Utilisation of ultrasound Doppler effect for studying foetal cardiac activity

Preliminary studies for a possible use of Doppier Signals in the analysis of systolic time intervals of fetal heart

“…In fact, some of these techniques (M-mode display, filtration of DOPPLER Signals) provide data of speculative interest, while others (combined use of pulsed DOPPLER and E. C. G., Q/M display) are technically too complex to be of clinical use. Five DOPPLER Signals can be obtained for each cardiac cycle in the fetus and in the adult [3,9,12], In previous fetal studies [12] we integrated and rectified these irregulär biphasic Signals in t o five regulär waves. The ultrasonic technique we adopted is easy to perform and provides informative data.…”

“…In previous studies each foetal and adult cardiac cycle were seen to produce five DOPPLER signals [3,12]. The different phase of the cardiac cycle in which they appear could be identified with the simultaneous recording of parameters commonly used in cardiology (Fig.…”

“…By rectification (from biphasic to monophasic) and Integration, we have transformed these waves into more simplified signals with a more regulär shape [10]; the same process is used in the common cardiotocographs for the preliminary elaboration of the ultrasound (U. S.) signal of the foetal heart. Our work and similar researches carried out on the U. S. signal of the foetal, adult and canine heart [9,11,12,13] have shown that every cardiac cycle produces more than one signal. This has created some difficultes in setting up foetal cardiotacometry but was seen äs a possible, valuable source of information for foetal cardiac activity.…”

“…A 2.25 MHz probe with a power of 28 mW/cm 2 was used. The DOPPLER signal was rectified and integrated, s we have already described [12], by means of a BECKMAN coupleur n° 9852. We defined the cardiac area with a teleroentgenogram before scanning it with the ultrasound transducer.…”

“…In fact, the temporal relationship between the ECG and these U. S, waves suggested that they were the result of specific and different cardiac events [3,11,12].…”