Session P7F.1

Non-Invasive Determination of Electromechanical Time Intervals of Cardiac Cycle Using Abdominal ECG and Doppler Ultrasound Signals from Fetal Hearts

AH Khandoker*, Y Kimura, M Palaniswami

The University of Melbourne
Melbourne, Australia

Congenital heart defects and fetal distress are the most common major causes of congenital abnormalities and fetal mortality. Fetal ECG and Doppler ultrasound signals provide clinically significant information concerning the physiological state of a fetus. In this study, we propose a novel non-invasive system to recognize the timings of fetal cardiac events on the basis of analysis of electrical (fetal ECG) and mechanical (Doppler ultrasound (DUS) signals) heart activity together. Simultaneous collection of DUS signals and the abdominal ECG (for signal reference), with recordings from 10 normal subjects (38-41 weeks of gestation) was made with an average length of around 10 minutes. Fetal ECG was extracted using a method consisting of the cancellation of the mother’s ECG and blind source separation with the reference signal. Doppler ultrasound data demonstrated with wide variations in the signal content observable on a beat-to-beat basis. Multiresolution wavelet analysis enabled the frequency contents of the Doppler signals to be linked to the opening and closing of the heart's valves (Aortic and mitral) and two wall motions (ventricular and atrial contraction). The time intervals from R peak of fetal ECG to opening and closing of aortic valve were found to be 99.16±22.07 (msec) and 222.70±21.83 (msec) respectively. The time intervals from R peak to opening and closing of mitral valve were found to be 125.97±65.01 (msec) and 37.84±18.23 (msec) respectively. These results suggest means by which the six events that contribute to the Doppler signal may be distinguished, providing information that should enable an improvement in calculating PR and QT intervals of fetal ECG for better recognizing the fetal arrhythmia, anoxia and heart failure.

(Abstract Control Number: 219)