CVS Practice Test

The QRS axis is the heartbeat feature that primarily informs about the direction of the heart's electrical impulse. The QRS complex represents the depolarization of the ventricles, which is the electrical activity leading to ventricular contraction. The axis can indicate the predominant direction of this electrical activity in the frontal plane of the body.

By analyzing the QRS axis, healthcare professionals can assess the orientation of the heart's electrical conduction system, which can provide insights into various cardiac conditions. A normal QRS axis typically varies between ±30° and ±90°, while deviations can indicate issues like hypertrophy or conduction abnormalities. Understanding the QRS axis is fundamentally important in clinical settings for diagnosing and treating cardiac problems.

On the other hand, the ST segment primarily reflects the period between ventricular depolarization and repolarization but does not indicate the direction of impulse. The T wave represents ventricular repolarization but lacks information about impulse direction during the heartbeat. The P wave signifies atrial depolarization and mainly informs about the electrical activity of the atria, not the direction of the overall impulse through the ventricles.