Application of spatio-temporal filtering to fetal electrocardiogram enhancement.

In this paper we propose a new structure of the instrumentation for electrocardiographic fetal monitoring. We apply a single-channel approach to maternal electrocardiogram suppression in the recorded four abdominal bioelectric signals. Then we exploit spatial and temporal properties of the extracted four-channel fetal electrocardiogram to construct a new channel with higher signal-to-noise ratio. Finally, we perform detection of fetal QRS complexes. The proposed approach is investigated with the help of the constructed database of the maternal abdominal signals. During the detection tests, the spatio-temporal filtering allowed us to decrease significantly the number of the detection errors of different detectors applied. Moreover, we present visually that even if the fetal QRS complexes are buried in noise, the spatio-temporal filtering can produce the signal with the discernible ones.

Towards noise immune detection of fetal QRS complexes.

The noninvasive fetal electrocardiography is a source of more precise information on the fetal heart activity than the measurements based on Doppler ultrasound signals. However, the clinical diagnostic applications of this technique are limited by difficulty with successful detection of small amplitude fetal QRS complexes. In this study, we investigate the influence of different stages of fetal signals processing on the detection performance. The main propositions of the paper are: application of normalized matched filtering to fetal QRS complexes enhancement and a new approach to the final detection of the complexes. Compared to the classical detectors, the proposed new one allows a significant increase of the detection performance for signals of very different quality.

The maternal ECG suppression algorithm for efficient extraction of the fetal ECG from abdominal signal.

At present, noninvasive recording of abdominal fetal electrocardiogram and analysis of the fetal heart rate variability seems to be the most promising method to detect the fetal hypoxia. The main problem is to obtain a good quality fetal ECG, which is strongly distorted by maternal component of dominating energy. The paper presents the new method of maternal electrocardiogram recognition and suppression relying on determination of template maternal PQRST complex and its subtraction during consecutive maternal cardiac cycles. The efficiency of the developed method was evaluated and related to three other selected methods for maternal ECG suppression using dedicated coefficients created for this comparison.

Data management system for computer aided biophysical monitoring.

The Data Stream Management System designed to be applied in medical monitoring systems is presented. Such approach simplifies the structure of the monitoring system. Communication between management and monitoring systems is based on the formal query language. The developed theory and query language is adapted to specific requirements of the signal processing in biophysical monitoring systems.

Instrumentation for fetal cardiac performance analysis during the antepartum period.

Cardiotocography as a simultaneous recording of fetal heart rate (FHR) and uterine contraction activity is a basic method for evaluation of fetal condition. Continuous variability of the fetal heart rate is an indirect sign of adequate oxygenation of a fetus. Unfortunately, the reverse case is not always true, signs suggesting pathological changes can also appear in recording when the fetal is not at risk. The cardiotocography shall then be recognized as a more screening than diagnostic method. It will be interesting to develop a noninvasive method being complementary to routine cardiotocography. This method should allow the adequate prediction of a bad clinical outcome when the test is abnormal. The paper presents the system that makes possible cardiotocograms analysis in parallel with the assessment of additional parameters determined from comparison of mechanical and electrical fetal heart activity signals. The studies are aimed at development of set of parameters that are high correlated with fetal outcome.

Timing events in Doppler ultrasound signal of fetal heart activity.

Among various methods of monitoring fetal heart activity a Doppler ultrasound technique is the most often used. Complexity and variability of Doppler signal make difficult the precise measurement of timing dependences defining individual phases of cardiac cycle. Aim of the work was to carry out detailed comparative analysis of Doppler echo coming from movement of two different objects within fetal heart: valve and wall. Joint time frequency analysis were applied. Fetal monitor performed a role of input device in our measurement station based on LabView environment. Doppler signal was acquired from analog outputs with a help of dedicated data acquisition card. Average recording time in a group of 15 patients was 20 minutes. Analysis comprised determination and comparison of spectrograms and power density spectrums corresponding to individual phases of cardiac cycle.

Fetal monitoring based on bioelectrical signals from maternal abdomen

Conventional fetal monitoring to evaluate fetal state is based on ultrasound Doppler technique. A new approach proposed in this work relies on analysis of bioelectrical signals recorded from maternal abdominal...

Using of a simple method of maternal ECG processing for fetal heart rate determination

Signals of electrical activity being recorded from maternal abdominal surface contain more information than currently used mechanical heart activity measurement based on ultrasound signals...