Hans-Joachim Seewald

Signal Analysis of Auditory Evoked Cortical Fields in Fetal Magnetoencephalography

Magnetoencephalography (MEG) using auditory evoked cortical fields (AEF) is an absolutely non-invasive method of passive measurement which utilizes magnetic fields caused by specific cortical activity. By applying the exceptionally sensitive SQUID technology to record these fields of dipolar configuration produced by the fetal brain, MEG as an investigational tool could provide new insights into the development of the human brain in utero. The major constraint to this application is a very low signal-to-noise ratio (SNR) that has to be attributed to a variety of factors including the magnetic signals generated by the fetal and maternal hearts which inevitably obscure a straightforward signal analysis. By applying a new algorithm of specific heart artefact reduction based on the relative regularity of the heart signals, we were able to increase the chance of extracting a fetal AEF from the raw data by the means of averaging techniques and principle component analysis. Results from 27 pregnant, healthy women (third trimester of their uncomplicated pregnancy) indicate an improved detection rate and the reproducibility of the fetal MEG. We evaluate and discuss a-priori criteria for signal analyses which will enable us to systematically analyze additional limiting factors, to further enhance the efficiency of this method and to promote the assessment of its possible clinical value in the future.

MRI of the pelvic ring joints postpartum: Normal and pathological findings

To assess the joints of the pelvic ring postpartum and to discern normal postpartum findings and pathologic lesions using MRI.

Maternal and fetal side effects of tocolysis using transdermal nitroglycerin or intravenous fenoterol combined with magnesium sulfate

OBJECTIVE To compare the maternal and fetal side effects of transdermal nitroglycerin and intravenous fenoterol combined with magnesium sulfate in a prospective randomised study. STUDY DESIGN Fifty pregnant women between 27 and 35 weeks of gestation with preterm labour were treated with either nitroglycerin (0.4-0.8 mg/h) or fenoterol (60 - 120 microg/h). Outcome parameters were (1) the effects on fetal and maternal heart frequency (FHF/MHF) and blood pressure, and (2) subjective experiences of adverse effects assessed by utilising a questionnaire. RESULTS In the fenoterol group, elevated mean MHF, FHF and systolic blood pressure were recorded compared to nitroglycerin. Fewer maternal side effects were reported in the nitroglycerin group. Palpitations (82%), tremor (68%) and restlessness (64%) were most common in the fenoterol group (two drop-outs), whereas nitroglycerin caused headaches in 71% of the cases (four drop-outs). CONCLUSION Transdermal nitroglycerin appears to be a safe therapy for the mother and fetus and is a promising new option for the treatment of preterm labour.

Nitric oxide donors: effects on fetoplacental blood flow

OBJECTIVE To investigate fetal and uteroplacental blood flow after transdermal administration of glyceroltrinitrate (GTN) in pregnancies at risk for preterm delivery. STUDY DESIGN Twenty-five pregnant women who received GTN patches (Nitroderm TTS 10) with a dosage of 0.8 mg/h, because of risk for preterm delivery, were included in the prospective study. Doppler measurements (resistance index, RI) of the umbilical artery (UA), the middle cerebral artery (MCA) and the uterine arteries of the placental (UTA-P) and the non-placental (UTA-NP) side, with calculation of the mean-RI (UTA-mean), were performed before and after 24, 48 and 72 h of the 1st GTN application. Wilcoxon test and Holm correction were used for statistical analysis. RESULTS The initial RI values were in the normal range. Significant decreases of the RI of UTA-NP ( P = 0.02 ) and UTA-mean ( P = 0.03) were observed 24h after GTN application. The other RI values did not show significant changes. CONCLUSION Transdermal nitroglycerine used for the treatment of preterm labour does only reduce uterine vascular impedance at the non-placental side with primary higher resistance. It does not affect fetal perfusion and uterine perfusion at the placental side with normal blood flow resistance.

Fetal magnetoencephalography: a non-invasive method for the assessment of fetal neuronal maturation

Objective To assess the maturation of auditory evoked cortical responses in the human fetus using fetal magnetoencephalography.

