Clinical Examination of the Heart
Investigations of the Cardiovascular System in Humans
Clinical Examination of the Heart
The time-honoured sequence of operations used in the clinical examination of any region or organ is inspection, palpation, percussion and auscultation. Put in more direct terms, you look at it, feel it, tap it, and finally listen to it (like a wrapped Christmas present). The heart is an ideal organ on which to practice this sequence, so persuade one of your group to strip to the waist and lie on the examination couch at an angle of about 45o.
Look at the chest; if the light is suitable you may be able to detect a rhythmical movement near the left nipple, corresponding with the heart beat. You may also be able to see arterial pulsations in the neck region.
(a) Standing on the right side of the subject, place the pulps of the fingers of your right hand lightly on the chest wall over the heart (the precordium). You should be able to feel the pulsation of the heart. The furthest point downwards and laterally at which this can be felt is called the apex beat; mark this with a ball point pen, and work out its position with respect to intercostal space and the mid-clavicular line.
(b) Place your right hand flat on the chest wall between the apex beat and the midline. With practice it is possible to make an assessment of the force of the heart's contraction (the cardiac impulse). In the resting healthy subject this is not very pronounced, but it is accentuated by exercise.
This is an important diagnostic technique which would you do well to master at an early stage. The procedure is to place the fingers of your left hand flat on the chest of the subject and strike the middle phalanx of the middle finger sharply with the tip of the middle finger of the right hand. The sound that is produced varies with the character of the structures that lie under the body wall. Try this technique on the right side of the chest, and work downwards until your hand is over the liver; you should be able to detect a change from resonant to dull in the percussion note. Then try to map out the outline of the heart and mark it on the skin with a pen.
Auscultation is a difficult technique, but it is of enormous importance and you should practice as much as possible. Stethoscopes vary in design, especially the form of the chest piece. There are two types: the bell, which is particularly good for lower-pitched sounds provided that it is applied lightly to the chest wall, and the diaphragm, which gives a greater overall sound intensity but emphasises the high-pitched sounds in particular. Many people find this the most useful for all purposes at first, but when their discrimination of the sounds is a particular persons conversation in a crowded room where many people may be in conversation simultaneously. The art of doing this must be acquired by practice.
There are two important heart sounds: the first ('LUBB') is associated with closing of the artrio-ventricular valves and the early part of ventricular contraction, and the second ('DUPP') is produced by closure of the pulmonary and aortic valves. The relative contribution of the valves to the sounds that are heard varies with the listening position, and selected areas are used for each. These areas do not correspond necessarily with the surface marking of the valve; they are simply the places in which the particular valve can be heard more distinctly.
Pulmonary area - 2nd left intercostal space, close to midline
Aortic area - second right intercostal space, close to midline
Tricuspid area - bottom of sternum
Mitral area - at the apex beat
Listen to these areas and note the difference in intensity and quality of the sounds that are heard. Note the time interval between the 1st and 2nd sounds of a cardiac cycle and between the 2nd sound of one cycle and the 1st sound of the next. Which of these intervals is longer?
Listen carefully over the pulmonary area to the 2nd heart sound (P2) and note the changes in this sound immediately after the subject completes a deep inspiration. The second sound appears to be composed of two separate sounds (splitting). How may this be explained?