Objectives As postnatal identification of accelerated idioventricular rhythm (AIVR) relies on specific electrocardiographic patterns, prenatal diagnosis of this condition is challenging and its true incidence is unknown. The objectives of this study were to evaluate the performance of prenatal ultrasonography in identifying intrauterine cardiocirculatory events linked to specific electrocardiographic signs of postnatal AIVR, including left or right ventricular origin, and to assess the prenatal prognosis of this arrhythmia. Methods We reviewed Doppler tracings from the superior vena cava/ascending aorta (SVC/Ao), ductus venosus (DV), ductus arteriosus (DA) and aortic isthmus (AoI), as well as simultaneous M-mode recordings of septal and left ventricular wall motions of fetuses diagnosed with AIVR from January 2004 to December 2014. Results Three cases of AIVR were identified among 27 912 fetuses. SVC/Ao Doppler flow recordings revealed atrioventricular dissociation (ventricular rates within 20% of atrial rates) in all three fetuses and episodes of isorhythmic atrioventricular dissociation in one, while M-mode confirmed normal left ventricular shortening fraction in all cases. Fusion beats were observed on AoI tracing in one fetus, while simultaneous recordings of AoI and DA revealed signs of right bundle branch block in one case and left bundle branch block in the other two. On DV Doppler recordings, retrograde a-waves in the presence of simultaneous atrial and ventricular contractions were observed in all three fetuses, leading to an increase in central venous pressure in all and hydrops fetalis in two cases without evidence of ventricular dysfunction. Conclusions Echocardiographic criteria required for postnatal diagnosis of AIVR can be documented in utero using specific ultrasonographic approaches. During fetal life, AIVR may not be a benign entity. Hydrops fetalis is frequently associated with AIVR because of increase in central venous pressure related to simultaneous atrioventricular contractions; thus, the ultrasonographic investigation protocol of fetuses with unexplained hydrops fetalis should aim at ruling out AIVR and include Doppler flow recordings in SVC/Ao, DV, AoI, DA and umbilical vein. Copyright (C) 2016 ISUOG. Published by John Wiley & Sons Ltd.

To determine the factors responsible for the onset of the retrograde telesystolic flow normally observed at the level of the aortic isthmus (AoI) during the second half of gestation. Doppler recordings on normal fetuses aged 18 to 37 weeks of gestation were retrospectively selected in the database of the Fetal Cardiology Unit at CHU St-Justine. The following variables were measured: peak systolic velocities (PSV) and systolic nadir (Ns) of the AoI Doppler waveforms allowing calculation of the systolic index (ISI = Ns ÷ PSV); the total duration of systole (Ttotal) and the duration of the telesystolic retrograde flow (Tretro) for the calculation of the reverse isthmic telesystolic index (RITSI = Tretro ÷ Ttotal). The pulsality index of the umbilical artery (UAPI) and the ductus venosus (DVPI) are routinely measured in our Unit. Descriptive and correlational analyses have been performed. A total of 226 fetuses are included in this study. The systolic AoI flow is entirely antegrade from 18 to 28 weeks of gestation. The RTSF in the AoI appears at the gestational age of 29 weeks and shows a linear increase up to 37 w of gestation (F = 21.92, p < 0.001); ISI and RITSI are inversely correlated (r = −0.79, p < 0.001). No correlation was found between ISI nor RITSI and the PIs in UA and DV. The onset of RTSF occurs when the PIs in the UA and the DV are relatively stable explaining the lack of correlation observed. On the other hand, the appearance of the RTSF corresponds clearly to the start of the fall of the pulsatility index in the MCA as described by Mari. This physiological decline in the MCA resistances during the third trimester is known to cause an increase in superior vena cava flow returning to the right ventricle (RV) and a secondary rise in its stroke volume. Since the RV ejection has a retrograde effect on the flow in the AoI, the physiological change observed in the cerebral vascular network seems to be the principal factor determining the onset of the RTSF.

