3.3.8 Palpation and percussion
In addition to palpation of arterial and jugular pulses, the cardiac impulse should also be palpated over the area of its maximal intensity (the apex beat area). This is the point at which the ventricle contacts the chest wall, rather than the true cardiac apex. The apex beat results from twisting of the ventricle at the onset of systole and helps to identify the timing of systole and diastole. It can also be a useful guide to the position of the heart in the thorax, and is of value in identifying the position of the valve areas. Gross cardiomegaly may be detected when the apex beat is displaced caudally. The cardiac apex may also be abnormally positioned when the heart is displaced by a mass in the chest. The force of the cardiac impulse should be noted; however, this alters markedly depending on the cardiac output and the thickness of the chest wall. The impulse will therefore be relatively weak in fat, thick-chested animals and strong in an excited ThorThe apical impulse will also be reduced in animals with myocardial failure or a pericardial effusion.