OBJECTIVE: As fetal complete heart block with hydrops carries a poor prognosis, intrauterine pacing appears the most logical treatment. However, premature labor following hysterotomy remains a major obstacle to open procedures. Therefore, we developed a new lead for fetal pacing that avoids the need for intrauterine open surgical procedures. METHODS We successfully implanted a new T-bar-shaped lead into the myocardium of a fetus at 25 weeks gestation presenting with complete heart block (heart rate = 47 beats per minute), hydrops, and structural heart defects. The procedure was performed under ultrasound guidance, and the lead was introduced through the tip of a specially designed, 18G needle. The new lead was then connected to a Biotronik Actros pulse generator, which was implanted subcutaneously in the maternal abdominal wall. RESULTS: The stimulation resistance was 357 omega, and the sensed fetal R wave was 6.4 mV. The voltage strength-duration curve remained relatively constant at pulse widths > 0.6 msec. An echocardiogram on the first postoperative day revealed a mild pericardial effusion. The fetal heart rate was sTable , with low stimulation thresholds and no stimulation failures. No uterine contractions were observed during the postoperative period. However, the fetus died 36 hours after the procedure, probably due to cardiac tamponade. CONCLUSION: To our knowledge, this is the first documentation of voltage strength-duration curves for the acute myocardial stimulation threshold of a human fetus that survived 36 hours after intrauterine pacemaker implantation. This case emphasizes that percutaneous fetal pacing with the new lead is feasible and may minimize the chances of premature labor.
Cardiac surgical procedures; Heart block; Pacemaker artificial; Hydrops fetalis
