What aspect of EKG interpretation assesses the heart’s electrical axis?

The determination of the heart's electrical axis primarily relies on analyzing the direction of the QRS complex in the limb leads. The electrical axis indicates the average direction of electrical impulses as they move through the heart during depolarization. By examining the QRS complexes in the standard limb leads (I, II, III, aVR, aVL, and aVF), one can ascertain which direction the predominant electrical activity is moving.

For instance, if the QRS is predominantly positive in leads I and aVF, the electrical axis is considered to be within a normal range (generally between -30° and +90°). If the QRS complex is negative in lead I and positive in lead aVF, it indicates a right axis deviation. Leafing through these patterns can reveal important information about potential underlying cardiac conditions, such as hypertrophy or conduction blocks.

Other aspects mentioned in the choices do not directly assess the heart's electrical axis. The height of the R wave may provide insight into ventricular mass, but it does not reflect the axis. The interval between P waves deals with atrial activity rather than the orientation of ventricular depolarization. ST segment elevation is significant for diagnosing specific types of ischemia or infraction but does not contribute to understanding