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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.
The normal apex beat can be palpated in the precordium left 5th intercostal space, half inch medial to 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.
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 vertebrae
The character of the apex beat may provide vital diagnostic clues:
- A forceful impulse indicates volume overload in the heart (as might occur in aortic regurgitation)
- An uncoordinated (dyskinetic) apex beat involving a larger area than normal indicates ventricular dysfunction; such as an aneurysm following myocardial infarction
- A pulse deficit between the PMI and periphery may occur in some arrhythmias, such as premature ventricular contraction or atrial fibrillation.
An algorithm for the classification of some common apex beat characteristics is shown in the image.
- Lynn S. Bickley; Peter G. Szilagyi (1 December 2008). Bates' guide to physical examination and history taking. Lippincott Williams & Wilkins. pp. 357–. ISBN 978-0-7817-8058-2. Retrieved 1 May 2013.