Use of time frequency analysis to follow transitory modulation of the cardiac autonomic system in clinical studies

Heart rate variability (HRV) can be assessed through a time frequency analy sis, the smoothed pseudo Wigner-Ville transformation (SPWVT). Such an analy sis has allowed the calculation of ICF, a frequential index, extremely sens itive to the modulation of the sympatho-vagal balance. The use of ICF has b een applied in the present study to two clinical situations for which a rol e of this balance was probable, brain death and atrial fibrillation (AF). T he use of the time frequency analysis immediately identified the timing of brain death. No difference could be found in the analysis of the 30 min pre ceding an atrial fibrillation episode. It is suggested that a time frequenc y analysis should be used in clinical situations in which transitory fluctu ations of the sympatho-vagal balance are expected and crucial to the well b eing of the patients. (C) 2001 Elsevier Science B.V. All rights reserved.