# Sinus Tach or SVT



## FFMedic1911 (May 1, 2008)

Was wondering if some one could have Sinus Tach with a rate above 150bpm.I have been told that even if p waves are present and the rate is above 150bpm it is technically SVT.I have also been told if the p wave hasn't superimposed into the QRS it is Sinus Rhythm even if you had a rate above 150.Some one give me your take on it.Also please give references to where you are getting your info thanks.


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## johnrsemt (May 1, 2008)

one of our medical directors was talking that true SVT is 220-persons age;  so when my partner (who is 23) gets up to the 185 range (asymptomatic) she is in Sinus Tach,  just more annoying than her normal self.


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## Ridryder911 (May 1, 2008)

Sinus rhythms (tachycardia, brady, etc.) all originate from the atrium, thus the origination of the "P" wave. Tachycardia is above 100 bpm, and if the rate is above 120 and if one can still see a "P" wave; we still know that it is still coming from the atrium. Above 120 it is considered atrial tachycardia. The term "SVT" is a generic term which = supra (above) ventricular (ventricles) tachycardia (fast hear rate) and can literally mean ST, AT,, thus any fast heart rate that is known to originate from the atrium. One can also detect this by looking at the morphology of the QRS. If it is narrow and  WNL and pronounced, we know that is also coming from the normal pathway. SVT is really a slang and the definition varies as usually one above the normal tachycardia, and above the AT range.. 

Source.. many cardiology books, AHA, Emergency Cardiac Care .. common ECG interpretation skills.  

R/r 911


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## jedirye (May 2, 2008)

Ridryder911 said:


> Sinus rhythms (tachycardia, brady, etc.) all originate from the atrium, thus the origination of the "P" wave. Tachycardia is above 100 bpm, and if the rate is above 120 and if one can still see a "P" wave; we still know that it is still coming from the atrium. Above 120 it is considered atrial tachycardia. The term "SVT" is a generic term which = supra (above) ventricular (ventricles) tachycardia (fast hear rate) and *can literally mean ST, AT,, thus any fast heart rate that is known to originate from the atrium.* One can also detect this by looking at the morphology of the QRS. If it is narrow and  WNL and pronounced, we know that is also coming from the normal pathway. SVT is really a slang and the definition varies as usually one above the normal tachycardia, and above the AT range..
> 
> Source.. many cardiology books, AHA, Emergency Cardiac Care .. common ECG interpretation skills.
> 
> R/r 911






Would not junctional tach also be included in SVT, considering that the impulses originating are also above the ventricles (AV junction) but not necessarily isolated to the atrium?

-rye


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## Ridryder911 (May 2, 2008)

jedirye said:


> Would not junctional tach also be included in SVT, considering that the impulses originating are also above the ventricles (AV junction) but not necessarily isolated to the atrium?
> 
> -rye


Actually junctional is NOT above the atrium rather it is at the "junction" hence the name as such. It is also called "nodal" and to be specific the node is divided into three (3) divisions, high, middle, low. One can tell by the presentation of the P-R and configuration, upright versus buried into the R wave.  Remember, Junctional tachycardia is only really considered tachycardia because it is tachycardia above its normal intrinsic rate (not really tachycardia in the norm of things).


R/r 911


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## Katie (May 2, 2008)

Ridryder911 said:


> Above 120 it is considered atrial tachycardia.



wouldn't atrial rhythms (those generated from irritable sites in the atria other than the SA node) also have a different looking p-wave?  notched, diphasic, pointed were a few mentioned in our book.  so even at that rate would you be able to differentiate if it was sinus tach or atrial tach?  or would it just be too fast to make that kind of distinction?


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## jedirye (May 2, 2008)

Ridryder911 said:


> Actually junctional is NOT above the atrium rather it is at the "junction" hence the name as such.
> 
> R/r 911




You are correct, junctional is not above the atrium. However, with SVT (_Supra_ventricular Tachycardia), why would junctional tach be discluded because it _is _above the ventricles and is a tachycardia. I was just under the impression SVT was an umbrella term for atach, jtach, etc. I'm fairly sure I'm right, but it never hurts to break out that bright orange book of mine (well, it's usually always out actually.)

-rye


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## Ridryder911 (May 2, 2008)

Katie said:


> wouldn't atrial rhythms (those generated from irritable sites in the atria other than the SA node) also have a different looking p-wave?  notched, *diphasic*, pointed were a few mentioned in our book.  so even at that rate would you be able to differentiate if it was sinus tach or atrial tach?  or would it just be too fast to make that kind of distinction?


