How does the axis shift in response to an infarction?

In the context of an infarction, particularly in the setting of myocardial infarction (MI), the electrical axis of the heart typically shifts away from the area of damage or infarction. This occurs due to the loss of electrical activity in the affected myocardium. When a section of the heart muscle is damaged and unable to generate or propagate electrical impulses effectively, the normal electrical activity from surrounding healthy tissue can create a compensatory shift.

This shift happens because the intact, electrically active myocardial tissue exerts greater influence on the overall electrical conduction pathways of the heart. As a result, the axis tends to move away from the dead or necrotic tissue towards healthier areas, reflecting the changes in the heart's electrical activity post-infarction. Understanding this axis shift is crucial for clinicians as it aids in diagnosing the location and extent of heart damage seen on an electrocardiogram (ECG).