The Journal of Pediatrics
Volume 155, Issue 1 , Pages 9-11, July 2009

Prenatal Diagnosis of Congenital Heart Disease in an Era of Near-Universal Ultrasound Screening: Room for Improvement

  • Erik C. Michelfelder, MD

      Affiliations

    • Corresponding Author InformationReprint requests: Erik C. Michelfelder, MD, The Heart Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2003, Cincinnati, OH 45229.
    • ,
  • James F. Cnota, MD

The Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio

Article Outline

AIUM, American Institute of Ultrasound in Medicine, CHD, Congenital heart defect

 

See related article, p 26

In this issue of The Journal, Friedberg et al1 report the prenatal detection rate of major congenital heart defects (CHDs) among 3 major tertiary pediatric centers in northern California. For those who routinely diagnose and manage newborns with congenital heart disease, this study's results are not entirely unexpected; however, for those outside of the pediatric cardiac care community, they may be surprising. In the authors' study cohort, only 28% of major CHDs—lesions likely to present with congestive heart failure, low cardiac output, and/or hypoxemia in early infancy—were detected prenatally, despite near-uniform (99%) access to screening ultrasounds during the pregnancy. The question that follows is: If access to ultrasound screening is not the limiting factor, then why do we detect so little CHD prenatally?

Since the advent of real-time 2-dimensional and Doppler ultrasound, technological advances in ultrasound hardware, image processing speeds, and digital image analysis have dramatically improved the quality of anatomic imaging2 and access to high-performance imaging systems. These developments have led to an increased use of screening ultrasound in obstetric care,3 despite questions regarding the impact of this practice on perinatal outcomes,4 particularly in the United States. To be fair, prenatal detection rates have improved. For example, in a study of the Atlanta metropolitan area, Montana et al5 found that prenatal detection of major CHD ranged from 5% to 28% between 1990 and 1994, with an average prevalence of detection of 6%. In a similar era, the prevalence of detection reported in Europe ranged from 24% to 38%.6, 7 The data reported by Friedberg et al suggest that in northern California, prenatal ultrasound screening is performed in nearly all patients, with many patients undergoing multiple studies. In this setting, detection of major CHDs in 2004-2005 ranged from 20% to 82%,1 a clear improvement but still certainly relatively low on average (28%).

Friedberg et al reports that the 2 most important factors influencing prenatal detection of CHDs are the specific type of CHD and the type of medical practice performing the screening ultrasound. These 2 factors likely are related. To understand the connection, it is useful to review the standards for ultrasound screening of fetal cardiac anatomy in obstetrical practice. The American Institute of Ultrasound in Medicine (AIUM) has published guidelines outlining the basic components of fetal cardiac anatomic assessment.8 The “basic” examination includes a single “4-chamber view” of the fetal heart, obtained in transverse section of the fetal chest, which allows assessment of the right and left ventricles, atria, and atrioventricular valves. The recommendations then state that “if technically feasible, an extended basic cardiac examination can also be attempted to evaluate both (right and left ventricular) outflow tracts.” With this in mind, examining the detection of lesions by CHD type in various series,1, 5, 9, 10 reveals a relatively high rate of detection of lesions apparent on a 4-chamber view of the heart (eg, atrioventricular canal defects, hypoplastic left heart, complex single ventricles). In contrast, the rate of detection is low for such lesions as tetralogy of Fallot and transposition of the great arteries, for which accurate diagnosis requires “extended” imaging of the outflow tracts. In Friedberg et al's series, prenatal detection of d-transposition of the great arteries (19%), total anomalous pulmonary venous return (0%), and tetralogy of Fallot (31%) was relatively low, whereas that of hypoplastic left heart syndrome (61%), other single ventricles (64%), atrioventricular canal defect (50%), and complex heterotaxy (82%) was relatively high. The authors go on to describe the overall inconsistency with which abnormalities of the ventricular outflow tracts were identified and/or reported. One could infer from these findings that many of the undiagnosed cases of CHD could be explained by the ultrasound provider's relative lack of familiarity with techniques for assessing the ventricular outflow tracts by ultrasound or limited fund of knowledge regarding normal and abnormal outflow tract anatomy.

