Which of the following rhythms has a characteristic wide QRS complex greater than 0.12 seconds?

The rhythm that features a characteristic wide QRS complex greater than 0.12 seconds is PVC, or premature ventricular contraction. This occurs because PVCs originate in the ventricles rather than the atria or junctional tissue, leading to a delay in the conduction of the electrical impulse through the ventricles. As a result, the QRS complex appears wider than normal, reflecting the slower propagation of the impulse through the ventricular myocardium.

In normal conditions, the electrical impulses usually travel down the conduction pathways efficiently, resulting in a narrower QRS complex. However, with PVCs, since they bypass the typical conduction system of the heart, the QRS complex is wider. Recognizing the wide QRS complex is crucial in clinical settings, as it indicates that the heart is beating irregularly and could affect patient treatment and management decisions.