Ventricular asystole is characterized by which of the following?

Ventricular asystole is defined by the absence of any electrical activity in the ventricles, which means that there is no ventricular rhythm present on the electrocardiogram (ECG). This condition reflects a state of complete cardiac standstill, where there are no contractions occurring in the ventricles, leading to no blood being pumped out of the heart. It is a life-threatening situation that requires immediate intervention, typically in the form of cardiopulmonary resuscitation (CPR) and advanced cardiac life support (ACLS) measures.

The other options refer to different cardiac conditions. The presence of P waves indicates that there is some electrical activity in the atria, which would not be consistent with asystole. Frequent premature ventricular contractions (PVCs) reflect irregular extra beats originating from the ventricles, again indicating some level of electrical activity rather than the complete absence seen in asystole. A rapid heart rate suggests tachycardia, which indicates increased electrical activity and rhythm in the heart, contradicting the very nature of asystole as there would be no rhythm to measure a rate. Thus, option B is the only choice that accurately represents the characteristics of ventricular asystole.