pulse

The pulse is the gentle thump you can feel in an artery — at the wrist or neck — each time the heart beats. When the heart squeezes, it sends a pressure wave surging down the arteries, and that wave briefly expands the vessel wall enough to feel under your fingertips.

The pulse is a window onto the heartbeat from the outside. By feeling it, a clinician can count the rate, judge whether the rhythm is regular or irregular, and gauge how strong and full each wave is. A weak, thready pulse can signal low blood pressure or shock; a bounding pulse can accompany other conditions. Common spots are the radial artery at the wrist and the carotid artery in the neck.

An important subtlety: the pulse reflects beats that actually reach the arteries, which is not always the same as the heart rate measured at the heart. In some arrhythmias the heart contracts but pumps too little blood to produce a felt wave, creating a pulse deficit where the wrist count is lower than the true heart rate.