To assess the prognostic value of the systolic flow through the aortic isthmus, reflecting the relative performances of the left (LV) and right (RV) ventricles in the recipient twin of monochorionic pregnancies complicated by Twin–twin transfusion syndrome (TTTS) treated by laser coagulation. Fetal echocardiography and outcome data of consecutive cases of TTTS treated by laser photocoagulation were retrospectively reviewed. Hemodynamic and cardiac function parameters were collected pre and post treatment with photocoagulation of placental vascular anastomoses. The isthmic systolic index (ISI) was calculated by dividing the end-systolic velocity by the peak systolic velocity, before and after treatment. Results were compared using Kruskal-Wallis and Mann–Whitney statistical tests. Between February 2006 and January 2015, 105 laser coagulations were performed. Quintero staging was divided between stage 1 (12%), 2 (40%), 3 (46%) and 4 (2%). Survival rates in the entire cohort were 17%, 22% and 61% for zero, one or two twins respectively. At least one twin was delivered alive in 83% of the pregnancies. The neonatal suvival rate was 72% for the recipient twin. Due to the retrospective nature of this study, ISI values were available for 43 recipients pre and 33 post laser. Before laser, the median recipient ISI was 0.19 (range −0.23; 0.36) before laser and 0.18 (range −0.43; 0.32) after laser. The recipient's ISI before laser was related to the occurrence of intrauterine fetal demise (p = 0.047) and survival at birth (p = 0.058). We found significant prognostic value of preoperative recipient ISI in TTTS treated by laser photocoagulation.

To assess the impact of changes in systemic venous returns (decreased inferior vena cava and relative increase in superior vena cava flows) on respective ventricular performances and O2 transport to the brain. In this prospective multicenter study, the aortic Isthmic Systolic Index (ISI = systolic nadir divided by the peak velocity of the waveform) and the Isthmic Time Systolic Index (ITSI = duration of systolic reverse flow divided by the total time of systolic ejection) were measured weekly in a cohort of growth restricted fetuses and compared to a population of normals. Pulsatility indices of the umbilical (UPI) and middle cerebral arteries (MCAPI) were also calculated. Data were analyzed by ANOVA for mean comparison and partial correlations, corrected for gestational age using SPSS 20.0. Sixty-two (62) IUGR fetuses between 24 and 37 weeks of gestation were compared to a population of normals, matched for gestational age. The systolic nadir of the AoI started to be retrograde at 26w in the IUGR group, compared to 31w in the normals. From 29w, the ISI became significantly lower in the IUGR group (F = 9.61, p = 0.021); this difference remained significant up to 32w. The ITSI was significantly correlated to the MCAPI (r = −0.36, p = 0.008). With the appearance of a reverse flow in the isthmus of IUGR fetuses, the brain is partly perfused by poorly oxygenated red cells turning in circle, both in systole and diastole. From the aortic isthmus towards aortic arch, brain, superior vena cava, right atrium and ventricle, ductus arteriosus and back to the isthmus, without the benefit of passing through the placenta. The relation between this “isthmic-brain hypoxic circle” and the incidence of abnormal post-natal neurodevelopmental sequellae deserves further investigations. This investigation (Placental Insufficiency and Aortic isthmus flow, The PIAF study) was supported by a research grant from the Canadian Institute for Health Research (CIHR); grant#MOP-97986.

To test the hypothesis that the anacrotic notch (AN) observed in a preliminary study on the aortic isthmus flow waveforms (AoI-FWF) of fetuses with aortic stenosis (AoS) may reflect opposite influences of right and left ventricular ejections on blood flow direction through fetal AoI. This is an observational retrospective study on fetuses with isolated valvular AoS.Time to peak velocities (TPV) of FWFs above the aortic(Ao) and pulmonary)PA) valves, and time to the AN on the AoI were measured and compared. 11 fetuses were included: 3 bicuspid Aov, 2 mild, 3 moderate and 3 with severe AoS. Seven presented a distinct AN in the AoI-FVWF (Fig.), a finding that has never been described previously. TPVs above the Ao (median: 0.055 sec. ± 0.035 to 0.075) was greater than those above the PA (0.040, ± 0.020 to 0.050). The times to the AN ( 0.04, ± 0.03 to 0.05) were similar to the values for TPV above the PA and correlated negatively with the severity of the AoS. Supporting information can be found in the online version of this abstract Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

