A PVC originating from the right ventricle and propagating to the left ventricle would produce what deflection in lead V1?

• A. Positive deflection in V1
• B. Negative deflection in V1
• C. No deflection in V1
• D. Biphasic in V1

Answer: (B)

The deflection in a lead reflects the direction of the ventricular depolarization vector relative to that lead’s axis. A PVC starting in the right ventricle depolarizes and spreads toward the left ventricle, so the overall depolarization vector moves leftward. Lead V1 is placed on the right side of the chest and essentially “faces” toward the left side of the heart; a leftward-moving vector moves away from V1, producing a negative QRS deflection in V1. So this RV-origin PVC would cause a negative deflection in V1. If the activation moved toward V1, the deflection would be positive, and if it were perpendicular, you’d get a biphasic or isoelectric pattern.