Fetal Cardiac Timing Events Estimation from Doppler Ultrasound Signal Cepstrum Analysis

Early diagnosis of the cardiac abnormalities during the pregnancy may reduce the risk of perinatal morbidity and mortality. Doppler ultrasound signals (DUS), which is commonly used for monitoring the fetal heart rate, can also be used for identifying the event timings of fetal cardiac valve motions. In this paper, we propose a non-invasive technique to identify the fetal cardiac timing events on the basis of analysis of fetal DUS (10 normal subjects and 6 abnormal subjects). We proposed using the cepstrum analysis which enabled the frequency contents of the Doppler signals to be linked to the opening and closing of the heart's valves (Aortic and mitral). The time intervals from R peak of fetal ECG to opening and closing of aortic valve were found to be 123.83 +/- 7.41 (msec) and 222.85 +/- 21.21 (msec), respectively. The time intervals from R peak to opening and closing of mitral valve were found to be 295.03 +/- 13.62 (msec) and 31.97 +/- 3.34 (msec), respectively. This feature is essential for diagnosing the disorder of cardiac rhythm, extremely used for diagnosis of heart abnormalities.