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Calculating cardiac axis when interpreting 12 lead ECG is one of the steps that must be done by the interpreter to get accurate ECG interpretation. There are some simple ways when determining the cardiac axis. But I just do not want you to understand without understanding it correctly in studying the cardiac axis, so that you will continue to remember it without having to leaf through the book again. Ok ....
In accordance with the topic of cardiac electrophysiology that I described earlier, that the heart has its own uniqueness that is having some place or the central pacemaker of the SA node, AV node or junction area, as well as fiber furkinje. Where the normal cardiac pacemaker located in the SA node impulses that emit as much as 60-100 x minutes.
Impulses are issued by the SA node will spread throughout the muscle cells of both the atrium through the cardiac conduction system. After all atrial muscle cells didepolarisasi, impulse transmitted to mendepolarisasi ventricular muscle cells of the cardiac conduction system through the AV node, bundle his, until furkinje fiber. So what is the axis of the heart?
I will give you a parable to explain the cardiac axis. Before that I want to emphasize that there is the term axis atrial cardiac muscle which is determined by looking at the P wave, and no axis cardiac ventricular muscle determined by looking at the QRS complex. Because the atrial muscle composition is smaller than ventricular muscle, the heart muscle to evaluate atrial axis sometimes omitted. So to determine the cardiac axis, simply by specifying the axis cardiac ventricular muscle by looking at the QRS complex.
I will give you a parable to explain the cardiac axis. A is the SA node, B, C, D is the atrium of the heart muscle that must be in depolarization by A (SA node). Impulses are issued by the SA node will spread throughout the body where ECG electrodes we place all over the body surface will record bioelektrikal activity issued by the SA node. Suppose the distance between A and B = 1 m, A with C = 3 m, A with C = 2 meters. So the average distance or time is needed to mendepolarisasi BCD A likely average would lead to a C because they have more time and distance compared with BD.
Likewise with the ventricular muscle, the impulse will be spread throughout the ventricular muscle and whole body which will be recorded by the ECG electrodes we place on the body surface. For electrodes that produces recordings with the highest amplitude, indicating the axis of the heart leads to the electrodes.
Normally the cardiac axis leads from the right hand toward the left leg approximately 30-60 degrees because the muscles of the left ventricle is thicker than other cardiac muscle. The normal heart axis between -30 degrees s / d +110 degrees below the age of 40 years, -30 degrees s / d +90 degrees above 40 yrs.
If the cardiac axis between-30 s / d -90 degrees is called left axis deviation (LAD), +110 degrees when s / d +180 degrees is called Right axis deviation (RAD), when the cardiac axis between +180 degrees s / d +270 degrees or -90 degrees s / d -180 degrees called extreme axis.
In case of abnormalities or disease in the SA node, then the second main pacemaker of the AV node will take over the main function as a generator or generators to replace the SA node impulse with the impulse to spend between 40-60x/menit. Despite the overall relatively normal hemodynamics but these circumstances must be quickly identified the cause of the failure of the SA node as a primary generator. Because the impulse released by the AV node, the atrial muscle cells will be retrograf didepolarisasi so it will appear obvious difference in the EKG wave especially P.
How to calculate or determine the axis of the heart:
There are several ways below in determining the cardiac axis, have also said that the axis of the heart also can be specified through the horizontal plane. But well I'd suggest to calculate the frontal area is the use of leads I, II, III, aVR, aVF, aVL like my explanation as follows:1. You see the leads I and aVF ---> if the two leads is predominantly described the positive deflection, you do not hesitate to say normal because it is still in the area axis normal axis.2. If you find one of the leads I or aVF is negative, then use this procedure. Suppose the deflection leads aVF pasitip 5 mm (5 small box = 1 large box) and a negative deflection of 10 mm (10 small squares) so its dominance in leads aVF negative deflection ---> (-10mm) - (+5 mm) =-5mm , whereas in leads I suppose 11mm positive deflection (11 small squares) and negative deflection of 2 mm (2 small boxes). So in the lead I positive deflection dominance ---> (+11 mm) - (-2mm) = + 9mm. You can just count 5mm negative direction leads aVF, and 9 mm in the positive direction leads I. After that set the meeting point of the two leads, then connect the meeting point with the center point. Well segitulah aksisnya.3. Find the leads that have the greatest amplitude (both positive and negative). Suppose the largest amplitude was found in leads I and dominant positive deflection, then the axis of the heart is O degree (Normal axis). Suppose the largest amplitude is found in lead III with dominant negative deflection, then the axis of the heart opposite direction to the negative lead III lead III is a positive direction of +120 degrees (RAD).4. Find the leads that are biphasic or biphasic deflection approaching (50:50) both in the direction towards the positive and negative deflections. Suppose you find leads to biphasic in lead aVF, then you are looking for leads that are perpendicular to the lead aVF (ie lead I). Notice of leads I, which way defleksinya? (Negative or positive) when the leads I defleksinya dominant positive, then the positive direction leads aksisnya I (which is O degrees or normal axis), otherwise I lead a dominant negative, then the negative direction leads aksisnya I (ie -180 degrees or RAD) .
