Background-Untreated isolated fetal complete atrioventricular block (CAVB) has a significant mortality rate. A standardized treatment approach, including maternal dexamethasone at CAVB diagnosis and ␤-stimulation for fetal heart rates Ͻ55 bpm, has been used at our institutions since 1997. The study presents the impact of this approach. Methods and Results-Thirty-seven consecutive cases of fetal CAVB since 1990 were studied. Mean age at diagnosis was 25.6Ϯ5.2 gestational weeks. In 33 patients (92%), CAVB was associated with maternal anti-Ro/La autoantibodies. Patients were separated into those diagnosed between 1990 and 1996 (group 1; nϭ16) and those diagnosed between 1997 and 2003 (group 2; nϭ21). The 2 study groups were comparable in the clinical presentation at CAVB diagnosis but did differ in prenatal management (treated patients: group 1, 4/16; group 2, 18/21; PϽ0.0001). Overall, 22 fetuses were treated, 21 with dexamethasone and 9 with ␤-stimulation for a mean of 7.5Ϯ4.5 weeks. Live-birth and 1-year survival rates of group 1 were 80% and 47%, and these improved to 95% for group 2 patients (PϽ0.01). The 21 patients treated with dexamethasone had a 1-year survival rate of 90%, compared with 46% without glucocorticoid therapy (PϽ0.02). Immune-mediated conditions (myocarditis, hepatitis, cardiomyopathy) resulting in postnatal death or heart transplantation were significantly more common in untreated anti-Ro/La antibody-associated pregnancies compared with patients treated with steroids (0/18 versus 4/9 live births; Pϭ0.007). Conclusions-A standardized treatment approach, including transplacental fetal administration of dexamethasone and ␤-stimulation at heart rates Ͻ55 bpm, reduced the morbidity and improved the outcome of isolated fetal CAVB.

Ductus arteriosus aneurysm likely develops in the third trimester perhaps due to abnormal intimal cushion formation or elastin expression. Although it can be associated with syndromes and severe complications, many affected infants have a benign course. Given the potential for development of other cardiac lesions associated with connective tissue disease, follow-up is warranted.

An undisputed feature of fetal circulatory dynamics is that the two ventricular pumps perfuse the same systemic circulation in a parallel fashion. Under normal conditions, the blood ejected by the right ventricle (RV) perfuses the subdiaphragmatic organs and carcass, with approximately 10-15% going into the pulmonary circulation, while the cephalic part of the fetus receives blood exclusively from the left ventricle (LV) 1,2 . Another generally accepted characteristic of the fetal circulation is the presence of intracardiac and extracardiac shunts; among the latter is the ductus arteriosus (DA). Although the fetal DA is actually part of the normal vascular outlet of the RV forming 'the pulmonary arch' with the main pulmonary artery (MPA) and descending thoracic aorta (DAo), its recognition as a vascular shunt has never been an issue for physiologists and perinatologists. Yet, a shunt, as defined in an electrical circuit, joins two points of the network and 'serves to divert part of the current' 3 . In postnatal life, where the ventricles are disposed in series, a patent DA does indeed divert blood from either the systemic or the pulmonary circulation, depending on the downstream impedances of the two circulatory systems. In fetal life, if blood flow going through the pulmonary arch down into the DAo had to be considered as a right-to-left shunt taking blood away from the lungs, then the two ventricles would have to be regarded as disposed in series as in postnatal life; the classical description of the parallel ventricular arrangement would then become irrational. The concept of a fetal circulation based on two circulatory systems arranged in parallel fashion (a concept which is fully justified) is incompatible with the identification of the DA as a shunt. In utero, the arterial vascular segment that conforms to the definition of, and behaves like, a shunt is the aortic isthmus. Indeed, the isthmus, located between the origin of the left subclavian artery and the aortic end of the DA, establishes communication between the two arterial outlets that perfuse in parallel the upper and lower body of the fetus (Figure 1a). This logical approach bears not only physiological significances but could have many clinical implications, especially with the advent of Doppler ultrasound in fetal monitoring. PHYSIOLOGICAL CONSIDERATIONS Normal isthmic flow patternsDue to the disposition of the two arterial circuits on each side of the aortic isthmus, blood ejected by the fetal LV and RV has opposite effects on the direction of flow through the isthmus. Left ventricular stroke volume will cause forward flow while right ventricular ejection will have the opposite effect (Figure 1b). The final systolic pattern of isthmic flow will be determined by the relative contributions of left and right ventricular stroke volumes as well as the balance between vascular impedances of the upper and lower body.In diastole (Figure 1c), when the two semilunar valves are closed, the direction of isthmic blood flow will be influenced only by the two ...

