To document the duration of fetal cardiac time intervals in uncomplicated singleton pregnancies using a novel non-invasive fetal electrocardiography (fECG) system and to demonstrate this technique's ...ability to acquire recordings in twin and triplet pregnancies.
Prospective cross sectional observational study.
Antenatal wards and clinics, day assessment unit and centre for fetal care at a tertiary referral hospital, London, UK.
Three hundred and four singleton and multiple pregnancies, 15–41 weeks of gestation.
Using electrodes sited on the maternal abdomen, a fetal electrocardiography (fECG) system was developed and tested on 304 pregnant women from 15 to 41 weeks of gestation, of whom 241 were uncomplicated singletons, 58 had twin and 5 had triplet pregnancies. The composite abdominal signals were stored on a laptop computer and the fECG derived off-line using a digital signal processing technique. For singletons, linear regression was used to analyse PR, QRS, QT and QTc intervals, and construct time-specific reference ranges.
Duration of fECG time intervals as a function of gestational age. Success of signal seperation in singleton, twin and triplet pregnancies.
For singletons, a total of 250 recordings was obtained from 241 individuals with a signal separation success rate of 85% (213/250). Success rates were significantly poorer between 27 and 36 weeks of gestation (2 × k χ
2,
P < 0.0001), with 84% (31/37) of separation failures occurring during this period. P, Q, R and S waves were seen in all cases where fetal signals were separated and were used to generate fECG time interval reference ranges. In 22% (43/199) of analysed cases, no T waves were identified, 63% (27/43) of whom were ≤24 weeks of gestation. In twins and triplets, separate fetal signals were obtained in 78% (91/116) and 93% (14/15), respectively; P, Q, R and S waves were evident in all averaged fECGs, while T waves were identified in 59% (54/91) and 57% (8/14).
This study provides reference ranges with gestation for fECG intervals derived non-invasively from normal singleton pregnancies and demonstrates the feasibility of obtaining complete fECG recordings non-invasively across a wide gestational range in pregnancies of all pluralities. The fECG time intervals described will enable the identification of pathological fECG recordings from high risk pregnancies where fECG abnormalities are suspected.
The outcome of cardiac disease diagnosed before birth is paradoxically worse than that diagnosed postnatally. In part, this is because fetal screening detects cases that are already showing failure ...of cardiac growth which are usually progressive with secondary damage to the myocardium, lungs and brain. Fetal valvuloplasty has been proposed for cases of critical aortic and pulmonary stenosis or atresia, and atrial septostomy for a restrictive oval foramen associated with aortic stenosis, hypoplastic left heart syndrome and transposition of the great arteries. The rationale for fetal therapy is to restore forward flow and reduce intraventricular pressure, thus improving coronary perfusion and minimizing ischaemic damage. Successful valvuloplasty has reduced systemic venous pressures and reversed fetal hydrops, thus prolonging pregnancy. It has resulted in improved ventricular growth in some cases and spontaneous opening of a closed oval foramen with normalization of pulmonary venous waveforms. These signs suggest better fetal cardiopulmonary development and improved surgical outcomes.
Objective:Approximately 2.8% of pregnancies are Ro/La antibody positive. 3–15% of fetuses develop complete heart block (CHB). First-degree atrioventricular heart block (1° AVB) is reported in a third ...of Ro/La fetuses but as most have a normal postnatal ECG this may reflect inadequacies of Doppler measurement techniques.Methods:Comparison was made between mechanical (mPR) and electrical (ePR) intervals obtained prospectively using Doppler and non-invasive fetal ECG (fECG) in 52 consecutive Ro/La pregnancies in 46 women carrying 54 fetuses in an observational study at a fetal medicine unit.121 mPR and 37 ePR intervals were recorded in 49 Ro/La fetuses. Five were referred with CHB and excluded. ePR was measured successfully in 35/37 (94%) and mPR was measured in all cases. 1° AVB was defined as PR >95% CI. Logistic regression predicted abnormal final fetal rhythm from first mPR or ePR.Results:The ePR model gave 66.7% sensitivity (6 of 8 final abnormal fetal rhythm cases were predicted correctly in fetuses >20 weeks) and 96.2% specificity. mPR gave 44.4% sensitivity (4 of 9 cases) and 88.5% specificity. Z scores for ePR (zPR) were calculated from 199 normal fetuses. The area under the receiver operator characteristic (ROC) curve was 0.88 (95% CI, 0.754 to 1.007). A cut-off of 1.65 gave a sensitivity of 87.5% and specificity of 95% for those with prolonged and normal ePR intervals, respectively.Conclusion:zPR is better than mPR at differentiating between normal and prolonged PR intervals, suggesting that fECG is the diagnostic tool of choice to investigate the natural history and therapy of conduction abnormalities in Ro/La pregnancies.
