ECG - EKG Leads - Bipolar Limb Leads - Electrocardiography - Cardiology

right today we are going to talk about ECG leads right and above before I go into detail of bipolar limp leads or unipolar limb leads or the chest leads right I want to tell you what exactly the word ECG lead means what is the meaning of it eg lead what is the real concept of ECG lead when we talk about ECG lead we have to learn it at three level ECG lead as a circuit ECG lead and it's axis you see you need and pattern they write derived from it right so let's start with it as we know that if you need is basically a set of laptop with the wires connected on one side with the ECG recording machine and other side electrodes are applied on the body surface and the purpose of those electrodes is to record the electrical activity of the heart as we know that when there is heart is undergoing electrical activity like atrial depolarization and then ventricular depolarization and repolarization electrical vectors are produced the right electrical electro-motive forces are produced when heart is undergoing electrical events those electrical events of the heart those electrical events of the heart can be recorded by the ECG leads so let me tell you what is the meaning of lead right then we'll go into detail let's suppose here you are okay you are very happy because you are about to learn the real concept of order ECG did here you are I'm not going to draw other organs now let's suppose here is your heart right I will just focus on major ventricular depolarization that when major part of the ventricle is undergoing depolarization that electrical current is moving downward leftward if we talk about the frontal plane right why let me draw it here suppose this is left ventricle this is right ventricle this is intraventricular septum right Wendie polar ventricular septum when ventricle is undergoing depolarization right in previous lectures I have explained in two detail that first there is septal depolarization then there's major ventricular depolarization and after that there is basal part of the ventricle underway depolarization right now I will just focus that let's pose when quicker measurement tubular depolarization is going on when there is major ventricular depolarization going on when tubular cells undergo depolarization from endocardium to yes epicardium that wave of depolarization is spreading from inside to the outside of the ventricle and this movement of depolarization produces millions of vectors millions of electro-motive forces right and these electrical vectors are electrical electro-motive forces which are generated when the major ventricular depolarization is going on these forces can be represented by this vector which is showing the depolarization of right ventricle and can be presented by this vector which is showing the depolarization of the yes left ventricle and because right ventricle in left ventricle are undergoing depolarization simultaneously they are undergoing depolarization simultaneously so these two vectors can be added to each other and if we add these two vectors together the net vector will be as you know that vector of left ventricular depolarization is more forceful as left ventricle is thicker and because it is thin right larger number of cells are undergoing raishin so there's stronger vector produced by the left ventricular depolarization and relatively weaker vector is produced by right ventricular depolarization so when you add these two vectors together then we say there is mean vector right which is in frontal plane which is directed downward and left world right what is this this is the mean this is the mean you can say QRS vector or we can say this is the mean electro-motive force along with its magnitude which is represented by the length of the vector and its direction which is presented by direction of the arrow right this is me electro-motive force the presenting vector when major parts of the ventricles are undergoing depolarization or we can call it mean QRS vectors even though in previous lectures I told that initially there is sep 24 edition which is rightward is that right and then major ventricular depolarization which is leftward and downward and then there is basal D position which is upward right but if we talk about only this vector this is mean vector mean vector mean average of all those vectors and at any moment mean does not mean cheap vector means better mean that there are millions of the vectors when they are added together right we end up with the mean QRS vector is it clear now let's force this is your heart and this is your mean vector which is representing yes major ventricular depolarization or now onward I will call this vector QRS vector right now if we want to make a lead now we come back if you want to look at the electrical activity of this heart right and how to record these electrical activity how to record these electrical activity before that a little concept as you know bodies of volume conductor what is a volume conductor it has a lot of electrolytes and fluid so it can conduct that conduct accounts if you don't believe it put your finger in any plug and check it for yourself electric plug don't do that anyway so what I'm saying our body as it has a lot of fluid and electrolyte so very good conductor of the crime so when this vector is moving when this electrical vector is generated by the depolarization of the major part of ventricles what happens that this electrical current spreads all over the body it surprised all over the body are all fluids around the heart and then it spreads into Bronk and from the trunk this electrical current will spread into arms and legs is that right and this electrical current right which is generated by the electrical activity of the heart can be picked up from the surface of the body can be picked up from the surface of the body and recorded by ECG machine right now how to regard it recorded one way is that here is your ECG machine let's suppose this is your ECG machine it's a very simple galvanometer I am going to make it a very simple governmen a meter right and let's suppose that this is your needle right here is the drop of ink here is ECG paper moving is that right this paper is moving in this direction now let's suppose here is the positive electrode what is this positive electro a positive