Which drug is associated with Ebstein anomaly (abnormal tricuspid valve)?

• A. Valproic Acid
• B. Lithium
• C. Methimazole
• D. Alcohol

Answer: (B)

The key idea is how certain drugs taken during pregnancy can affect fetal heart development, specifically the tricuspid valve. Ebstein anomaly involves downward displacement of the tricuspid valve leaflets into the right ventricle, creating an atrialized portion of the ventricle and usually significant tricuspid regurgitation.

Lithium exposure in early pregnancy is classically linked to Ebstein anomaly. Lithium crosses the placenta and can disrupt the normal formation of the tricuspid valve during the first trimester, increasing the risk of this specific malformation, though the absolute risk remains small.

The other substances have different teratogenic profiles: valproic acid is more associated with neural tube defects and facial/brain anomalies; methimazole can cause defects such as scalp lesions (aplasia cutis) and thyroid-related issues; alcohol causes fetal alcohol spectrum disorders. But Ebstein anomaly is the association most often linked to lithium.