ABSTRACTObjectiveLeft ventricular ejection causes forward flow in the fetal aortic isthmus while the right ventricle has a retrograde influence. The aim of this study was to create reference values for an isthmic systolic index (ISI) reflecting the changing influence of right and left ventricular performance on Doppler flow velocity waveforms of the aortic isthmus throughout normal pregnancy.MethodsDoppler recordings of 260 normal fetuses with a gestational age of 18–37 weeks were reviewed. Peak systolic velocity (PSV) and end‐systolic velocity (or systolic nadir; Ns) were measured on all aortic isthmus waveforms. An ISI was derived from the ratio Ns/PSV. Left and right ventricular outputs were also calculated.ResultsUp to 22–23 weeks' gestation, the mean ISI is stable at around 0.2. At about 28 weeks, a brief end‐systolic deceleration wave is observed on the aortic isthmus waveforms, progressing steadily with gestation and causing a fall of ISI towards a mean value of zero between 30 and 31 weeks. This trend continues thereafter and a mean value of –0.4 was observed at the end of pregnancy. An inverse correlation was found between right ventricular output and Ns (r = –0.334, P = 0.001). Simultaneous recordings of the isthmus and the ductus arteriosus Doppler waveforms demonstrated that the primary cause of the end‐systolic deceleration and ultimate reversal of flow at the isthmus is the increasingly dominant flow from the right ventricle.ConclusionThe transitional changes of the respective right and left ventricular outputs throughout pregnancy are well profiled by the ISI. This index highlights the physiological increase in fetal right ventricle flow preponderance as pregnancy progresses. Alteration of the ISI profile could be expected in clinical conditions associated with unbalanced alteration of the fetal ventricular outputs. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd

To evaluate changes in systolic flow through the aortic isthmus reflecting the relative performances of the left (LV) and right (RV) ventricles in monochorionic pregnancies complicated by twin–twin transfusion syndrome (TTTS). To compare the values of the isthmic systolic index (ISI, nadir of end-systolic velocity / peak systolic velocity) before and after treatment with laser photocoagulation, and between donor and recipient twin. To assess the prognostic value of the ISI to predict the intra-uterine fetal demise (IUFD) of each twin. Fetal echocardiography and outcome data of 90 cases of TTTS treated by laser photocoagulation between 2007 and 2013 were retrospectively reviewed. The aortic isthmus flow was measured in the sagittal plane in both donor and recipient twin, before and after laser treatment of TTTS. The Doppler measures of the aortic isthmus were available in 29 twin pregnancies pre laser and 25 post laser. Statistics used the Fisher exact test, the Mann-Whitney U-test or the Wilcoxon test. Before laser, the median ISI was 0.17 [interquartile range 0.13–0.25] in the donor and 0.19 [0.15–0.23] in the recipient. After laser, the median ISI was 0.19 [0.14–0.26] in the donor and 0.19 [0.15–0.24] in the recipient (all p > 0.05). Pre and post laser ISI values were similar to those of healthy fetuses at the same gestational age. Amongst the 90 cases, IUFD occurred in 11 donors and 14 recipients. Values of the ISI did not differ between cases of IUFD and controls, both in the donor and the recipient, before and after laser photocoagulation. The sole predictor of donor IUFD was a preoperative absent or reversed end-diastolic (ARED) flow in the donor (p = 0.03), and the sole predictor of recipient IUFD was a post-operative ARED flow in the recipient (p = 0.02). We found no significant impairment in the LV and RV relative performances in TTTS treated by laser photocoagulation. ARED flow in the umbilical artery was associated with IUFD after laser treatment.

To characterize the prenatal circulatory dynamics of simple transposition of the great arteries (TGA). A study group of 36 fetuses with TGA was compared to 77 normal fetuses (controls) matched for gestational age. In all cases, Doppler recordings and diameter measurements were available above the aortic and pulmonary valves as well into the ductus arteriosus (DA). Blood flow through the lungs (flow above the pulmonary valve minus net flow through the DA) was calculated. In the TGA group, flow through the foramen ovale (FO) was assumed to be equal to the net flow through the DA. Second (T2) and third (T3) trimester data were analyzed separately. The mean gestational ages of the control and TGA groups were 24.3 ± 4 and 23.4 ± 2.7 respectively for T2, 31 ± 3.7 and 33 ± 2.6 respectively for T3. Table 1 summarizes the actual cardio-circulatory data observed in the two groups. Contrarily to the control group, the TGA shows a preponderant LV throughout T2 and T3, a higher lungs flow in T2, a lower QRV and an elevated QFO in T3. The distribution of CCO of fetuses with TGA is quite different from normals. The clinical implications of these specific features, especially at the level of the lungs, deserve further investigations.