apex beat
The apex beat is the spot on the chest wall where the beating heart can be felt most strongly with the fingertips — the point of maximal impulse. As the left ventricle contracts and twists, its rounded tip taps against the chest from inside; finding where that tap is strongest is one of the simplest and oldest pieces of the cardiac examination.
In a healthy adult it is normally felt in the fifth space between the ribs, just inside an imaginary line dropped from the middle of the left collarbone. Its location and character carry information. If the heart enlarges, the apex beat shifts outward and downward; if the chest is over-inflated or fluid surrounds the heart, the beat may be hard to feel at all. A forceful, sustained heave suggests a thickened, pressure-loaded ventricle, while a brisk, displaced, diffuse impulse suggests a dilated one.
Like much of the hands-on examination, the apex beat is a quick, no-cost clue rather than a precise measurement; body shape, breathing, and position all affect it. Modern imaging such as echocardiography gives exact chamber sizes, but a displaced apex beat at the bedside still flags an enlarged heart and prompts that further testing.
In a patient with a dilated, failing heart, the apex beat is felt well outside the normal line and lower on the chest, a sign of an enlarged left ventricle later confirmed on echocardiography.
An outward, downward shift of the apex beat is a bedside clue to an enlarged left ventricle.
A normally placed apex beat is reassuring, but it cannot be felt in everyone — in larger chests, emphysema, or pericardial fluid it may be impalpable without meaning the heart is healthy.