Noninvasive Assessment of the First Derivative of Left Ventricular Pressure by Apexcardiogram : 1

To estimate noninvasively the first derivative of left ventricular pressure (LVP-dP/dt), apexcardiogram (ACG) and the first derivative of ACG (dA/dt) were recorded in 37 pts [12 valvular heart diseases, 20 ischemic heart diseases and 5 idiopathic cardiomyopathies] within a week before cardiac catheterization. The dA/dt wave and its calibration were obtained electrically. We assumed that ACG has similar configuration with LVP and the total deflection of ACG is corresponded with the brachial peak systolic pressure (BSP) measured by cuff method. Noninvasively, peak dP/dt (=dP'/dt) was calculated with a formula as follows. Peak (+) dP'/dt=BSP・(B/A)・(a/b) mmHg/sec : the total deflection of ACG : A, peak (+) dA/dt : B, calibration factor of the A : a, calibration factor of the B : b. Mean values of peak (+) dP/dt and peak (+) dP'/dt were 1282±274 and 1245±282 mmHg/sec (mean±SD), respectively. There was little difference [37±172 mmHg/sec (mean±SD) : NS] between the two values. The peak (+) dP'/dt was significantly (Y=0.83X+178, r=0.81, p<0.001) correlated with peak (+) dp/dt. Then, we calculated the time interval from R of electrocardiogram (EKG) to peak (+) dP/dt : R-dP/dt, and the time interval from R of EKG to peak (+) dP/dt : R-dA/dt. Mean values of R-dP/dt and R-dA/dt were 65±16, 63±21 msec (mean±SD), respectively. There was no significant difference between two values and there was significant correlation (r=0.65, p<0.001). We concluded that dA/dt wave reflects well dP/dt wave in isometric contraction time and peak (+) dP'/dt can estimate well noninvasively peak (+) dP/dt of LVP.