EKG: Axis and Amplitude

[X-treme]

In a previous thread I was linked to several sites to help me interupt EKG's. The links were helpful, except I am still having difficulties understanding Axis and Amplitude when reading the material. I simply don't grasp the concept and it's purpose and how it applied to the EKG on paper.

Any help would be great!

Thanks

[GilaRRT]

Explain what about amplitude you do not understand.

Axis is a little tricky to explain. Again, I will try to post pictures when I have access to a computer.

Imagine the heart all by it's self. Then, draw a circle around the heart. The 12 oclock position is -90 degrees, the 3 oclock position would be 0 degrees, the 6 oclock would be +90 degrees, and the 9 oclock would be +180 degrees. These are the rough axis directions of the heart. The general direction of the flow of electrical activity through the heart is a good way to roughly define axis. So, with this in mind, where do we want the wave of depolarization to flow? From the top to bottom generally speaking. So, in the normal heart the flow will want to go in the direction of the left ventricle. The normal axis is from 0 to + 90 degrees. On our little heart picture this will be between the 3 oclock and 6 oclock position. Or generally toward the left ventricular area.

Deviation from this norm can be defined as physiologic or pathologic. In some cases you can also develop what is called right shoulder deviation or no mans land. This is often the result of a pacemaker or a ventricular rhythm such as ventricular tachycardia. In fact, looking for right shoulder deviation can help us tell V-tac from certain types of SVT.

Break it down like this:

Normal: 0 to +90

Physiologic LAD: 0 to -30

Pathologic LAD: -30 to -90

RAD: +90to 180

Right Shoulder: -90 to 180

General causes of LAD

-left BBB

-Inferior wall MI

-Ascites

-Left vent hypertrophy

-Obesity

-pregnancy

General Causes of RAD

-Right vent hypertrophy

-COPD and pulmonary disease

-Right BBB

-Thin/slender

I will try to post a quick and easy picture where you simply look for positive or negative QRS deflection in leads I,II,III.

A quick down and dirty method is to simply look at the 12 lead printout. You should see something that states QRS Axis. The number of the QRS axis will be the axis.

[Altra, BSN, RN]

X-treme, one thing ... you're learning to interpret EKGs, you're not interrupting them.

Typos happen ... but correct word usage is important to effective communication.

[shock-me-sane]

X-treme, one thing ... you're learning to interpret EKGs, you're not interrupting them.

Typos happen ... but correct word usage is important to effective communication.

I think that is obvious what she meant when you read the rest of the post. I don't see how that was necessary.