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The apex beat (lat. ictus cordis), also called the apical impulse, is the pulse felt at the point of maximum impulse (PMI), which is the point on the precordium farthest outwards (laterally) and downwards (inferiorly) from the sternum at which the cardiac impulse can be felt. The cardiac impulse is the vibration resulting from the heart rotating, moving forward and striking against the chest wall during systole. The PMI is not the apex of the heart but is on the precordium not far from it.
Contents
Identification
The normal apex beat can be palpated in the precordium left 4th intercostal space, at the point of intersection with the left midclavicular line. In children the apex beat occurs in the fourth rib interspace medial to the nipple. The apex beat may also be found at abnormal locations; in many cases of dextrocardia, the apex beat may be felt on the right side.
Interpretation
Lateral and/or inferior displacement of the apex beat usually indicates enlargement of the heart, called cardiomegaly. The apex beat may also be displaced by other conditions:
Sometimes, the apex beat may not be palpable, either due to a thick chest wall, or conditions where the stroke volume is reduced; such as during ventricular tachycardia or shock.
The character of the apex beat may provide vital diagnostic clues:
An algorithm for the classification of some common apex beat characteristics is shown in the image.