Prenatal Diagnosis of Congenital Heart Disease

Transcription

1 Prenatal Diagnosis of Congenital Heart Disease Pei-NiJone, MD a, Kenneth O. Schowengerdt, Jr., MD b, * KEYWORDS Fetal echocardiography Prenatal diagnosis Neonatal heart disease Fetal echocardiography, an accurate and safe method to diagnose congenital heart disease, has become widely used in pediatric cardiology and perinatology. It allows detailed prenatal diagnosis of suspected or known congenital heart disease and serves as a general screening tool for possible congenital heart disease. With the advent of better technology, fetal echocardiography can delineate the details of fetal cardiac anatomy, thus broadening our understanding of the development of the fetal heart and fetal cardiac defects. Outcomes of infants with severe cardiac malformations may improve with prenatal diagnosis of congenital heart disease. 1 3 Fetal echocardiography allows for improved counseling of families after a prenatal diagnosis of congenital heart disease; it allows them to better anticipate the expected course of the pregnancy, and leads to a better understanding of the postnatal prognosis. It also allows for referral of mothers with affected fetuses to tertiary cardiac care centers for timely neonatal management. The early diagnosis of congenital heart disease allows prompt evaluation of genetic syndromes and analysis of the fetal karyotype. Prenatal detection of arrhythmias by fetal echocardiography allows for in utero treatment in many instances. Fetal echocardiography can also serve to identify patients for in utero cardiac interventions that may be performed at certain select centers. GOALS OF FETAL ECHOCARDIOGRAPHY The goals of fetal echocardiography are to exclude congenital heart disease and, when present, to diagnose the specific malformations of the heart. It serves as a diagnostic tool for determining fetal cardiac anatomy and fetal arrhythmias. Fetal echocardiography provides a better understanding of fetal cardiac anatomy and developmental malformations of the heart, such as development of hypoplastic a Division of Pediatric Cardiology, University of Colorado, Denver, CO, USA b Pediatric Cardiology, Cardinal Glennon Children s Medical Center, Saint Louis University School of Medicine, 1465 S. Grand Boulevard, Saint Louis, MO 63104, USA * Corresponding author. address: [email protected] (K.O. Schowengerdt). Pediatr Clin N Am 56 (2009) doi: /j.pcl pediatric.theclinics.com /09/$ see front matter ª 2009 Elsevier Inc. All rights reserved.

2 710 Jone & Schowengerdt ventricles related to obstruction of the respective outflow tracts. Fetal echocardiography may also serve as a navigator for fetal cardiac interventions in selected instances. SCREENING WITH FETAL ECHOCARDIOGRAPHY The optimal transabdominal fetal echocardiogram can be performed at 16 weeks of pregnancy and onwards. However, typical general obstetric ultrasounds for low risk pregnancies are performed at 18 to 22 weeks gestation. By this time, details of the fetal cardiac anatomy can be well visualized and evaluated, such as the atrioventricular and ventriculoarterial connections. Fetal echocardiographic images actually may be difficult to obtain beyond 28 to 30 weeks gestation because of fetal rib shadowing, fetal position, or maternal body habitus. INDICATIONS OF FETAL ECHOCARDIOGRAPHY Pregnancies at high risk for structural, functional, or rhythm-related fetal heart disease constitute indications for fetal echocardiographic assessment. Indications for fetal echocardiography can be stratified into three categories: fetal, maternal, and familial. 4 7 These are outlined in Box 1. Increased nuchal thickening in the first trimester has been associated with an increased incidence of congenital heart disease This increase in nuchal thickening may be associated with left-sided Box 1 Indications for fetal echocardiography Fetal Abnormal screening obstetric ultrasound Extracardiac anomalies (omphalocele, duodenal atresia, VACTERL, spina bifida) Chromosomal abnormalities (trisomies, microdeletions) Increased first-trimester nuchal translucency measurement Nonimmune hydrops Tachyarrhythmias Bradyarrhythmias Maternal Diabetes Phenylketonuria Teratogen exposure Maternal congenital heart defect Familial Previous child with congenital heart defect Paternal congenital heart defect Tuberous sclerosis Noonan syndrome Velocardiofacial syndrome

