Episode 187 Palpitations In Pregnancy

We explain why palpitations and a fast heart rate are so common in pregnancy, and how to separate normal physiological change from signs that need urgent assessment. We walk through the questions we ask, the tests we choose, and how we stay reassuring while still taking symptoms seriously. 
• normal pregnancy physiology and a typical 10 to 20 bpm rise in resting pulse 
• why a high heart rate is a general sign of illness rather than a diagnosis 
• infection screening in pregnancy including urine and chest symptoms 
• iron deficiency anaemia and why low haemoglobin drives tachycardia 
• thyroid function tests as part of a sensible blood work-up 
• when breathlessness and oxygen levels point towards lung causes 
• recognising red flags for pulmonary embolism and checking for leg clots 
• ECG as a snapshot and why intermittent symptoms may need longer monitoring 
• what a 24-hour tape involves and how an event log helps interpretation 
• likely results including sinus rhythm and sinus tachycardia 
• rarer arrhythmias in pregnancy including SVT and atrial fibrillation or flutter 
• treatment options including carotid sinus massage, medication, and MDT care 

Want to know more?

https://www.nhs.uk/symptoms/heart-palpitations/

https://www.sciencedirect.com/science/article/pii/S1470211824054617

https://www.nhs.uk/conditions/supraventricular-tachycardia-svt/

https://www.medicinesinpregnancy.org/leaflets-a-z/bisoprolol/

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Thank you all for listening,  My name is Florence Wilcock I am an NHS doctor working as an obstetrician, specialising in the care of both mother and baby during pregnancy and birth. If you have enjoyed my podcast please do continue to subscribe, rate, review and recommend my podcast on your podcast provider.
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Its easy to explore my back catalogue of episodes, I have a wide range of topics that may help you make decisions for yourself and your baby during pregnancy as well as some more reflective episodes on life as a doctor.
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My bea...

Transcript

Welcome To The Obspod

Florence 0:00

Hello, my name's Florence. Welcome to the Obspod. I'm an NHS obstetrician, hoping to share some thoughts and experiences about my working life. Perhaps you enjoy Call the Midwife. Maybe birth fascinates you, or you're simply curious about what exactly an obstetrician is. You might be pregnant and preparing for birth. Perhaps you work in maternity and want to know what makes your obstetric colleagues tick, or you want some fresh ideas and inspiration. Whichever of these is the case, and for that matter anyone else that's interested, the obspod is for you.

Why Palpitations Prompt A Check

Florence 0:48

Episode 187, palpitations in pregnancy. Quite commonly we will see a woman in the antenatal clinic or perhaps in our triage area who is saying she's got palpitations. That is she's aware of a fast heartbeat, sometimes a bit disconcerting. Maybe she can also hear it ringing in her ears, or she feels it jumping around in her chest. Sometimes these days she may not have noticed anything. Or perhaps the midwife or obstetrician has done a set of observations. Checking blood pressure at a routine appointment and pulse is a normal thing to do, and maybe we've noted that her pulse is a bit fast. This is a really common issue, and therefore something that I thought I'd do an episode on.

The Normal Heart Rate Rise

Florence 1:58

The first thing to say is that having a raised heart rate is a completely normal effect of pregnancy. The reality is that your body is working a bit harder. You're pumping a lot of blood to the placenta, to the womb, and therefore there are physiological changes, so changes in the way your body is working to support this completely new organ. On average, people's pulse goes up 10 to 20 beats per minute. So if you normally have a heart rate of maybe 60 or 70, your normal resting heart rate might go up to 80 to 90. The problem is that a raised heart rate can also indicate some underlying issues, and therefore we have to try and differentiate when is a woman's pulse rate higher because she's unwell from when is a woman's pulse rate higher because that's just how her body has adapted to pregnancy. The other thing that's really important to say is that a high heart rate is a sign of lots of different illnesses. It's the way the body responds, and it doesn't mean that there's an underlying heart problem. So much of what I'm going to talk about today doesn't actually relate to the heart at all.

