Influence of acute K-strophanthidin administration on left ventricular diastolic phase in healthy young adults

The effects of digitalis on the left ventricular (LV) diastolic phase have not been defined adequately. Thus, in 9 young adult healthy subjects (5 mal es and 4 females aged 30-37 years, mean 31 +/- 5) we studied the diastolic phase using echo-Doppler technique to evaluate diastolic mitral valve flow before and at 30 minutes of a 5-minute i.v. injection of 0.25 mg of k-strop hanthidin. We considered the following parameters: peak E and A wave veloci ties, E and A wave integrals, E and A wave acceleration and deceleration ti mes, E and A waves acceleration and deceleration rate, E and A waves durati on, E/A velocity ratio, E/A duration ratio, total flow duration, and isovol umic relaxation times. In addition we also considered PR intervals, RR inte rvals, arterial blood pressures, LV end-diastolic and systolic diameters, f ractional shortening, and mean rate of circumferential shortening. From the analysis of our overall findings, strophanthidin seems to affect peak E ve locity (mean values from 76.09 +/- 10 to 82.0 +/- 15.07 cm/s p < 0.05) and A wave acceleration rate (mean values from 723 +/- 267 to 857 +/- 346 cm/s( 2)p < 0.01). Because RR and PR intervals, blood arterial pressure values, a nd fractional and mean rate of circumferential shortening were not modified , a hypothetical explanation of the significant effects of strophanthidin o n the above-mentioned variables might be due to a venous constrictive actio n of the drug leading to an increase of atrial pressures and contraction. T he increase in atrial pressure should induce an increase in atrioventricula r gradient pressure, which is considered the major determinant of LV early filling (related to peak E wave velocity). This augmentation of the atrial preload might explain, at least in past, the increase of the A wave acceler ation rate.