3 Prenatal Diagnosis of Congenital Heart Disease 711 obstructive lesions or chromosomal abnormalities with possible associated cardiac defects such as trisomy 21 and Turner syndrome. 10,13 ADVANTAGES OF FETAL ECHOCARDIOGRAPHY Fetal echocardiography provides potential benefits for both the neonate and the family. Prenatal diagnosis of congenital heart disease allows for more specific family counseling to be rendered, and allows parents to ask questions related to the pregnancy and postnatal prognosis. A detailed explanation of the potential cardiac surgical procedures that the infant will require and their timing can be provided, with the opportunity for parents to prepare emotionally before birth. Arrangements for delivery at a tertiary care center providing neonatal cardiac care can and should be made. Neonatal hypoxemia and acidosis can be prevented by early institution of prostaglandin E infusion for ductal dependent lesions immediately after delivery. It should also be mentioned that a negative fetal echocardiogram could provide needed reassurance to the family who had had a previous child with a congenital heart defect. Studies show improved postnatal outcome when a prenatal diagnosis of congenital heart disease is made. 3,15,16 Prenatal diagnosis is associated with decreased preoperative morbidity, decreased incidence of acidosis, reduced risk of hemodynamic compromise, and better end-organ perfusion. 17 Thus, fetal echocardiography can play an important role in identifying fetuses with types of congenital heart disease requiring specific early postnatal therapy, especially those with ductal dependent lesions such as critical left heart obstructive lesions, transposition of great arteries, and pulmonary atresia. Franklin and colleagues 1 demonstrated that infants with a prenatal diagnosis of severe coarctation had improved survival compared with those with a postnatal diagnosis, with cardiovascular collapse and death being more common in the latter group. Fetal echocardiography is also useful in diagnosing and managing fetal arrhythmias. M-mode tracings of the atria and ventricles can delineate the fetal rhythm. Isolated premature atrial and ventricular contractions in the fetus are benign and do not require treatment. Tachyarrhythmias in the fetus, most commonly fetal supraventricular tachycardia, can be controlled by treatment of the mother with antiarrhythmic agents. 18 In utero treatment of fetal arrhythmias has been useful in preventing hydrops and fetal demise. Jaeggi and colleagues 19 have demonstrated that a prenatal diagnosis of complete atrioventricular block was associated with high fetal and neonatal mortality, and was often associated with anti-rho or anti-la antibodies. In this case, maternal treatment with steroids or sympathomimetics may be beneficial to the fetus whose bradycardia has resulted in decompensated heart failure. 20 Identifying congenital complete heart block prenatally can prepare families and health care providers for the need for delivery at a tertiary center should the fetus require temporary or permanent pacing after delivery. SPECTRUM OF CONGENITAL HEART DISEASE DIAGNOSED BY FETAL ECHOCARDIOGRAPHY Using current state-of-the-art echocardiographic equipment and methods, fetal echocardiography can diagnose major cardiac malformations in detail. The spectrum of ventricular hypoplasia syndromes such as hypoplastic left heart syndrome, unbalanced atrioventricular canal defect, severe tricuspid stenosis, or tricuspid atresia can be readily seen in the four-chamber view (Fig. 1). As the fetus relies on the ductus arteriosus for survival, ductal flow patterns are routinely assessed. A prenatal diagnosis of hypoplastic left heart syndrome is particularly important, as normal somatic growth of the fetus can occur in this setting and these infants may appear normal

4 712 Jone & Schowengerdt Fig.1. Fetal echocardiogram demonstrating finding of hypoplastic left heart syndrome. Note the enlarged right atrium (RA) and right ventricle (RV). The left atrium (LA) is small, and there is no appreciable left ventricular cavity. The interatrial septum (IAS) is identified by the arrow. for varying periods after delivery. Only after the ductus arteriosus begins to close do these infants become hemodynamically compromised. Often, severe acidosis is present when the diagnosis is suspected. Right-sided lesions encompassing the spectrum of tetralogy of Fallot include varying degrees of obstruction or atresia of the right ventricular outflow tract (Fig. 2). These lesions can best be visualized by examining the outflow tracts anterior to the four- chamber view. The branch pulmonary arteries can also be visualized using the outflow tract views and their relative size assessed. Retrograde filling of the branch pulmonary arteries from the aorta by way of the ductus arteriosus may be seen, indicative of severe pulmonary stenosis or pulmonary atresia. The ductus arteriosus may be small or tortuous depending on the severity of the obstruction of the right ventricular outflow tract. Transposition of the great arteries, double-outlet right ventricle, and subaortic ventricular septal defects can also be diagnosed prenatally by fetal echocardiography. Fetuses with these lesions will grow and be tolerant of these defects because of the unique features of the fetal circulation. 5 Fig. 2. Fetal echocardiogram demonstrating findings consistent with tetralogy of Fallot. The right ventricular outflow tract is not well visualized, and the pulmonary arteries (PA) are hypoplastic. The size discrepancy with the aorta (AO) is apparent.