terminal and this is the negative terminal and if we apply positive terminal here and negative terminal on this end what will be we doing we will be doing we will we will be recording the electrical potential difference between the positive terminal and the negative terminal and this potential difference in these two points is being produced by the grunt depolarization Krantz or repolarization Krantz which are being generated by the cardiac electrical activity I will repeat it it's worth repeating that when Hart is undergoing electrical events electrical vectors are being produced these electrical vectors or the events are being conducted throughout the body you can put electrode at any two points in the body any two points in the body and when this current is flowing it will be conducted in this area also and these electrode will Meyer that difference of potential between these two electrode if there is no electrical activity in the heart let's suppose if there is no electrical activity in the heart then nothing will be sensed by these two electron and if there is electrical activity in the heart that is conducted in the body then these two points will sense the potential at negative terminal suppose point a right and point B if there is electrical activity in the heart right that will be conducted in this area actually everywhere including this area here we have put negative electron there we have put positive electrode and these two electrode will record the potential difference right between the electrical potential at Point a and the point B that potential difference will basically lead to fluctuation of this needle is that right is it clear now actually what we have done by this circuit by putting a positive electrode right which is also called exploring electron and other side we have put negative electron in and some other ECG leads arrangement we put our reference electrode right which has zero potential but here we have put one positive electron other negative electrode these two electrodes along with their wires along with their wires on one side one side attached with the electrocardiograph machine and other side electrons are applied on the body surfaces and completing a circuit this circuit is called circuit of the lead right this circuit is called circuit of the lead so now another thing whatever electrical potential is present at this shoulder the same will be conducted in the arm the right in the same way whatever electrical potential is present at this left shoulder same will be conducted in the left so for convenience actually rather than applying these leads negative terminal on the shoulder just for convenience it's easier to apply on the wrist it is easier to apply on the wrist and in the same way positive terminal rather than putting there we can apply our rest on the left side now we can say right arm has what negative term here left left side left arm Bristol's positive terminal these two terminal along with their wire with the electro graphic machine who the system is called circuit of the lead right now this lead circuit actually how this lead is how this lead is recording the electrical activity or sensing the electrical activity this is the circuit right this is the circuit now I will give you an idea that let's suppose I put this lead system here right I put this lead system here this is your machine is there right here I put yes positive electrode is that right and there I put negative electrode and because these electrodes are making one positive pole other negative pole this lead should be having two poles so we will call it bipolar lead we call it bipolar lead and because this is applied on the limbs this must be called bipolar limb believes this should be called bipolar limb believes now before I go into detail I want to give you some simple example to understand actually you can imagine that this vector okay I will make it red color this vector red color or let's suppose before I go into that now this is an imaginary line which we are drawing between the electrodes I mean we can draw here this is an imaginary line which we have drawn between the negative terminal and the positive terminal or negative electrode or the positive electrode now this line represents the yes it is not the circuit of a lead this line is axis of the night electrical axis of the lead right so you know what is the circuit of lead and what is the electrical axis of the lead right actually let's suppose if I put this positive electrode remove here if I remove positive electrode from here and put the positive electrode here then electrical axis will become different direction so electrical axis of the lead is determined by the placement of the electrons on the body electrical axis of the lead are determined by the placement of the electrode in the body again I will repeat if I put a negative electrode here positive electrode here this is the axis of the lead and this these two electrode with wires connected with the machine this is the circuit of the lead so there is circuit of the lead there is excess of the lead now if you put negative electrode here and put positive electrode here or on the foot now imaginary line which draws the negative pole and the positive pole they are directed downward and left world this is it right so excess of the lead I've chained so what is excess of the lead excess of our leaders and imaginary line drawn from the negative electrode or from the reference electrode towards the positive electrode which is also called exploring the electrode does that right so this is axis of the lead now next concept which I want that you must be clear what is the pattern of the need let me explain this

Channel: Dr. Najeeb Lectures

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Keywords: ekg, cardiology, ECG, Dr. Najeeb Lectures, electrocardiogram, chest leads, Electrocardiography, limb leads, 12 lead EKG, leads, 12 lead ecg, bipolar limb leads, interpretation, heart, Clinical Medicine, ecg leads, ekg leads, anatomy, Basic Medical Sciences, ecg interpretation, cardiac, repolarization, precordial, tachycardia, arrhythmia, cardiovascular, precordial leads, electrodes, avF, aVR, aVL, dr najeeb, dr najeeb lectures, usmle, usmle step 1, medical lectures, medical videos

Id: wt35_OK_beI

Length: 16min 49sec (1009 seconds)

Published: Sat Apr 28 2018