Friedberg et al found no relationship between sociodemographic variables and prenatal diagnosis. In fact, 99% of the study population underwent at least one screening ultrasound, suggesting that access to prenatal care was not a factor in prenatal diagnosis. In contrast, the type of practice performing the ultrasound study significantly affected the prevalence of prenatal diagnosis, with university-based practices detecting 71% to 100% of major CHDs and non–university-based practices demonstrating substantially lower rates of detection, ranging from 0 to 39%. These data point to a system-based explanation for the low rate of prenatal CHD detection in northern California. Although ultrasound has a high diagnostic accuracy for CHDs in the hands of pediatric cardiologists trained in fetal echocardiography,11, 12, 13, 14, 15 the vast majority of ultrasound screening studies are performed by health care professionals trained in either radiology or obstetrics, who practice in a wide variety of settings. The data suggest a system-based problem at the “front lines” of fetal anatomic screening. For example, US community-based obstetrical ultrasound centers demonstrate very low compliance with AIUM standards,16 suggesting a lack of familiarity with accepted standards for diagnostic obstetric ultrasound in these settings. The results of Friedberg et al suggest that ultrasound studies performed in higher-volume, centralized university centers are superior, at least in the region of northern California that these centers serve. In 1993, the RADIUS Study Group reported a prenatal detection rate for all major fetal anomalies of 35% among US centers.4 In contrast, the reported detection rate for a similar era in Europe, where ultrasound centers are more centralized, was 61%.17

This is not simply an issue of getting the diagnosis correct. Although data associating prenatal diagnosis of CHDs with improved neonatal surgical outcomes are sparse,18 there is a growing body of data suggesting that prenatal diagnosis of major CHDs result in less shock/acidosis19, 20 and short-term neurologic morbidity21 in the immediate neonatal period. As outcomes in congenital heart surgery have improved, the focus has shifted away from merely achieving surgical survival toward optimizing neurodevelopmental outcomes and quality of life. It is likely that prevention of perinatal acidosis, shock, and hypoxemia will affect the overall outcome of these children.

So where do we go from here? Further work is needed to confirm whether or not the findings reported by Friedberg et al are generalizable on a wider geographic scale. Both access to and delivery of prenatal care may differ in other regions of the United States. But if these trends are found to be widespread, then improvements are clearly needed. As suggested by Friedberg et al, better education of ultrasound professionals may be needed to increase their familiarity with normal and abnormal cardiac anatomy. The ultrasound training of residents in obstetrics—who will sit on the diagnostic “frontline”—also may need improvement. Underscoring this notion, a 2003 survey of residents in obstetrics and gynecology revealed that only 16% believed that fetal ultrasound training was a mandatory program requirement.22 Other strategies for improvement may include moves toward high-volume, centralized diagnostic obstetric ultrasound centers and stricter accreditation standards for centers performing obstetric ultrasound. Technological advances also may play a part. For example, advanced 3- and 4-dimensional ultrasound systems have the ability to acquire “volumes” of data, as opposed to standard 2-dimensional planar images. Developments in automated display of the fetal heart by 3-dimensional imaging23 may allow clinicians to visualize a comprehensive set of fetal cardiac anatomic images without requiring the ultrasound operator to physically obtain multiple anatomic views of the fetal heart. In addition, advances in digital data storage, transfer, and analysis offer various strategies for telemedicine, which could improve access to experts trained in fetal anatomic imaging.

The report of Friedberg et al illustrates the challenges and complexities associated with detecting prenatal CHDs. Their data suggest that, at least in northern California, detection has not kept pace with advances in ultrasound imaging technologies, improved access to prenatal care, and nearly universal obstetric ultrasound screening. Given the potential impact of undiagnosed major CHDs on perioperative status and long-term neurodevelopmental outcome, we must acknowledge that there is room for improvement and take steps as a field to improve these trends.

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References 

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PII: S0022-3476(09)00218-2

doi:10.1016/j.jpeds.2009.02.057

Refers to article:

  • Prenatal Detection of Congenital Heart Disease , 27 April 2009

    Mark K. Friedberg, Norman H. Silverman, Anita J. Moon-Grady, Elizabeth Tong, Jennifer Nourse, Beatrice Sorenson, Jaimie Lee, Lisa K. Hornberger
    The Journal of Pediatrics July 2009 (Vol. 155, Issue 1, Pages 26-31.e1)

The Journal of Pediatrics
Volume 155, Issue 1 , Pages 9-11, July 2009

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