Difference between atrial and ventricular rate?

MunoRN, RN · Sep 23, 2013

It says NO P WAVES in the book I'm using. Those aren't P waves; those are F waves...sawtooths. Those are two different kind of waves... So I count the F waves to find the atrial rate in atrial flutter?

"F" waves, or Flutter waves, are a type of P wave in that they represent a conduction impulse that originates in the atria, so they do represent the atrial rate. The term "F" wave is a little outdated and comes from when we used to decipher EKG's based primarily on what we saw on the EKG, rather than what the EKG represents physiologically.

heyitsme728 · Sep 23, 2013

So...how do I find the atrial rate in atrial flutter? I would just take the range 150-450 and memorize it? Is it like a potassium level? That you just have to know?

heyitsme728 · Sep 23, 2013

So F waves represent P waves? So can I count the F waves and multiply the # of F waves by 10 to get the atrial rate for atrial flutter?

TiffyRN, BSN, PhD · Sep 24, 2013

To the OP, to try to answer your most recent question, yes, in atrial flutter, you would count the number of flutter waves (p waves, F waves) per 6 second strip and multiply x 10 to obtain the atrial rate. Clinically, the atrial rate in atrial flutter is not significant. I do understand though that formal education and clinical significance don't always run hand in hand.

As far as clinical significance, the more important question is if the ventricular rate is doing a good job of keeping the patient asymptomatic, not too low and not too high and not too irregular (A-flutter can be regular or irregular).

Please be sure you understand all the ways to calculate rate and don't always assume you have a six second strip. But to clarify, when you are dealing with irregular rhythms, counting complexes per 6 seconds is pretty much the standard.

As far as PVCs counting or not counting in heart rate, it's not very simple. For one, there is the question of if the PVC perfuses the patient. This is difficult to know without something like an arterial line. The reason being that if the PVC does not create a heart beat with enough force to decently push blood around, then it shouldn't count toward the heart rate. This is a commonly debated topic in arrhythmia interpretation.

Let me search allnurses for you:

https://allnurses.com/general-nursing-discussion/pvcs-heart-rate-666591.html

https://allnurses.com/nursing-student-assistance/do-pvcs-count-202355.html

Another frequently debated topic is what to call aberrant ventricular beats when they are found in an irregular rhythm such as atrial fibrillation. If such beats were to be found in a regular rhythm such as sinus rhythm and they are earlier than one would have expected a regular complex, they would be called PVCs. Many argue that it is impossible to have a Premature Ventricular Contraction when the rhythm is irregular. Some like to call A-fib with such beats A-fib w/Ventricular Ectopy. In practice, what they are called is not significant, what is significant is. . .wait for it. . . is if the patient is perfusing and tolerating the rhythm. If the patient isn't moving blood with those aberrant beats (PVCs, VE) then they are at risk for heart failure and a higher number of those beats can mean ventricular irritation and high risk for deterioration into v-tach/v-fib.

MunoRN, RN · Sep 24, 2013

So F waves represent P waves? So can I count the F waves and multiply the # of F waves by 10 to get the atrial rate for atrial flutter?

F waves and P wave represent electrical impulses associated with atrial contraction. You can't usually use the 6 second strip method (counting f/p waves and multiplying by 10) because the f/p waves will disappear behind the QRS complexes, even though they are still probably there, although you can if you 'march out' the atrial waves that are most likely hidden under the QRS complexes. You have to remember that an EKG basically reads two different rhythms simultaneously; the atrial rhythm and ventricular rhythm. The electrical impulses of the ventricles are stronger than that of the ventricles starting with AV node on down, and will obscure or alter readings from the atria during most of the QRS and T wave. So unless you can find a six second section of EKG where no QRS's occur, you can't use the 6 second method (and if you can easily find six seconds of strip with no QRS's, there are bigger problems).

Another way is to use the R to R method, which in this case would be P to P (or F to F). Measure the time in seconds between a P wave and the next P wave using the same point on each P wave (preferably the peak). Use the boxes to measure; a small box is .04, a larger box is 0.2 seconds. Divide 60 by the P to P time and that is the atrial rate.

heyitsme728 · Sep 24, 2013

Why divide by 60?

