EKG Interpretation, part 8: Ventricular Rhythms
by Cathy Parkes July 04, 2020 Updated: August 09, 2023 4 min read
In this article, you will learn about the different ventricular dysrhythmias, including premature ventricular complexes, ventricular tachycardia, torsades de pointes, ventricular fibrillation, idioventricular rhythm, as well as asystole. The EKG Interpretation video series follows along with our EKG Interpretation Flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI exams, and NCLEX.
As we explained in our article on the natural pacemakers of the heart, a ventricular rhythm is the third backup for the heart. When the sinus node fails to kick off an electrical impulse to make the heart beat, the atrial foci are the first backup, and if that fails, the junctional foci are the next backup, and if that fails, the ventricular foci will take over and create a ventricular rhythm.
The inherent rate of a ventricular rhythm is very slow, between 20-40 beats per minute. The defining characteristics of ventricular rhythms are the lack of P waves and the wide QRS complexes. The QRS complex will be over 0.12 seconds in duration (over three small boxes wide).
Premature ventricular complexes
This EKG strip shows a premature ventricular complex (PVC). A PVC is an abnormal impulse that originates from the ventricle and occurs early.
The PVC will not have a P wave, and it will have an abnormally wide QRS complex. Remember that the normal width for a QRS complex is under three small boxes wide. You can see in the EKG strip above that the QRS complex is definitely over three small boxes wide
PVCs are often asymptomatic and don't require treatments. If a PVC is symptomatic, antiarrhythmics can be used. Antiarrhythmics are one of the key medication classes you will need to know for your Pharmacology exams and they are covered in our Pharmacology Flashcards for nursing students.
Ventricular tachycardia is an abnormal, fast heartbeat originating from the ventricles.
The components of a ventricular tachycardia as shown above are missing P waves and wide QRS complexes. In the strip above, you can see that the QRS complexes are regular, so the ventricular heart rhythm is regular. In the strip above, there are 10 small boxes between QRS complexes, and 1500 divided by 10 is 150, so the pulse is 150 beats per minute. Tachycardia is defined as a heart rate over 100 BPM, so we know that this is indeed tachycardia.
If the patient has a pulse, then their ventricular tachycardia can be treated with cardioversion or antiarrhythmics. If the patient does not have a pulse, then they should be treated immediately with defibrillation.
Torsades de pointes
Torsades de pointes is a type of ventricular tachycardia that doesn't look anything like a normal EKG strip.
There are no standard P waves or obvious-looking QRS complexes. The QRS complexes are in fact present, but they are abnormally wide and quite irregular (random). They will have an inconsistent appearance.
It may help you to know that torsades de pointes is french for "twisting of the points," because the P wave appears to be twisting around the baseline.
The heart rate shown here is high. You can see between the QRS complexes shown in the strip above, there are only four or five small boxes. 1500 divided by 5 is 300, so you know that this type of tachycardia is occurring.
Treatment of torsades de pointes usually includes administration of IV magnesium. Other treatment options include antiarrhythmics as well as pacing. So an artificial pacemaker might be necessary for this patient,
Ventricular fibrillation is a heart rhythm disturbance marked by the heart ventricles quivering ineffectively instead of pumping blood.
When you see ventricular fibrillation on an EKG strip, it's difficult to assess the heart rate. There are no P-waves to assess. The QRS complexes are replaced with "v-fib waves" instead. If you see an ekg strip with little bumps as shown above, then that is V-fib.
The treatment for ventricular fibrillation is defibrillation. The hint for remembering this treatment is that you should "de-fib V-fib!"
Idioventricular rhythm is a slow, regular ventricular rhythm.
In an idioventricular rhythm, there are no P-waves, and a wide QRS complex. Those are your clues that you are seeing a ventricular rhythm. The regularity of the atrial rhythm can't be assessed because of the lack of P waves, but the regularity of the ventricular rhythm can be assessed due to the presence of QRS complexes. In this strip shown above, there are equal distances between the QRS complexes so the ventricular rhythm is regular.
With idioventricular rhythms, the heart rate is expected to be under 40 beats per minute. It is possible to have an accelerated ventricular rhythm, which would mean a heart rate over 40.
Viewing this EKG strip, you can probably guess that the heart rate will be slow. But if you count, you can determine that there are 43 small boxes between the QRS complexes. 1500 divided by 43 is 35, so the heart rate is 35 BPM.
Idioventricular rhythms are usually transient and often don't require any treatment.
Asystole is the rhythm you never want to see on your patient, but you do want to see on your exam, because it is the easiest one to pick out. It looks the closest to a flat line.
The heart rate is zero. There is no atrial or ventricular heart rhythm. There is no P wave nor QRS complex.
If you see an asystole, immediate CPR is needed. Do NOT shock asystole; this is not done, regardless of how often it is shown on TV!
Cathy does like to note that if your patient is upright and talking and you see an asystole, it is likely that their telemetry leads have been disconnected, so use your common sense. If your patient is unresponsive, however, immediately begin chest compressions.
