Cardiac Axis Deviations Made Easy

hello guys greetings from a tube channel presenting another educational video on cardiac axis deviations now a cardiac axis is defined as the average direction of depolarization wave through the ventricles but before we go into the correct axis deviations let's first review some general concepts the first thing is that when the electricity which is the depolarization waves of course when the electricity moves towards a lead we get a positive deflection of QRS complex on an ECG so it moves upwards whether when the electricity moves away from a lead then we get a negative deflection of QRS complex we look at the limb bleeds to determine the cardiac axis not the precordial chest leads and the limp leaves are basically categorized into two categories the first is the bipolar limp leads which are leads one two and three and the second is the Augmented unipolar limb leads which are AVR AVL and a VF and pretty much actually all you need to look at is leads one two and AVF to determine the Corrick axis but we're gonna see different methods term in the quartic axis shortly and here again we can see a good representation of the six limb leads now please note that these are called the limp leads not the limp electrodes the lectroids are actually the electrodes which are placed on your limbs and the limb bleeds are calculated in a certain way from the limp electrodes giving an average spatial electrical direction of each lead so for example we have lead one which is directed horizontally to the left at 0 degrees we have lead 2 which is directed downward and a little bit to the left at positive 60 degrees we have lead AVF which is directed downwards at exactly positive 90 degrees and etc for all the leads and here on this drawing we can see a representation of an normal cardiac axes and you can see that the normal cardiac axis is actually tilted to the left and that's because of the thicker left ventricle and a thicker left bundle branch and according to the illustration here which is commonly known as the Cabrera system which shows the average direction of the limb bleeds we can see that from this drawing the cardiac action this drawing is about positive 45 degrees somewhere in here and this is normal but a normal cardiac axis actually has a range and the normal range for our normal cardiac axis is anywhere between minus 30 degrees to a positive 90 degrees and anywhere outside that is an abnormal cardiac axis as we will be seeing shortly here on this drawing we can see an inferior wall myocardial infarction with the left axis deviation and the left axis deviation in an inferior wall myocardial infarction is usually due to a concomitant left anterior Hemi block but an inferior wall record infarction can cause it itself without the Hemi block and on the illustration here a left axis deviation is anywhere between minus 30 degrees to minus 90 degrees so this cardiac axis actually should be tilted a little bit upwards so it fits between minus 30 and minus 90 degrees on this drawing here we can see a right axis deviation and the right axis deviation is anywhere between positive 90 degrees to a positive 180 degrees so you can see here it's that's about 135 degrees so here again to summarize we have the normal cardiac axis anywhere between minus 30 degrees and positive 90 degrees the left axis deviation is anywhere between minus 30 degrees to minus 90 degrees a right axis deviation is anywhere between positive 90 degrees to positive at 180 degrees and finally the extreme axis deviation which is anywhere between a minus 90 degrees to of 180 so right here so now finally let's move to the ECG how does the cardiac axis look at the ECG so again the normal cardiac axis we said it's going to direct towards anywhere between minus 30 and positive 90 so do you expect lead to want to be positive or negative and the answer is positive because the cardiac axis is moving towards lead one do you expect lead 2 to be positive or negative and the answer is again positive because the cardiac axis is moving towards lead - how about a VF and the answer again is positive but actually a VF could be negative just between 0 and minus 3 in this little bit here and that because between 0 and minus 30 degrees the cardiac axis would be more than 90 degrees away from the a VF so as a general rule if the cardiac axis is more than 90 degrees away from that specific lead then it would be negative so let's say a VF so psychotic X is anywhere between above 0 or above 180 right here then that lead would be negative on the other hand if you cardiac axis is within 90 degrees of a specific lead so let's for example pick up a VF if the cardiac is between 90 degrees in any direction then we consider it as positive and we would consider the cardiac axis to be moving towards that lead so again the cardiac axis is more than 90 degrees away from the lead in any direction then we will consider the cardiac anxious to be moving away from that lead if it's between 90 degrees of a specific lead as for example between 0 and 90 and 90 180 of a VF they will consider the cardiac access to be moving towards that specific lead and that lead would be positive the last condition is what if the cardiac axis is exactly perpendicular at 90 degrees of specifically then the let's lead with look either electric or the ECG the positive concurrence and the negative concurrence of the QRS would be equal so isoelectric so let's pick up our first example on a normal cardiac axis so again all you need to look at is actually just