Cheaters' Shortcuts for Rhythm Interpretation

Specialties CCU


I am wondering whether anyone else out there uses the same "cheaters' shortcuts" that I do when interpreting rhythms. I have never seen these in a text book but I have formulated them from watching my colleagues interpret. Although the majority of textbooks take the student through a laborious step by step analysis an experienced RN seems to leap over these steps and straight to pattern recognition.

By watching my colleagues I think I have caught on to some of the subconscious cues we are using to come to an answer in the 2 second or less it usually takes to work out what the rhythm is.

1) Look at the pulse counter on the monitor - if the pulse counter is jumping wildly by 5 to 10 BPM then it is probable the patient is in Atrial Fibrillation. This is only a probability of course and you still need to read the strip but it is a valuable first clue.

2) Pulse counter is also a often a first clue for atrial flutter - knowing that flutter waves are usually 300 minute or thereabouts. If the rate is staying at a division of the 300 or so it is probable that it is an atrial flutter with a block. i.e. rate of 150 atrial flutter with a 2:1 block rate 100 atrial flutter with a 3:1 block. Once again you must check the printed rhythm strip using a step by step process.

3) Instead of counting the little squares in the P-R interval to determine first degree block I look along the strip to find a "p" wave that lines up with the beginning of a large square and then check to see if the QRS falls in the same large square. If it does the P-R is less than 0.2 so is not a first degree block.

Of course with all of these you still have to do the rest of the analysis but these are valuable first clues that can save time.

live4today, RN

5,099 Posts

Specializes in Community Health Nurse.

Very interesting gwenith. Thanks for sharing. I work telemetry so any helpful hints are appreciated. Have a great day now! :)


20 Posts


Just long have you been a nurse? I really enjoy reading your posts, and find them helpful.


gwenith, BSN, RN

3,755 Posts

Specializes in ICU.

Quite a long time it, like my age is a real secret:lol2:


314 Posts

more more more!

gwenith, BSN, RN

3,755 Posts

Specializes in ICU.

What I will do here is write a series of short explanations to help people interpret cardiac rhythms. As I will be breaking up the sections please feel free to come in with questions and feedback. Because I am doing this in the most long distance manner imaginable it is important for you to tell me if something does not make sense. Oh! and P.S. I call them ECGs not EKGs

1. Working out the rate

Each small square on the ECG paper is 0.04 of a second there are five of these small squares to one large square. Each large square is therefor 0.2 of a second and there are then 300 large squares a minute.

Although there are many different methods of calculating the rate of a rhythm on an ECG most of them are "overkill". Usually it is not necessary to get an exact figure - that can be gotten from the pulse counter anyway - what is important is to work out whether the rate is too fast (tachycardia) normal or too slow(bradycardia).

So a quick method of working out the rate is this. If you have a QRS complex in every ;large square then the rate has to be 300/minute if it there is a complex every 2 large squares it is 150 every 3 = 100 and so on. Not very accurate but it gives us the broad determination we need.

The following link shows an ECG with bradycardia

An example of sinus tachcardia

When reading these ECG's it is important only to look at the PQRS the shape of the T wave is not a factor in reading rhythms - IT IS important when reading the entire ECG and determining myocardial damage but for rhythms it is not important.

Look at the two examples I have given. The lead that is best to use to read rhythm is lead II.

jnette, ASN, EMT-I

4,388 Posts

Specializes in Hemodialysis, Home Health.

Good stuff there, Gwenith ! :) Don't use strips or even really "need" this knowledge in what I do, but I've always been fascinated by it, and loved learning it in school... I just ate it up. These are really good little tips. Thanx !


44 Posts

Thanks gwenith for the info---I've been out of nursing for a year since I got married and so if you don't use it you lose it ---- is sooooooooo true. So I printed out your info to keep for further reference --who knows maybe one day I'll decide to go back and play for awhile. :cool:


322 Posts

Specializes in critical care, med/surg.

Those are great pointers, gwenith. I always have to measure them out or I can't conceptualize what I'm looking at.

gwenith, BSN, RN

3,755 Posts

Specializes in ICU.

I will vary the links each time if I can for two reasons - !) sometimes links drop out and 2) the more and varied the rhythm strips you look at the better your skills become.

2) What is "Sinus" Rhythm?

It is a rhythm that has a P wave followed within 0.2. second by a QRS configuration. That is it.

Follow this next link to other examples of sinus tachycardia and bradycardia.

These are different examples of sinus rhythm. The first example states it is a "sinus rhythm with a right bundle branch block". this simply means that the bundle of His that conducts the impuse to teh right ventricle has an area of infarct or blockage in the nerve pathway.

This site shows a simple explanation of bundle branch blocks

I will be back shortly with atrial fib and atrial flutter

gwenith, BSN, RN

3,755 Posts

Specializes in ICU.

This site expalains atrial flutter well and simply.

If you look at the flutter waves on the example you will see that there is approxeimately one every large square (300/minute) This is only approximate as we are talking about an organic system not a mechanical system. Hoverever my "shortcut I mentioned earlier still holds. The text in the link tell about the atrial reate in erlation to the ventricular response.

Look at the example given and tell me whether it is a 2:1, 3:1 or a 4:1 ratio.


433 Posts

Thanks Gwenith...these are great tips. Always nice to learn helpful tips. I have to measured mine out as well Telenurse.

This topic is now closed to further replies.

By using the site, you agree with our Policies. X