Arteriosclerosis and Hypertension, with Chapters on Blood Pressure / 3rd Edition.

by Louis M. Warfield

Heart Boundaries

In order to be able to estimate the departures from normal in the boundaries of the heart, it is essential that there be a definite appreciation of the boundaries of the normal heart in relation to the chest wall.

It is frequently stated that the right limit of cardiac dullness is normally, in the adult, just at the right border of the sternum. This is not strictly accurate. Careful dissections at the autopsy table and x-ray plates of the chest made at a distance of two meters from the tube show that the border of the right auricle is from one to one and a half and even two centimeters from the edge of the sternum at the level of the fourth rib, and on the living subject this can be also demonstrated. The right border of the heart usually is from 3 to 4 cm. from the midsternal line at the level of the fourth rib.

Again there is a term used in defining the apex, known as the point of maximum impulse. As this does not always coincide with the apex beat and with the outer lower left border of the heart, it would be better to use the term apex beat.

Normally, then, the cardiac dullness, the so-called relative cardiac dullness, begins above at the upper border of the third costal cartilage, as a rule, and taking a somewhat curved line with the concavity inward, descends to the fifth interspace or beneath the fifth rib from 9 to 10 cm. from a line drawn through the center of the sternum parallel to its length, the midsternal line. This seems to me to be a better method of recording the size of the heart than by the lines commonly used; viz., the nipple, or midclavicular, or parasternal line. Below, the cardiac dullness is merged into the tympany from the stomach and the dullness from the liver. At the sixth right costosternal articulation there is a sharp turn upwards forming at that point with the liver the cardiohepatic angle. At the fourth right cartilage or the third interspace, the dullness is from one to two centimeters from the edge of the sternum. We have then a somewhat pear-shaped area or triangular area with the apex at the apex of the heart. The so-called absolute cardiac dullness does not appear to me to be of any great significance. In reality it is the limit of lung resonance and may be greater or less, not so much on account of variations in the size of the heart, as of variations in size of the lungs and shape of the chest wall.

The really crucial question which should always be asked is, Is the heart enlarged or decreased in size? The position of the apex beat alone can not determine this, neither can the limit to the right of the sternum. The distance between these two points and the depth of the dullness at a distance of 5 cm. from the midsternal line on the left side, will give the size of the heart as nearly as can be obtained in the living subject. A series of measurements in normal adults average 13 to 14 cm. and 9 to 10 cm. respectively. For women they are about 1 cm. less in each direction.

The elaborate mechanism known as the orthodiagraph is probably the best means of determining the actual limits of the heart, but few men have such an expensive instrument, and, moreover, at the bedside such an instrument could not be used. From comparative measurements I concur in the belief of those who affirm that careful percussion will furnish equally as accurate limits.

The first step in making an examination of the heart is to expose the patient's chest in a good light, and, sitting at his right side, carefully inspect the chest. The position of the apex beat, heaving, bulging, retraction of interspaces, etc., can easily be seen if visible. After careful inspection has given all the data which it is possible to obtain, one next lays the palm of the hand over the heart and attempts to palpate the apex beat. The thrust of the apex in a hypertrophied heart can readily be felt, and one can feel whether the heart is regular, irregular, intermittent, or has other change in rhythm. The shock of the closing valves, particularly the aortic, can be felt, and that and the forcible apical impulse are very suggestive signs of hypertrophy and hypertension. Thrills may also be felt and can be timed in relation to the heart cycle.

Percussion

It is to percussion that we next proceed, and for the data in regard to the size of the heart, it is, for our purpose, the most valuable of all the physical methods of heart examination.