Infection Anaemia Thyroid Checks

Florence 3:31

One of the commonest reasons to have a high heart rate is actually to have an infection. Infections can be a bit more common in pregnancy, particularly urine infections or chest infections. So one of the first things that we'll do when we notice you have a high heart rate is ask you lots of other questions about how you're feeling. Are you feeling well? Take your temperature, have you had any symptoms like a cough or cold or burning or stinging when you're passing urine? You might find this a bit strange. You come because you're worried about palpitations, and actually, we're asking you a load of other completely unrelated questions or seemingly unrelated. To us, they're very important. Another common pregnancy problem that can make your pulse go up is anemia. So you're a bit short of iron, your blood count has dropped a bit, and therefore your body is working that bit harder to provide your body with the oxygen it needs. It hasn't got as much hemoglobin, the compound in your red blood cells, that helps carry oxygen. It's got to make up for that deficit by pumping blood more quickly around your body. So one of the first things we will check when you have a high heart rate is your blood count and see if you're anemic because anemia is so common in pregnancy. If we're taking blood tests, we will also take thyroid blood tests. It would be unusual to find a thyroid problem in pregnancy, but remember pregnancy is a window onto someone's health. Women that may not have seen a doctor for years will come and see midwives. So we will check for thyroid hormones and TSH, thyroid stimulating hormone, because an overactive thyroid can also increase someone's pulse rate. One of the symptoms could be palpitations and a high heart rate. Once we've done all those things, ruled out infection and done those simple blood tests, we'll then focus in on the heart, or maybe I should say the heart and lungs themselves.

Breathlessness And Clot Red Flags

Florence 6:08

One of the questions we'll ask is whether there's any breathlessness or shortness of breath when you get the palpitations. And we'll ask questions about when you get the palpitations. Are you doing anything in particular? Palpitations when you're sitting down chilling out are obviously more concerning than palpitations when you might be exercising or perhaps climbing the stairs. One of the reasons I said lungs is that a high heart rate palpitations could potentially be a sign of a blood clot on the lungs, so-called pulmonary embolus. This is a rare complication, but is a bit more common in pregnancy. And I talked about blood clots in much more detail in episode 112. So you can go back and have a bit of a listen to that if you're interested in knowing more. So we'll look at your oxygen levels, listen to your chest, check your legs for any blood clots because that's where clots in lungs originate. And if we're happy that a blood clot is unlikely, or we've done the test for a blood clot and ruled it out, we'll then focus in a little bit more on the heart itself.

ECG Then A 24 Hour Tape

Florence 7:32

We might ask for an ECG, that's an echocardiogram. So that's a recording of the electrical activity in your heart. And that can be really useful as a snapshot to see what's going on. Are there any signs of any heart problem or heart disease in that immediate moment? This is done by attaching a number of leads to your chest as well as your arms and legs for a couple of minutes and taking a tracing. Most of the time, this will be completely normal. But that isn't especially helpful if at the time you're seeing us you're not experiencing the symptoms, the palpitations that you're really worried about. This means that the next step is to do something called a 24-hour tape. This is when you wear a little monitor that records your heartbeat, the electrical activity in your heart, that ECG, for a period of 24 hours. I've ordered many of these over the years for women that I've seen in clinic. And whilst I knew the principles of what I was doing, I didn't know what it would actually feel like to wear a heart monitor. But recently I had to have one myself. So I finally had first hand experience of what I'd been requesting. It's a tiny little gadget, the size of a pager, if you've ever had one of those, or about a third of the size of a mobile phone. It clips to your waistband or your bra and is quite light and unobtrusive. It attaches to you with three wires which are attached to some sticky pads on your chest. I'm going to put some pictures on my Instagram if you want to see what it looks like. You wear it for a period of 24 hours, and if you have symptoms during that time, you note it down in an event log so that when the technician analyses the 24-hour tape, they can see what your heart was doing at that moment when you felt you had symptoms. Whilst I was going about my day-to-day, which happened to be my day off, so I was walking around doing the shopping, going on the tube, etc., in London, it's not very easy to lift up your shirt, whip out your little recorder, and check the actual time on the monitor. The other minor problem I had was in bed at night, where to put the monitor and how to sleep comfortably while it was in place. However, I did find the whole experience not only interesting to see what it was like, but also less disruptive than I perhaps had imagined. So your midwife or doctor may well suggest you have a 24-hour tape. It's not a difficult thing to do, and it gives us a much longer period of that ECG electrocardiogram on which to see what is happening with your heart rate. Importantly, most of the time I organise this test. The results are entirely normal, what we call sinus rhythm, the normal electrical activity and regular rhythm of the heart that we want. That doesn't mean to say that that's not causing symptoms, but it does mean that there's no pathology there, there's no disease or problem causing those palpitations.

