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Analysis of experimental in vivo telemetric monitoring

      Objective

      To investigate the feasibility of telemetric fetal ECG recording via implantable mini-sensor and computerized T/QRS analysis in a fetal lamb model.

      Study design

      A 2 lead telemetric mini-ECG sensor (EA-F20; DSI®, Minnesota) was implanted subcutaneously in a fetal lamb at d119 (term = 147 d). Daily recordings were made using a Keithley A/D card for digitalisation and recording by a program developed with Testpoint®. Signal capture was done via the abdomen of the free ambulating ewe. We developed a program in Visual Basic® for digital signal processing and visual interface, determining automatically fetal heart rate (FHR) and T/QRSratio.

      Results

      Telemetric fetal ECG transmission and computerized T/QRS analysis were obtained daily for 11 d. On the last day an elevation in the ST-segment and bradycardia were present, suggesting fetal hypoxia. On d12 no fetal ECG signal could be obtained anymore and the lamb was stillborn two days later .

      Conclusion

      Telemetric fetal ECG monitoring with computerized T/QRS analysis is feasable. After further development it may be applied in fetal sugery or during labor allowing maternal mobilization.
      Figure thumbnail gr1
      Tabled 1Results
      d 1d 2d 5dd 7d 8d 11
      ST(T/QRS)0.360.240.250.230.260.220.47
      baseline FHR212177174185153152108