-diastolic volume: group 1, 66.3 ± 12; group 2, 118.1 ± 20; and group 3, 218.2 p 48 ml. PWR(max) was the maximal product of simultaneous left ventricular pressure and rate of volume change. PWR(max) end-diastolic volume (EDV) data were fit to a power function, PWR(max) = αEDV(β) (where α is a scaling factor and β is the power coefficient), and the preload sensitivity of β and PWR(max)/EDV(β) ratios (β = 1, 2, or best fit) were compared. Results: β Varied directly with chamber size: β = 0.004. (EDV + 0.56), r = 0.65, p < 0.0001. However, it was equally well approximated by 1.0 in groups 1 and 2 (ESV <75 ml, EF >40%), whereas β = 2 was more appropriate in group 3. Conclusion: PWR(max)/EDV provides adequate preload independence in all but dilated hearts with reduced LV function, whereas PWR(max)/EDV2 is required in the latter. These data should help clinical application of a noninvasive PWR(max) index for assessing chamber contractility and contractile reserve in human beings.

頁(從 - 到)281-288
期刊American Heart Journal
出版狀態Published - 1998


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