324: DISEASES OF THE HEART. 



apex. Under normal conditions the apex almost always beats at the 

 fifth intercostal space, and it is only when the spaces are very wide, 01 

 when the abdomen is distended, that the apex beats at the fourth 

 space, and when the spaces are narrow, at the sixth space. According 

 to SeitZj it is more often felt hi the fourth than in the fifth space in 

 children. The point in the fifth intercostal space, at which the apex is 

 usually felt, is from half an inch to an inch below the nipple, at the 

 parasternal line (that is, a vertical line running midway between the 

 nipple and the left border of the sternum). Sometimes the beat is a 

 little without this line, more rarely somewhat within it. If the heart 

 be considerably enlarged, the impulse is not exclusively visible at the 

 apex, as the chest suffers a jar from contact with other portions of the 

 organ. Hence, we must know how to find the apex. The rule is, to 

 assume that the lowest and most external point at which the impulse 

 is distinctly felt corresponds to the apex. In all forms of excentric hy- 

 pertrophy the total form, as well as that of either side the apex may 

 be displaced to the left, and in total or left-sided hypertrophy it may 

 likewise move farther downward, and be found in the sixth or even the 

 seventh intercostal space. This very seldom happens when the right 

 side is affected, and only when the right ventricle projects beyond the 

 apex. With a little care and practice it is easy to distinguish the 

 sensation arising from pressure of the heart against the thoracic wall 

 (which is the sole guide for estimating the extension of the cardiac 

 impulse) from that caused by participation of the surrounding region in 

 the shock. 1 



Percussion. The normal region of dulness over the heart forms a 

 triangle which is bounded inwardly by the left border of the sternum, 

 from the fourth rib downward ; externally by an imaginary line drawn 

 from the sternal edge of the fourth rib to the point at which the apex 

 beats. Below, the dulness is usually merged in that of the left lobe 

 of the liver, and it is only in cases where the latter extends less to the 

 left than usual that the cardiac dulness is bounded on the lower side 

 by the sixth rib or seventh intercostal space. 



This normal dulness of the cardiac region becomes greater in excen- 

 tric hypertrophy of the heart. In hypertrophy of the left side it 

 becomes longer, in that of the right broader, and in total hypertrophy 

 it is increased both in the vertical and transverse directions, i. e., is both 

 longer and broader. In hypertrophy of the left ventricle, wherein the 

 cardiac dulness extends downward rather than upward, observation 

 of the situation of the heart-stroke is of more moment, in diagnosis 

 than percussion, which here often fails. 



Besides the cardiac dulness, that is, the dulness upon percussion 

 arising from contact of the compact heart with the wall of the chest 



