Atrial Fibrillation in Pregnancy: What is it? How is it managed?

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When you’re pregnant, your entire body changes to adjust to the increased load of supporting another life. Your body not only goes through hormonal changes, but it also goes through immense physical changes. These changes stress all of your internal organs, including your heart.

Your heart is a muscle that pumps blood throughout your body. Blood carries oxygen to all of your muscles, including your heart muscle, so they can continue to do the work of keeping you alive. One of the changes your heart adapts to when you’re pregnant is an increase in the volume of blood in your body. An increased blood volume means your heart has to work even harder to circulate it. This can affect its function.

The extra blood volume causes your heart muscle to stretch more. Imagine a rubber band. The more you stretch it, the stronger it contracts. This can be good if you’re trying to pump more blood through a pregnant body.

However, there is also an electrical signal that travels through the heart. When the heart is stretched, that means the signal has to travel further and spread out more. This can disrupt the heart’s normal rhythm. A disruption in the heart’s normal rhythm is called an arrhythmia.

What is Atrial Fibrillation?

An arrhythmia can affect the two chambers at the top of your heart (the atria) or the two chambers at the bottom (the ventricles). One of the arrhythmias that affects one or both upper chambers of your heart is called atrial fibrillation. Atrial fibrillation (AF) is the most common adult heart arrhythmia. It is mostly seen in older adults and is relatively rare in pregnancy.

If you have been diagnosed with AF prior to your pregnancy, you will want to consult with your doctor about which medications would be safe to continue taking. Some common medications used in managing AF can be harmful during your pregnancy.

If you develop AF in pregnancy, it’s important that your doctor evaluates you for an underlying heart condition that may have not been previously diagnosed, such as congenital heart disease or rheumatic valve disease. Further, your blood should be checked for possible electrolyte abnormalities and hyperthyroidism.

Atrial fibrillation in the presence or absence of any other condition is concerning because it could lead to hemodynamic instability. That is, you may experience a drop in blood pressure that could compromise the blood supply to your developing baby. Atrial fibrillation also puts you at increased risk for developing dangerous blood clots.

How is Atrial Fibrillation Treated?

Treatment of atrial fibrillation is composed of a three-pronged approach: anticoagulation (preventing blood clots from forming), rate control (slowing the speed at which the heart beats), and rhythm control (coaxing the heart to maintain a normal sinus rhythm).

Blood thinners are a mainstay of anticoagulation treatment in AF. However, many commonly used blood thinning medications are not considered safe for use during pregnancy and should be avoided. These medications include warfarin (Coumadin), dabigatran (Pradaxa), apixaban (Eliquis), and rivaroxaban (Xarelto).

Your doctor may prescribe heparin, which is an anticoagulant medication that does not cross the placenta and is considered safe in pregnancy.

For rate control, digoxin and certain heart-specific beta-blockers (like metoprolol or atenolol) have been shown to be effective and generally safe during pregnancy. However, care must be taken with beta-blockers because they could slow your baby’s heart rate as well as your own. Additionally, beta-blockers may cause low blood sugar and low blood pressure in your developing baby.

That brings us to rhythm control. All of the anti-arrhythmic medications currently in use to treat atrial fibrillation cross the placenta and can have an effect on your baby. Amiodarone (one of the most commonly used anti-arrhythmic medicines in AF) should be avoided in pregnancy as it is associated with severe side effects causing fetal thyroid dysfunction. On the other hand, quinidine and procainamide have been used effectively during pregnancy to control the heart rhythm disturbances associated with AF, but should be used with caution. Finally, if necessary, electrical cardioversion from atrial fibrillation to normal sinus rhythm can be performed safely in all stages of pregnancy to prevent disruption to your baby’s blood supply.

Though rare in pregnancy, atrial fibrillation can cause serious complications for your baby. Proper management of this heart rhythm disturbance is essential. Management comprises a three-pronged approach addressing anticoagulation, rate control, and rhythm control. With proper management you can have a safe and healthy pregnancy.

Janette DeFelice
Dr. Janette DeFelice is a writer currently focusing on how the changing environment affects our health. She holds a Doctor of Medicine degree from Chicago Medical School where she taught clinical and diagnostic skills to beginning medical students, and a Master’s degree in Humanities from the University of Chicago. She also has a Bachelor’s degree in Political Science. Her writing can be seen online at BeTheChangeMom, ChicagoNow, and Medium, and she’s very excited to have published her first novel, Delia Rising: A Ballet in Three Acts. She lives in Chicago’s west suburbs with her school-age twins, her husband, and a family cat named Clara Barton.

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