Article ID: CJ-08-0954
Background: The maximum rate of the ventricular pressure rise (dp/dtmax) provides a reliable measure of ventricular contractility. However, its estimation requires invasive measurement of left ventricular (LV) pressure, limiting its bedside clinical applicability. In the present study, 2 hypotheses were tested: (1)that the ratio of dp/dtmax between the aorta (Ao) and LV is consistent among patients despite marked differences in underlying cardiac disease, contractile state and heart rate when vascular mechanical and loading properties are taken into account, and (2)that using such a relationship, LV dp/dtmax can be estimated from Ao dp/dtmax, potentially providing a method of noninvasive determination of LV contractility. Methods and Results: Data from 30 control children and 45 pediatric patients with various cardiovascular diseases revealed that the characteristic impedance (Zc) and mean arterial pressure were significant determinants of the Ao-LV dp/dtmax relationship in both control and disease groups. LV dp/dtmax estimated using the regression obtained in the control children (Ao dp/dtmax/LV dp/dtmax = 0.64+1.45*10-4*Zc-3.73*10-3*MAP, r=0.87) correlated well with the measured LV dp/dtmax in the disease group, including measurements taken after dobutamine and atrial pacing (r=0.89). Conclusions: Ao dp/dtmax and LV dp/dtmax are closely correlated through the vascular loading properties and LV dp/dtmax can be derived from Ao dp/dtmax, which has potential as a noninvasive method of determining LV contractility.