5 Prenatal Diagnosis of Congenital Heart Disease 713 Major cardiac malformations should be followed serially by fetal echocardiography as progressive alterations in flow may affect growth of cardiac structures over time; for example, the development of ventricular hypoplasia in the setting of significant outflow obstruction. In addition, assessment of left atrial size, restriction of flow across the foramen ovale, and pulmonary venous flow patterns can be useful in identifying those infants with hypoplastic left heart syndrome at high risk of morbidity and mortality after birth. 21 Mild defects such as mild coarctation of the aorta and mild valvar stenoses can be observed in utero; but, because of the unique fetal circulation, fetal development is not affected. The large ductus arteriosus allows equalization of systolic blood pressure in the great arteries, thus a pressure gradient does not develop in utero. 5 A subtle clue suggesting mild coarctation is a dilated right ventricle resulting from increased systemic vascular resistance. 22 Tricuspid regurgitation and mitral regurgitation can be seen readily in the fourchamber view by fetal echocardiography. Severe tricuspid regurgitation can result in severe heart failure and hydrops fetalis (Fig. 3). 23 The causes of tricuspid regurgitation are right ventricular volume overload (severe pulmonic stenosis or constriction of the ductus arteriosus), ventricular dysfunction or dilation (cardiomyopathy), or structural abnormalities of the tricuspid valve (Ebstein anomaly, dysplastic tricuspid valve, and common atrioventricular canal). Mitral regurgitation is less common. Severe mitral regurgitation can cause similar effects of volume overload of the left heart. LIMITATIONS OF FETAL ECHOCARDIOGRAPHY Fetal echocardiography, like other ultrasound tests, is operator dependent and relies on the expertise of the pediatric cardiologist and screening perinatologist. Technical limitations include poor fetal positioning in which the fetal lie does not allow for adequate image acquisition and difficult imaging due to maternal body habitus. In obese gravid patients, image acquisition is poor and scanning the fetus becomes difficult. Multiple fetuses also create a shadowing phenomenon that may not allow adequate cardiac visualization. Small ventricular septal defects are difficult to visualize and identification of a secundum atrial septal defect versus flow through the foramen ovale can be difficult. Importantly, total anomalous pulmonary venous return may be difficult to diagnose in utero because the pulmonary veins carry little blood flow prenatally. 24 Fig. 3. Prominent ascites seen in a case of fetal hydrops.

6 714 Jone & Schowengerdt FETAL CARDIAC INTERVENTIONS Fetal echocardiography serves as a guide for fetal cardiac catheter-based interventions. Several specialized centers offer catheter-based interventions in utero to dilate stenosis of the pulmonary or aortic valves. 25 Evidence suggests that early relief of severe outflow tract obstruction can reverse the progression of ventricular hypoplasia in some instances by improving flow and thereby creating a stimulus for growth of the ventricle. 26 Prenatal diagnosis of congenital heart defects is crucial in identifying patients who are suitable candidates for fetal cardiac intervention. A severely restrictive atrial septal defect in hypoplastic left heart syndrome can be dilated in utero to prevent fetal demise or minimize morbidity and mortality after birth. Fetal cardiac intervention is an evolving field and warrants further research to provide in utero treatment for the fetus who would otherwise not survive. SUMMARY Advancements in the field of fetal echocardiography have had a significant impact within the fields of pediatric cardiology, perinatology, and neonatology. A detailed and accurate prenatal diagnosis of congenital heart disease allows for improved counseling of the parents, not only regarding the prognosis for their affected child, but also the potential risks in future pregnancies. Prenatal diagnosis may guide the timing and optimal location of delivery. Infants with significant congenital heart disease should be delivered at a tertiary care center with pediatric cardiology and congenital heart surgery support. A prenatal diagnosis allows appropriate planning and consultation between the cardiologist and neonatologist before the delivery to optimize the care of the newborn and prevent postnatal hemodynamic compromise that can occur with severe cardiac malformations. If immediate interventions are anticipated, these can be planned so that they may occur in a timely way. In addition to identifying structural heart disease, fetal echocardiography has been shown to be accurate in diagnosing and managing fetal arrhythmias. Appropriate treatment of these rhythm disturbances can prevent fetal demise and the morbidity and mortality associated with severe hydrops. Finally, fetal echocardiography is able to identify potential candidates for in utero cardiac intervention and serves as the imaging guidance technique for these procedures. Future advancement may lead to additional techniques that alter the natural history of abnormal cardiac development and improve survival. REFERENCES 1. Franklin O, Burch M, Manning N, et al. Prenatal diagnosis of coarctation of the aorta improves survival and reduces morbidity. Heart 2002;87: Maeno YV, Kamenir SA, Sinclair B, et al. Prenatal features of ductus arteriosus constriction and restrictive foramen ovale in d-transposition of the great arteries. Circulation 1999;99: Tworetzky W, McElhinney DB, Reddy VM, et al. Improved surgical outcome after fetal diagnosis of hypoplastic left heart syndrome. Circulation 2001;103: Boughman JA, Berg KA, Astemborski JA, et al. Familial risks of congenital heart defect assessed in a population-based epidemiologic study. Am J Med Genet 1987;26: Cohen MS. Fetal diagnosis and management of congenital heart disease. Clin Perinatol 2001;28:11 29, v vi. 6. Snider AR. Two-dimensional and Doppler echocardiographic evaluation of heart disease in the neonate and fetus. Clin Perinatol 1988;15:

