Donofrio et al Diagnosis and Treatment of Fetal Cardiac Disease 7

autoantibody (anti-Ro/SSA or anti-La/SSB) positivity in the general population is unknown. In prospectively examined preg-nancies of mothers with known antibodies and no prior affected child, the reported incidence of fetal CHB was between 1% and 5%. The number of affected pregnancies increases to 11% to 19% for those with a previously affected child with CHB.13–17 In addition, women with both autoantibodies and hypothyroidism

are at a 9-fold increased risk of having an affected fetus or neo-nate compared with those with SSA or SSB alone.18

In addition to abnormalities in the conduction system, up to 10% to 15% of SSA-exposed fetuses with conduction sys-tem disease may also develop myocardial inflammation, endo-cardial fibroelastosis, or atrioventricular (AV) valve apparatus dysfunction.94 Because of the perception that the inflammatory effects resulting from antibody exposure may be preventable if detected and treated at an early stage, it has been recommended that SSA/SSB-positive women be referred for fetal echocar-diography surveillance beginning in the early second trimes-ter (16–18 weeks).14,16,95 The mechanical PR interval has been measured in fetuses at risk with the use of a variety of M-mode and pulsed Doppler techniques and compared with gestational age–adjusted normal values.96 Although the value of serial assessment for the detection of the progression of myocardial inflammation or conduction system disease from first-degree block (PR prolongation) to CHB has not been proved, serial assessment at 1- to 2-week intervals starting at 16 weeks and continuing through 28 weeks of gestation is reasonable to per-form because the potential benefits outweigh the risks. For women who have had a previously affected child, more fre-quent serial assessment, at least weekly, is recommended.

Medication ExposureMost of the current literature implicating maternal medications in congenital abnormalities comes from retrospective patient interviews and voluntary registries and therefore may be sub-ject to bias. Nevertheless, a number of human teratogens are used clinically in women of childbearing age, and exposure to these medications in the period of cardiogenesis increases the risk of CHD. Among the most studied include anticonvul-sants, lithium, angiotensin-converting enzyme inhibitors, reti-noic acid, selective serotonin reuptake inhibitors (SSRIs), and nonsteroidal anti-inflammatory agents (NSAIDs).

AnticonvulsantsAnticonvulsants used in pregnancy include carbamazepine, diphenylhydantoin, and valproate. In a meta-analysis including a group of untreated epileptic women as control subjects, 1.8% of 1208 carbamazepine-exposed fetuses exhibited cardiac malfor-mations.21 This proportion was similar whether the mothers were taking carbamazepine alone or in combination with other anti-epileptic drugs. The incidence of malformations in the unmedi-cated epileptic control subjects was similar to that for the normal population. Fetal echocardiogram may be considered, although its usefulness has not been established if exposure occurs.

Lithium Lithium has been reported to be associated with cardiac malformations in up to 8% of offspring in a registry study.25 However, more recent prospective case-control studies22 and literature analyses97 have suggested that the risk is not as high as initially thought, with a risk ratio for cardiac anomalies of 1.1 (95% confidence interval [CI], 0.1–16.6).22 Fetal echocar-diogram may be considered, although its usefulness has not been established if exposure occurs.

Angiotensin-Converting Enzyme InhibitorsAngiotensin-converting enzyme inhibitor exposure in the first trimester is associated with increased risk for CHD, with

Table 3. Common Indications for Referral for Fetal Echocardiogram

Indications with higher risk profile (estimated >2% absolute risk)

Maternal pregestational diabetes mellitus

Diabetes mellitus diagnosed in the first trimester

Maternal phenylketonuria (uncontrolled)

Maternal autoantibodies (SSA/SSB+)

Maternal medications

ACE inhibitors

Retinoic acid

NSAIDs in third trimester

Maternal first trimester rubella infection

Maternal infection with suspicion of fetal myocarditis

Assisted reproduction technology

CHD in first degree relative of fetus (maternal, paternal or sibling with CHD)

First or second degree relative with disorder with Mendelian inheritance with CHD association

Fetal cardiac abnormality suspected on obstetrical ultrasound

Fetal extracardiac abnormality suspected on obstetrical ultrasound

Fetal karyotype abnormality

Fetal tachycardia or bradycardia, or frequent or persistent irregular heart rhythm

Fetal increased NT >95% (≥3 mm)

Monochorionic twinning

Fetal hydrops or effusions

Indications with lower risk profile (estimated >1% but <2% absolute risk)

Maternal medications

Anticonvulsants

Lithium

Vitamin A

SSRIs (only paroxetine)

NSAIDs in first/second trimester

CHD in second degree relative of fetus

Fetal abnormality of the umbilical cord or placenta

Fetal intra-abdominal venous anomaly

Not indicated (≤1% risk)

Maternal gestational diabetes mellitus with HbA1c <6%

Maternal medications

SSRIs (other than paroxetine)

Vitamin K agonists (Coumadin), although fetal survey is recommended

Maternal infection other than rubella with seroconversion only

Isolated CHD in a relative other than first or second degree

ACE indicates angiotensin-converting enzyme; CHD, congenital heart disease; HbA

1c, hemoglobin A1c; NSAID, nonsteroidal anti-inflammatory drug; NT, nuchal translucency; and SSRI, selective serotonin reuptake inhibitor.

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