SVT OR AF

[Girlgolfer]

Please could somebody give me clarity on a simple question. Is AF the same as SVT. If they are different how do they differ. I had a diagnosis of SVT but as heart was very fast and irregular, is AF more appropriate. I had a p wave on the ECG at the time of the SVT episode so does this rule out AF. Also does the DVLA need informing for SVT like it does for AF. Thank you for helping me with these questions.

[MichaelJH Heart Star]

Hello and welcome to the forum!

Both AF and SVT are types of arrhythmias. There is a page on these and a downloadable booklet here:

bhf.org.uk/informationsuppo...

You can also discuss your condition further with the BHF nurses who are available M - F, 09:00 - 17:00.

As regards the DVLA I believe most arrhythmias need notifying to the DVLA. Again the BHF nurses may be able to advise. You should also notify your insurance company. The DVLA criteria for HGV and PSV licences are far stricter.

[Hidden]

With the caveat that I’m not remotely medically qualified, and this is my understanding as a layperson...

No, SVT and AF are not the same thing. Both are technically forms of supraventricular tachycardia, in that both originate from the atria, and episodes of both are associated with ectopic contractions as triggers, but in the condition commonly referred to by patients and medics as SVT, the rhythm is usually completely regular only ‘stuck’ at too high a rate. The heart contracts fully, but rather than the electrical signal that tells it to contract passing through the SA node and the heart beating once, the signal goes round and round the node like a circular race track. What we tend to call SVT is actually either a condition called atrioventricular nodal reentrant tachycardia (AVNRT) or atrioventricular reciprocating tachycardia (AVRT), it’s just we don’t distinguish them that way. On ecg, it will usually look like a normal, or close to normal waveform, just recurring very quickly.

In AF, the rhythm is irregular as a result of the heart failing to fully contract, so instead it quivers and flutters whilst trying to beat. The lack of full contraction means that there’s a risk of blood pooling, which leads to a risk for other issues such as heart attack and stroke, which is why patients with AF usually take a blood thinner in addition to medication(s) to reduce ectopics and slow the heart rate. The rate in AF is also not usually at the same levels as many episodes of SVT - with major bouts of SVT, it’s common to get rates in excess of 180bpm, with AF it tends to be less than this. Episodes of AF can also be much more persistent, to the point that it occurs most or all of the time (described as being in permanent AF), whereas SVT is usually distinct episodes: the episodes can be frequent, but although they can last for hours, and help should be sought for any episode lasting more than 30 minutes, or if accompanied by chest pain or feeling unwell, they will usually end spontaneously. Of the two, AF is considered to be a more serious arrhythmia due to the fact that it’s an irregular rhythm and there is a risk of complications. SVT is unpleasant and inconvenient, but generally considered to be benign by comparison, although issues can occasionally arise if someone is having very frequent, intense, and/or prolonged episodes, which is why patients experiencing episodes like that are normally offered ablation.

Ecg interpretation is a very complex thing, but my understanding is that there is no p wave present during AF, whereas there will be one present in SVT. There are other forms of supraventricular tachycardias that have more than one p wave present, so the presence or absence on ecg is a diagnostic element. Although it’s generally a regular rhythm just supercharged, so to speak, it’s entirely possible to have a more irregular ecg during SVT, particularly with AVNRT, so irregularity on its own doesn’t automatically mean it’s AF.

With regards to the DVLA, you need to notify them of anything where there is a risk of losing control of the vehicle e.g. due to dizziness or fainting. During my first episode of SVT, I felt completely well to begin with, I was just aware of my heart beating extremely fast. After half an hour, my bp crashed and I began to feel a bit grim, but I would have stopped the car with the palpitations, so that wouldn’t have been considered a risk. My last major episode of SVT had me feeling extremely unwell almost from the outset, so was reportable to the DVLA. The guidance is here, although not that helpful, and if you have even the slightest doubt about whether to report or not, you should ask your GP or consultant:

gov.uk/tachycardia-and-driving

Hope that helps.

[jeanjeannie50 in reply to Hidden]

What an excellent and informative post Charlie_G.

Do you know how SVT differs to atrial flutter please?

Jean

[Hidden in reply to jeanjeannie50]

Hi Jean. Not my area of ‘expertise’, but my understanding is that atrial fibrillation is the irregular beating of the atria, where flutter is the atria beating regularly but too quickly, and more quickly than the ventricles: for every 4 atrial contractions, there might only be one ventricular one.

