| Autor: |
Stefadouros, Miltiadis A., Williams, Maryon J. |
| Předmět: |
|
| Zdroj: |
Angiology; Jul1981, Vol. 32 Issue 7, p489-501, 13p |
| Abstrakt: |
A computer program was developed to simplify the conventional method for determining the maximal contractile element shortening velocity at zero load (Vmax) by analysis of pressure-velocity graphs during the isovolumic contraction period. From an uncalibrated left ventricular (LV) pressure signal and its first derivative (dP/dt), the graph relating developed LV pressure (Pd) to the corresponding instantaneous value of (dP/dt)/28 Pd was constructed by the computer. The segment of the graph that encompassed approximately the second half of the isovolumic contraction period, as determined by analysis of the dP/dt waveform, was then extrapolated to provide Vmax on the ordinate. This Vmax was compared with the conventional Vmax obtained from calibrated LV and aortic pressure signals. In 5 dogs both in the control state and during inotropic (epineprine, propranolol) and noninotropic interventions (phenylephrine or dextran infusion), a high degree of correlation was found relating Vmax and Vmax both derived by either linear (Vmax = 0.91 Vmax + 0.14; r = 0.933; P < 0.001) or exponential (V'max = 0.99 Vmax - 0.06; r = 0.959; P < 0.001) extrapolation of the pressure-velocity graph to zero load. By use of this program, Vmax can be easily and reliably estimated from the uncalibrated LV pressure signal and its first derivative. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
