Non-invasive investigation of heart rate variability in growth restricted and normal fetuses using magnetocardiography

Abstract

RESTRICTED AND NORMAL FETUSES USING MAGNETOCARDIOGRAPHY JOSHUA CAMPBELL, HARI ESWARAN, HUBERT PREISSL, JAMES WILSON, PAM MURPHY, CURTIS LOWERY JR, University of Arkansas, Applied Science, Little Rock, Arkansas, University of Arkansas for Medical Sciences, Obstetrics and Gynecology, Little Rock, Arkansas, University of Arkansas for Medical Sciences, Ob/Gyn, Little Rock, Arkansas, University of Arkansas at Little Rock, Graduate Institute of Technology, Little Rock, Arkansas, University of Arkansas for Medical Sciences, Little Rock, Arkansas OBJECTIVE: To investigate differences in common heart rate variability parameters in normal and intra-uterine growth restricted (IUGR) fetuses using non-invasively recorded fetal magnetocardiograms. STUDY DESIGN: We recorded fetal magnetocardiograms (fMCG) in 18 IUGR fetuses and 83 healthy fetuses with gestational ages ranging from 25 to 38 weeks at UAMS SARA (Squid Array for Reproductive Assessment) fetal cardiac research center. The fMCG traces are analogous to a surface ECG (with an orthogonal vector) and provide more information than can be obtained with other noninvasive techniques. Post-processing was performed to attenuate the maternal cardiographic signals. After attenuation of the maternal cardiographic signals, the fetal RR intervals were acquired using a peak detection algorithm. The heart rate of all fetuses was calculated from the RR intervals, and various heart rate variability (HRV) parameters were calculated. The Mann-Whitney U Test was implemented to compare differences between the healthy fetuses and the IUGR fetuses. Statistical significance was defined by a P ! .05. RESULTS: Calculation of the heart rate and HRV parameters was successful for all healthy and IUGR fetuses. Using the HRV parameters calculated from the heart rate of the healthy and IUGR fetuses, significant differences between the groups were found in the maximum heart rate(P ! .005), standard deviation (P ! .001), and approximate entropy (ApEN) P ! .001). CONCLUSION: FMCG has proven to be a rapid, safe, non-invasive, and reliable technique for monitoring fetal cardiac function in healthy and IUGR fetuses. The findings presented support the fact that fetal HRV parameters can be used as indicator of fetal development as demonstrated by the significant differences between the various HRV parameters. 604 ELECTIVE CESAREAN DELIVERY IS INEFFECTIVE IN PROTECTING AGAINST IN-UTERO MECONIUM EXPOSURE OF FETAL MYELOMENINGOCELE CARL ROSE, JOSEPHINE WYATT-ASHMEAD, ANDREW PARENT, JAMES BOFILL, ALEXANDRA ASHMEAD, JOHN MORRISON, University of Mississippi Medical Center, Obstetrics & Gynecology, Jackson, Mississippi, University of Mississippi Medical Center, Pathology, Jackson, California, University of Mississippi Medical Center, Neurosurgery, Jackson, Mississippi, University of Mississippi Medical Center, Jackson, Mississippi OBJECTIVE: To determine if elective cesarean section following confirmation of fetal lung maturity but prior to onset of labor prevents in-utero meconium exposure of neural tissue in parturients with fetal myelomeningocele. STUDY DESIGN: In this retrospective case series 32 (17 male/15 female) with prenatally-diagnosed myelomeningocele underwent elective cesarean birth over a 4.5 year period. The mean EGA was 37.2 weeks and delivery followed confirmation of fetal lung maturity. All myelomeningoceles were repaired promptly (2.4 days) and the sacs were sent for pathologic examination. Amniotic membranes were also examined for evidence of microscopic meconium and intrauterine infection. Additionally, 23 placentas underwent histopathologic gross and microscopic examination. RESULTS: Gross meconium staining was noted in 3 cases. Meconium staining was detected microscopically in 32/32 (100%) of amniotic membrane samples and all (23/23) placental specimens demonstrated meconium histiocytosis while features of acute infection were noted in only 3/23 (13%). CONCLUSION: Fetuses with myelomeningoceles typically have intrinsically defective gastrointestinal function and are likely to pass meconium in-utero remote from term. Unfortunately, elective cesarean delivery prior to labor does not protect against exposure to potentially toxic meconium. Antenatal surgical repair could prove effective at reducing or mitigating destructive effects of meconium on open neural tissue.