7 Prenatal Diagnosis of Congenital Heart Disease Shipp TD, Bromley B, Hornberger LK, et al. Levorotation of the fetal cardiac axis: a clue for the presence of congenital heart disease. Obstet Gynecol 1995;85: Devine PC, Simpson LL. Nuchal translucency and its relationship to congenital heart disease. Semin Perinatol 2000;24: Hafner E, Schuller T, Metzenbauer M, et al. Increased nuchal translucency and congenital heart defects in a low-risk population. Prenat Diagn 2003;23: Hyett J, Perdu M, Sharland G, et al. Using fetal nuchal translucency to screen for major congenital cardiac defects at weeks of gestation: population based cohort study. BMJ 1999;318: Hyett JA, Perdu M, Sharland GK, et al. Increased nuchal translucency at weeks of gestation as a marker for major cardiac defects. Ultrasound Obstet Gynecol 1997;10: Makrydimas G, Sotiriadis A, Ioannidis JP. Screening performance of first-trimester nuchal translucency for major cardiac defects: a meta-analysis. Am J Obstet Gynecol 2003;189: Nicolaides KH. Nuchal translucency and other first-trimester sonographic markers of chromosomal abnormalities. Am J Obstet Gynecol 2004;191: Zosmer N, Souter VL, Chan CS, et al. Early diagnosis of major cardiac defects in chromosomally normal fetuses with increased nuchal translucency. Br J Obstet Gynaecol 1999;106: Chang AC, Huhta JC, Yoon GY, et al. Diagnosis, transport, and outcome in fetuses with left ventricular outflow tract obstruction. J Thorac Cardiovasc Surg 1991;102: Verheijen PM, Lisowski LA, Stoutenbeek P, et al. Prenatal diagnosis of congenital heart disease affects preoperative acidosis in the newborn patient. J Thorac Cardiovasc Surg 2001;121: Bonnet D, Coltri A, Butera G, et al. Detection of transposition of the great arteries in fetuses reduces neonatal morbidity and mortality. Circulation 1999;99: Simpson LL. Fetal supraventricular tachycardias: diagnosis and management. Semin Perinatol 2000;24: Jaeggi ET, Hamilton RM, Silverman ED, et al. Outcome of children with fetal, neonatal or childhood diagnosis of isolated congenital atrioventricular block. A single institution s experience of 30 years. J Am Coll Cardiol 2002;39: Groves AM, Allan LD, Rosenthal E. Therapeutic trial of sympathomimetics in three cases of complete heart block in the fetus. Circulation 1995;92: Taketazu M, Barrea C, Smallhorn JF, et al. Intrauterine pulmonary venous flow and restrictive foramen ovale in fetal hypoplastic left heart syndrome. J Am Coll Cardiol 2004;43: Hornberger LK, Sahn DJ, Kleinman CS, et al. Antenatal diagnosis of coarctation of the aorta: a multicenter experience. J Am Coll Cardiol 1994;23: Hornberger LK, Sahn DJ, Kleinman CS, et al. Tricuspid valve disease with significant tricuspid insufficiency in the fetus: diagnosis and outcome. J Am Coll Cardiol 1991;17: Yeager SB, Parness IA, Spevak PJ, et al. Prenatal echocardiographic diagnosis of pulmonary and systemic venous anomalies. Am Heart J 1994;128: Kohl T, Sharland G, Allan LD, et al. World experience of percutaneous ultrasoundguided balloon valvuloplasty in human fetuses with severe aortic valve obstruction. Am J Cardiol 2000;85: Hornberger LK, Sanders SP, Rein AJ, et al. Left heart obstructive lesions and left ventricular growth in the midtrimester fetus. A longitudinal study. Circulation 1995; 92: