IMPROVED EQUIPMENT FOR ABDOMINAL FETAL ELECTROCARDIOGRAM RECORDING - DESCRIPTION AND CLINICAL-EVALUATION

Reliable computer-based equipment for transabdominal or indirect recor ding of fetal electrocardiogram (FECG) is described. The proposed equi pment allows a real-time displaying of the signals (fetal + maternal E CG) without averaging procedures and it does not require the employmen t of a shielded room; moreover, it is user-friendly to medical personn el. An elementary form of semi-automatic computation of the fetal hear t rate (FHR) was also implemented. The equipment simultaneously acquir es three signals from seven electrodes, six placed on the maternal abd omen following the three space axes, and one placed on the left leg as a indifferent electrode. The signals are magnified and analogically f iltered before undergoing digital finite impulse response (FIR) filter . Then the signals are displayed on the screen of a personal computer (PC). The PC also provides the possibility of storing the acquired sig nals for further analysis or elaborations. The quality of the recordin gs allows the analysis of both the rapid and slow electrical phenomena of the fetal heart, and it is not significantly influenced by the occ urrence at the same time of uterine contractions. The performance of t his method was assessed in 140 pregnant women with gestation periods o f 29-42 weeks. In 131 cases (93.6%) the fetal QRS complex was detected and the FHR was obtained. A reliable evaluation of P and QRS waves an d of ST interval, in spite of the interference of the maternal complex es, was possible in 102 cases (72.8%).