4. Q Wave Overview - ECG assessment and ECG interpretation made easy

[Music] hello everyone as a continuation of ecg lecture series in this session i will be discussing about the q wave so if you take this particular q wave it is a negative wave or a negative complex in the ecg and why this particular q wave is a negative complex let me discuss in detail so if you take this particular q wave it is a negative wave now why is this particular q wave negative is because first you see this question direction of septal depolarization is right to left left to right towards the apex of the heart towards the base of the heart so what you need to understand here is the q wave it is formed due to septal depolarization all right it is formed due to septal depolarization and you see this is the septal depolarization and the direction of the septal depolarization is from left to right so that is the reason why you see for example you have placed lead v6 here then v5 then v3 then v4 this is your v1 and v2 so if you take the direction of the depolarization of the septum the direction of the depolarization of the septum is from left to right that is away from the electrode so if the wave of depolarization if it is moving away from the electrode then you will have a negative wave or the negative complex so this is the negative q wave right this is your negative q wave so direction of septal depolarization remember it is from left to right right it is from left to right and the q wave is a negative deflection that precedes the r wave so after the q wave you will have the r wave and then you have the s wave so this is q r and as well as s and this q wave as i have said you it represents the normal left to right depolarization of the interventricular septum now let me show you the q waves in the different leads in a normal ecg the q wave it is very small right so you have a small q waves in most of the leads and small septal q waves are typically seen in the left sided leads that is one avl v5 v6 they are your later leads or the left sided leads so you can see here this is lead one this is your avl and v5 and as well as v6 you will have a small septal q waves and remember under normal circumstances you will not have q wave from v one to v three leads that is in right sided leads you will not have the q wave okay so you see these are your light right sided leads v one v two and as well as v3 you don't have the q waves okay now these are your v1 v2 and as well as v3 so the depolarization is moving towards the electrode so the negative complex which has to come your q wave is a negative wave so you should have a negative complex but the wave of depolarization is towards the electrode in v1 and as well as v2 so that negative complex whichever has to come it gets neutralized so thereby you will not have the q wave in v1 v2 and as well as v3 now so in a normal individual the q wave it should be a very small q wave but what are the conditions where you will have pathological q wave what is the criteria for the pathological q wave right let me show you a question so if you see this all of the following are the features of the pathological q wave except options are more than 40 milliseconds duration more than 2 mm deep more than 25 percent of the depth of the qrs complex less than 1 mm deep right less than 1 mmd so all the first three they are the criteria of the pathological q wave right they are the criteria of the pathological q wave duration should be more than 40 milliseconds that means it should be more than one small box and depth should be more than 2 mm deep that means 2 small boxes or the depth should be more than 25 percent of the depth of the qrs complex right more than 25 percent of the depth of the qrs complex and less than 1 mm white this is not the criteria of the pathological q wave okay now let me just show you a ecg with the pathological q wave so this is the ecg with the pathological q wave so it should be more than 40 milliseconds wide you see here right so the duration is more than one small box and if you take the depth it should be more than 1 mm deep right so here it is almost more than 2 mm even more than 2 mm is also considered as a pathological q wave and the depth of the qrs complex right how much it should be or the depth of the q wave it should be more than 25 percent of the depth of the qrs complex right more than 25 percent of the depth of the qrs complex and this particular pathological q wave in this ecg they are present in the inferior leads right why because your 2 3 and as well as avf they are considered as the inferior leads right they are considered as the inferior leads okay now after having discussed about the criteria of the pathological cue wave now you see one more question deep dagger-shaped q waves are seen in myocardial infarction hypertrophic cardiomyopathy lead placement error rotation of the heart that is clockwise or anti-clockwise direction so where do you have the deep dagger-shaped q-waves they are seen in case of the hypertrophic cardiomyopathy so in hypertrophic cardiomyopathy you will have deep dagger shaped cue waves now why do you have that particular deep dagger-shaped q waves in hypertrophic cardiomyopathy let me explain you so you see this particular ecg along with the heart with the hypertrophy cardiomyopathy so in case of hypertrophic cardiomyopathy remember it is the septum which is hypertrophy right it is the septum which is hypertrophy and you place this v5 and as well as