SVT Versus AFib

[Bunkular]

Is there any difference between Supra-Ventricular Tachy and Atrial Fib?

[CDreamer]

Technically yes. SVT is a general term Supra Ventricular Tachycardia = fast heart rate with a source that originates from above the ventricles. For some people AF can induce SVT and they then have tachycardia whilst in AF whilst others with SVT will have tachycardia without the irregular rhythm that AF induces. Think rate v rhythm. AF always has an irregular, irregular rhythm whilst tachycardia the rhythm will be regular but the rate fast.

You will see if it is AF on an ECG if there is any confusion because Lead 1 will not have a P wave,

Arrhythmias are tricky things to diagnose so this is why we need specialist cardiology consultations. None of the GPs in our surgery except one who trained in cardiology could read an ECG - which I found rather disturbing. But what do I know?

Hope that helps.

[Bunkular in reply to CDreamer]

Thank you!

[frazeej in reply to CDreamer]

CD: >>But what do I know?<<

Sounds to me that at least you know more about reading an ECG than all (save one) of the GPs in your surgery! Perhaps a part time consultancy in the future? LOL!

JimF

[CDreamer in reply to frazeej]

🤪🤣🤣 Maybe NOT. The more I learned (and I did an uni open resource course on it) the more I realised the complexity and hence the need for specialists!

[mjames1]

Like CDreamer said, technically yes, they are the same. However, in terms normal practice/usage, quite different, where SVT is separated and treated differently from both afib and aflutter.

To simplify, SVT is from the right side. Afib from the left. Afib is a lot more serious and harder to treat. SVT ablations, should your situation warrant it, are much easier on the patient and have over 95% success rates.

Jim

[Bunkular]

Thank you.

[Autumn_Leaves]

Yes, quite different. In AF the upper chambers of the heart beat chaotically whereas with SVT the heart may be beating fast but the upper chambers are still regular. The only way of knowing what is going on is to have a full ECG interpreted by someone who is experienced in reading them. If you are having episodes of SVT you still need medical care, especially if you are having prolonged episodes.

[Bunkular in reply to Autumn_Leaves]

Thank you for the info. Much appreciated! I have a phone consult tomorrow with my doctor and I want to have some knowledge about this.

[Ppiman]

AF is a description of what is happening to the left atrium, whereas SVT is an umbrella term for what is happening to the left ventricle when it has a sustained beat above 100bpm. Often, the AF causes SVT, but there are other causes. Runs of PVCs are also called SVT, sometimes, for example, I believe.

Steve

[baba in reply to Ppiman]

“SVT is an umbrella term for what is happening to the left ventricle”

That is not correct.

SVT=Supra Ventricular Tachycardia. Happening above the ventricles.

[Ppiman in reply to baba]

I always thought that the tachycardia (being the symptom of concern) described what was happening to the ventricles, i.e. in general, a sustained rate above 100bpm, but that this was caused by the "supra-ventricular” chambers of the heart, I.e. the atrium and its hyperactivity.

Steve

[Mugsy15]

Just to add a very simple note to Autumn Leaves' excellent post; I spent several months in persistent AF and never had tachycardia.

[Mugsy15]

There seems to be some confusion here about which of the four chambers are affected by AF and SVT. Neither are conditions in which one side or the other is affected in isolation.

For clarity, AF and SVT both originate in one or both of the atria and both affect all four chambers. Neither can be said to originate from or affect left or right chambers in isolation.

It is important, however, to distinguish between upper and lower chambers in terms of where either condition originates. Fibrillation and Tachycardia are both far more serious and indeed life-threatening when originating in the ventricles.

[Autumn_Leaves in reply to Mugsy15]

The left side explanation didn’t make sense to me either. I haven’t heard of that before.

One thing that people sometimes get confused with re SVT is that Supra Ventricular means originating ABOVE the ventricles, which almost always means the atria. SVT is not a ventricular tachycardia, but quite a few of people on these forums seem to believe (mistakenly) that it is.

[Mugsy15 in reply to Autumn_Leaves]

You have it spot-on.

PVC is, obviously, a condition arising in the ventricles. It therefore cannot be Supraventricular.

Supraventricular Tachycardia was previously called Atrial Tachycardia. As I understand it, it was changed to take into account the fact that rogue signals may in some cases arise from the AV node as well as the atria. This being the case, I've often wondered why AF hasn't also been changed to SVF.

Perhaps tachy can start in the AV node but Fib cannot? That would explain it.

[mjames1 in reply to Mugsy15]

The vast majority of a fib is comes from the pulmonary veins therefore PVI (keft side) is in most cases the first intervention. What is called an SVT ablation is on the right side nearAV node.

Jim

[mjames1 in reply to Autumn_Leaves]

In common usage, Afib ablation (PVI) is left side. SVT ablation is right side near AV node.

Jim

[Mugsy15 in reply to mjames1]

The most common rogue signals emanate from around the entry points of the pulmonary veins in the left atrium as you say. Which is why the focus of most first ablations is there. However it is just a fact that AF arises from either or both atria . It is very common to require a second ablation, often using radio frequency, to combat signals from the right atrium.

So it is misleading to write: 'AF Ablation (PVI)' as if all AF ablations are PVI and therefore in the left atrium.

[mjames1 in reply to Mugsy15]

Never suggested a fib only emanates from the pulmonary vein. However, statistically, it is the main culprit and that's why it's usually the first intervention.

Jim

[Mugsy15 in reply to mjames1]

Do we agree that AF arises in both atria?

[mjames1 in reply to Mugsy15]

In the sense that both right and left atriums are fibrillating, yes, but I was referring to the fix, i.e. ablation, which again is most often initially done on the left side with a PVI. If afib still persists, then they look elsewhere, such as the Ganglionated Plexi (GP), however again mostly on the left side, but starting to get a bit above my pay grade here as GP do also exist on the right side.

Jim

[Mugsy15]

I think we've arrived at a reasonable level of agreement.

Interestingly, the Cox-maze procedure has been shown to have a higher rate of success than catheter ablation, and according to what I read about it, the main reason for the superior results is that both left and right atria are treated.

[FraserB in reply to Mugsy15]

Does the Cox-maze also include ablating the ganglionated plexi of the autonomic system?

[Mugsy15]

I'm not qualified to say a definitive 'no' to that; what I can say is that according to what I've read, the Maze procedure includes two sets of ablation lines on the right atrium. The first are along the Superior and Inferior Vena Cavae*; the second are on the free wall*of the atrium down to the tricuspid valve* annulus.

The latest variant utilises both Cryo and RF and also includes surgical excision of the Left Atrial Appendage, which of course is where the majority of stroke-inducing clots are thought to form.

*It might help some readers of this post if I clear up a couple of terms. The Vena Cavae are very large veins which bring deoxygenated blood back to the right atrium. The tricuspid valve allows that blood to flow down into the right ventricle but not back up. I'm not sure what is meant by 'free wall', so I'm sticking my neck out a bit to say I think it's the wall of each chamber which is not shared with the other three.