Protocols for High-Risk Pregnancies. Группа авторов

PROTOCOL 6 Fetal Echocardiography

       Joshua A. Copel

      Departments of Obstetrics, Gynecology and Reproductive Sciences, and Pediatrics, Yale School of Medicine, New Haven, CT, USA

Overview

      Congenital heart disease occurs in approximately eight of 1000 live births. Of these, approximately half are relatively minor ventricular septal defects or valve stenoses that are of little hemodynamic significance. Some of these can be identified prenatally with sensitive color Doppler flow mapping with little clinical impact, while many others are undetectable prenatally. The remainder are significant lesions that may benefit from prenatal detection, parental counseling, and obstetric‐pediatric planning for delivery and neonatal care.

Pathophysiology

      Most types of congenital heart disease are thought to be inherited in multifactorial fashion, with both genetic and environmental contributions. The indications used for fetal echocardiography, a prenatal ultrasound technique that can detect most significant congenital heart disease, reflect that etiological diversity. Many patients referred for fetal echocardiography have had prior affected children or other affected family members, and the recurrence risk for these families is about 2–3% if there has been a prior affected child, and 3–5% if one of the parents has congenital heart disease.

      The pathophysiology of congenital cardiac anomalies varies with the type of anatomical abnormality that is present. The underlying mechanisms include failures of cell migration leading to failure of a structure to form, or diminished flow, inhibiting the normal growth of a downstream structure (e.g., poor flow across the foramen ovale and mitral valve predisposing to a coarctation of the aorta).

Structural heart disease

      Diagnosis and work‐up

In patients without risk factors for congenital heart disease, full fetal echocardiography, which is generally more time‐consuming and expensive than general obstetric sonography, is not indicated unless cardiac anomalies are suspected. Many risk factors for congenital heart disease have been described (Table 6.1).

The four‐chamber view of the heart has been suggested as an easy way of screening for congenital heart disease, although its sensitivity to significant cardiac anomalies has varied in the literature. Approximately one‐third of cases of major heart disease are detected on screening prenatal ultrasound, according to a review of the world’s literature. Our own experience suggests that it has a very high positive predictive value, with about half of patients referred for abnormal four‐chamber views actually having cardiac anomalies. Current recommendations from US medical societies, including the American College of Obstetricians and Gynecologists (ACOG), the American Institute of Ultrasound in Medicine (AIUM), and the International Society of Ultrasound in Obstetrics and Gynecology, all call for including outflow tract views in the standard (or so‐called “Level 1”) obstetric scan.

Table 6.1 Indications for fetal echocardiography

Full fetal echocardiography includes obtaining all the views in the fetus routinely obtained in postnatal echocardiography (Table 6.2) using both real‐time gray‐scale and color Doppler imaging. Additionally, spectral Doppler, cardiac biometry, and M‐mode data can be obtained as indicated. Fetal echocardiographers use these latter techniques variably. The two‐dimensional examination should be sufficient to exclude significant heart disease in the vast majority of affected individuals. The more sophisticated studies are especially useful in cases of suspected structural or functional abnormalities.

In a recent Practice Parameter, the AIUM has described required and optional components of the detailed fetal echocardiographic examination, shown in Table 6.3.

Table 6.2 Standard fetal echocardiographic views and what to see

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