Fetal Atrioventricular Heart Block

Summary

DOI: 10.1373/clinchem.2013.212035

As part of routine prenatal care, the obstetrician of a 25-year-old gravida 1, para 0 woman performed fetal heart-rate monitoring at 22 weeks gestational age. The fetal heart rate was 90 bpm, below the expected range of 120–160 bpm. This finding prompted a subsequent fetal ultrasound and echocardiogram.

Student Discussion

Student Discussion Document (pdf)

Michael A. DiMaio^1* and James D. Faix¹

¹Department of Pathology, Stanford University Medical Center, Stanford, CA.
*Address correspondence to this author at: Department of Pathology, Stanford University Medical Center, 300 Pasteur Drive, Lane 235 MC 5324, Stanford, CA 94305-5324. Fax 650-725-6902; e-mail [email protected]

Case Description

The ultrasound exam showed no evidence of hydrops. Cardiac anatomy was normal, with 4 appropriately sized chambers, no valvular defects, and no abnormal communications between the right and left circulations. However, the electrocardiogram demonstrated a 2:1 atrioventricular heart block (1 ventricular beat for every 2 atrial beats). Previously, a first-trimester screen to detect fetal aneuploidy had been performed and the results were normal. Results of serologic testing for hepatitis B, varicella, and rubella viruses were consistent with maternal immunity. Results of syphilis and HIV antibody tests were also negative. The expectant mother had no significant medical history, was taking no medications, and had no history or symptoms of autoimmune disease.

Questions to Consider

What conditions can cause an abnormally slow fetal heart rate?
What conditions can cause congenital heart block?
What additional testing should be performed?

Final Publication and Comments

The final published version with discussion and comments from the experts appears in the March 2014 issue of Clinical Chemistry, approximately 3-4 weeks after the Student Discussion is posted.

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