Which medication is used to treat tachyarrhythmias during pregnancy?

Propranolol is commonly used to treat tachyarrhythmias during pregnancy due to its effectiveness in managing abnormal heart rhythms. It is a beta-blocker that helps to slow down the heart rate and can alleviate symptoms associated with tachyarrhythmias, which can include palpitations, dizziness, and anxiety.

The use of propranolol in pregnant patients is often based on its relatively well-established safety profile when used appropriately, although monitoring is necessary to ensure both maternal and fetal safety. It can be particularly helpful if the tachyarrhythmia poses a risk to either the mother or the fetus, as it aids in stabilizing heart function.

In contrast, the other medications listed are not indicated for the treatment of tachyarrhythmias during pregnancy. Ampicillin is an antibiotic, Heparin sodium is an anticoagulant used primarily to prevent blood clots, and Digoxin is primarily used for heart failure and certain types of arrhythmias but carries risks during pregnancy that may limit its use. Therefore, propranolol is the most suitable choice in the context of managing tachyarrhythmias in pregnant patients.