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Hey guys, in this lesson we are going to talk about premature ventricular contractions- also called PVCs. We are going to break down the characteristics of PVCs on an EKG and talk about nursing interventions and treatments. So let’s get started!
So in a premature ventricular contraction there is an additional stimulation in the ventricles that causes the ventricles to contract prematurely. Look at this strip here, we have a P wave followed by a QRS expect here where you can see a wide and abnormal looking QRS. Irritable cells in the ventricles that produce an additional firing so the ventricles decide to contract before they are supposed to. This decreases cardiac output during the contraction because the ventricles did not have enough time to rest and fill up with blood, less blood is being pumped out. The QRS complex is usually wider looking usually the signal starts in the right ventricle it causes the right ventricle to contract and then it travels to the left ventricle so the left ventricle contracts. Normally both ventricles contract at the same time in a normal QRS, so in a PVC the QRS complex is wider. Just like in PACs, there must be an underlying rhythm, there can’t just be a bunch of PVCs! So let’s do the 6-step method and break down the characteristics of PVCs on an EKG.
OK so in step 1 let’s look at the rhythm, is it regular or irregular. In this strip, it is a sinus bradycardia so it’s a regular rhythm and irregular during the PVC. The regularity depends on the underlying rhythm, if it was A-fib it would be irregular. So here we are regular. In step 2 we need to count the heart rate. We are going to count the R waves so we multiply 4 by 10 and our heart rate is 40 beats per minute. And yes, you do count the PVC- every QRS is counted. Some EKG monitors will not count the PVC in the heart rate so it will show a really low HR, so always double check it yourself and count the QRS complex during a PVC. In step 3 we do the P:QRS ratio, do we have one P wave for every QRS, that depends on the underlying rhythm, here we do but during a PVC it is not measurable. So in step 4 we need to look at the PR Interval, again since we have no P waves during the PVC it is not measurable. It would be measurable depending on the underlying rhythm. In step 5 we need to look at the QRS complex, so during the PVC it is 4 boxes or 0.16 seconds, it is about 2 boxes on the others or 0.08 seconds. It is normal for the most part but during the PVC it is wider. So in step 6 we identify the rhythm and we have sinus bradycardia with PVCs. If the heart rate was normal or greater than 100 it would be called normal sinus rhythm with PVC or sinus tachycardia with PVCs. Because PVCs occur from irritable cells in the ventricles, it is very common to see PVC in all rhythms including A-flutter, A fib, and heart blocks. So let’s talk about managing PVCs.
So most people that present with PVCs will report a feeling of a skipped heartbeat or a pounding heartbeat during depending on the PVC frequency. The nursing interventions for PVC are to know the underlying rhythm and to determine the frequency of the PVCs. If one shows up every now and then, its ok, we can just continue to monitor them. If it is happening more frequently we need to do something about it. If you ever hear the term bigeminy, it means they are having a PVC every other beat. Every third beat would be considered trigeminy, so having two normal QRS complex and a PVC would be trigeminy. Always know how frequent the PVC are occurring since it predisposes a person to V-tach and we need to prevent that from happening. So let’s talk about how to treat PVCs.
So therapeutic management for PVC are to determine the cause, just like in PACs, increased caffeine intake, electrolyte imbalance especially potassium and magnesium, hypoxia and medications can cause PVC and so can an MI. So if you can determine the cause, treat the cause! If patients are asymptomatic and the PVC are not that frequent just continue to monitor them. If they are symptomatic and we have frequent PVCs we need to do something so they do not go into V-tach. We can give them some antiarrhythmics and beta blockers and calcium channel blockers. If they continue to have frequent PVCs, they may get an implantable cardioverter defibrillator or ICD, the ICD is implanted under the skin and the wires go straight to the heart. So the defibrillator senses if a patient is going into V-tach or V-fib and it shocks the heart so it goes back into a normal sinus rhythm. It’s almost like walking around with a defibrillator and being attached to the pads, if a lethal rhythm happens it will shock it back to normal rhythm. Lastly, if people continue to have frequent PVCs, they will have an ablation to burn the irritable part in the ventricle so it quits sending off an electrical stimulation
So the key points to remember for this lesson are the abnormalities of PVCs. It is an early contraction of the ventricles, the QRS complex is wider during the PVC greater than 0.12 seconds. Main nursing interventions are to know the underlying rhythm and the frequency of the PVCs if they are not too often we continue to monitor, if they are more frequent we need to do something about it. The treatment depends on the frequency of the PVCs.
I hope that you guys have a better understanding of PVC and know their characteristics and management. Make sure you check out all of the resources attached to this lesson. Now, go out and be your best self today! And, as always, happy nursing!