[Fetal phonocardiography with a novel approach]

The long-term recording of the fetal heart rate (FHR) variability is one of the most frequently used tools of routine fetal diagnostics which is usually carried out by the means of ultrasound cardiography. Frequent measurement of FHR is recommendable, however the cost of high quality ultrasound devices is unfortunately so high that this technology is not viable for low-cost devices used in the home-care sector. An alternative approach of FHR recording can be based on the fully non-invasive, passive acoustic recording, called phonocardiography. The evaluation of fetal phonocardiograms is complicated by various internal and external noise factors. The development of accurate and robust fetal phonocardiographs has been studied by biomedical researchers since long. This paper presents a novel two-channel phonocardiographic device and an advanced signal processing method, which provides a performance comparable to that of ultrasound cardiography. The proposed system offers an optimal trade-off between complexity and feasibility and it is viable in low-cost, stand-alone, battery-powered FHR monitoring devices. The developed system provided 83% accuracy compared to the simultaneously recorded reference ultrasound records.