03.06 Premature Atrial Contraction (PAC)

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Study Tools

PAC Strip (Image)
Parts of EKG waveform (Image)
10 Common EKG Heart Rhythms (Cheat Sheet)
EKG Chart (Cheat Sheet)
EKG Electrical Activity Worksheet (Cheat Sheet)
Heart Rhythms Signs and Symptoms (Cheat Sheet)
Heart Rhythm Identification (Cheat Sheet)

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Hey guys in this lesson we are going to talk about premature atrial contractions also known as PAC, and we are going to use the six steps to identify it on an EKG. We are also going to talk about the characteristics, nursing interventions and treatments. So let's get started!

Normally the SA node Initiates the electrical impulse which travels down the AV node bundle his right and left bundle branches and purine fibers. In premature atrial contraction the impulse is initiated by another cell in the atria producing an early heartbeat. As you can see on this strip, we have a normal sinus rhythm and right here we have a P wave that comes early followed by a QRS. The P waves look abnormal in PAC, the atria do not have enough time to fill up with blood so the ventricles do not get enough blood and cardiac out and stroke volume will be decreased causing symptoms.
You can also see there's a little pause after the PAC and then the SA node starts up again to a normal sinus rhythm. The only good thing about PAC is that they are normal and a lot of people have them, its ok as long as not happening too
frequently. Something else I want to point out with PAC is that you have to
have an underlying rhythm you can’t just have a rhythm called premature atrial contractions. You have to have an underlying rhythm and then then PAC, if it was just PACs it would be something like atrial tachycardia. Now let's do the six-step method and break it down on an EKG.

In step number 1 let's find out if I rhythm is regular or irregular, so let's count the boxes that are not included in the PACs. So from here to here we have about 22 from here to here we have about 21.Now where
the PAC comes along we have 13 boxes and here we have 15 boxes so our rhythm is regular and irregular with the PAC. In step two let’s count the heart
rate. So we have a 6-second strip so let's count the r waves 7 R waves multiply that by 10 that gives us a heart rate of 70 beats per minute. The 1500 method is harder to do when you have an irregular rhythm. So the best thing to do when it's irregular make sure you count the apical pulse for a full minute. Now let's move on to the P to QRS ratio. And if you look at this strip every P wave has a QRS behind it so the P to QRS ratio is one to one, now let's do the PR interval and we'll do it from here to here so we have about three boxes which is 0.12 seconds which is normal. Now let's do the QRS complex from here to here we have about a box and a half so it's 0.06 seconds which is also normal. So in step 6 we identify the underlying rhythm and we have a sinus rhythm with premature atrial contractions. If the heart rate was 110 it would be sinus tachycardia with PAC or if it was 55 it would be sinus bradycardia with PAC. So let's recap the characteristics of this rhythm, the rhythm is regular and becomes irregular with PAC, the heart rate depends on the underlying rhythm. The P to QRS ratio is one to one, PR interval is normal and QRS complex is normal. Again always know your underlying rhythm. Let’s talk about what to do when patients have PACs.

When patients have premature atrial contractions their signs and symptoms are a fluttery feeling in their chest and they will say it feels like their heart is skipping a beat. Because of decreased cardiac output patients complain of dizziness and lightheadedness. The main nursing interventions for PAC are to determine the underlying rhythm and find out the frequency of the PAC. One or two PACs every now and then is okay but when they start occurring more often it can cause A-flutter, A-fib or atrial tachycardia. So let's talk about how to treat PACs.

So the therapeutic management for premature atrial contraction are to determine the cause, usually drinking more caffeine than normal or an electrolyte being abnormal can cause PAC a more serious cause would be somebody that has an MI and has heart muscle damage. So the treatments for PACs would obviously be to treat the cause. If symptomatic they will get beta blockers, if they are asymptomatic and we just monitor them.
So the key points to remember with PAC are the abnormalities, it is an early atrial contraction that causes the ventricles to contract and it produces an early heartbeat. The p waves are abnormal during the PAC. The nursing interventions are to know the underlying rhythm and the frequency of the PACs. Treatments would just be to monitor the patient if they are asymptomatic and if they are symptomatic then medications can be given to help decrease the heart rate.

I hope you guys have enjoyed this lesson and understand what occurs during a PAC and keep it simple, just remember there is usually an underlying rhythm and little bloop decides to come along. Make sure you check out all of the resources attached to this lesson and keep looking at different rhythms with PAC so you can become more familiar. Now, go out and be your best self today! And, as always, happy nursing!
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