How do you determine qrs axis

Since lead I and aVF are perpendicular to each other, you can use those two leads to quickly determine axis. Lead I runs from right to left across a patient's body, positive at the left hand: See figure If the QRS in lead I is positive mainly above the baseline , the direction of depolarization will be in the positive half right half of the circle above. You can make a diagram and shade in the positive half of the circle. Lead aVF runs from top to bottom across a patient's body, positive at the feet: See figure If the QRS in lead aVF is positive mainly above the baseline , the direction of depolarization will be in the positive half lower half of the circle above.

The causes of RAD are listed below. Back to Healio. ECG Basics Save. Determining Axis The axis of the ECG is the major direction of the overall electrical activity of the heart. Read more about electrocardiogram. Related Content. Please refresh your browser and try again. If this error persists, please contact ITSupport wyanokegroup. An important concept in determining the heart axis is the fact that electricity going towards a lead yields a positive deflection in the electric recording of that lead.

Imagine the leads as cameras looking at the heart. Lead I looks horizontally from the left side. Lead II looks from the left leg. A positive deflection here is defined as the QRS having a larger 'area under the curve' above the baseline than below the baseline. With these basics in mind, one can easily estimate the heart axis by looking at leads I and AVF:.

This indicates a normal heart axis. Usually, these two leads are enough to diagnose a normal heart axis! The largest vector in the heart is from the AV-node in the direction of ventricular depolarization. Under normal circumstances, this is directed left and down. The position of the QRS vector is given in degrees.