SVT, PAC and Anxiety questions

[djb85]

I have suffered with Anxiety since I was about 16 so about 7 years. Over the Past few weeks I have cut out Alcohol, Caffeine and I haven't had a PAC or PVC since. I can usually just feel my pulse for a minute and feel at least 2 or three happen at that point at any point in the day and when I would go to bed they would happen until I finally managed to get to sleep. Now not a twitch and I am so calm in general. I WISH!! I had researched how Caffeine effects adrenaline release when I was younger as I am truly starting to believe this has been the cause of most my problems all along, im not saying I will never get SVT again but things already feel much better.

I have never really had an answer from my Cardiologist as to what Is going on when I have SVT so I have been reading about it and I could have this all wrong as I am not a doctor. The first 2 times I had SVT it could not be stopped with Adenosine and when the SVT was finally controlled I was left with Atrial Fib until I had Flecainide to stop this also. The most recent time I had this, Adensoine stopped the SVT there was no AFib (Maybe due the 50 mg pill in pocket of Flecainide I took when the SVT Started) and I was able to go home straight away instead of staying overnight.

I have read that Caffeine is almost Identical to Adenosine and that caffiene can block Adenosine from being effective as it should be as it sits in the Adenosine receptors, could this be why it was not effective the first few times as I had been at work all day consuming lots of tea and Coffee yet on the occasion the SVT was stopped with Adenosine I had not had 1 cup all day.

Also I have read that when using Adenosine this can actually cause AFib to occur, could this be what has happened in my first 2 cases as no one has really every explained what is happening to me?

Thanks

[LindaTX]

Last time I had a stress test, they had to chemically induce it and the adenosine ended up inducing a-fib which then turned into v-tach several minutes later. Sometimes I think the very thing that can put you into an arrythmia can also get you out of it. Strange concept, huh?

[djb85]

Thank you.

This now makes more sense. I will raise this all on my next visit and hopefully they will sit down and Explain this more, as understanding what is going on is making the fear of this happening again far less intense.

[is_something_wrong]

Hi,

It's important to know that Adenosine will not stop all forms of SVT. Adenosine is effective against a specific common SVT named AVNRT (atrioventricular nodal reentry tachycardia), where a second pathway through the AV node (connection point between your heart's upper and lower chambers) is activated, usually caused by a PAC firing close to the previous beat.

As a result, the impulse travels down the second pathway, up the first, again and again, creating a line of fast heart beats (a tachycardia). This arrhythmia is easy to recognize due to it's characteristic feeling of heart beats in your throat/neck, because your upper chambers are activated at the same time as lower chambers, when the valves between the chambers are shut, and blood will backfire from upper chambers when they contract (not dangerous), a "Cannon A wave".

Adenosine temporarely "shuts down" your AV node and clears impulses, stopping the tachycardia.

There are other SVT arrhythmias, such as ectopic atrial tachycardia, where a point in your upper chambers just decide to fire off lines of PACs. Adenosine will not be effective against this as the AV node is not involved. And - in some cases, AVNRT just cannot be converted with adenosine, for different reasons. No treatment is 100% effective.

Afib is a quite common side effect of adenosine. When electrical activity in your heart is (temporarily) wiped out by adenosine, you will have a sinus arrest (the normal pacemaker stops firing) for 2-4 seconds and other spots in your heart (atrial or ventricular) will try to "help". If this happens simultanous (several spots fire at the same time) Afib can occur. In very rare cases Vfib can occur as well. This is why administration of adenosine is only done under heart rate monitoring and with defibrillation equipment in close range. If a dangerous arrhythmia occurs, it will be taken care of immediately.

Afib can be terminated by a defibrillator as well, but this is considered quite drastic and medical convertion is first choice (verapamil, flecainide, etc).

As you are saying, caffeine is a adenosine receptor blocker (it binds to the same parts of your cells as adenosine) and will make adenosine less effective (to some degree). It's possible this is why adenosine was ineffective. You should ask those questions to your doctor, though. There are no doctors in this forum :)