leads one to an AV F so you can see here that one has a positive deflection Li two has a positive deflection and lead a VF has a positive deflection therefore this is a normal cardiac axis and you can expect that the cardiac axis is kind of moving downwards to the left so towards the left lower quadrant and you could confirm it here again on this illustration you can see that if it's moving right just like this to the left on downwards your one - an AV F will be positive and if you would like just to confirm you can see that AVR is negative so it's moving away from AVR like this downwards to the left you can see that three is positive so again it's moving kind of within 90 degrees of lead three so right here and you can see that AVL is isoelectronic so this puts the axes actually perpendicular to AVL so exactly add positive 60 degrees but I'm sorry for the to much confusion again all you need to look at it just leads one to an AV f to determine the cardiac axis is it normal or not here we can see an example on left axis deviation we can see that lead one is positive lead two is negative and AV F is negative so the axis is moving towards lead one and away from leads to an AV f we can see on this illustration that the cardiac axis with the moving towards lead one so about right here but since two and AVF are negative so it's gonna be somewhere here so it's within ninety degrees of lead one within ninety degrees but it's away from two and fef more than 90 degrees away so it's going to be somewhere in this between minus 30 degrees and minus 90 degrees now please note for our left axis deviation to happen you have to have late one positive and both leads to an AV F negative because just imagine with me for a second it leads one and two were positive but only a VF was negative that means the cardiac axis will be somewhere between 0 and minus 30 degrees because it would be moving towards both leads 1 & 2 so somewhere in here at the same time it's moving away from a VF it's more than 90 degrees away you remember so the cardiac axis actually would be normal you have to have both leads to an AV f- and lead one positive for left axis deviation to happen here this ECG we can see an example of a right axis deviation first we can see that lead 1 is negative and lead AV F is positive so on this illustration we can see that lead 1 is negative so that means it has the cardiac axis must be anywhere between minus 90 to positive 90 because lead 1 is negative so it's more than 90 degrees away in each direction and the second thing is that since a VF is positive that means the cardiac axis must be in this quadrant the right lower quadrant because it's moving towards a VF within 90 degrees now please note that lead to doesn't really matter and right axis deviation and that's because the range of a right axis deviation is pretty wide and therefore a positively to could fall and the right axis deviation quadrant the right lower quadrant and even and negatively to could fall within the right axis deviation quadrant so that's why le 2 doesn't really matter in right axis deviation so again all you need to have is a negative lead one and positive AVF and that equals right axis deviation and now coming to a last example the extreme axis deviation and making long story short all you need to have is a negative lead one and a negative AVF and to confirm on this illustration if you have a negative lead one that means it's anywhere between this minus 90 degrees to positive 90 degrees because it's more than 90 degrees away in each direction and the second thing is that since AVF is negative that means it's also away from AVF more than 90 degrees in each direction and to combine both that means you cardiac axis must be in this quadrant away from both leads one and AVF so this is called extreme axis deviation and to confirm you can also see that AVR is positive so it's towards AVR and you can see that also 2 & 3 are negative so it's also away from 2 & 3 this is extreme actions deviation now please note in all of the previous examples we have been using the quadrant method to determine the cardiac axis deviation but what if we want to know how much exactly is the cardiac axis deviation what is the degree of the cardiac axis because the quadrant method cannot really tell you how much is your cardiac axis deviation it could only tell you what is your cardiac axis is it a normal one or is it a left axis deviation is a right axis deviation or is it an extreme axis deviation but what if we wanted to know how much is your our cardiac axis then we will be using the second method the ISO electric late method and it's pretty simple the first thing is that you need to find the isoelectric lead on the ECG and the second thing is that find the positive leads and the cardiac axis will be towards the positive leads for example let's say the isoelectric lead was AVL or the ECG so your cardiac acts this must be perpendicular to the AVL it has to be at 90 degrees so the cardiac axis will be either pointing the positive 60 degrees or 2 minus 120 degrees and you can determine which side is the correct one by looking at the other leads so for example it leads one to an AVL for positive and AVL is isoelectronic of course then you quarry axis must be pointing to the positive 60 degrees and not to the hunt to the minus 120 degrees whereas if a VL was the isoelectronic lead leads one to an AVL for negative and the lead AVR was the positive one then your cardiac axis must be pointing at exactly minus 120 degrees in this direction so let's