Valsalva maneuver for SVTs question

[Transformers]

Random question...why is Valsalva effective for terminating SVTs. Especially when there are several phases and only the first and fourth phase gives you bradycardia, while the second and third gives you a tachycardia....so why is this maneuver helpful?!

http://www.cvphysiology.com/Hemodynamics/H014.htm

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[redpanda]

Random question...why is Valsalva effective for terminating SVTs. Especially when there are several phases and only the first and fourth phase gives you bradycardia, while the second and third gives you a tachycardia....so why is this maneuver helpful?!

http://www.cvphysiology.com/Hemodynamics/H014.htm

The Valsalva maneuver increases the amount of vagal tone on the AV node, basically making it more refractory to depolarize to break the electrical loop of a reentrant rhythm, thus the loop gets terminated and hopefully the person goes back to a nice sinus rhythm.

 

[Psai]

my understanding is that there is an ectopic focus of depolarization which goes around in a circle which keeps on stimulating contraction at a certain rate. valsalva increases vagal tone which breaks that circle of depolarization by slowing things down and hopefully allows the sa node to take over again

 

[Transformers]

I mean I understand the need for vagal tone. I don't get why Valsalva is useful in generating the vagal tone via the baroreceptor reflex.

When you hold your breath two things happen. Introthroacic pressure increases to compress your vessels (aorta and SVC)...hence VR decreases and aortic pressure rises, triggering the baroreceptor response to slow the heart down....BUT eventually the decreased VR (hence low CO and BP) passes through the aorta triggering the BReflex and you get a tachycardia. Hence my point being, why is valsalva useful if you get an eventual tachycardia which can potentially worsen your SVT...is all the money on the initial bradycardia? Contrast this with the carotid massage which purely gives you a vagal response too the heart.

 

[Psai]

there should be no more svt to be worsened

 

[TooMuchResearch]

Don't do carotid massage for SVT.

 

[Jabbed]

You won't increase the rate of SVT through the baroreceptor reflex because SVT doesn't appreciably increase in rate through sympathetic tone. This has to do with the reentry circuit that forms. Technically what we call SVT is actually AV nodal reentrant tachycardia. The reentry circuit forms within the AV node between the two collateral conduction fibers (slow and fast) and involves both anterograde and retrograde conduction. The stability of the circuit lies in the fact that the refractory period of the electrogenic tissue is short enough that it repolarizes immediately before it is restimulated by the circuit. Sympathetic innervation to the heart (mainly B1 receptors) controls pacing by timing the rate of spontaneous depolarizaton and by increasing the rate of conductance (decreasing the duration of the refractory period) through the AV node. Neither of these will affect the rate of established SVT.

The benefit of Valsalva, as alluded to previously, is that vagal stimulation of the AV node decreases the conductance, which means that the reentry circuit will (hopefully) encounter refractory tissue that then terminates the circuit.

 

[Raryn]

Don't do carotid massage for SVT.

Except it's the first line treatment. Gives you something to try while the nurse is drawing up the adenosine. Almost certainly harmless (practically theoretical 0.1% stroke risk in someone with really bad stenosis) and does occasionally work.

 

[Instatewaiter]

SVT is kind of a crap diagnosis. It really is an amalgamation of atrial arrhythmias, not just AVNRT but also AVRT, AT and a small handful of others.

Really narrow complex tachycardias should be broken down into long and short RP tachycardias as you can very often catch P waves burried in the beginning or end of the QRS.

Valsalva/carotid massage tend to work best for AVNRT and not for much else. It is rare for AT to respond to vagal maneuvers. Be careful with AVRT as it is often associated with WPW and if your vagal maneuvers actually work and block the AV node, you will be in a world of hurt as they conduct 1:1 and then VF (which I hear is bad).

 

[PL198]

so many abbreviations

 

[TooMuchResearch]

Except it's the first line treatment. Gives you something to try while the nurse is drawing up the adenosine. Almost certainly harmless (practically theoretical 0.1% stroke risk in someone with really bad stenosis) and does occasionally work.

I don't bother because there isn't much evidence for it, but I do try a good Valsalva (i.e. quick 250+ fluid bolus, push on the belly/have them attempt to blow the plunger of a large syringe).

I also go for verapamil rather than adenosine. If the attending blocks my CCB, midazolam goes in before adenosine.

 

[username456789]

Two of my first pages in intern year were for patients in SVT. I broke one just by having the patient valsalva, and the other initially broke with valsalva but quickly returned to SVT and required adenosine.

One of the young tele nurses, after witnessing the first one, thought I was the greatest thing since sliced bread.

 

[Psai]

Two of my first pages in intern year were for patients in SVT. I broke one just by having the patient valsalva, and the other initially broke with valsalva but quickly returned to SVT and required adenosine.

