Jean-Claude Fouron

Early Intertwin Differences in Myocardial Performance During the Twin-to-Twin Transfusion Syndrome

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 0.105±0.047 and 0.097±0.026 seconds, respectively, for the recipient twins versus 0.0561±0.46 and 0.065±0.03 seconds, respectively, for the donor twins (P<0.001). These changes in the isovolumic periods were mainly due to significant prolongation of isovolumic relaxation times. A change in left ventricular MPI ≥0.09 combined with a change in right ventricular MPI ≥0.05 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.

Isolated Ductus arteriosus aneurysm in the fetus and infant : A multi-institutional experience

OBJECTIVES The purpose of this study was to describe the clinical characteristics and outcome and to elucidate the pathogenesis of ductus arteriosus aneurysm (DAA). BACKGROUND Ductus arteriosus aneurysm is a rare lesion that can be associated with severe complications including thromboembolism, rupture and death. METHOD We reviewed the clinical records, diagnostic imaging studies and available histology of 24 cases of DAA, diagnosed postnatally (PD) in 15 and antenatally (AD) in 9 encountered in five institutions. RESULTS Of PD cases, 13 presented at <2 months, and all AD cases were detected incidentally after 33 weeks of gestation during a late trimester fetal ultrasound study. Of the 24, only 4 had DAA-related symptoms and 6 had associated syndromes: Marfan, Smith-Lemli-Opitz, trisomies 21 and 13 and one possible Ehlers-Danlos. Three had complications related to the DAA: thrombus extension into the pulmonary artery, spontaneous rupture, and asymptomatic cerebral infarction. Six underwent uncomplicated DAA resection for ductal patency, DAA size or extension of thrombus. In the four examined, there was histologic evidence of reduced intimal cushions in two and abnormal elastin expression in two. Five of the 24 died, with only one death due to DAA. Of 19 survivors, all but one remain clinically asymptomatic at a median follow-up of 35 months; however, two have developed other cardiac lesions that suggest Marfan syndrome. A review of 200 consecutive third trimester fetal ultrasounds suggests an incidence of DAA of 1.5%. CONCLUSIONS 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.

The unrecognized physiological and clinical significance of the fetal aortic isthmus.

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.

Prenatal diagnosis of complete atrioventricular block associated with structural heart disease: combined experience of two tertiary care centers and review of the literature

To review the pattern of presentation, management and outcome of fetal complete atrioventricular block (CAVB) associated with major structural congenital heart disease (CHD), when compared to isolated CAVB.

Profiling fetal cardiac function in twin–twin transfusion syndrome

Cardiomyopathy in the recipient twin is a marker of severity in twin–twin transfusion syndrome (TTTS), making it a potentially valuable tool for staging the disease. This study aimed to provide a quantitative description of cardiac function in the recipient twin.

Management of fetal tachyarrhythmia based on superior vena cava/aorta Doppler flow recordings

Objective: To evaluate a management protocol of fetal supraventricular tachycardia (SVT) based on prior identification of the underlying mechanism. Design and setting: Prospective study in a mother–child tertiary university centre. Patients: During a consecutive 36 month period, 18 fetuses with sustained SVT underwent a superior vena cava/ascending aorta (SVC/AA) Doppler investigation in an attempt to determine the atrioventricular (AV) relation and to treat the arrhythmia according to a pre-established management protocol. Main outcome measure: Rate of conversion to sinus rhythm. Results: Seven fetuses had short ventriculoatrial tachycardia, five of these with a 1:1 AV conduction suggesting re-entrant tachycardia. The first choice drug was digoxin and all were converted. One fetus had AV dissociation leading to the diagnosis of junctional ectopic tachycardia, which was resistant to digoxin and sotalol; amiodarone achieved postnatal conversion. One fetus had SVT and first or second AV block; the diagnosis was atrial ectopic tachycardia (AET), which responded to sotalol given as a drug of first choice. Seven fetuses had long ventriculoatrial tachycardia: one with sinus tachycardia (no treatment), one with permanent junctional reciprocating tachycardia (PJRT), and three with AET. The first choice drug was sotalol and all were converted. One AET was classified postnatally as PJRT. Six fetuses had intra-atrial re-entrant tachycardia: five with 2:1 AV conduction and one with variable block. The first choice drug was digoxin. Conversion was achieved in all but one, who died after birth from advanced cardiomyopathy. Conclusion: The electrophysiological mechanisms of fetal SVT can be clarified with SVC/AA Doppler. The proposed management protocol has so far yielded a good rate of conversion to sinus rhythm.

Quantitative assessment of circulatory changes in the fetal aortic isthmus during progressive increase of resistance to umbilical blood flow.

BackgroundThis study investigated the effects of impairment to placental flow on flow patterns through the aortic isthmus because in the fetus, this vascular segment is the link between the parallel vascular systems perfused by the left and right ventricles. Methods and ResultsA progressive increase in resistance to blood flow through the placenta was created in seven exteriorized fetal lambs by mechanical umbilical vein compression. Blood flows were measured in the ascending aorta, pulmonary artery, aortic isthmus, and umbilical artery at baseline and at each compression level. The severity of the levels of compression was determined by changes in the flow profile through the umbilical artery. An increase in placental resistance causing a fall in umbilical blood flow of approximately 50% was associated with a retrograde diastolic flow through the aortic isthmus even though the diastolic flow through the umbilical artery remained forward. Because of the systolic predominance, however, the net flow in the isthmus was forward. With a more severe increase in placental resistance corresponding to a decrease of 75% in umbilical blood flow, the net flow through the isthmus approached zero. A strong positive correlation was found between the umbilical blood flow and the net flow through the aortic isthmus (r=.89). ConclusionsVariations in Doppler blood flow velocity waveforms and integrals of the aortic isthmus can be used as a sensitive indicator of the state of the umbilical circulation.