In this video, we are going to talk about ventricular rhythms. If you recall from one of my previous videos, the inherent rate of a ventricular rhythm is very slow. It's between 20 and 40 beats per minute. With a ventricular rhythm, there will not be a P wave and the QRS complex will be wide. So it will be over 0.12 seconds in duration, or over three small boxes wide. So in this video, we will be covering premature ventricular complexes, ventricular tachycardia, torsades de pointes, ventricular fibrillation, idioventricular rhythm, as well as asystole.
Okay, so when we look at this strip, we can see that the right-hand side of this strip looks really normal. We've got nice little P waves, followed by a nice narrow QRS complex.
Our rhythm looks regular and our rate looks about right, but what went down over here?
Well, what went down is a premature ventricular complex or PVC. So a PVC is an abnormal impulse that originates from the ventricle and occurs early.
So with a PVC, the premature complex will not have a P wave, so you don't see a P wave here, and the QRS complex will be very wide. So it is definitely over three small boxes wide.
So PVCs are often and asymptomatic and don't require treatment. However, antiarrhythmics can be used for patients who have symptomatic PVCs.
Okay, in this strip we have ventricular tachycardia.
So you can see we have these wide QRS complexes. They're definitely over 3 small boxes wide.
We don't have any P waves. These QRS complexes are wide, but they are regular, so our ventricular heart rhythm is regular.
So in terms of heart rate, if I kind of measure the distance between these QRS complexes, there's about 10 small boxes between them. So 1500 divided by 10 is 150 beats per minute, so we're definitely experiencing tachycardia here.
So in terms of treatment of ventricular tachycardia, if the patient has a pulse, then we can treat it with either cardioversion or antiarrhythmics. However, if the patient has ventricular tachycardia without a pulse, then we need to treat immediately with defibrillation.
Okay, in this rhythm we have something called torsades de pointes, which I hope I'm saying that right. I might be butchering it, because it's definitely not above me to butcher a name.
So when we look at this strip, this doesn't look anything like a normal EKG strip. We don't have nice little P waves and QRS complexes so these are all QRS complexes that are abnormally wide and kind of random. They have this inconsistent appearance.
And if you look at these waves, they kind of appear to twist around the EKG baseline. So anytime you see this kind of abnormal P wave that kind of twists around the baseline, that will be torsades de pointes.
The heart rate of this is high. So you can see between these QRS complexes, there's only four or five small boxes. So we definitely have a heart rate over 100 beats per minute, which is what you would expect with this dysrhythmia.
And in terms of treatment, treatment of torsades de pointes, usually, includes administration of IV magnesium. Other treatment options include antiarrhythmics as well as pacing. So a pacemaker may be necessary for this patient as well.
Here, in this strip, we have what's called ventricular fibrillation or V-fib.
So it's difficult when you see this to really assess the heart rate.
There's no P waves to assess.
These QRS complexes are replaced with these V-fib waves instead. So if you see something that looks like just a bunch of little bumps down here like this, then that's V-fib.
And in terms of treatment, you're going to want to do immediate defibrillation. So the hint here is defib, V-fib.
Here, we have an idioventricular rhythm.
So you can see we don't have any P waves here. So there's no P waves, and we have a really wide QRS, which is how we know that we are dealing with a ventricular rhythm. So we can't assess the regularity of the atrial rhythm because we don't have P waves, but we can assess the regularity of the ventricular rhythm. And it is regular; there's an equal distance between the QRS complexes.
So this is going to be a very slow heart rate, we can already tell. But if we calculate it, there's about 43 small boxes between these QRS complexes. So if I take 1,500, divide it by 43, the heart rate is going to be 35.
So with ventricular rhythms, and with an idioventricular rhythm such as this, we can expect a slow heart rate that would be under 40 beats per minute. So with this one, we have 35 beats a minute, so that definitely fits the bill for an idioventricular rhythm.
It is possible to have an accelerated ventricular rhythm, which would have a heart rate that would be over 40, but for a normal idioventricular rhythm, we would expect a heart rate under 40.
So in terms of treatment, idioventricular rhythms are typically transient and often don't require treatment at all.
Finally, here, we have asystole. So this is the rhythm you never want to see on your patient, but you always want to see on your exam because it's pretty easy to pick out, right? So this is asystole.
The heart rate is zero.
There's no atrial or ventricular heart rhythm.
There's no P wave.
There's no QRS complex.
And you will need to perform CPR on a patient with asystole pronto. Okay?
Of course, if your patient is up and talking and you see this rhythm, chances are that their tele leads are just not on, so definitely use your common sense.
But if your patient is unresponsive and you see asystole, then definitely get going on the chest compressions.
That wraps up ventricular rhythms, and in my next video, we will start talking about heart blocks. So thank you so much for watching!
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EKG Interpretation, part 3: Analysis of Heart Rhythm, Heart Rate, P wave, PR interval and QRS complex
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