Here's a photo of what I think is how to find the atrial rate for atrial flutter. Is this right?

http://untitled728.webs.com/apps/photos/album?albumid=15119233

Altra, BSN, RN · Sep 24, 2013

I just viewed the link provided. I'd like to call for a little "time out".

The link displays a purported 6-second strip, and calculations that conclude "atrial rate = 0.0046bpm". For an atrial flutter rhythm, no less. :facepalm:

Stop and think about that for a second. If after that pause you believe that that "number" has any basis in reality, please STOP, and review your cardiac A & P before continuing your assignment.

If you realize that the number has no basis in reality ... then continue reading.

The .04 and 0.20 are the lengths of time (in seconds) represented by the small and large boxes, respectively. The entire strip is 6 seconds.

In your strip there are 7 QRS complexes for a ventricular rate of 70 (7 complexes in 6 seconds ... 70 complexes in 60 seconds).

In your strip there are approximately 27 p-waves, for an atrial rate of approx. 270. This is the textbook definition of atrial flutter: in simple terms, the atria are "fluttering" or "quivering" due to an electrical conduction defect -- this impulse to contract at that high rate is not being conducted to the ventricles, so those chambers are operating a more normal rate of 70 bpm.

heyitsme728 · Sep 24, 2013

Okay....to the above posters, I was asking if that was correct and according to the textbook I used for school its not correct.

http://untitled728.webs.com/apps/photos/album?albumid=15119233

There's other photos which I scanned of the atrial flutter section...and in the book, it states that there are no p waves in atrial flutter. Just F waves. So P waves do not represent F waves. If you are using another book which states otherwise please share? Thanks.

MunoRN, RN · Sep 25, 2013

A P wave is an electrical tracing of an atrial depolarization, so yes p waves exist in both atrial flutter and a-fib for that matter. Some textbooks (although definitely the minority) will say these are not actually P waves, even though this represents an outdated way of looking at EKG's. We know that the atria are depolarizing at a rapid rate in atrial flutter, and the P waves, F waves, whatever you want to call them represent that. So if the question you are being asked is what is the atrial rate in A-flutter based on an EKG, that means we are counting the electrical depolarizations of the atria, what you prefer to call them makes absolutely no difference.

If you define an atrial rate as being something that only exists in sinus rhythm, are you then saying that the atrial rate in atrial flutter is zero?

TiffyRN, BSN, PhD · Sep 25, 2013

If you define an atrial rate as being something that only exists in sinus rhythm, are you then saying that the atrial rate in atrial flutter is zero?

I would agree that in A-fib/flutter the sinus node atrial contraction is probably zero. But I seriously doubt this student's (possibly outdated) arrhythmia book is going to that depth. I cannot agree though that there is no atrial rate (as defined by electrical activity stimulating atrial contraction) in A-flutter.

And the calculation for the rate is done completely wrong on that work sheet. The calculated atrial rate would be 1500 divided by 7 for an atrial rate of 214. Your ventricular rate is 71.

MunoRN, RN · Sep 25, 2013

I would agree that in A-fib/flutter the sinus node atrial contraction is probably zero. But I seriously doubt this student's (possibly outdated) arrhythmia book is going to that depth. I cannot agree though that there is no atrial rate (as defined by electrical activity stimulating atrial contraction) in A-flutter.
And the calculation for the rate is done completely wrong on that work sheet. The calculated atrial rate would be 1500 divided by 7 for an atrial rate of 214. Your ventricular rate is 71.

The SA node produces electrical impulses, not contractions, the impulses themselves produce contractions, usually. But the rate of atrial contraction is influenced by electrical impulses from numerous foci within the atria (and even outside the atria), not just the SA node.

Altra, BSN, RN · Sep 25, 2013

OP, did you stop and consider WHY the answer cannot be "the atria are contracting 0.004(whatever ridiculous number less than 1) times per minute"?

Until you understand that, I don't think there are any magical words we can say here that will lead you to the correct answer. Review your cardiac A & P.