v6 so how is the septal depolarization septal depolarization is away from v5 and v6 so that is the reason why right that is the reason why you see in case of v5 and as well as v6 what is that you are having you are having deep q waves and these q waves they are in the shape of a dagger right these q waves they are in the shape of a dagger okay so now here these individuals with hypertrophic obstructive cardiomyopathy the drug of choice is your beta blockers right these drug of choices the beta blockers okay now now let me tell you what all the other conditions where you will have the deep pathological q wave one is your hypertrophic obstructive cardiomyopathy and second thing is in case of myocardial infarction and the other conditions are rotation of the heart wherever there is extreme clockwise or counterclockwise direction or rotation of the heart there you will have the pathological q wave and as well as the lead placement error that is upper limb leads placed on the lower limbs and lower limb leads placed on the upper limbs so these are all the differential diagnosis where you can have the pathological q wave now i'll show you one ecg here right so identify the ecg anterior wall mi inferior wall mi lateral wall mi the posterior wall mi so you see here where all you will have the st elevations and as well as the q wave because in patients with mi you will have st segment elevation okay so let me tell you one of the very very important point here the earliest ecg change in mi right the earliest ecg change in mi is the presence of tall t wave write the presence of or appearance of the toilet wave and followed by that the individual will have the st segment elevation right followed by that the individual will have st segment elevation in mi so where all you have st segment elevation mi st elevation that is from v1 to v4 so v1 to v4 you have the st segment elevation and along with that you see the individual is also having deep pathological q wave where exactly in the anterior leads right exactly in the anterior leads so this particular ecg is suggestive of the anterior wall mi so in patients with anterior wall mi also you will have or in mi you will have the q wave and by the time the q wave is formed we call it as right by the time the q wave is formed we call it as evolved mi in the sense the individual has a transmural myocardial infarction i'll also explain you the reason why you have a deep q wave in mi right you see this so for example you take in this clinical scenario v6 it corresponds to your lateral wall right right it corresponds to your lateral wall now in this individual he has the later wall being completely infected right the later wall it has been completely infected okay so when the lateral wall is completely infected that means this lateral wall it acts as a window knob right because the myocardium it is not an active myocardium so this particular v6 whatever is placed right this particular v6 whatever is placed will pick up the electrical activity directly from the septum now you don't have the later wall because lateral wall is dead so now v6 is picking up the electrical activity directly from the septum and your septal depolarization is away from the electrode that is the reason why you will have the q wave which is a negative complex right that is the reason why you will have a q wave which is a negative complex okay so in evolved mi you can have the pathological q wave right now the other condition where you can have this particular q wave is pathological q wave is you see here identify the abnormality in this ecg so what leads are given 2 3 avf and avl so 2 3 avf what are they they are your inferior leads right there your inferior leads and what is that you are having you are having the deep q waves in your inferior leads and along with this particular deep q waves you are having just only the t wave inversion there is no st segment elevation so presence of the q wave only q wave without st segment elevation you can consider this as a previous mi so differential diagnosis of q wave is one is your hocm i have shown you that particular ecg then anterior volume i evolved mi either anterior wall or inferior wall or lateral wall whatever it is if it's an evolved mi what do you understand by the word evolve it should be the entire myocardium that should be dead transmural myocardium should be there transmural myocardial infarction should be there that is what is called as evolved and the other condition where you will have the q wave is in case of the old mi you will have this particular q wave so these are some of the very important points where you will have the q wave and you should know all the conditions wherever you are having q wave this completes the discussion on the abnormalities of the q wave in the ecg thank you very much

Channel: Dr.G Bhanu Prakash Animated Medical Videos

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Keywords: q wave, pathological q wave, septal q wave, q wave mi, abnormal q wave, q waves, q wave and mi, q wave ecg, ecg leads and q wave, physiologiacal q wave, intermittent q waves, pathological q waves, ecg q wave, deep q wave, pathological q wave in ecg, q wave in ecg, q wave abnormalities, intermittent pathological q waves, transmural infarct and q wave, q wave in mi, q waves ecg, q waves ekg, non q wave myocardial infarction, non q wave mi, ekg, ecg, ecg waves, ekg course

Id: FXqEPdwutJ0

Length: 15min 22sec (922 seconds)

Published: Sat May 28 2022