Fetal echocardiographic screening in twins for

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Fetal echocardiographic screening in twins for

  1. 1. Chinese Medical Journal 2007; 120(16):1391-1394 1391 Original article Fetal echocardiographic screening in twins for congenital heart diseases LI Hui, MENG Tao, SHANG Tao, GUAN Yun-ping, ZHOU Wei-wei, YANG Guang and BI Li-hua Keywords: twins; ultrasound, heart; malformations; antenatal diagnosis; echocardiography Background Congenital heart disease (CHD) is the most common congenital disorder at birth. Yagel and colleagues’s method of heart examination has been proved valuable in finding CHD prenatally in single pregnancies. The aim of this study was to analyze the frequency of CHD in twin pregnancies and the sensitivity of the method. Methods A total of 1103 pregnant women with twins were enrolled in this study, including 127 cases with high-risk for CHD. Five transverse ultrasound measurements were used for fetal heart examination, including the upper abdomen view, four-chamber view, five-chamber view, pulmonary artery bifurcation view, and three-vessel view. In the fetuses who were diagnosed with CHD and whose parents requested termination of the pregnancy, autopsy of the fetal heart was performed after an abortion, and a blood sample was collected from the heart for chromosome evaluation. In the other fetuses, a close follow-up was conducted by echocardiography within one year after birth. Results Antenatally, CHD was found in 12 twins, of which 4 were from the high-risk group (3.15%), and 8 from the low-risk group (0.82%). In 2 pairs of the twins, the two fetuses had a same kind of CHD (one pair had tetralogy of Fallot (TOF), another pair had rhabdomyoma). Another pair had different types of anomaly (one fetus had TOF, and the other duodenal atresia with a normal heart). Termination of pregnancy was performed in these three pairs and the autopsy of the fetal heart confirmed the ultrasound findings. In the other 9 pairs, CHD was detected in one fetus, and a normal heart in the others. In the cases who received chromosome evaluation, 2 had abnormal chromosomes. During the follow-up after birth, heart examinations confirmed the prenatal diagnosis in 7 of the 9. The diagnosis of CHD was missed antenatally in 2 pairs of twins. In both the cases, one fetus was normal, and the other was confirmed as having CHD after birth (small ventricle septum defect in one, and persistent open ductus arteriosus in the other). Thus, the total frequency of CHD was 16 (7.3/1000), which was similar to that in single pregnancies. The sensitivity of fetal echocardiography was 87.5% and the specificity was 100%. Conclusions The frequency of CHD is the same in twin as in single pregnancies. Systemic ultrasound scanning with five transverse views is effective in diagnosing fetal CHD in twin pregnancies. Chin Med J 2007;120(16):1391-1394 ongenital heart disease (CHD) is the most common congenital disorder at birth. Although advances in medical and surgical treatments over the past decades have led to a higher survival rate, about half of the newborns with CHD face the prospect of future surgery, arrhythmia, heart failure, and even premature death.1,2 It is now well recognized that mothers and fetus in twin pregnancies are at a higher risk of complications and adverse outcome than in single pregnancies. An excess of structural anomalies has been observed in twin pregnancies compared to the single ones.3 Structural heart malformations in monozygotic (MZ) twins without twin-twin transfusion syndrome are four times more common than that in the general population.4 Yagel and colleagues’ method of heart examination has been proved valuable in finding CHD prenatally in single pregnancies.5 The aim of this study was to analyze the frequency of CHD in twin pregnancies and the sensitivity of the method. METHODS Patients A total of 1103 pregnant women with twins (aged 21 to 39 years), who were treated at the Shengjing Hospital of China Medical University, Shenyang Maternal and Infant Hospital, and Dalian Maternal and Infant Hospital from 2003 to 2006, were enrolled in this study (conjoined twins were excluded). Among them, 127 cases were at a high risk of fetal CHD, and the other 976 at a low risk. Fetal echocardiography was performed on all the cases during gestational weeks 20 to 37. Among the cases with high risk of CHD, 4 had family history of CHD, 16 women had delivered a