Synonyms: Apex impulse; Point of Maximal Impulse (PMI)
It is normally located in the left fifth intercostal space, about 1 centimeter medial to the mid-clavicular line.
In children less than 7 years of age, the apex beat is located in the 4th intercostal space, lateral to the mid-clavicular line.
How it is produced:
One of my students asked a very pertinent question. When the heart contracts, it expels blood towards the great arteries, that are towards the base of the heart. Then why does the apex move 'outward' in the chest? This defies logic as the perceived movement is in the opposite direction of the expected movement.
The answer lies in the cardiac anatomy. Heart is a spirally arranged muscle in syncytium. When this muscle contracts, the heart rotates while it is contracting and the apex actually moves forward toward the chest wall and taps it.
Method of examination:
Position the flat of your hand so that the middle finger lies on the left 5th intercostal space of the patient, covering the anterolateral ribcage. Other fingers are positioned on the spaces above and below. If no pulsation is felt, move the hand in other directions, feeling for a pulsation.
Once the apex is felt, ascertain whether it is the most prominent pulsation. Then to identify the position, palpate the sternal angle (angle of Louis). It is the angle between the manubrium and the body of the sternum. The second rib corresponds to this angle. Below the second rib is the corresponding intercostal space. Starting from that space, count the intercostal spaces and reach the palpable apex and identify the space in which it is located.
Follow this by measuring the distance between the pulsation and the mid-clavicular line. If the pulsation is nearer to any other vertical landmark line, like the anterior or middle axillary lines, it is better to state the position in relation to those lines rather than mid-clavicular line. For example, instead of mentioning that the apex is 6 cm lateral to mid-clavicular line, it is better to document as 1 cm medial to mid-axillary line.
Points to note in apex:
- Size (is it localized or diffuse?)
- Amplitude (is it forceful?)
- Duration (is it abnormally sustained?)
- Type (assess based on above parameters, details are given below)
Causes for absence of apex beat:
Absent apex may be due to physiological and pathological causes.
Mnemonic: DR POPE
- Dextrocardia. Though it will be absent at the 'usual' location on the left side, it will be present on the right side.
- Apex behind a Rib. In this case it may not be palpable in an intercostal space. Just turning the patient to the left lateral position will reveal the apex beat, confirming this cause.
- Pericardial effusion
- Obesity and thick chest wall
- Pleural effusion (left sided)
Causes for displaced apex beat:
This has to be assessed along with tracheal position. If trachea is also shifted along with the displacement of apex beat, then it is due to mediastinal shift as a result of lung fibrosis, collapse, pneumothorax etc.
If the trachea is central but the apex is displaced, the causes may be:
- Left ventricular enlargement - the apex will be displaced downwards and laterally.
- Right ventricular enlargement - the apex will displaced laterally.
- Cardiomegaly due to significant enlargement of other chambers can also cause displacement
- Pectus excavatum
- Situs inversus/ dextrocardia
Abnormal types (characters) of apex beat:
The normal apex beat is localized pulsation in the normal location as described above. Here are some abnormal characters (please refer to the picture too):
- Tapping Apex - This is an almost normal apex beat with a palpable first heart sound. This is due to a loud first heart sound heard in mitral stenosis.
- Hyperdynamic Apex - This is classically seen in volume overload conditions where there is ventricular dilatation (aortic regurgitation, hyperdynamic circulation etc). This is a forceful but ill-sustained apex that is palpable over a larger area than normal (diffuse).
- Heaving Apex - Classically seen in pressure overload conditions that result in ventricular hypertrophy (aortic stenosis, systemic hypertension etc). This is a forceful and sustained apex that is usually localized.
- Double Impulse Apex - Two impulses felt during systole rather than the normal single upstroke. This is seen on HCM - hypertrophic cardiomyopathy).
- Dyskinetic Apex - An apex that is uncoordinated, seen in myocardial infarction when there are dyskinetic movements of the infarcted myocardium.
Some apex related terminology clarified:
- Localized apex: Palpable in a single intercostal space and the longest diameter of the pulsation is within 2.5 cm. This is normal.
- Diffuse apex: Apex palpable in more than one intercostal space or longest diameter more than 2.5 cm, even within a single space.