Terminology Problems

1. What is the difference between cardiac enlargement and cardiac hypertrophy?

ANS: Cardiac enlargement means dilatation or increase in chamber volume with or without proportionate hypertrophy, i.e., not hypertrophy alone. Pure hypertrophy should not be called enlargement because the chamber volume may remain normal or even be encroached on by the hyper-trophied muscle.

2. What is usually meant by the term apex beat?

ANS: It refers to the apex of the left ventricle (LV).

3. How does the apex of the LV actually relate to the apex beat?

ANS: The part of the heart striking the chest wall is not necessarily the LV apex. In patients with a large enough right ventricle (RV), the apex beat may be due to an RV impulse.

4. What two forces produce the usual palpable LV apex beat?

ANS: During isovolumic contraction, the heart rotates counterclockwise as viewed from below and usually the lower part of the anterior LV strikes the chest wall. Also, a recoil force produced by the ejection of blood into the aorta in an upward, rightward, and posterior direction thrusts the LV against the chest wall in an inferior, leftward, and anterior direction, a thrust opposed by the systolic decrease in cardiac volume.

5. What is meant by the term PMI, and what are the term's drawbacks?

ANS: The term PMI is often used as a synonym for an apex beat. However, it has also been used to mean point of maximum intensity, i.e., the site of the loudest murmur. Second, as stated in the pamphlet prepared by Hurst and Schlant for the Committee on Medical Education for the American Heart Association, the term PMI should be avoided because the maximum precordial pulsations may be due to such abnormalities as a dilated pulmonary artery, a large RV, a ventricular aneurysm, or an aortic aneurysm. In describing what is thought to be the most lateral cardiac impulse nearest the true apex, the preferable term, even though not perfect, is apex beat.

This counterclockwise rotation occurs during isovolumic contraction, i.e., before blood is ejected from the ventricles.

Aortic aneurysm

Pulmonary artery dilatation

Ventricular aneurysm

Apex beat

The point of maximum impulse (PMI) should not be equated with the apical impulse.

The point of maximum impulse (PMI) should not be equated with the apical impulse.

Note: Palpate around the right sternoclavian joint for the faint pulsations of a right-sided aortic arch, which is common in severe tetralogy or pulmonary atresia. Also palpate the sternal area for the pulsation of a large aneurysm of the descending aorta pushing the heart forward during systole.

Boldface type indicates that the term is explained in the glossary.

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