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QRS axis: Difference between revisions
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==How do you determine the electrical heartaxis== | ==How do you determine the electrical heartaxis== | ||
[[Image:ECG_lead_angulation.png|thumb]] | |||
[[Image:hartas2.jpg|thumb|The heartaxis indicates the average direction of the depolarization wave. A normal heartaxis, the picture shows an example, is between -30 and +90 degrees. In this example, the heartaxis is +45 degrees.]] | [[Image:hartas2.jpg|thumb|The heartaxis indicates the average direction of the depolarization wave. A normal heartaxis, the picture shows an example, is between -30 and +90 degrees. In this example, the heartaxis is +45 degrees.]] | ||
[[Image:hart_axis.png|thumb]] | |||
[[Image:einthhartas.png|thumb|200px|left|Heartaxis from the original publication of Einthoven. Reprinted from The Lancet, March 30 1912, Einthoven W., ''The Different Forms of The Human Electrocardiogram and Their Signification'', 853-861, 1912, with permission from Elsevier]] | [[Image:einthhartas.png|thumb|200px|left|Heartaxis from the original publication of Einthoven. Reprinted from The Lancet, March 30 1912, Einthoven W., ''The Different Forms of The Human Electrocardiogram and Their Signification'', 853-861, 1912, with permission from Elsevier]] | ||
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 heartaxis. Especially a change of the heartaxis or an extreme deviation can be an indication for pathology. | 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 heartaxis. Especially a change of the heartaxis or an extreme deviation can be an indication for pathology. | ||
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So positive deflections in I and II indicates a normal heartaxis. | So positive deflections in I and II indicates a normal heartaxis. | ||
====Interpretation==== | ====Interpretation==== | ||
The interpretation of the electrical heartaxis has a few rules of thumb: | The interpretation of the electrical heartaxis has a few rules of thumb: | ||