Reference values for time intervals between atrial and ventricular contractions of the fetal heart measured by two Doppler techniques

Further studies are needed to confirm the above clinical sequelae and to determine whether our findings also apply in the case of patients with some form of intrinsic heart disease. 1. Doucette JW, Corl PD, Payne HM, Flynn AE, Goto M, Nassi M, Segal J. Validation of a Doppler guide wire for intravascular measurement of coronary artery flow velocity. Circulation 1992;85:1899–1911. 2. Wilson RF, Wyche K, Christensen BV, Zimmer S, Laxson DD. Effects of adenosine on human coronary arterial circulation. Circulation 1990;82:1595– 1606. 3. Friedman HS, Scorza J, McGuinn R, Shaughnessy E. The effects of atrial fibrillation on myocardial blood flow and energetics. Proc Soc Exp Biol Med 1985;180:1–8. 4. Wichmann J, Ertl G, Rudolph G, Kochsiek K. Effect of experimentally induced atrial fibrillation on coronary circulation in dogs. Basic Res Cardiol 1983;78: 473–491. 5. Wichmann J, Ertl G, Hohne W, Schweisfurth H, Wernze H, Kochsiek K. Alpha-receptor restriction of coronary blood flow during atrial fibrillation. Am J Cardiol 1983;52:887–892. 6. Ertl G, Wichmann J, Kaufmann M, Kochsiek K. Alpha-receptor constriction induced by atrial fibrillation during maximal coronary dilatation. Basic Res Cardiol 1986;81:29–39.

Ventriculo-atrial time interval measured on M mode echocardiography: a determining element in diagnosis, treatment, and prognosis of fetal supraventricular tachycardia

Objective To determine whether M mode echocardiography can differentiate fetal supraventricular tachycardia according to the ventriculo-atrial (VA) time interval, and if the resulting division into short and long VA intervals holds any relation with clinical presentation, management, and fetal outcome. Design Retrospective case series. Subjects 23 fetuses with supraventricular tachycardia. Main outcome measures A systematic review of the M mode echocardiograms (for VA and atrioventricular (AV) interval measurements), clinical profile, and final outcome. Results 19 fetuses (82.6%) had supraventricular tachycardia of the short VA type (mean (SD) VA/AV ratio 0.34 (0.16); heart rate 231 (29) beats/min). Tachycardia was sustained in six and intermittent in 13. Hydrops was present in three (15.7%). Digoxin, the first drug given in 14, failed to control tachycardia in five. Three of these then received sotalol and converted to sinus rhythm. All fetuses of this group survived. Postnatally, supraventricular tachycardia recurred in three, two having Wolff-Parkinson-White syndrome. Four fetuses (17.4%) had long VA tachycardia (VA/AV ratio 3.89 (0.82); heart rate 226 (10) beats/min). Initial treatment with digoxin was ineffective in all, but sotalol was effective in two. Heart failure caused fetal death in one and premature delivery in one. All three surviving fetuses had recurrences of supraventricular tachycardia after birth: two had the permanent form of junctional reciprocating tachycardia and one had atrial ectopic tachycardia. Conclusions Careful measurement of ventriculo-atrial intervals on fetal M mode echocardiography can be used to distinguish short from long VA supraventricular tachycardia and may be helpful in optimising management. Digoxin, when indicated, may remain the drug of choice in the short VA type but appears ineffective in the long VA type.

Doppler and M-Mode ultrasonography to time fetal atrial and ventricular contractions

Objective To compare ease of recording and reliability of ultrasonographic approaches used to time fetal heart atrial and ventricular contractions. Methods Seventeen consecutive fetuses seen at our fetal cardiology unit for possible fetal cardiac arrhythmia were included in this study. The same ultrasonographer obtained M-mode tracings of atrial and ventricular free walls, atrial wall and opening of the aortic valves, a peak of the mitral valve, and the opening of the aortic valves; and Doppler signals of flow-velocity waveforms in the outflow tract of the left ventricle and simultaneous flow-velocity waveforms in the aorta and superior vena cava. The outcome measures were rate of successful attempts and intra- and interobserver reliability coefficients. Results Valid recordings were made for all patients with one M-mode (atrial and ventricular free walls) and two Doppler (intraventricular, superior vena cava, and ascending aorta) approaches. Atrioventricular intervals were significantly longer with M-mode compared with Doppler ultrasonography. Reliability coefficients were excellent (at least 0.89) for all intraobserver measurements. Comparisons of atrioventricular and ventriculoatrial interval measurements made by two observers gave the following intraclass correlation coefficients (95% confidence interval): atrioventricular = M-mode: 0.87 (0.79, 0.91), left ventricular outflow: 0.93 (0.89, 0.96), superior vena cava–aorta: 0.98 (0.97, 0.99); ventriculoatrial = M-mode: 0.79 (0.67, 0.87), left ventricular outflow: 0.97 (0.95, 0.98); superior vena cava–aorta: 0.99 (0.98, 0.99). Conclusion Fetal atrioventricular intervals measured indirectly from M-mode or Doppler tracings were equally reliable when measured by the same observer; the Doppler approaches had better correlation between measurements made by two different observers.