Numerous heart conditions can cause an audible sound known as a heart click. A heart click is merely an abnormal clicking sound that occurs before, during, or immediately after each heart beat. Typically, these sounds are the result of heart value problems such as mitral valve prolapse, mitral stenosis, or pulmonary stenosis. In short, because various heart valves do not open or close properly, they make a clicking or snapping sound that can be heard with a stethoscope. Known as adventitial sounds, heart clicks are an audible medical sign of possible structural problems within the heart.

One of the most common reasons a physician or other medical professional might hear a heart click is mitral valve prolapse. The mitral valve allows blood from the left atrium to flow into the left ventricle and out to the rest of the body. As blood flows out, the mitral valve closes to prevent any blood from returning into the left atrium. Patients with mitral valve prolapse have deformed, overly large, or otherwise defective mitral valves that do not properly close. When the valve closes, a tell-tale audible click, known as a mid-systolic click, is heard.

Alternatively, the mitral valve in patients with mitral stenosis does not open correctly. Whereas in mitral valve prolapse the valve does not close properly during heart contractions, mitral stenosis occurs when the muscle relaxes, a period known as diastole. Between contractions, at the very beginning of diastole, the mitral valve opens. Hearts with mitral stenosis produce a snapping sound as the valve opens, which can also sound like a heart click.

Pulmonary stenosis, also known as pulmonary valve stenosis, is the result of an obstruction between the right ventricle and the pulmonary artery. Such obstructions are typically congenital, much like mitral valve prolapse and mitral stenosis. Also like mitral stenosis, pulmonary stenosis produces a heart click when the pulmonary valve does not fully open. Blood flow into the lungs, intended to absorb oxygen for transport to the left side of the heart, is restricted. Resulting in a heart click known as an ejection click, pulmonary stenosis produces a slightly different clicking sound than clicks produced by mitral valve problems.

Although the result of defects in various heart valves, most heart click sounds cause little in the way of symptoms or issues beyond the audible sound. Severe deformities, additional heart problems, and age can wear out defective valves, eventually leading to heart or pulmonary problems. Most patients, however, experience little, if any, problems stemming from a heart click.