One of the young tele nurses, after witnessing the first one, thought I was the greatest thing since sliced bread.

Is there more to the story or did it just end there

 

[Jabbed]

Two of my first pages in intern year were for patients in SVT. I broke one just by having the patient valsalva, and the other initially broke with valsalva but quickly returned to SVT and required adenosine.

One of the young tele nurses, after witnessing the first one, thought I was the greatest thing since sliced bread.

If you really want to impress the nurses, hold out your hand and pretend that you're channeling the Force to break SVT (along with Valsalva). When they ask where you learned how to do that, say that you took an OMT course.

 

[Instatewaiter]

I don't bother because there isn't much evidence for it, but I do try a good Valsalva (i.e. quick 250+ fluid bolus, push on the belly/have them attempt to blow the plunger of a large syringe).

I also go for verapamil rather than adenosine. If the attending blocks my CCB, midazolam goes in before adenosine.

Yes from your extensive experience as a medical student...

 

[link2swim06]

Except it's the first line treatment. Gives you something to try while the nurse is drawing up the adenosine. Almost certainly harmless (practically theoretical 0.1% stroke risk in someone with really bad stenosis) and does occasionally work.

Except for those with avrt with antidromic conduction. Those people you can throw into v-tach/fib with vagal/ccb/beta-blocker/adenosine and kill.

I don't bother because there isn't much evidence for it, but I do try a good Valsalva (i.e. quick 250+ fluid bolus, push on the belly/have them attempt to blow the plunger of a large syringe).

I also go for verapamil rather than adenosine. If the attending blocks my CCB, midazolam goes in before adenosine.

I haven't seen verapamil being used except once during med school.

The bottom line is you need to categorize it first:
1. Narrow Regular
2. Narrow Irregular
3. Wide Regular
4. Wide Irregular

Till you have classified it into these categories and hence have some clue what this "SVT" is then you really can't treat it safely. SVT is kinda a useless term. When pre-hospital tells me this all I assume is that it is a fast rhythm. It doesn't take that much effort to sit down and actually analyze a 12 lead.

 

[Jabbed]

Except for those with avrt with antidromic conduction. Those people you can throw into v-tach/fib with vagal/ccb/beta-blocker/adenosine and kill.



I haven't seen verapamil being used except once during med school.

The bottom line is you need to categorize it first:
1. Narrow Regular
2. Narrow Irregular
3. Wide Regular
4. Wide Irregular

Till you have classified it into these categories and hence have some clue what this "SVT" is then you really can't treat it safely. SVT is kinda a useless term. When pre-hospital tells me this all I assume is that it is a fast rhythm. It doesn't take that much effort to sit down and actually analyze a 12 lead.

90% of the time whenever someone says SVT they're talking about AVNRT or they're just wrong.

 

[TooMuchResearch]

Yes from your extensive experience as a medical student...

I did have good experiences as a medical student. Resident now.

 

[TooMuchResearch]

Except for those with avrt with antidromic conduction. Those people you can throw into v-tach/fib with vagal/ccb/beta-blocker/adenosine and kill.



I haven't seen verapamil being used except once during med school.

The bottom line is you need to categorize it first:
1. Narrow Regular
2. Narrow Irregular
3. Wide Regular
4. Wide Irregular

Till you have classified it into these categories and hence have some clue what this "SVT" is then you really can't treat it safely. SVT is kinda a useless term. When pre-hospital tells me this all I assume is that it is a fast rhythm. It doesn't take that much effort to sit down and actually analyze a 12 lead.

I use verapamil for svt (the narrow regular kind that isn't sinus tach) and it's awesome.

 

[Instatewaiter]

I did have good experiences as a medical student. Resident now.

I use verapamil for svt (the narrow regular kind that isn't sinus tach) and it's awesome.

Dude arent you like 6 months into your EM internship?

Verapamil works well. But, especially in the ER, you can just terminate the rhythm with adenosine, plus it's actually diagnostic as well. Run a rhythm strip and give adenosine and you will have much more information than you had before it. It will give you much information than just verapamil. Your cardiology consultant will appreciate it.

Furthermore, arrhythmias and systolic dysfunction tend to run together. Verpamil/Dilt shouldn't be used in these patients unless you have completely exhausted all other options. I can't tell you how many times I've seen someone dilt'ed show up in my CICU in cardiogenic shock because the ER decided to give verapamil or dilt as a reflex.

Except for those with avrt with antidromic conduction. Those people you can throw into v-tach/fib with vagal/ccb/beta-blocker/adenosine and kill.

Sure with WPW. In this setting anyway you should probably be putting pads on people and calling cardiology regardless.