Axis Deviation in ECG Made Easy, Causes, How to determine Axis in ECG Explained, ECG Lecture USMLE

okay in our video series of ECG interpretation Made Easy by six step method in this video we are going to talk about a step 4 of ECG interpretation the QRS assessment in QRS assessment we have three main steps our wave progression assessment access deviation and bundle branch blocks in this video we are going to talk about excess deviation in QRS assessment now coming to access deviation whenever a normal current flows through the heart it flows from SA node to AV node and from AV node to bundle of phase 2 per kanji fibers the flow of this current in heart is in the direction of left lateral downward Direction down left and to the front of the body is the normal flow of electrical current in the heart now whenever there is any damage to The myocardium any damage to the any part of heart the electrical flow gets Disturbed due to myocardial ischemia hypoxia hypertrophies these things disturb the normal flow of this current and it will result in deviation of this main Vector of current flow that is called as excess deviation this excess deviation can occur due to myocardial infarction due to hypertrophils due to bundle branch blocks due to fascicular blocks for example if there is any ischemia or myocardial tissue is dead over here on the right side now this right side of the heart is not contributing electrical current so this axis will deviate towards the left side if there is myocardial ischemia on the left side so this myocardial tissue will not contribute to this electrical vector and this Vector will deviate to the right side that is called as excess deviation basically it indicates that myocardial tissue is damaged same goes for hypertrophes and bundle branch blocks now this is a picture showing the normal flow of current this is a vector ratio in the left lateral and downward direction that is the normal flow of electrical current in the heart so we have this picture of hex axial plane in this hex axial plane we divide it into the four quadrants if it is present between 0 to Plus 90 degrees if the vector of the heart of the current flow is present in this quadrant it is normal if it is present over here then it shows right excess deviation it means that either there is myocardial ischemia on the left side of the heart or there is hypertrophy of the heart tissue on the right side therefore the excess has deviated towards the right side and now what if this Vector deviates in this quadrant if it is present from 0 to minus 90 degrees that is called as a left axis deviation and remember left if this deviation is divided into two pathologic left axis deviation and physiologic left axis deviation sometimes the deviation from 0 to 30 degrees is called as a physiologic deviation because sometimes in athletes there is left myocardial heart tissue becomes hypertrophic and that is a normal hypertrophy of the left side that can result in physiologic deviation from 0 to minus 30 degrees and that left axis deviation is considered physiologic that is considered normal because that is a normal hypertrophy in ethylates that results in deviation of excess from 0 to 30 degrees so minus 1 to minus 30 degrees is physiologic left axis deviation but if this excess deviates from more than minus 30 degrees more than minus 30 to less than minus 90 degrees that is a pathological left axis deviation because a normal hypertrophy uh hypertrophy in the ethylates a normal hypotrophic cannot cause this much deviation if there is more than minus 30 degree deviation if the vector is present over here this shows that the there is pathological problem pathology present in the heart that is causing left axis deviation that is pathologic yeah and what if this Vector totally deviates into an opposite quadrant this opposite coordinate of this Vector deviates into the opposite quadrant that is called as an indeterminate excess deviation it is rare to have the vector over here it's more common to find Vector in the right side or the left side and it is less common to find the vector in the opposite direction that is called as an indeterminate axis deviation or it is also called as a right extreme right Axis deviation or it is also called as extreme right Axis deviation and it is rare to find an extreme right Axis deviation you can see these type of deviations when the patient has developed severe ventricular tachycardias but more common is right and left axis deviation now how do you determine the excess deviation in an ECG when you have lead one lead one is present over here lead avf is present over here and the main Vector of the current flow is in this direction this is the main Vector of current flow now if you see whenever the current flows toward a lead there is positive deflection on ECG so the vector is Flowing towards the Lead 1 and lead avf on this side so 1 and avf are showing positive R wave there is positive deflection there is positive deflection in one and AVR now what if this Vector deviates towards this side if it deviates toward this side this avf will be lying in the opposite direction and the current will be flowing like this what if this axis deviates to this side to left side the current will be flowing opposite to the avf it will be flowing away from the evf and then there will be a negative deviation so to look at the axis deviation we have two important leads lead one and Lead avf now normally if you look at Lead 1 and Lead avf they both have positive deflection because Lead 1 is present over here lead avf is present over here and Vector is Flowing like this so both will show positive deviation positive R wave lead one will show positive R wave lead avf will show positive R wave and if both QRS are pointing upwards it is a normal axis now what if this x is this Vector deviates toward this side if this Vector deviates towards this side then this Vector will be flowing away from lead one and the lead one will show negative deflection if this Vector if this Vector flows over here and it this Vector is deviated toward the right side then this Vector will be flowing in the opposite direction of Lead 1 and the Lead 1 will show negative deflection and Lead avf will show positive deflection because it will be in the direction of current flow so if the lead one is showing negative deflection and Lead ABF is showing positive deflection that is called as a right Axis deviation so that occurs in right Axis deviation Lead 1 is negative lead avf is positive and Lead 1 is present on the top of ECG lead avf is present below so what you will see is that you will see the a pattern like this that lead 1 is deviated downward lead avf is pointed upward and they are pointing towards each other the qrs's are pointing towards each other they are reaching out for each other if the right or wave of avf and R wave of Lead 1 reach out for each other that is a right Axis deviation so the mnemonic to remember axis deviation is that right reaches the Lead 1 QRS is downward lead avf QRS is upward and they will reach out for each other right reaches now if this Vector if this Vector deviates from this quadrant and it goes into this quadrant now this Vector is lying opposite this Vector this current is flowing in opposite direction to lead AV F and Lead avf will show negative deflection and Lead 1 will show positive deflection because