Prediction of carotid pressure waveforms by mathematical transformation of pressure waves recorded from the radial artery

Radial pressure waves (RPWs) and carotid pressure waves (CPWs) were recorded using applanation tonometry in 6 healthy subjects (5M, 1F, all aged 21 yrs) at rest as well as after a vasodilator agent (sublingual glyceryl trinitrate [GTN] spray). For each subject, transfer functions between radial and carotid pressure waves were calculated by a nonparametric Fourier method. Using the transfer functions, CPWs were reconstructed from RPWs and compared to tonometrically recorded CPWs. The transfer functions accurately predicted CPWs at rest, however, post-GTN, there were significant differences between reconstructed and recorded CPWs. The timing of peak systolic pressure, as predicted by the reconstructed CPWs, was underestimated by 0.3% at rest and was overestimated by 2.3% post-GTN spray.