title: Feasibility of in utero telemetric fetal ECG monitoring in a lamb model.
abstract: OBJECTIVE
  If fetal ECG (fECG) devices could be miniaturized sufficiently, one could consider their implantation at the time of fetal surgery to allow permanent monitoring of the fetus and timely intervention in the viable period. We set up an experiment to evaluate the feasibility of in utero direct fECG monitoring and telemetric transmission using a small implantable device in a lamb model.
  
  
  METHODS
  A 2-lead miniature ECG sensor (volume 1.9 cm(3); weight 3.9 g) was subcutaneously implanted in 2 fetal lambs at 122 days gestation (range 119-125; term 145 days). The ECG sensor can continuously register and transmit fECG. The signal is captured by an external receiving antenna taped to the maternal abdominal wall. We developed dedicated software running on a commercial laptop for on-line analysis of the transmitted fECG signal. This was a noninterventional study, i.e. daily readings of the fECG signal were done without clinical consequences to the observations.
  
  
  RESULTS
  fECG could be successfully registered, transmitted by telemetry and analyzed from the moment of implantation till term birth in one case (24 days). In the second case, unexplained in utero fetal death occurred 12 days after implantation. In this subject, agonal fECG changes were recorded.
  
  
  CONCLUSIONS
  An implanted miniature (<2 ml) ECG sensor can be used to retrieve, process and transmit continuously a qualitative fECG signal in third-trimester fetal lambs. The telemetric signal could be picked up by an external antenna located within a 20-cm range. In this experiment, this was achieved through taping the external receiver to the maternal abdomen. Any acquired signal could be transmitted to a commercially available laptop that could perform on-line analysis of the signal.
authors.affiliation: Department ESAT-MICAS, Faculty of Engineering, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Hermans
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Lewi
authors.forename: Jacques
authors.initials: J
authors.lastname: Jani
authors.forename: Frederik
authors.initials: F
authors.lastname: De Buck
authors.forename: Jan
authors.initials: J
authors.lastname: Deprest
authors.forename: Robert
authors.initials: R
authors.lastname: Puers
mesh_terms: D000818:Animals; D004562:Electrocardiography / Q000295:instrumentation; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D005323:Fetal Monitoring / Q000295:instrumentation / Q000379:methods*; D005333:Fetus / Q000601:surgery*; D005865:Gestational Age; D006340:Heart Rate, Fetal; D008904:Miniaturization; D011247:Pregnancy; D012756:Sheep; D012815:Signal Processing, Computer-Assisted; D012984:Software; D013686:Telemetry / Q000295:instrumentation