neonate with malformations, 4 were complicated with diabetes, 21 were elderly pregnant women, 21 had abnormal amniotic fluid, 19 had fetal C Departement of Obstetrics and Gynecology, Shengjing Hospital of China Medical University, Shenyang 110004, China (Li H, Meng T and Shang T) Departement of Obstetrics, Shenyang Maternal and Infant Hospital, Shenyang 110014, China (Guan YP and Zhou WW) Departement of Obstetrics, Dalian Maternal and Infant Hospital, Dalian 116033, China (Yang G and Bi LH) Correspondence to: Dr. LI Hui, Department of Obstetrics and Gynecology, Shengjing Hospital of China Medical University, Shenyang 110004, China (Tel: 86-24-81361666. Fax: 86-24- 83955119. Email: fclihui@cmu2h.com) This study was supported by a grant from the Bureau of Science and Technology of Liaoning Province (No.200522500801)
  2. 2. Chin Med J 2007;120(16):1391-13941392 Table. Types of CHD and pregnancy outcome in the 12 twins No. GW Prenatal diagnosis (Sibling 1/ 2) Twin type Chromosome (Sibling 1/ 2) Pregnancy outcome Postnatal diagnosis (Sibling 1/ 2) 1 22 w TOF/N DZ N / N SVD (35 w) TOF/VSD 2 31 w TOF/N DZ N / N CS (37 w) TOF/N 3 34 w TOF/DA MZ 18 Tri / N Termination (34 w) TOF/DA 4 24 w TGV/N DZ N / N SVD (34 w) TGV/N 5 25 w AVSD/N MZ N / N SVD (36 w) AVSD/N 6 29 w VSD/N DZ N / N CS (38 w) VSD/N 7 26 w DORV/N DZ N / N CS (37 w) DORV/N 8 35 w DORV/N DZ N / N CS (36 w) TGV/N 9 20 w UH/N DZ N / N CS (37 w) UH/N 10 28 w HLHS/N DZ N / N CS (37 w) HLHS/N 11 32 w Mass/Mass MZ N / N Termination (33 w) Rha/Rha 12 23 w TOF/TOF MZ 21 Tri/ 21 Tri Termination (25 w) TOF/TOF GW: gestational week; TOF: tetralogy of Fallot; N: normal; DA: duodenal atresia; AVSD: atrial ventricular septal defect; VSD: ventricular septal defect; DORV: double outlet right ventricle; UH: univentricular heart; HLHS: hypoplastic left heart syndrome; DZ: dizygotic twin; MZ: monozygotic twin; Tri: trisomy; SVD: spontaneous vaginal delivery; CS: cesarean section; Rha: rhabdomyoma; TGV: transposition of the great vessels. growth restriction (FGR), 23 had been exposed to teratogen, 5 had other malformations, and 14 had arrhythmia. Machines GE VIVID7 Ultrasound Doppler machine (GE, USA) with 3.5 MHz or 5 MHz transducer and Acuson Sequoia 512 (Mountain View, USA) with a 6C2 transducer and fetal echocardiography program (automatic setting from 2.5 MHz to 6 MHz) were used in this study. Echocardiography The fetal heart scan was performed with the woman in a supine position, tilted 15º to the left. Five heart transverse sections were scanned with the method described by Yagel and colleagues,6 including the upper abdomen view, four-chamber view, five-chamber view, pulmonary artery bifurcation view, and three-vessel view. Management In case of severe fetal CHD, if the parents requested, the pregnancy was terminated after being permitted by the Medical Ethical Committee of the hospitals. Then, autopsy of the fetal heart was performed after obtaining consents from the parents. And blood from the umbilical cord or fetal heart was collected for chromosome analysis. For fetuses with a normal heart and those non-terminated cases with CHD, a close follow-up was given until one year after delivery. Neonatal heart examination was performed to confirm the accuracy of antenatal diagnosis. Judgment for types of twin Dizygotic (DZ) twin pairs were determined by the gender of the twins, type of the placenta, blood type analysis, and physical examinations after birth.7 RESULTS CHD was found in 12 pairs of twins prenatally, of which 4 were from the high-risk group (3.15%, 4/127), 8 from the low-risk group (0.82%, 8/976). In 2 of the 12 pairs, the two fetuses had a same kind of CHD (one pair had tetralogy of Fallot (TOF), and the other had rhabdomyoma). In another pair, the fetuses had different types of anomaly (TOF in one, and duodenal atresia in another). The prenatal and postnatal diagnoses and outcomes of the 12 twins with CHD are shown in Table. Among the 1103 cases, 1091 were diagnosed as having normal fetal heart prenatally. However, in 2 cases of the 1091, heart diseases were found after birth. In both of the cases, one baby was healthy and the other was confirmed as having CHD (small ventricle septum defect (VSD, Φ=5 mm) in one, and persistent open ductus arteriosus in the other). Thus, the total frequency of CHD in twins was 16 (7.3/1000), which was similar to that in single pregnancies. The sensitivity of fetal echocardiography was 87.5% and the specificity