Absent P waves - SVT or V Tach?

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I had a test question yesterday on a cardiac test for nursing school. The question read, "Your patient's monitor shows ABSENT P waves with a heart rate of 200 bpm. What rhythm is this?" I put VTach because it said ABSENT P WAVES but my instructor says that it is SVT. I'm sorry, but SVT has P waves but are hidden in the QRS because the rate is so high. I believe the answer should be V Tach. Any help appreciated!! (Only 5 months until graduation!!)

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ilovestargate said:
I had a test question yesterday on a cardiac test for nursing school. The question read, "Your patient's monitor shows ABSENT P waves with a heart rate of 200 bpm. What rhythm is this?" I put VTach because it said ABSENT P WAVES but my instructor says that it is SVT. I'm sorry, but SVT has P waves but are hidden in the QRS because the rate is so high. I believe the answer should be V Tach. Any help appreciated!! (Only 5 months until graduation!!)

Well the rate with SVT is going to be 150-250, so the 200 is right in the middle of that. Did they say anything about a wide and bizarre QRS? That would be a big hint for V-tach. The question seemed to be describing the EKG strip...so when you LOOK at the monitor you may not see any P-waves with SVT. They might be absent and hidden in the QRS like you said, but you will still say they're absent when you describe it since they're "hidden". The question didn't say the PATIENT doesn't have p-waves, it just says the monitor doesn't show them. But just because you don't see a P-wave, it doesn't meant it's V-tach. You could have A-fib(no discernible P-wave there), V-fib, etc. Did the question give any other description?

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The only info it gave was that there was a patient on a monitor and you notice that there are absent P waves and HR of 200. Then it asked what the interpretation was. My thinking is, yes with SVT you sometimes can't see the P waves when hidden in the QRS but they are there, but with V Tach, there are no P waves at all. I checked in my book and it said about the same thing but I'm going to speak with the instructor on a few other questions so I suppose I'll get an answer then :)

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Good luck to you on it. But just because you don't see P-waves, it could be a number of things.

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Specializes in Critical Care.

The difference between a Supraventricular rhythm and a Ventricular rhythm is found in the QRS. If the QRS is narrow then it originates in the junction or above, making it supraventricular, if it is wide then it originates below the junction and is most likely a ventricular rhythm (assuming no bundle branch blocks).

At a rate of 200, you wouldn't be able to see the P waves regardless of where the impulses are originating.

You can also have truly absent P waves in an SVT (junctional tach), a rate of 200 in JT is rare but it does happen.

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That's why I was asking about the wide bizarre QRS or not. You will also not have any discernible P-waves with A-fib, and you may have a nice tight QRS

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Specializes in being a Credible Source.

In order to pick VT over SVT you need to make an assumption about conditions not state in the problem stem: Specifically, regarding the bizarre QRS. Since they didn't specify same you must not assume that it's there and hence the only choice is is SVT.

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Specializes in ICU.

Isn't that Junctional rhythm?

Oops sorry - missed the heart rate of 200.

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MunoRN said:
The difference between a Supraventricular rhythm and a Ventricular rhythm is found in the QRS. If the QRS is narrow then it originates in the junction or above, making it supraventricular, if it is wide then it originates below the junction and is most likely a ventricular rhythm (assuming no bundle branch blocks).

At a rate of 200, you wouldn't be able to see the P waves regardless of where the impulses are originating.

You can also have truly absent P waves in an SVT (junctional tach), a rate of 200 in JT is rare but it does happen.

ding ding ding

Yep, the key information was the QRS width. You didn't have that.

Several rhythms could have an indiscernible P wave.

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