What does a flatline on an ECG typically indicate?

A flatline on an ECG typically indicates asystole, which is the absence of electrical activity in the heart. This condition represents a state where there is no measurable heartbeat; it is a critical medical emergency because the heart cannot effectively pump blood to the body's tissues.

In the context of heart rhythm assessments, a flatline suggests that there is no coordination of the heart's electrical signals, indicating a failure of the heart to function altogether. The body urgently needs intervention to restore cardiac activity, typically through advanced cardiac life support measures.

In contrast, conditions such as atrial fibrillation involve disorganized electrical signals resulting in irregular heartbeats, and ventricular tachycardia reflects a rapid heart rate originating from the ventricles but does not produce a flatline. Bradycardia indicates a slower than normal heart rate, but again, it does not correlate with a complete cessation of electrical activity seen in asystole. Thus, while the other conditions represent various types of heart rhythm abnormalities, a flatline specifically points to asystole.