Advances in genetics and computing have contributed to a better understanding of the mechanisms underlying cardiovascular development, its programming and possible therapeutic manipulation. ...Pre-conceptual folate can reduce the prevalence of cardiac malformations and improvements in imaging allow us to detect congenital heart disease and assess function at earlier gestations. Three- and four-dimensional imaging may improve the surgeons' understanding of complex vascular malformations as well as permitting remote diagnosis. Treatment of fetal arrhythmias may be rationalised by fetal electrocardiography and magnetocardiography and by further defining the natural history of complete heart block and mechanisms of tachyarrhythmia. Tissue engineering and robotics may improve the surgical outcome for children by creating conduits with growth potential thus reducing the need for multiple surgical procedures. These technologies may permit successful fetal surgical procedures. Cross discipline collaboration has been key in enabling these advances which have changed the face of fetal cardiology.
In twin-twin transfusion syndrome (TTTS), the donor and recipient fetus are exposed to differing volume loads and show discordant intertwin vascular compliance in childhood despite identical ...genotype. We hypothesized that discordance is prevented by intrauterine endoscopic laser ablation of placental anastomoses, which abolishes intertwin transfusion. We tested this by examining pulse wave velocity (PWV) in brachial arteries of twin survivors of TTTS treated with and without laser therapy.
One hundred children (50 twin pairs, 27 with TTTS) were studied. Group 1 comprised 14 monochorionic (MC) twin pairs with TTTS treated symptomatically; group 2 comprised 13 MC twin pairs with TTTS treated by laser. The control groups comprised 12 MC twin pairs without TTTS (group 3) and 11 dichorionic twin pairs (group 4). Fetal cardiovascular data, predictive factors for, and duration of TTTS and cord blood were collected prospectively. We measured blood pressure and PWV photoplethysmographically at a median corrected postnatal age of 11 months (range, 1 week to 66 months). Both TTTS groups showed marked intertwin PWV discordance, unlike MCDA control subjects. The PWV discordance seen in laser treated twin pairs resembled that of dichorionic control subjects (heavier individual with higher PWV), whereas group 1 showed the opposite (negative) intertwin discordance (ANOVA F (1,45)=4.5, P=0.04). No significant differences in blood pressure or intrauterine growth were observed between TTTS groups.
Vascular programming is evident in monozygotic twins with intertwin transfusion and is altered but not abolished by intrauterine therapy to resemble that seen in dichorionic twins.
Twin-twin transfusion syndrome permits investigation of vascular programming independent of genetic influence. Arterial distensibiity was lower in the donor twin during infancy, implying the ...intrauterine vascular remodelling might result in raised cardiac afterload and could influence later cardiovascular health.
Abstract Pulmonary Atresia with intact septum can be diagnosed by echocardiography from early pregnancy where a spectrum of morphology can be recognised. Important tricuspid regurgitation is common ...and the right ventricle develops at supra-systemic pressures leading to progressive ventricular hypertrophy and mineralisation that can be seen on serial echocardiograms. This is likely to compromise later ventricular function and only about a third of children achieve an eventual two-ventricle circulation. Fetal valvuloplasty has been proposed as a potential therapy to open the pulmonary valve, reduce right ventricular pressure and improve the potential for normal myocardial development. There is no evidence yet, however, that fetal pulmonary valvuloplasty alters the growth of the pulmonary or tricuspid valves or influences the ventricular size to change the eventual designation, although theoretical benefits in quality of the myocardium may lead to improved outcomes.
Abstract Background Mechanical surrogates are used to assess fetal cardiac electrical activity. Aims To compare electrical PR interval measured using non-invasive fetal electrocardiography (fECG) ...with mechanical atrioventricular (AV) interval using Doppler. Study design and subjects Prospective study of 55 recordings made in 50 human fetuses. Those with structural heart defects, second degree or complete heart block were excluded. Outcome measures Mechanical AV interval was measured from the onset of mitral A wave to onset of aortic ejection. Electrical PR interval was measured from a coherent averaged signal obtained using non-invasive fECG recorded from the maternal abdomen. Wilcoxon signed rank test was used to compare both methods. Agreement between AV and PR intervals was assessed using linear regression and by Bland–Altman plots. Bland–Altman analysis assessed inter-observer and intra-observer variability. Results There was no significant difference in the heart rates of the 55 paired traces measured consecutively using both methods ( p < 0.35). AV interval was longer than PR (median range 116 96–169 vs. 102 75–143 ms; p < 0.001), with mean difference − 16.47 ms (95% Confidence Interval − 43.43, 10.44), reflecting the increased proportion of the cardiac cycle measured. Using fECG, PR inter-observer and intra-observer mean differences were 0.4 ms (CI − 7.29, 8.09) and 0.7 ms (CI − 3.22, 4.62) respectively. R values for inter and intra-observer studies were 0.95 and 0.99 respectively. Using Doppler methods, AV inter-observer and intra-observer mean differences were − 2.69 ms, (CI − 15.33, 9.95) and 0.92 ms, (CI − 9.41, 11.26) respectively. R values for AV measurements were 0.93 for inter-observer and 0.96 for intra-observer variation. Conclusions Non-invasive fECG is a robust tool to measure the PR interval with narrow limits of agreement.
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