SVT And Other Rare Arrhythmias

Florence 12:16

It's just the heart doing its job, but in a rather faster way. What we're looking for in the tape is any sign of different rhythms that are problematic, one of which is something called SVT, supraventricular tachycardia. SVT has been reported at a rate of 22 to 33 per 100,000 pregnancies. And this is a very different sort of rhythm where the woman's heart rate can suddenly go up to about 200 or 220. So clinically, it's often quite obvious when this is the case. It's not that we're seeing a woman with a heart rate of 100 or 120, it's 200. It's almost always going to be SVT. And this needs treatment because usually the woman will be symptomatic, and the other type of arrhythmia that can be seen in pregnancy, which apparently is more common, 31 to 59 per 100,000 pregnancies, is atrial fibrillation or atrial flutter. Although I must say, in my NHS UK practice, I haven't seen AF or atrial fibrillation in pregnancy, but I have seen some cases of SVT or supraventricular tachycardia. Both of these are treatable. Slightly bizarrely, you may think. The first treatment for SVT is something called carotid sinus massage. This is by stimulating the carotid baroreceptors to slow the heart rate. So if you're stable and you're feeling okay, what the doctor will do is put some pressure on one side of the neck for a few seconds, which may slow your heart rate down. Sometimes once women have got a diagnosis of SVT, they know and learn how to do this themselves. If this doesn't work, then there is medication that is given, which will usually restore the heart to a normal rhythm. So women with SVT are often quite well, have these periods of very, very fast heart rate which need some treatment, and this needs attention from the multidisciplinary team, so involving cardiologists, obstetricians, andaests, but can be very safely managed during pregnancy. Out of pregnancy, a woman will need follow-up with a cardiology team and may need some definitive treatment, which can include something called ablation, where a minor procedure is performed on the heart to correct the electrical activity. But we definitely wouldn't undertake that in pregnancy. So I would say more than 95% of the time the 24-hour tape ECG that I order comes back as normal. Rarely it'll come back with an arrhythmia, such as SVT. More commonly, it will come back with a sinus tachycardia. And this could be a woman having a heart rate up to perhaps 140, 150, which can be fine but can be really quite unpleasant. So the action we take next will depend on the woman's symptoms. If she's having very fast runs of heart rate and feeling really unwell with it, then we can start treatment with a small dose of a medication called basoprolol. This is a beta blocker, and its effect is to just slightly slow the heart rate down so that a woman is less symptomatic, doesn't have those runs of perhaps 150, 160. So I'm going to put some links to all these different things in the show notes for you to explore more. Right,

Treatment Choices And Reassurance

Florence 16:50

zesty bit. First things first, if you're a pregnant woman with palpitations, tell your team looking after you, but don't worry. 99% of the time it'll be completely normal, it'll just be the way your body is responding to pregnancy. And don't forget, most of the causes of a high heart rate are actually nothing to do with your heart. There are common problems in pregnancy, such as being a bit anemic or having a urine infection. So go get checked out, but don't worry too much. If you're a midwife or healthcare professional, yes, we need to take a fast heart rate seriously, we need to look for the underlying causes, but it's unlikely that if you're detecting a steady pulse of a normal rhythm up to about 150, that the most likely thing is that this is normal or driven by some underlying issue. Arrhythmias are usually very rare and quite obvious. With atrial fibrillation or flutter, you get a very irregular pulse, and with SVT, as I said, you can get a pulse of around 200. We need to take a fast heart rate seriously, but again, most of the time it's going to be just the body's adaptation to pregnancy. So we need to do tests but also be reassuring to the women under our care.

Links Contact And Keeping It Free

Florence 18:28

I very much hope you found this episode of the Obspod interesting. If you have, it'd be fantastic if you could subscribe, rate and review on whatever platform you find your podcasts, as well as recommending the Obspod to anyone you think might find it interesting. There's also tons of episodes to explore in my back catalogue from clinical topics, my career and journey as an obstetrician, and life in the NHS more generally. I'd like to assure women I care for that I take confidentiality very seriously and take great care not to use any patient-identifiable information unless I have expressly asked the permission of the person involved on that rare occasion when it's been absolutely necessary. If you found this episode interesting and want to explore the subject a little more deeply, don't forget to take a look at the programme notes where I've attached some links. If you want to get in touch to suggest topics for future episodes, you can find me at the Obspod on Twitter and Instagram, and you can email me theobspod at gmail.com. Finally, it's very important to me to keep the Obspod free and accessible to as many people as possible. But it does cost me a very small amount to keep it going and keep it live on the internet. So if you've enjoyed my episodes and by chance you do have a tiny bit to spare, you can now contribute to keep the podcast going and keep it free via my link to buy me a coffee. Don't feel under any obligation, but if you'd like to contribute, you now can. Thank you for listening.