the vector is over here lead avf will show negative deflection Lead 1 will show positive deflection since it is in present near to the current flow and lead a VF is present opposite to the current flow so if the avf is negatively deflected and relied one is positively deflected that is left axis deviation and if you look at the ECG will solve the ECGs now in ECG Lead 1 is present on the top lead avf is present below and Lead one QRS complex is pointing upward lead avf QRS complex is pointing downwards so the QRS are leaving each other the QRS complexes are leaving each other if they are both pointing away from each other that is left axis deviation you can remember the simple mnemonic left leaves the left axis deviation the QRS complex is a 1 and avf leave and right reaches normal is upward that is a simple way to remember the excess deviations now if this Vector deviates totally into the opposite direction in this indeterminate quadrant now what you will see is that the current is Flowing opposite to lead one and Lead available the current is Flowing opposite to the both leads and both leads Lead 1 and avf will show negative deflection because the current is flowing in this direction and these leads are present over here and these leads will show negative deflection negative deflection if both leads are pointed downwards then it is an indeterminate axis and it is rare to find both leads pointing downwards now let's solve some ECGs if you look at Lead 1 Lead 1 is pointing upward if you look at lead avf avf is also pointing upward so both are pointing upward it is a normal axis now pause the video and solve this ECG yourself pause this and find out the access that whether it is normal it is left Axis or it is right Axis deviation or it is indeterminate now coming to the answer if you look at lead one in lead one the r wave is negatively deflected the r wave is downward and let's look at the avf avf is positively deflected so the lead one is downwards lead avf is pointing upward and they are reaching out for each other right reaches so this is a right Axis deviation it cannot be more simple than this this is a right access deviation pause the video look at the ECG and find out that where is the excess deviation in this now coming to the answer let's look at the lead one lead one is pointing upward positively deflected lead avf is negatively reflected the lead one is pointing upwards the lead avf is pointing downward so they are leaving each other left leaves so this is the left axis deviation both leads are opposite they are leaving each other now pause the video solve this ECG yourself find out the access in this where is the axis whether it is normal it is right Axis or left axis deviation now coming to the answer if you look at lead one lead one is predominantly positively deflected so it is a positive deflection deflection upward if you look at lead evf lead avf is predominantly deflecting downwards so the prom prominent deflection is downward there is somewhat upward deflection but the predominant part is downward so we will say that the lead ABF is pointing downward and Lead one is pointing upward and they are leaving each other the left leaves this is a left axis deviation now coming to the causes of left axis deviation remember as I said myocardial infarction hypertrophies bundle branch blocks all these things cause excess deviation it left excess deviation can be normal in older and obese people that physiologic deviation that I talked about from 1 to 30 degrees that can be a normal physiologic deviation mechanical shift in pregnancy you know since the heart is hanging down in the chest cavity like this now when there is pregnancy and uterus starts to swell up that heart start starts to become like this so there can be a left axis deviation due to the uterus pushing the heart upward emphysema left ventricular hypertrophy in the left ventricular hypertroph with the left ventricle gets big and it attracts all the currents toward it it is producing more currents therefore the back axis deviates towards the left side left anterior fascicular block inferior wall Mi left bundle branch block ventricular tachycardia so these are all the causes of left axis deviation now coming to write excess deviation anything that causes the hypertrophy of right heart will cause deviation of the excess toward the right side emphysema results in damage of the right side of the heart and there is hypertrophy because of the increased hypertension present in the pulmonary vessels increased pumping of the heart to the right side causes hypertrophy and that the muscles get big on the right side and they produce more currents therefore the there is deviation toward the right side right particular hypertrophy COPD has the same mechanism left posterior fascicular block right bundle branch block now what happens in the bundle branch blocks is that if there is a right bundle branch block if the current is not flowing toward the right side so the current quickly goes to the left side left side gets depolarized left side has the current then what happens is that since the right side is not receiving current this must this the muscle of the left ventricle starts sending currents to the right side and the current starts flowing in this direction rather other than flowing in the normal flow it starts blowing in this direction when the current flows in the rightward direction there is a right Axis deviation we will talk about hypertrophic indexes deviation in detail in the videos on hypertrophy ventricular tachycardia indeterminate excess deviation is less common it can be seen in ventricular tachycardia and biofascicular blocks now before going into the summary if you liked my video please click on the Subscribe button and check out my previous video on our way of progression and check out my next video on hypertrophies we talked about six step method in Step 4 we have the QRS assessment QRS assessment we talked about access deviation in this video we talked about what is excess deviation the normal X is what changes the X's our right X is deviation left axis deviation the normal physiological deviation from 0 to 30 degrees and then we talked about indeterminate excess deviation extreme right Axis deviation if they are reaching towards each other that is a right reaches right Axis deviation if they are leaving each other that is a left access deviation if both are downwards it is indeterminate and if both are upwards that is a normal axis then we practiced some ECGs right access deviation left axis deviation left axis deviation causes right Axis deviation causes causes of indeterminate axis deviation if you liked my video please click on the Subscribe button and check out my other videos on ECG interpretation Made Easy the link of those videos is given in the description below thank you very much

Channel: MedNerd - Dr. Waqas Fazal

Views: 67,151

Keywords: axis deviation ecg, axis deviation made easy, how to determine axis deviation in ecg, how to determine axis on ecg, ecg axis, ecg axis determination, ecg axis deviation made easy, ecg axis medical school, right axis deviation ecg, right axis deviation, left axis deviation ecg, axis deviation explained, ecg axis deviation explained, axis deviation usmle, axis deviation using 1 and avf

Id: wz4-aFLyP4w

Length: 15min 47sec (947 seconds)

Published: Sat May 13 2023