apply what we have just said if you can remember this is the first ECD that we have explained using the quadrant method and if you remember we have said that sense leads one to an AVL for positive then this is a normal cardiac axis but using the quadrant method we cannot really tell again how much is recording access because animal Kotik axis can be anywhere between minus 30 degrees to positive 90 degrees so you think the quantum method Lord cannot tell us how much is you cardig axis so how much using the isoelectric lead methods so first we look for the eyes electric leads which is the AVL its isoelectric the positive deflection equals the negative deflection which means the cardiac axis is exactly at 90 degrees angle to this lead so using the Cabrio system we can draw the cardiac axis being exactly perpendicular to the AVL but again the conic axis could be either pointing to the One Direction which is the minus 120 degrees or to the other direction which is positive 60 degrees and to know to which direction it is pointing we have to look at some of the other leads so for example you can see here that leads one to three and AVF are all positive so that means you cardiac axis must be pointing towards those leads leads one to a VF 3 and so your Kotik axis must be pointing to the positive 60 degrees and not to the minus 120 degrees and you can confirm that also by seeing that AVR is negative so it's pointing away from AVR so again the biggest advantage about using this isoelectronic lead method is that you kind of have a reference number which is that the cardiac axis is at 90 degrees angle to the isoelectric lead and now we have an example for left axis deviation so again first using the quadrant method we can see that lead one is positive and AVF is negative and lead to is kind of isoelectric and again we sit in the quadrant method we need to have both leads to an AV f negative so using the quadrant method we can say this is kind of borderline left axis deviation but using the isoelectric lead method our isoelectronic lead is of course lead to and using the Cabrera system we can go to lead two and then draw a perpendicular line to lead to so the aquatic axis is either pointing to the minus 30 degrees or to the positive 150 degrees and since leads 1 and AVL are positive then your Kotik axis is pointing to leech one and fel so your kartik axis must be minus 30 degrees which is actually a borderline lift X deviation literally because the left axis deviation is anywhere between minus 30 degrees and minus 90 degrees and to confirm you can also see that leads 3 IVF and AVR are all negative so it's pointing away from AVR 3 and fef and this confirms our finding and now let's get an example on one axis deviation and you can notice that this ECG is the same one that we have used previously or the quadrant method and you can see gain that lead one is negative and AVF is positive so that means white axis deviation and your cardiac axis is anywhere between positive 90 degrees to positive 180 degrees but how much exactly is your correct axis we have to use the isoelectric lead method and do your isoelectric lead here is lead to so using the Cabrio system we can we go to lead two and draw a perpendicular line to lead to so your cardiac axis is either pointing to minus 30 degrees or the positive 150 degrees so looking again at the other leads we can determine in which direction is your conic axis so you can see that lead 1 is negative and AVL is negative so it has to be pointing away from AVL and 1 so your conic axis must be at exactly a positive 150 degrees and you can confirm that by seeing that leads 3 fef and a vr+ psychotic axis is towards a VF 3 an AVR and this is exactly the opposite of a left axis deviation finding if you can notice and now coming to our last slide of this video the extreme axes deviation and again if you notice this ECG is the same one used from the quadrant method that we have used previously and using the quadrant methods we can see that lead one is negative and a VF is negative and that means your cardiac axis is in the right upper quadrant from minus 90 degrees to 180 degrees in the right upper quadrant but again how much exactly is your conic axis we have to use the isoelectric lead method I guess where the isoelectric lead isn't here that's right it's AVL and you can see that the positive deflection equals the negative deflection and going to AVL of the Cabrio system again we draw a perpendicular line to AVL so that means your conic axis is either pointing to the minus 120 degrees or the positive 60 degrees and again which the is the correct one we have to look at the other leads so looking at the other leads we can see that leads one two three and AVF are all negative so logically you conic axis must be going in the direction opposite to these leads so iconic axis must be at minus 120 degrees and to confirm you can see that lead AVR is positive so it's pointing towards lead if you are that would be all for this video thank you guys very much for watching and I really hope that you have been enjoying our ECT videos thank you again and have a great day interpreting your ECGs

Channel: MedTube

Views: 197,943

Keywords: Left Axis Deviation (Disease Or Medical Condition), Electrocardiography (Diagnostic Test), right axis deviation, Heart Axis, left axis deviation, Cabrera system, leads, Limb leads, Northwest axis deviation, QRS complex, Heart (Anatomical Structure), Health (Industry)

Id: rT1e7ffx06E

Length: 20min 41sec (1241 seconds)

Published: Thu May 21 2015