 Hi, welcome to nursing school explain and this first video in the atrial ventricular block series about first-degree av or hard blocks If you haven't already done so I highly recommend watching my basic introductory EKG interpretation videos termed basic electrophysiology and EKG interpretation basics about EKG paper and determination of heart rate as well as the normal intervals and rules to memorize that you can apply to every different rhythm strip so that you Always approach this in a very methodical and systematic approach So the atrial ventricular junction is a specialized conduction tissue that connects the electrical links between the atrium and the ventricles keep in mind that medical terminology always kind of gives away the term the The solution so av junction is the connection between the atrium and the ventricle but any conduction delay or interruption in the av junction and And the parts would be the av node the bundle of his or the his frikinji fiber system Can cause an av or hard block as it's sometimes also referred to and Today we'll be looking at this first-degree av block Which means that there's a conduction delay in the av node that causes a prolongation in the pr interval and remember the pri or pr interval represents the Time that it takes the impulse to reach Through the atrium all the way to the top part of the ventricles So now if we have a delay here in the av junction it's going to be represented by a prolonged pri and The first-degree hard block is an incomplete hard block Second-degree hard block is also determined as incomplete where third-degree will be a complete hard block But we'll look at those details in different videos So here's a brick brief review of the conduction system of the heart from the av to the av node to the bundle of his and then The prikinji fibers. So any conduction delay here in any of these Traveling down through the atrium will cause a delay and an av block and remember This is basically from the p to the r. So then we're gonna have this prolonged pri pr interval When we analyze a rhythm strip we always go about it in this methodical way But looking at the rate rhythm regularity the p-waves and the intervals So in a first-degree av block the rate is typically normal 60 to 100 It is usually pretty regular And we can see that here basically with the naked eye that these qrs's have the same distance We could also take the calibers and march this out or overlay this with a simple Piece of white paper and then march it out as I discussed in my other video to determine that this is a Regular rhythm now in terms of the p-wave in first-degree av block The p-waves will be normal and they will be upright and there will be one for every qrs But now because of this conduction delay that we discussed the pri is prolonged at 0.2 at greater than 0.2 zero or greater than five boxes And the qrs is typically normal at 0.12 or less than that So if we look at this fifth impulse here, we can see This p-wave starts at this thick line here and if I count these one two three four five Six at least six. So now I know this is greater than five boxes that would correspond to 0.24 So I know my pri is supposed to be up to zero point two zero so now I know that I'm dealing with a Prolonged pri and that there is this conduction delay through the av junction And then the qrs will typically be normal because once the impulse reaches the ventricles the ventricles Respond in a normal fashion So for example, we could look at this impulse here starting at this line one two three So this would be two boxes. So that would be an impulse of zero point zero eight Which is less than the zero point one two which makes the qrs normal So in a first-degree av block basically everything is normal except the pri is prolonged This is a little bit of a better look at this And if we just with the naked dialogue from this thick line the beginning of the p to the beginning of the r Which is right here We can already see that this is greater than just one box from the thick lines So we already know that this is a first-degree av block by knowing that the pri is greater than 0.20 second Causes for first-degree av blocks it may be a normal finding in athletes But it also may be due to injury or ischemia to the av node or junction that causes this conduction delay Certain medications can make the patient more prone to first-degree av blocks And these include beta blockers calcium genoblockers Dijoxin and amiodarone And we know that potassium is very important in conducting the electrical activities through the heart so hyperkalemia can make the patient Have a first-degree av block Certainly acute mi which goes along with this ischemia injury to the av node or junction that we discussed up here and then any Increased in vagal tones so stimulating the parasympathetic nervous system can also make the patient more prone for a first-degree av block For signs and symptoms patients are sometimes Asymptomatic as in these athletes that might have this as a normal finding But if it is associated with an mi the patient may have typical symptoms such as chest pain shortness of breath dizziness syncope sweating Diophoresis any of these typical mi symptoms Interventions for first-degree av block if the patient is aim symptomatic We might not need any But if there's an acute mi certainly we need to act on that and every hospital will have mi and acute coronary syndrome protocols to go by those and that usually The end goal is to get the patient to the cath lab and take a look by angiogram to see the extent of the blockage Here are some references and other websites for you to look at to practice your Rhythm strips because now that we're getting into these av blocks It's getting a little bit more complicated and I really recommend that you look at those rhythm strips So that you can start applying these rules and the more you practice of course the better you'll get at it I also have quizzes Posted on my Instagram page that come out every Monday that you can follow that will go Into quizzes about different EKG rhythms on a weekly basis Please also watch my other big videos in the EKG interpretation playlist These are all the videos and then specifically here we have the av blocks today was first-degree There will be other videos about second and third-degree av blocks. 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