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(pac) premature atrial contractions with bigeminy

My sister, who is 35 weeks pregnant, found out approximately 5 weeks ago that her baby has (pac) premature atrial contractions with bigeminy. She was referred from her midwives' practice (At Guthrie Medical Center, PA) to a high risk ob/gyn (at Arnot-Ogden Medical Center, NY), who has been following her weekly. At first, the specialist was not concerned, stating that this problem typically goes away or at least improves during fetal development. As of this morning, the specialist is becoming concerned, because there has been no change or improvement with the heartbeat, etc. He is seeing my sister again on Monday and is consulting a pediatric cardiologist at that time if there is still no change. She is due in late January, so there is not a lot of time left before the birth of the baby.

I have looked online and cannot find much information on this. I have found explanations of the electrical firing and premature "beat" or contraction, as well as what it looks like on a monitor. This doesn't help much because we don't know how to interpret that information to real-life concerns, etc. What we would like to know is what might this mean for the baby? Are we looking at medication (the ob/gyn mentioned that, and feels it is too risky for my sister to take because she does not have a heart problem), surgery, or watch and wait? Is there anywhere online to access more information about this?

It would be nice to figure out what causes this, if there is any answer to that, but that is not nearly as important as what to expect. There have been some health issues that my sister has faced during this pregnancy, which I can expand on if that would be helpful.

Thank you in advance for any input and information.
1 Responses
773637 tn?1327446915
Dear Amy,

As you’ve already ready, premature atrial contractions (PACs), abnormal early heartbeats that originate in the upper chambers of the heart, are frequently seen in utero, especially during the second trimester.  They can persist into the third trimester, but often go away during that time or soon after birth.  Bigeminy, for our othe r readers, means that every other beat is premature.  There are two issues that can become concerning here.  The first is what the underlying heart rate and ventricular function of the heart is.  Frequent PACs, even as much as bigeminy, don’t cause problems UNLESS they are causing the heart rate to be too slow for the baby’s needs.  This can manifest in congestive heart failure, or a form of what is called hydrops.  So, the important questions here are whether the baby has a structurally normal heart and also if the ventricles, the pumping chambers, are working adequately.  The second issue is that sometimes PACs can lead to supraventricular tachycardia, an abnormal sustained fast heart rate, which can also lead to problems, especially if it is sustained for a long period of time.  Often, we do not know the reason for PACs, though sometimes we do see a structure inside the right atrium called the Eustachian valve, a normal structure, that can be larger than usual.  It can be floppy and smack against the wall of the atrium during the normal cardiac cycle, which can cause these early beats.

Without knowing much more about the baby’s heart or the mother’s medical condition, it is difficult to be able to say much more about this.  A pediatric cardiologist who specializes in fetal cardiology would be an appropriate person to evaluate mother and baby at this time.  A fetal echocardiogram can be performed, which is a detailed cardiac ultrasound of the baby’s heart.  Your sister can look for a center that has this available and is, hopefully, relatively close to home.
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