QRS axis: Difference between revisions

Jump to navigation Jump to search
21 bytes added ,  14 January 2021
m
mNo edit summary
 
Line 26: Line 26:
[[Image:hartas2.jpg|thumb|The heart axis indicates the average direction of the depolarization wave. A normal heart axis, the picture shows an example, is between -30 and +90 degrees. In this example, the heart axis is +45 degrees.]]
[[Image:hartas2.jpg|thumb|The heart axis indicates the average direction of the depolarization wave. A normal heart axis, the picture shows an example, is between -30 and +90 degrees. In this example, the heart axis is +45 degrees.]]
[[Image:hart_axis.png|thumb]]
[[Image:hart_axis.png|thumb]]
<flashow>http://nl.ecgpedia.org/images/b/bc/Normal_SR_vector.swf|height=300px</flashow>
{{#widget:Html5media
|url=https://en.ecgpedia.org/images/4/40/Normal_SR_vector.mp4
|width=640
|height=360
}}
When you average all electrical signals from the heart, you can indicate the direction of the average electrical depolarization with an arrow (vector). This is the heart axis. A change of the heart axis or an extreme deviation can be an indication of pathology. To determine the heart axis you look at the extremity leads only (not V1-V6). If you focus especially on leads I, II, and AVF you can make a good estimate of the heart axis. 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. Lead III from the right leg and lead AVF from below towards the heart. 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:
When you average all electrical signals from the heart, you can indicate the direction of the average electrical depolarization with an arrow (vector). This is the heart axis. A change of the heart axis or an extreme deviation can be an indication of pathology. To determine the heart axis you look at the extremity leads only (not V1-V6). If you focus especially on leads I, II, and AVF you can make a good estimate of the heart axis. 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. Lead III from the right leg and lead AVF from below towards the heart. 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:
*Positive (the average of the QRS surface above the baseline) QRS deflection in lead I: the electrical activity is directed to the left (of the patient)
*Positive (the average of the QRS surface above the baseline) QRS deflection in lead I: the electrical activity is directed to the left (of the patient)

Navigation menu