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Background-In the twin-to-twin transfusion syndrome (TTTS), pressure rather than volume overload is increasingly considered as a key factor in the pathogenesis of the cardiomyopathy of the recipient twin. If this is the case, cardiac dysfunction should be among the first signs observed with TTTS. The objective of this study was to determine whether intertwin differences in myocardial function are modified early in the course of TTTS and whether they can help to differentiate this condition from intrauterine growth restriction (IUGR). Methods and Results-Eight variables were analyzed on the first fetal echocardiography on 21 pairs of twins with TTTS and 11 with IUGR. No difference was found between the 2 groups for the cardiothoracic ratio, pulsatility indices in the umbilical and middle cerebral arteries, and peak velocity of the middle cerebral artery. Significant difference was found for ventricular septal thickness, but with no association with the conditions under study. With TTTS, left ventricular shortening fraction was consistently greater in the donor twins, and myocardial performance indices (MPIs) were elevated in the recipient twins. This increase in MPI was caused by a lengthening of the isovolumic periods compared with those of the donor twin: left ventricular and right ventricular isovolumic periods 0.105Ϯ0.047 and 0.097Ϯ0.026 seconds, respectively, for the recipient twins versus 0.0561Ϯ0.46 and 0.065Ϯ0.03 seconds, respectively, for the donor twins (PϽ0.001). These changes in the isovolumic periods were mainly due to significant prolongation of isovolumic relaxation times. A change in left ventricular MPI Ն0.09 combined with a change in right ventricular MPI Ն0.05 would identify a TTTS with a sensitivity of 75% and a false-positive rate of 9%. Conclusions-The observed diastolic function impairment goes along with the pressure-overload pathogenic concept proposed in TTTS. Assessment of intertwin difference in MPI is a valuable tool for early differential diagnosis between TTTS and isolated IUGR.

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We intend to review our experience with the investigation and management of foetal arrhythmia on the basis of superior vena cava/ascending aorta (SVC/AA) Doppler flow velocity recordings. Irregular rhythms n = 307. Premature atrial and ventricular contractions were easily identified and generally self-limited in time. Sustained bradycardia n = 19. Four had sinus bradycardia, six presented with blocked atrial bigeminism, three showed 2:1, and five had a complete atrio-ventricular (AV) block. Another foetus that presented with first-degree AV block developed a Luciani-Wenckebach phenomenon 1 week later. These different types of bradycardia were all identified on SVC/AA Doppler recordings. Tachyarrhythmia n = 30. Five types of tachyarrhythmia were observed: Type I: Short ventriculo-atrial (VA) tachycardia (VA < AV), n = 11. Ten foetuses of this group presented a distinctive Doppler flow velocity pattern characterised by 1:1 AV conduction and a tall atrial wave ('a' wave) superimposed on the aortic ejection wave. They were considered to have re-entrant tachycardia through a fast-conducting AV accessory pathway; all 10 responded to digoxin therapy. The eleventh foetus with short VA tachycardia had atrial ectopic tachycardia with AV node dysfunction; he was treated successfully with sotalol. Type II: Long VA tachycardia (VA > AV): n = 8. In seven cases, an 'a' wave of normal amplitude with normal AV time interval could be clearly identified in front of the aortic ejection wave: one foetus in this group was considered to be in sinus tachycardia based on the variability of its heart rate; in another, sudden onset of tachycardia triggered by extrasystoles led to the possibility of permanent junctional reciprocating tachycardia (PJRT). The five other foetuses had atrial ectopic tachycardia. The last foetus presented with AV and VA intervals of the same duration and a heart rate of 210 beats/min; he did not respond either to digoxin or to sotalol, and was found after birth to have PJRT. The drug of first choice in this group was sotalol. Type III: Simultaneous onset of atrial and ventricular contractions: n = 3. These foetuses were classified as junctional ectopic tachycardia. Two responded to amiodarone. The other foetus converted spontaneously to sinus rhythm. Type IV: Flutter: n = 7. All presented with 2:1 AV relationship except one who had a variable block. Digoxin was prescribed as a first choice associated with sotalol in three cases. Conversion to sinus rhythm was documented in all; however, one hydropic foetus with advanced cardiomyopathy died one day after birth. Type V: Ventricular tachycardia: n = 1. This 30-week foetus presented alternance of AV dissociation (atrial rate: 130, ventricular rate: 170 beats/min) and atrial capture (ventricular rate of 138 beats/min). The arrhythmia responded well to propanol, and no recurrence was recorded after birth. Precise prenatal identification of arrhythmia type can be achieved with the SVC/AA Doppler approach. Such information allows for a better management and a rational c...