You mean bi-phasic (retrograde P wave
A yes & no.. Again, one may have abnormal ectopi of sinus pathways, (such as in Bachman's bundle) ans still be "normal" looking in a "monitoring lead" (hint: to view rhythms other than lead II).. Yes, one can have unusual configuration of "P" waves or maybe none at all be seen because it is buried in the "QRS".. This does not however mean it is a "junctional rhythm due to the short P-R interval, rather a complication of the speed of the rate. In true SVT such as a rate of >150 to 180 or greater, one usually cannot determine a P wave, rather realizes that it is coming from the atrium due to the normal QRS and vector direction according to the lead, one is reading. 



jedirye said:


> You are correct, junctional is not above the atrium. However, with SVT (_Supra_ventricular Tachycardia), why would junctional tach be discluded because it _is _above the ventricles and is a tachycardia. I was just under the impression SVT was an umbrella term for atach, jtach, etc. I'm fairly sure I'm right, but it never hurts to break out that bright orange book of mine (well, it's usually always out actually.)
> 
> -rye


 Because nodal rhythms or junctional rhythm intrinsic rate is not to be tachycardia, even junctional tach is not usually tachycardiac in speed. You are correct per anatomy wise, that the AV node is supra to the ventricles thus in technical terms it would be a supraventricular rhythm. Although, most may not consider it such because the heart had to resort to the AV node to become its dominant pacer.. (damage to the pacers in the atrium).. 

There is debate among cardiologist that determining a SVT vs. VT, some declare that very fast rates>180 are really V-tach in disguise..(with a narrow QRS).. The answer is still out.. That is why most still treat tachycardiac rhythm per QRS configuration. 

R/r 911


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## jedirye (May 8, 2008)

Well, after doing some reading and not necessarily on p wave morphology but I did happen to come across it, I believe both of you are correct. Either diphasic or biphasic will work, I believe they are interchangeable although in my bright orange book they favored the term diphasic.


I am still a bit confused about junctional tachycardia not being a true tachycardia. Your rationale is that it is not really a tachycardia because the heart had to use it as the dominant pacemaker (thus I guess it would be an accelerated junctional escape rhythm?). However, in the case of an irritable AV junction, the heart will use the fastest pacer (in this case the AV junction) which creates a junctional tachycardia but _not _because it had to rely on it for pacing but out of irritability. Essentially sustained PJB's??Eh?

-rye


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## So. IL Medic (May 14, 2008)

jedirye said:


> I am still a bit confused about junctional tachycardia not being a true tachycardia.
> 
> -rye



It is but think of it this way - tachycardia just refers to a rate that is faster than normal. 

Thus if the atrial sinus pacemaker rate is 60-100 bpm, then 110 would be sinus tach.

If the a-v junction pacemaker rate is 40-60 bpm, then a junctional rhythm rate of 80 would be a junctional tach.

The tachycardia is referring to the pacemaker rate not the absolute rate of beats. So a sinus pacemaker rhythm of 80 is normal sinus but a junctional pacemaker rhythm of 80 is junctional tach. Same rate but different pacemaker sites so different names.


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## firemedic31075 (May 14, 2008)

> If the a-v junction pacemaker rate is 40-60 bpm, then a junctional rhythm rate of 80 would be a junctional tach.




No. A junctional rate of 80 would be an accelerated junctional rhythm. A junctional rate above 100 would be considered junctional tach. Tachycardia refers to rate being greater than 100 bpm and has nothing to do with inherent rate of the pacemaker site.


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## ERnurse17 (May 19, 2008)

I was told that SVT is not a real rhythm.  It is a generic term for a fast heart rate.  there is still an underlying rhythm that can be interpreted.


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## fma08 (May 22, 2008)

i failed my static cardiology station thanks to me calling an "svt" a sinus tac, since there were p-waves present in the rhythm. I was later told that any narrow complex tachycardia above the rate of 150 is SVT due to the fact that while there may be a p-wave present, it is too fast to see if it is really a 2:1 A-flutter, or other arrhythmia originating in the atria. this is just my 2 cents here from what i've been told. 100-150 = sinus tach, >150 = SVT.


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## MSDeltaFlt (May 22, 2008)

fma08 said:


> i failed my static cardiology station thanks to me calling an "svt" a sinus tac, since there were p-waves present in the rhythm. I was later told that any narrow complex tachycardia above the rate of 150 is SVT due to the fact that while there may be a p-wave present, it is too fast to see if it is really a 2:1 A-flutter, or other arrhythmia originating in the atria. this is just my 2 cents here from what i've been told. 100-150 = sinus tach, >150 = SVT.



