Research results have shown that the reliability of cardiac percussion is very variable. For this reason the validity of cardiac percussion is under discussion and it is not currently part of the standard examination. However, because percussion of the left heart border in particular can sometimes still provide useful information – for example if the apex beat cannot be palpated – the procedure will briefly be described here.
Procedure
In supine position the hand should be placed parallel to the ribs at the 5th intercostal space. From the midaxillary line, the finger should be repeatedly moved 0.5 to 1 cm medially until a dull tone is found [Figure 10].
Figure 10: Percussion of the left heart border
Normally dullness to percussion is found on, or within, the midclavicular line. If it falls outside of this then cardiomegaly (e.g. left ventricular hypertrophy) or displacement of the heart (due to a right-sided tension pneumothorax) may be present.