Fetal magnetocardiography in the investigation of congenital heart defects

OBJECTIVES To investigate the changes of the fetal magnetocardiography (FMCG), a new noninvasive diagnostic tool in the analysis of electrophysiologic changes of the heart, in cases of congenital heart defect (CHD). METHODS The FMCG was analysed and compared to the postnatal ECG in eight cases of CHD: atrial septal defect ASDII (three cases), a combination of atrioventricular-septal-defect (AVSD) and Tetralogy of Fallot (TOF) (one case ), complete transposition of great arteries (d-TGA) (two cases), coarctation of aorta (COA) (one case), stenosis of the pulmonary artery (PS) and right ventricular hypoplasia (one case). RESULTS (1) The following FMCG changes were observed: a split R-wave (AVSD/TOF, ASDII), prolongation of QRS complex (COA, PS). (2) The notch of the R-wave could not be observed in the newborn with AVSD/TOF. (3) Neither the fetal FMCG nor the neonatal ECG revealed any changes in the cases of d-TGA. (4) All other neonatal ECGs were corresponding to the FMCG. CONCLUSIONS The FMCG can unearth changes of the cardiac electrophysiologic activity in the case of CHD. The method provides additional information concerning the effect of a CHD on the cardiac conductory system. As in the neonate, the FMCG changes do not reflect the severity of the CHD. FMCG cannot serve as a primary diagnostic tool in the case of CHD as compared to echocardiography.

Prenatal diagnosis of the Wolf‐Parkinson‐White‐syndrome by fetal magnetocardiography

Sir, Blondel et al. have demonstrated the apparent effect on rates of preterm and postterm birth rates when changing from menstrual to early ultrasound dating. Although confidence intervals for the differences in the results of the two methods is not provided in this paper, the large database of over 44,000 is likely to make the confidence intervals very narrow. The authors state that the ultrasound dating was based on the fetal biparietal diameter usually carried out between 16 and 18 weeks but do not tell us which formula was used. No doubt this could have varied between the two centres and over the time of the study. Two commonly used published formulae (Hadlock et al. and Altman and Chitty) differ by 3.5 days for a biparietal diameter measurement of 41 mm (approximately equivalent to 18 weeks of gestation). We have carried out an audit of ultrasound dating in a singleton pregnancy population restricted to those pregnancies with spontaneous onset of labour and delivery of a live healthy infant. In this audit, dating was also based on biparietal diameter, usually between 18 and 20 weeks. The audit has shown that the preterm rate can vary between 1.8% and 3.7% according to the two formulae referred above. This represents a 51% difference. This is another factor that needs to be taken into account when interpreting epidemiological reports on the changes in preterm and postterm births and we recommend that authors publish which dating formula has been used.

Lessons from reproductive immunology for other fields of immunology and clinical approaches

Reproduction is indispensable to evolution and, thus, life. Nonetheless, it overcomes common rules known to established life. Immunology of reproduction, and especially the tolerance of two genetically distinct organisms and their fruitful symbiosis, is one of the most imposing paradox of life. Mechanisms, which are physiologically used for induction of said tolerance, are frequently abused by pathogens or tumors intending to escape the hosts immune response. Understanding the regulation of immune responses in pregnancy and the invasion of allogeneic fetus-derived trophoblast cells into the decidua may lead to new therapeutic concepts. In transplantation, knowledge concerning local physiological immunotolerance may be useful for the development of new therapies, which do not require a general immune suppression of the patient. In immunological disorders, such as autoimmune diseases or allergies, immune deviations occur which are either prevented during pregnancy or have parallels to pregnancy. Vice versa, lessons from other fields of immunology may also offer new notions for the comprehension of reproductive immunology and may lead to new therapies for the treatment of pregnancy-related problems.

Die extralobare Sequestration einer fetalen Lunge

Summary The extralobar sequestration is a rare pulmonary malformation. An accurate antenatal evaluation is required for a timely therapy and subsequently a good outcome. Here an unusual case of extralobar pulmonary sequestration in a male human fetus is reported. Antenatal ultrasound at 28th week of gestation has revealed a fetal hydrothorax in coexistence with pulmonary hypoplasia and an isolated pulmonary structure. Authors summarise their postnatal findings with special reference to the pathogenesis of an accessory lung. The aim of this report is to define the association of clinical, gross, and histological features of this rare congential malformation in order to improve the antenatal diagnosis. This case indicates that an extralobar pulmonary sequester is not connected to the tracheobronchial tree, and that the arterial as well as the venous blood supply is realised by aberrant systemic vessels. Moreover, histologically revealed dilatations of the normally differentiated terminal airways within the sequester suggest that hyperechogenity can not be a reliable diagnostic criterion. For the accurate assessment of a pulmonary sequestration a detailed antenatal evaluation of both, the arterial and the venous blood supply is essential.