What is considered a potentially life-threatening arrhythmia?

Ventricular fibrillation is considered a potentially life-threatening arrhythmia because it results in chaotic electrical activity in the ventricles, leading to ineffective pumping of blood. This disruption prevents the heart from effectively circulating blood to the organs, which can quickly lead to loss of consciousness, and if not treated promptly, it can result in death. The urgency of addressing ventricular fibrillation is critical; immediate defibrillation is often required to restore a normal heart rhythm.

In contrast, atrial flutter typically may not be immediately life-threatening, though it can lead to complications such as stroke or heart failure if not managed. Bradycardia, which refers to a slower than normal heart rate, is not always life-threatening unless it becomes severe and causes hemodynamic instability. Premature atrial contractions (PACs) are generally benign and unlikely to result in serious health issues on their own. Therefore, ventricular fibrillation stands out as the most critical and dangerous arrhythmia among the given options.