Effects of Captopril on Specific Harmonic Indexes of the Peripheral Pressure Pulse Waveform

There were evidences that the blood pressure measured on the radial artery under some vasodilators treatments will overestimate than which measured on the central artery. Our previous studies infer that the harmonic proportion of the 4th harmonic (C4) of the peripheral pressure pulse waveform could be an index related to the peripheral vascular tone. In this study, we used a vasodilator drug, captopril to verify the relationship between C4 and vasoactive drug. Thirteen male Wistar Kyoto rats weighing 270 to 350 grams were studied. The blood pressure waveforms measured on the tail artery were averaged every 10 minutes and Fourier transformed into frequency domain. The data measured 20 minutes before captopril (0.83mg/1kg) injection was used as control. Four 10 minutes after-drug data sets were compared with the control. The diastolic (DBP) and systolic (SBP) blood pressures decreased rapidly after captopril injection. The mean pulse pressure A0 has the same decreasing trend but less conspicuously. The harmonic proportion of the 4th harmonic decreases at the beginning but then increases dramatically. These results suggest that C4 could be an index related to the peripheral vascular tone. We present a harmonic based pulse waveform analysis method to provide a peripheral pressure waveform index which may be used to estimate the cardiovascular risk.