Atrial Fibrillation: When Heart Rate Exceeds Pulse Rate

Atrial fibrillation (AFib) is a condition where the heart's rhythm becomes irregular and often rapid. One of the notable characteristics of AFib is that the heart rate is typically higher than the pulse rate. The heart rate refers to the number of times the heart beats in one minute, which can be measured using a stethoscope or an electrocardiogram (ECG). On the other hand, pulse rate is determined by counting the number of pulses felt at a peripheral artery, such as the radial artery on the wrist.

Understanding the Difference Between Heart Rate and Pulse Rate

Under normal conditions, each heartbeat generates a pulse, meaning the heart rate and pulse rate are equal. However, during atrial fibrillation, the heart's electrical signals become chaotic, leading to irregular contractions of the heart muscle. This results in some heartbeats being stronger than others, and not every heartbeat is effective enough to generate a detectable pulse.

Why Pulse Rate May Be Lower Than Heart Rate in AFib

In AFib, the heart may beat so rapidly and irregularly that some contractions occur before the heart chambers have had time to fill with blood. When this happens, the heart may contract again without having enough blood to pump effectively. As a result, some heartbeats do not produce a sufficient blood pressure wave to be felt as a pulse in the peripheral arteries.

This mismatch between heart rate and pulse rate is an important clinical sign that helps healthcare providers identify atrial fibrillation. It's one reason why checking both the heart rate and pulse rate is a key part of cardiovascular assessment, especially in patients experiencing symptoms like palpitations, dizziness, or shortness of breath.