In accordance with the topic of cardiac electrophysiology that I described earlier, that the heart has its own uniqueness that is having some place or the central pacemaker of the SA node, AV node or junction area, as well as fiber furkinje. Where the normal cardiac pacemaker located in the SA node impulses that emit as much as 60-100 x minutes.
Impulses are issued by the SA node will spread throughout the muscle cells of both the atrium through the cardiac conduction system. After all atrial muscle cells didepolarisasi, impulse transmitted to mendepolarisasi ventricular muscle cells of the cardiac conduction system through the AV node, bundle his, until furkinje fiber. So what is the axis of the heart?
I will give you a parable to explain the cardiac axis. Before that I want to emphasize that there is the term axis atrial cardiac muscle which is determined by looking at the P wave, and no axis cardiac ventricular muscle determined by looking at the QRS complex. Because the atrial muscle composition is smaller than ventricular muscle, the heart muscle to evaluate atrial axis sometimes omitted. So to determine the cardiac axis, simply by specifying the axis cardiac ventricular muscle by looking at the QRS complex.
I will give you a parable to explain the cardiac axis. A is the SA node, B, C, D is the atrium of the heart muscle that must be in depolarization by A (SA node). Impulses are issued by the SA node will spread throughout the body where ECG electrodes we place all over the body surface will record bioelektrikal activity issued by the SA node. Suppose the distance between A and B = 1 m, A with C = 3 m, A with C = 2 meters. So the average distance or time is needed to mendepolarisasi BCD A likely average would lead to a C because they have more time and distance compared with BD.
Likewise with the ventricular muscle, the impulse will be spread throughout the ventricular muscle and whole body which will be recorded by the ECG electrodes we place on the body surface. For electrodes that produces recordings with the highest amplitude, indicating the axis of the heart leads to the electrodes.
Normally the cardiac axis leads from the right hand toward the left leg approximately 30-60 degrees because the muscles of the left ventricle is thicker than other cardiac muscle. The normal heart axis between -30 degrees s / d +110 degrees below the age of 40 years, -30 degrees s / d +90 degrees above 40 yrs.
If the cardiac axis between-30 s / d -90 degrees is called left axis deviation (LAD), +110 degrees when s / d +180 degrees is called Right axis deviation (RAD), when the cardiac axis between +180 degrees s / d +270 degrees or -90 degrees s / d -180 degrees called extreme axis.
In case of abnormalities or disease in the SA node, then the second main pacemaker of the AV node will take over the main function as a generator or generators to replace the SA node impulse with the impulse to spend between 40-60x/menit. Despite the overall relatively normal hemodynamics but these circumstances must be quickly identified the cause of the failure of the SA node as a primary generator. Because the impulse released by the AV node, the atrial muscle cells will be retrograf didepolarisasi so it will appear obvious difference in the EKG wave especially P.
How to calculate or determine the axis of the heart:
There are several ways below in determining the cardiac axis, have also said that the axis of the heart also can be specified through the horizontal plane. But well I'd suggest to calculate the frontal area is the use of leads I, II, III, aVR, aVF, aVL like my explanation as follows:1. You see the leads I and aVF ---> if the two leads is predominantly described the positive deflection, you do not hesitate to say normal because it is still in the area axis normal axis.2. If you find one of the leads I or aVF is negative, then use this procedure. Suppose the deflection leads aVF pasitip 5 mm (5 small box = 1 large box) and a negative deflection of 10 mm (10 small squares) so its dominance in leads aVF negative deflection ---> (-10mm) - (+5 mm) =-5mm , whereas in leads I suppose 11mm positive deflection (11 small squares) and negative deflection of 2 mm (2 small boxes). So in the lead I positive deflection dominance ---> (+11 mm) - (-2mm) = + 9mm. You can just count 5mm negative direction leads aVF, and 9 mm in the positive direction leads I. After that set the meeting point of the two leads, then connect the meeting point with the center point. Well segitulah aksisnya.3. Find the leads that have the greatest amplitude (both positive and negative). Suppose the largest amplitude was found in leads I and dominant positive deflection, then the axis of the heart is O degree (Normal axis). Suppose the largest amplitude is found in lead III with dominant negative deflection, then the axis of the heart opposite direction to the negative lead III lead III is a positive direction of +120 degrees (RAD).4. Find the leads that are biphasic or biphasic deflection approaching (50:50) both in the direction towards the positive and negative deflections. Suppose you find leads to biphasic in lead aVF, then you are looking for leads that are perpendicular to the lead aVF (ie lead I). Notice of leads I, which way defleksinya? (Negative or positive) when the leads I defleksinya dominant positive, then the positive direction leads aksisnya I (which is O degrees or normal axis), otherwise I lead a dominant negative, then the negative direction leads aksisnya I (ie -180 degrees or RAD) .