was 100%. DISCUSSION Since an excess of structural anomalies has been observed in twin pregnancies compared to the single ones, it is necessary to scan fetal structure including fetal heart prenatally in twins. However, fetal crowding has been demonstrated to significantly worsen the screening performance of ultrasonography in twins, owing to the recently increased number of multiple pregnancies from assisted reproduction techniques.8,9 Dedicated, highly experienced equipments have achieved 87% - 91% sensitivity and 99.8% specificity in the detection of CHD in twin pregnancy by serial ultrasound examinations.9-11 In this study, the twins were scanned by experienced operators using the method of Yagel and colleagues,6 which achieved a sensitivity of 87.5% and a specificity of 100%. Also, we found that the total frequency of CHD in twins was 7.3/1000, which is similar to that in the single pregnancies (8‰-10‰).12 In the cases at a high risk of CHD, the detecting rate was even higher (3.15%). However, since in our cases, two third of the cases diagnosed with CHD were from the low-risk group, we suggest that fetal echocardiography should be performed in all the women with twin pregnancy. In most of the twins that were diagnosed as having CHD, only one fetus is affected, and in approximately 15% of them, both the fetuses are affected by a same structural anomaly.13 It also happened in our study, two twins were
  3. 3. Chinese Medical Journal 2007; 120(16):1391-1394 1393 found having a same CHD in both the fetuses (one pair was TOF, the other was rhabdomyoma), and one twin pair was found to have different structural anomaly (one baby was TOF, another was extra-heart abnormality). Approximately 1% to 2% of twin pregnancies may face the dilemma of expectant management versus selective termination following diagnosis of an anomaly affecting only one fetus.13 Selective fetocide can be performed by ultrasound-guided injection of potassium chloride (KCl) into the fetal heart or into the umbilical cord, this technique is now well-established and technically successful in approximately 93% of reported cases before 24 gestational weeks.14 Alternatively, embolization of the umbilical cord using sclerosant agents (absolute alcohol, coils, or enbucrilate gel) and umbilical cord ligation or laser coagulation by fetoscopy were choices for monochorionic (MC) twin pregnancies since the presence of placental anatomoses does not allow the injection of any lethal agent to achieve selective fetocide in MC twin pregnancies.15-17 However, selective termination may in fact increase the risk of miscarriage and lead to damage of the co-twin, particularly in MC pregnancies, expectant management might be considered an alternate strategy in discordant twin pregnancies. In this study, no parents chose to selective fetocide but expectant management, we suggest a careful and completed fetal structure scanning for such twins. Chromosome abnormalities are correlated with fetal CHD and approximately 50% of aneuploidy individuals suffer from CHD at the same time.18 Our results show that 3 CHD fetuses in the 12 twins with heart disorders had abnormal chromosome (12.5%, 3/24, two trisomy 21 and one trisomy 18), while in single pregnancies, the rate was 25%.5 However, in the studies reported by Paladini and colleagues, the incidence of aneuploidy was 6.7% in twins with CHD and 25.9% in singletons.9,19 Therefore, we suggest amniotic centesis or cord-centesis for twins with CHD for chromosome analysis although the centesis is complicated and difficult in twins. The risk of recurrent fetal CHD is 4%, if the parents have delivered a fetus with CHD. 20 We found that in twins with congenital disorders, the incidence of structural abnormalities in both the fetuses at the same time was 25%, and CHD in the both at the same time was 20%. Such cases occurred more often in MZ twins, but also happened in DZ twins. Hereditary factors play an important role in the pathogenesis of CHD, and heredity degree is significant higher in twins than in singletons. However, in 75% of the twins with CHD, the anomaly occurred in only one of the fetuses, suggesting that CHD is not only genetically determined, environment in the uterus and individual gene mutation contribute to the pathogenesis also. It is impossible to detect CHD prenatally, because small VSD cannot be detected by ultrasonography21 and the ovale foramen and ductus arteriosus are not closed until birth. These factors limited the sensitivity and specificity of fetal echocardiography. The sensitivity and specificity of detecting fetal heart abnormality was 92% and 99.6% in single pregnancies. 