[Carolx in reply to Hidden]

Wow Charlie_G! What a mind of information you are!I have SVT (lifelong) and you have taught me so much from your post.

You explain it so well.

Thank you so much.

The mri results are like trying to decipher algebra and Latin, whilst reciting Shakespeare! 🤪

Have a lovely day

Carol x

[Suze43 in reply to Hidden]

This is a really helpful explanation Charlie, thank you so much. You may not be medically qualified but you certainly explain it better than the medics. I get fast AF which seems to be a combination of SVT & AF!

[Hidden in reply to Suze43]

I think a lot of doctors often forget we didn’t go to medical school, but we do have to live with these things when we leave the appointment! Glad it’s helped you and some others 🙂

[RapidRandomHeart1 in reply to Hidden]

Wow Charlie thank you for explaining. I was recently diagnosed as having SVT during labour in February and trying to find out information in layman’s terms is a minefield online. I just had my first consultation appointment and I think ablation is on the cards for me but afraid of the potential risks - I’m only 30 and was prescribed metoprolol since the last 4 months but not sure whether to risk weaning off it since I lived the first 30 years without it. Yet the last few episodes I’ve needed intervention since I haven’t been able to stop it on my own (I used to be able to hold breath and bear down to make it disappear)

[Hidden in reply to RapidRandomHeart1]

Congratulations, and commiserations at the same time! I hope you and Baba are fine otherwise, and I’m glad my reply has helped you a bit.

Although they don’t always work for everyone, had I been offered ablation when I first started having SVT at 24, I would have taken it. I didn’t receive good care from the outset, and in spite of high doses of beta blockers, was left having very prolonged episodes 2 or 3 times a month, sometimes 2 or 3 a week, for about 6 years. I’ve never been able to end them using vasovagal manoeuvres like bearing down, so I either had to go to A&E, or just wait them out, but I was perpetually exhausted. I now know I should have been offered an ablation, but for whatever reason - and I have some ideas - never was. Having said that, after my last episode, where I felt extremely unwell and again needed adenosine, I read up on ectopics and made some major lifestyle changes. In combination with medication, cutting out things that are known to increase the frequency of ectopics (which are the trigger for SVT) has resulted in managing to go without a single episode since that last one in 2015. I still have some ectopics each day, but the burden has come way down, and I’ve been lucky enough to remain SVT free as a result, so not being offered an ablation is now a moot point.

Unfortunately, not everyone benefits from making lifestyle changes, partly because we still don’t really understand the underlying causes, and it does depend on whether your ectopics originate from the sympathetic or the parasympathetic nervous system, or if you have an underlying condition causing the SVT like Wolff Parkinson White syndrome (WPW, can be diagnosed via an echo), but it’s medically confirmed that some people can and do benefit. You may not be sensitive to all of them, or even any of them, but the main things to look at are stimulants, so all caffeine (including tea); dark chocolate and white chocolate; some meds such as antihistamines, pseudoephedrine which is found in many cough and cold remedies, asthma inhalers, and anything containing adrenaline, including some forms of local anaesthetic; tobacco; alcohol. Anecdotally, some people also have a problem with eating ginger (myself included), and others have had good success by cutting out spicy food. That’s in addition to managing the other medically accepted lifestyle factors, which are insufficient sleep, and stress and anxiety. I always tell people with SVT that they have nothing to lose by modifying lifestyle, and potentially a lot to gain. I do really miss proper coffee, though!

If you’re not keen on the idea of ablation, it might be worth exploring the above and seeing what happens? Unless the met is causing you issues, though, I would stay on it. I definitely wouldn’t advocate stopping it without speaking to a medic, if only because it does have a protective function within the heart. SVT is an inconvenience, but very frequent SVT is potentially problematic longer term, so beta blockers (or CCIs instead) do have a place even for those with good control.

[Kristin1812 Heart Star]

Really useful, Charlie. Thanks lots for your descriptions. I never understood AF and SVT before!

[Hidden in reply to Kristin1812]

Glad it helped 🙂

[Girlgolfer]

Thank you Charlie....you have totally confirmed what I was told at the time I had an SVT episode from the medics in hospital. However, my GP calls it AF which totally confused me. Basically the GP is wrong as you have informed me well and I definitely had a SVT and not AF.