Which are examples of ventricular ectopic foci?

Which are examples of ventricular ectopic foci?

• A. PVC and ventricular tachyarrhythmia
• B. Atrial fibrillation
• C. Sinus tachycardia
• D. First-degree AV block

Answer: (A)

Ventricular ectopic foci are abnormal pacemaker sites within the ventricles that fire impulses independent of the normal SA nodal drive. When such a ventricular focus initiates beats, the result is premature ventricular contractions, which present as early, wide QRS complexes without a preceding P wave and with a ventricular origin. If these ectopic beats occur in rapid succession, they can trigger a ventricular tachyarrhythmia, a fast rhythm arising from the ventricles. The other options come from the atrial region or the normal conduction system rather than an ectopic ventricular site: atrial fibrillation starts in the atria, sinus tachycardia is driven by the SA node, and first-degree AV block reflects delayed conduction through the AV node, not ventricular ectopy. So PVCs and ventricular tachyarrhythmias are classic examples of ventricular ectopic foci.

Ventricular ectopic foci are abnormal pacemaker sites within the ventricles that fire impulses independent of the normal SA nodal drive. When such a ventricular focus initiates beats, the result is premature ventricular contractions, which present as early, wide QRS complexes without a preceding P wave and with a ventricular origin. If these ectopic beats occur in rapid succession, they can trigger a ventricular tachyarrhythmia, a fast rhythm arising from the ventricles. The other options come from the atrial region or the normal conduction system rather than an ectopic ventricular site: atrial fibrillation starts in the atria, sinus tachycardia is driven by the SA node, and first-degree AV block reflects delayed conduction through the AV node, not ventricular ectopy. So PVCs and ventricular tachyarrhythmias are classic examples of ventricular ectopic foci.