Comparison of techniques for time-frequency analysis of the ECG during human ventricular fibrillation

Ventricular fibrillation (VF) is a catastrophic and potentially lethal brea kdown of heart rhythm. Despite its importance, it remains poorly understood ; there are no effective techniques for predicting or preventing VF, and it can only be reliably terminated by a large current pulse: defibrillation. There is currently great interest in using linear and nonlinear signal proc essing techniques to characterise recordings of VF. Five episodes of VF wer e recorded from patients in a Coronary Care Unit. Time-frequency distributi ons (TFDs) of the first 10s of these recordings were estimated with the sho rt-time Fourier transform, Wigner-Ville, smoothed Wigner-Ville and Choi-Wil liams algorithms. The smoothed Wigner distribution was found to give a TFD reasonably free of cross-terms, without the additional computational cost o f the Choi-Williams algorithm. Used in tandem with the predictable short-ti me Fourier transform, the smoothed Wigner TFD is a valuable tool for charac terising the TFD of human VF.