The apex beat (lat. ictus cordis),
also called the point of maximum impulse (PMI), is the
furthermost point outwards (laterally) and downwards (inferiorly) from the sternum at which the cardiac impulse can be
felt. The cardiac impulse is the result of the heart rotating, moving forward and striking against the
chest wall during systole.
It is also known as the "apical
impulse".
Identification: The normal apex beat can be palpated in the precordium left 5th 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:
- Pleural or pulmonary
diseases
- Deformities of the chest
wall or the thoracic vertebra
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:
- A forceful impulse indicates
pressure overload in the heart (as might occur in hypertension)
- An uncoordinated (dyskinetic) apex beat involving a
larger area than normal indicates ventricular dysfunction; such as an
aneurysm following myocardial infarction
An algorithm for the classification of some
common apex beat characters is shown in the image.
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