Safe Medications for Tachycardia During Pregnancy: Options & Considerations

Question
I have been taking atenolol for about 3 years for tachycardia.  My numerous doctors have not been able to find a reason for the tachycardia.  I am on 25mg of atenolol each night and my heart rate still stays about 95-100.  My husband and I would like to start trying for a baby soon, but am unsure of any medication that is safe for me to take during pregnancy.  Are there any medications that my doctor might prescribe for me that are safer than atenolol?  Thanks so much for your time and effort, Beth

Answer
Dear Beth,

There are some conflicting reports. Atenolol is classified as a FDA Pregnancy Risk Category D drug, however I have seen where it is also generally reported as appearing safe for use in pregnant patients with chronic hypertension, though it has caused fetal bradycardia (slow heartbeat) and growth retardation. Another beta-blocker choice which has a slightly better FDA Pregnancy Risk Category of C is metoprolol, but is also has the same findings as the atenolol for bradycardia and growth retardation.

The problem is that during pregnancy there are some profound hemodynamic shifts and changes, as well as during labor/delivery and during the post-partum period. During pregnancy, blood volume increases 40-50% during normal pregnancy, cardiac output rises 30-50% above baseline, stroke volume increases during the first and second trimesters, but then declines in the third trimester. During labor/delivery, each uterine contraction results in the displacement of 300-500 ml of blood into the general circulation. Stroke volume increases, with a resultant rise in cardiac output by an additional 50% with each contraction. Mean systemic pressure also rises, in part due to maternal pain and anxiety. Blood loss during delivery (300-400 ml for a vaginal delivery and 500-800 ml for a C-section) can further compromise the hemodynamic state. I know that all these things are really complicated and you may not care about the details, but all these things will potentially cause havoc with your unexplained tachycardia. So a discussion with your cardiologist is definitely warranted prior to becoming pregnant.

I hope this has helped you and answered your question. I wish you well.

Brenda