An anterior hemiblock will cause which type of axis deviation?

An anterior hemiblock will cause which type of axis deviation?

• A. Right axis deviation
• B. No axis deviation
• C. Left axis deviation
• D. Inferior axis deviation

Answer: (C)

Anterior hemiblock, also known as left anterior hemiblock, typically leads to left axis deviation on the electrocardiogram (ECG). This condition occurs when there is a blockage in the left anterior fascicle of the left bundle branch, which alters the normal electrical conduction through the heart.

In a healthy heart, the electrical impulses travel in a coordinated fashion, causing the heart to contract effectively. However, when there is an anterior hemiblock, the left ventricle is activated later than the right ventricle because the impulse is delayed. This causes a deviation in the overall electrical axis of the heart towards the left side.

The typical range for a normal electrical axis is between -30 degrees and +90 degrees. In the presence of left axis deviation, the electrical axis shifts to less than -30 degrees. Hence, the patient with an anterior hemiblock will typically show left axis deviation which can be confirmed by the appropriate analysis of the ECG leads, specifically looking at leads I and aVF.

Understanding this deviation is crucial for accurate diagnosis and can imply underlying cardiac issues that may require further investigation or management.