Limitations of the zero crossing detector in the analysis of intracoronary doppler: A comparison with fast fourier transform analysis of basal, hyperemic, and transstenotic blood flow velocity measurements in patients with coronary artery disease

Abstract

The current clinical standard for the analysis of intracoronary Doppler signals is the application of a zero-crossing (ZC) detector. However, the accuracy of the method is questionable, especially in areas of disturbed flow, as confirmed by in vitro studies, animal experiments, and intraoperative observations. The aim of this study is the comparison of a conventional ZC detector and a custom-designed spectral analyzer (fast Fourier transform, FFT) in the analysis of intracoronary Doppler signals obtained in 19 patients undergoing coronary angioplasty. A 3F catheter with an end-mounted Doppler ceramic crystal was placed over an 0.014" guidewire in a normal or near-normal segment proximal to the lesion to be dilated. The Doppler signal was recorded before and after intracoronary infusion of 12.5 mg of papaverine. In 9 patients high flow velocities could be recorded when the catheter was advanced across the stenosis. The blood flow velocity measurements obtained with ZC were significantly lower than the maximal FFT flow velocity measurements (16 +/- 12 cm/s vs. 29 +/- 18 cm/s, p < .001). In all the conditions of Doppler signal acquisition (baseline, hyperemia, stenosis) a large scattering of the signed differences between corresponding measurements was observed. The standard deviation of the difference ZC-FFT was +/- 11 cm/s and +/- 5 cm/s for the maximal and mean FFT flow velocity, corresponding in both cases to +/- 37% of the mean of the ZC and FFT measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Utilization of translesional hemodynamics: Comparison of pressure and flow methods in stenosis assessment in patients with coronary artery disease

“…A user-defined diameter was also measured at the site of the Doppler sample volume in order to calculate coronary blood flow as the product of mean blood-flow velocity and cross-sectional area. After real-time processing of the quadrature audio signal using a fast-Fourier transform algorithm [6], the Doppler system calculates and displays on-line several spectral variables, including time-averaged (mean of two beats) peak velocity. The instantaneous peak velocity is calculated after spectral analysis of the Doppler signal [6] and is also available as a calibrated analog signal for continuous recording [7].…”

“…After real-time processing of the quadrature audio signal using a fast-Fourier transform algorithm [6], the Doppler system calculates and displays on-line several spectral variables, including time-averaged (mean of two beats) peak velocity. The instantaneous peak velocity is calculated after spectral analysis of the Doppler signal [6] and is also available as a calibrated analog signal for continuous recording [7]. Mean flow velocity was calculated as time-averaged peak velocity/2, assuming a fully developed flow velocity profile [8].…”

Coronary flow reserve in hypertrophic cardiomyopathy: relation with microvascular dysfunction and pathophysiological characteristics

“…After real-time processing of the quadrature audio signal, a fast-Fourier algorithm was used to increase the reliability of the analysis. 20 The flow velocity measurements obtained with this system have been validated in vitro and in an animal model using simultaneous electromagnetic flow measurements for comparison. 21 CFR was defined as hyperaemic divided by basal velocity.…”

Heterogeneity of Coronary Flow Reserve in the Examination of Multiple Individual Allograft Coronary Arteries

“…11 Previous studies have measured the Doppler shift with a zero-cross methodology that appears to overestimate flow compared with the fast Fourier transform spectral analysis used by the Doppler guidewire. 20,21,48 The Doppler guidewire has been validated in both in vitro and in vivo models. 20 CFRs measured in PET studies in transplant patients correlate more closely with measurements made with the Doppler guidewire than those made with the intracoronary Doppler catheter.…”