6 And in our study, they are 87.5% and 100% in twin pregnancies. It is difficult to differentiate double outlet of right ventricle (DORV) from transposition of the great vessels (TGV) and TOF prenatally. A previous study has shown that the accurate rate of prenatal diagnose for fetus with conotruncal anomalies is 77%.22 The rate depends on the operator’s experience, technology, fetal position, gestational age, amniotic fluid volume, and maternal fat, etc. In our study, one case was diagnosed as DORV prenatally, but was confirmed as TGV after autopsy. Both DORV and TGV have parallel aorta and pulmonary artery; however, the aorta and pulmonary artery are both from the right ventricle in DORV; while in TGV, the aorta is from the right ventricle and the pulmonary artery from the left. In our view, it is not important to differentiate conotruncal anomalies prenatally since they have similar prognosis. In conclusion, the diagnostic performance of fetal echocardiography in twin pregnancies is comparable with that in single pregnancies. Five-transverse sections screening is simple and effective, time-saving for fetal heart examination. We suggested fetal echocardiography for twin pregnancies as a routine clinical examination. REFERENCES 1. Nieminen HP, Jokinen EV, Sairanen HI. Late results of pediatric cardiac surgery in Finland: a population-based study with 96% follow-up. Circulation 2001; 104: 570-575. 2. Thorne S, Deanfield J. Long-term outlook in treated congenital heart disease. Arch Dis Child 1996; 75: 6-8. 3. Mastroiacovo P, Castilla EE, Arpino C, Botting B, Cocchi G, Goujard J, et al. Congenital malformations in twins: an international study. Am J Med Genet 1999; 83: 117-124. 4. Karatza AA, Wolfenden JL, Taylor MJ, Wee L, Fisk NM, Gardiner HM. 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  4. 4. Chin Med J 2007;120(16):1391-13941394 Diagnosis and outcome of congenital heart disease in fetuses from multiple pregnancies. Prenat Diagn 2005; 25: 403-406. 10. Berghella V, Pagotto L, Kaufman M, Huhta JC, Wapner RJ. Accuracy of prenatal diagnosis of congenital heart defects. Fetal Diagn Ther 2001; 16: 407-412. 11. Perolo A, Prandstraller D, Ghi T, Gargiulo G, Leone O, Bovicelli L, et al. Diagnosis and management of fetal cardiac anomalies: 10 years of experience at a single institution. Ultrasound Obstet Gynecol 2001; 18: 615-618. 12. Allan L. Antenatal diagnosis of heart disease. Heart 2000; 83: 367. 13. Bryan E, Little J, Burn J. Congenital anomalies in twins. Baillieres Clin Obstet Gynaecol 1987; 1: 697-721. 14. Evans MI, Goldberg JD, Horenstein J, Wapner RJ, Ayoub MA, Stone J, et al. Selective termination for structural, chromosomal, and mendelian anomalies: international experience. Am J Obstet Gynecol 1999; 181: 893-897 15. Denbow ML, Overton TG, Duncan KR, Cox PM, Fisk NM. High failure rate of umbilical vessel occlusion by ultrasound-guided injection of absolute alcohol or enbucrilate gel. Prenat Diagn 1999; 19: 527-532. 16. Challis D, Gratacos E, Deprest JA. Cord occlusion techniques for selective termination in monochorionic twins. J Perinat Med 1999; 27: 327-38. 17. Hecher K, Hackeloer BJ, Ville Y. Umbilical cord coagulation by operative microendoscopy at 16 weeks' gestation in an acardiac twin. Ultrasound Obstet Gynecol 1997; 10: 130-132. 18. Ferencz C, Neill CA, Boughman JA, Rubin JD, Brenner JI, Perry LW. Congenital cardiovascular malformation associated with chromosome abnormalities: an epidemiological study. J Pediatr 1989; 114: 79-86. 19. Paladini D, Russo M, Teodoro A, Pacileo G, Capozzi G, Martinelli P, et al. Prenatal diagnosis of congenital heart disease in the Naples area during the years 1994-1999 --- the experience of a joint fetal-pediatric cardiology unit. Prenat Diagn 2002; 22: 545-552. 20. Benacerraf BR, Sanders SP. Fetal echocardiography. Radiol Clin North Am 1990; 28: 131-147. 21. Benacerraf BR, Pober BR, Sanders SP. Accuracy of fetal echocardiography. Radiology 1987; 165: 847-849. 22. Tometzki AJ, Suda K, Kohl T, Kovalchin JP, Silverman NH. Accuracy of prenatal echocardiographic diagnosis and prognosis of fetuses with conotruncal anomalies. J Am Coll Cardiol 1999; 33: 1696-1701. (Received November 13, 2006) Edited by LUO Dan

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