Cardiac Axis in 5 min

hi my name's Nick and this five-minute talk is about the cardiac access so what is the cardiac access it's the average direction of the flow of electricity or depolarization through the heart the mean electrical vector since most electrical activity takes place in the left ventricle with some contribution from the right it makes sense that most of the mean impulse will be in that direction the more muscle that's in the left ventricle the more the access will move to the left the more muscle that's in the right ventricle the axis will rotate to the right damage to the cardiac muscle will also to the direction of flow and cause the access to deviate so how do we determine the access the three limb leads will give us a view from the right AVR the left AVL and the foot a VF but there are three further limb leads on a 12-lead ECG where do they come from you may have heard of iron havens triangle it's details is beyond the scope of this talk but essentially you can create three further virtual leads lead one by combining the information from AVR and AVL lead two by combining the information from AVR and AVF and lead three by combining the information from AVL and ADF these leads will look at the heart the following angles or vectors this may be a diagram that you're familiar with from your textbooks as you may be able to see this is why we like looking at lead to so much when monitoring ECGs because the majority of the inputs in a normal heart should be traveling towards it giving us the best general view so back to our axis the normal cardiac access is considered to be from plus 90 to minus 130 degrees left axis deviation goes from minus 30 to minus 90 degrees right axis deviation goes from plus 90 to plus 180 degrees anything outside this is termed extreme access deviation which is rare so how do we calculate the access as you know the more an impulse travels towards a lead then the greater the amount of positive deflection compared to negative deflection it causes the more it travels away from the lead then the greater the amount of negative deflection compared to positive if the impulse is at 90 degrees to the lead then you get an equal positive and negative deflection all you need to do is to find a lead where you have an equal amount of positive and negative deflection or as close to as possible we know that the impulse must be moving at 90 degrees to this lead it could be in either direction look at the lead that runs along this vector if the impulse is traveling away from it there will be a large negative deflection if the impulse is traveling towards it there will be a large positive deflection congratulations you've just worked out the cardiac access so let's do that again with a 12 lead ECG the most dec we physically dizzied one so the impulse must be traveling at 90 degrees to this which means either plus or minus 90 degrees looking at the lead on this vector lead a VF we can see that the impulse is traveling towards it therefore the cardiac access must be plus 90 degrees which is just about normal but close to right axis deviation this gives us the access to the nearest 30 degrees which is fine if the access is grossly normal or grossly abnormal but if it's near the limits like this we need to be a bit more accurate go back to the equi phasic lead is it truly a queer phasic equally positive and negative or is it slightly more positive or slightly more negative if it's truly a queer phasic then you found your access if it's slightly more positive then you can shift the access by 15 degrees towards the Aqua phase it lead in this case it's slightly more negative therefore you can shift the access by 15 degrees away from the aquifer as it lead this patient has write access deviation they go the basics of the cardiac access in under five minutes use this information to dig deeper into the codec access and going to see them as many ECGs as you can and make sure you work out the access on them we hope you found this useful you

Channel: Nick Smith

Views: 631,970

Rating: 4.8595686 out of 5

Keywords: ECG, Cardiac axis, Axis deviation

Id: _CCUWdAaQoA

Length: 4min 36sec (276 seconds)

Published: Tue Nov 12 2013