I disagree.  There are different types of tachycardia.  You have your Sinus, Atrial, Ventricular, Junctional, and Supraventricular.  Supraventricular is a generic term because, on an adult pt, any HR >150 it is *usually* difficult to see any descernable P waves.  

How do you differentiate a P wave from a flutter wave?  A flutter wave wil have sawtooth characteristics.  A P wave will look like a P wave.  When it comes the human body you never say never, and you never say always.  I doubt they really know why you failed that station.

You see, SVT's are *usually* too fast to descern a definitive P wave.  But that is still very relative; definitely not an absolute.  It depends on 

1. how narrow the QRS complex is,
2. how narrow the P wave is,
3. how short the PRI is,
4. how narrow the T wave is,
5. and the length of the QT interval.

Neonates can have HR's >200 without batting an eyelash.  You can still see a descernable P wave.  Granted the physiologies differ, but last I checked electricity still moves at the same speed.  See #'s 1-5 above.

They wanted you to officially call it "SVT" and go through the appropriate algorhythm.

The devil's in the details.


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## fma08 (May 22, 2008)

yeah, forgot to specify adult for that and >200 is SVT in infants... but devils in the details is right, going by the 5 rules of ECG interpretation, that rhythm was sinus tac


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## Remote Medic - Instructor (May 28, 2008)

*svt vs sinus tach*

First I would like to agree with firemedic31075 - junctional rhythms of inherant rate are 40-60bpm, accelerated junctional 61-100 and over 100 is junctional tachy.

Sinus tach is a rate over 100 that originates from the SA node. The rate that each individual can produce from their SA node is different but a rule of thumb is 220 minus the pt's age give the apx. max SA node rate. The main issue is treating the patient and not the monitor! The monitor is a tool, albeit a major tool. If the pt's rate is significantly above the apx. max SA node rate it is a SVT - and any rhythm that originates from the AV node up is Supraventricular in nature. If the rate is close to the max SA rate then the question is whether the pt has a significant cause to have a high hr - i.e. Sepsis, severe dehydration, pain, anxiety, etc. One would have to have a serious issue going on to have a resting heart rate any where near their max SA node rate. Then there are tools such as turning off the lights, having pt sit down and relax, talking quietly, etc. and if those cause the hr to drop a little it is most likely a Sinus rhythm and is not a heart problem - it is a body problem that is causing the heart to do what it is designed to do. Actually a Sinus Tach is a Supraventricular Tachy; however, we use SVT to mean a heart disfunction. SVT usually comes on and off quickly while sinus rhythms tend to change more slowly. SVT will not likely change to lights, etc. the heart is not working right and does not care about the environment. So it is important to use all the tools together to evaluate the patient. There is no magic number that differentiates between sinus rhythm and SVT!

I hope this helps and I look forward to any comments.


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## mikeylikesit (May 28, 2008)

Ridryder911 said:


> Sinus rhythms (tachycardia, brady, etc.) all originate from the atrium, thus the origination of the "P" wave. Tachycardia is above 100 bpm, and if the rate is above 120 and if one can still see a "P" wave; we still know that it is still coming from the atrium. Above 120 it is considered atrial tachycardia. The term "SVT" is a generic term which = supra (above) ventricular (ventricles) tachycardia (fast hear rate) and can literally mean ST, AT,, thus any fast heart rate that is known to originate from the atrium. One can also detect this by looking at the morphology of the QRS. If it is narrow and  WNL and pronounced, we know that is also coming from the normal pathway. SVT is really a slang and the definition varies as usually one above the normal tachycardia, and above the AT range..
> 
> Source.. many cardiology books, AHA, Emergency Cardiac Care .. common ECG interpretation skills.
> 
> R/r 911


Indubitably, remember that the p-wave which signifies the depolarization of the atria must be a present factor for a sinus rhythm regardless. Just for note the T wave is the depolarization of the ventricles. AD, VD, AR, VR. for depolarization and re polarization in your PQRST.


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## fma08 (May 28, 2008)

sure the T wave is not re-polarization of the ventricles? the QRS i believe is the depolarization of the ventricles.


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## mikeylikesit (May 28, 2008)

fma08 said:


> sure the T wave is not re-polarization of the ventricles? the QRS i believe is the depolarization of the ventricles.


what did i say it was late. but yes the first half of the QRS complex is ventricular depolarization and the descent is the re-polarization of the atria. and of coarse the T wave is the re-polarization of the ventricles.


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## fma08 (May 28, 2008)

no worries ^_^


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