Careful inspection of the anterior chest may reveal the location of the apical impulse or point of maximal impluse (PMI), or less commonly, the ventricular movements of a left-sided S3 or S4. Tangential light is best for making these observations.
Use palpation to confirm the characteristics of the apical impulse. Palpation is also valuable for detecting thrills and the ventricular movements of an S3 or S4. Be sure to assess the right ventricle by palpating the right ventricular area at the lower left sternal border and in the subxiphoid area, the pulmonary artery in the left 2nd interspace, and the aortic area in the right 2nd interspace. Review the diagram on the next page. Note that the "areas" designated for the left and right ventricle, the pulmonary artery, and the aorta pertain to the majority of patients whose hearts are situated in the left chest, with normal anatomy of the great vessels.
Begin with general palpation of the chest wall. First palpate for impulses using your fingerpads. Hold them flat or obliquely on the body surface, using light pressure for an S3 or S4, and firmer pressure for S1 and S2. Ventricular impulses iay heave or lift your fingers. Then check for thrills by pressing the ball of our hand firmly on the chest. If subsequent auscultation reveals a loud mur-ur, go back and check for thrills over that area again.
Thrills may accompany loud, harsh, or rumbling murmurs as in aortic stenosis, patent ductus arteriosus, ventricular septal defect, and, less commonly, mitral stenosis. They are palpated more easily in patient positions that accentuate the murmur.
The Apical Impulse or Point of Maximal Impulse (PMI)—Left Ventricular Area. The apical impulse represents the brief early pulsation of the left ventricle as it moves anteriorly during contraction and touches the chest wall. Note that in most examinations the apical impulse is the point of maximal impulse, or PMI; however, some pathologic conditions may produce a pulsation that is more prominent than the apex beat, such as an enlarged right ventricle, a dilated pulmonary artery, or an aneurysm of the aorta.
If you cannot identify the apical impulse with the patient supine, ask the patient to roll partly onto the left side—this is the left lateral decubitus position. Palpate again using the palmar surfaces of several fingers. If you cannot find the apical impulse, ask the patient to exhale fully and stop breathing for a few seconds. When examining a woman, it may be helpful to displace the left breast upward or laterally as necessary; alternatively, ask her to do this for you.
On rare occasions, a patient has dextrocardia—a heart situated on the right side. The apical impulse will then be found on the right. If you cannot find an apical impulse, percuss for the dullness of heart and liver and for the tympany of the stomach. In situs inversus, all three of these structures are on opposite sides from normal. A right-sided heart with a normally placed liver and stomach is usually associated with congenital heart disease.
Once you have found the apical impulse, make finer assessments with your fingertips, and then with one finger.
With experience, you will learn to feel the apical impulse in a high percentage of patients, but obesity, a very muscular chest wall, or an increased anteroposterior diameter of the chest may make it undetectable. Some apical impulses hide behind the rib cage, despite positioning.
Now assess the location, diameter, amplitude, and duration of the apical impulse. You may wish to have the patient breathe out and briefly stop breathing to check your findings.
■ Location. Try to assess location with the patient supine, since the left lateral decubitus position displaces the apical impulse to the left. Locate two points: the interspaces, usually the 5th or possibly the 4th, which give the vertical location; and the distance in centimeters from the midsternal line, which gives the horizontal location. (Note that even though the apical impulse normally falls roughly at the midclavicular line, measurements from this line are less reproducible since clinicians vary in their estimates of the midpoint of the clavicle.)
See Table 7-1, Variations and Abnormalities of the Ventricular Impulses (p._).
The apical impulse may be displaced upward and to the left by pregnancy or a high left diaphragm.
Lateral displacement from cardiac enlargement in congestive heart failure, cardiomyopathy, ischemic heart disease. Displacement in deformities of the thorax and mediastinal shift.
■ Diameter. Assess the diameter of the apical impulse. In the supine patient, it usually measures less than 2.5 cm and occupies only one interspace. It may be larger in the left lateral decubitus position.
■ Amplitude. Estimate the amplitude of the impulse. It is usually small and feels brisk and tapping. Some young persons have an increased amplitude, or hyperkinetic impulse, especially when excited or after exercise; its duration, however, is normal.
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