D

IAGNOSIS of diseases of the

aorta depends in great measure upon recognition of the variations in its normal size. Unless this is determined, and the borders of the great blood vessels at the base of the heart are correctly delineated, many persons will be erroneously condemned to aortic diseases or many severe lesions of that vessel will remain unrecognized. Vaquez and Bordet state that on post-mortem examination it is common to find many different lesions of the aorta which have not during life been recognized; that sometimes considerable dilatations or aneurisms are seen, more often those "middle states" of aortitis, consisting of moderate enlargement of the vessel together with the gelatiniform or atheromatous patches on the walls, and that these types of aortitis may escape observation completely and not be indicated by any perceptible sign on percussion or auscultation. They predict that the number of these accidental findings will diminish with the progress of roentgenology which already shows the most minute alterations in the shape of the aorta in the incipient stages.

The normal size of the aorta is so variable and depends so much upon the sex, age, weight, conformation of the chest and the stature of the individual, that it is necessary that a basis

ANNALS OF CLINICAL MEDICINE, VOL. III, No. 8

of its normality be established, as the slightest modification in its size may reveal an underlying pathology. Roentgenology is of great help in the diagnosis of the aorta, and is far more illuminating and of greater diagnostic value than it is in cardiac conditions. Percussion of the great blood vessels at the base of the heart is considered by the major portion of cardiologists, even by some of the most skilful, as difficult, uncertain and misleading. Authorities on cardio-vascular diseases bewail the futility of percussion as a means of delimiting the shape, size and position of the heart, yet, it is less difficult accurately to map out the cardiac borders than to delineate those of the great blood vessels and the aorta.

The illuminating anatomical-roentgenological experiments of Robert Chapron cleared up the existing confusion due to the diversity of opinion as to what anatomical structures produce shadows at the region of the great blood vessels. Until this was definitely settled and proven it was impossible to determine with any degree of accuracy any underlying pathology of the aorta, for the simple reason that authorities confuse the borders of the superior vena cava with those of the aorta which give an erroneous aspect of the size of that vessel. Chapron definitely determined that the right

border of the cardio-vascular shadow is formed above principally by the superior vena cava, and below by the right auricle and the inferior vena cava. He further states that, depending on the volume of the heart and the variable length of the sternum, the superior vena cava may be partly hidden by the sterno-vertebral shadow, especially above, and in young subjects; but as a rule in the adult it overlaps the spine and the sternum to the right. His assertions were contradictory to the opinion held by many of the foremost internists and roentgenologists who claimed that the shadow of the right border of the great blood vessels was due both to the superior vena cava and to the ascending aorta. Theo and Frantz Groedel, Dietlen, Vaquez, Bordet, Jauceas, Albert Weil, Lutembacher, and others, were of that opinion.

Granger in his review of the work of Delherm and Chapron writes:

Contrary to the opinion generally held, the aortic shadow in none of their subjects, two of whom were seventy-three and eightythree years old, respectively, and all having marked senile aortitis, extended beyond the

right border of the superior vena cava, and they were forced to conclude that heretofore the diameter of the whole or part of the superior vena cava has been included in the measurements of the transverse diameters of the arch of the aorta.

In one of their subjects, the radiograph made before injecting the large vessels with the opaque solutions showed a marked increase in the size of the shadow at the base of the heart; the radiograph made after the large vessels had been injected under fluoroscope control, showed that the aorta was only slightly enlarged, lying behind the sternum, at the same distance from the superior vena cava and in no wise responsible for the enlarged shadow noted above.

approximately within 25 mm. of the mid-sternal line. He gives its length to be 7 cm., but that it is subject to considerable variations, and states its diameter to be about 22 mm.

The left border of the area of the

great blood vessels at the base of the heart is formed by the arch and the descending aorta, and the pulmonary

artery. artery. The thoracic aorta consists of an ascending portion (the ascending aorta) which begins at the left ventricle and passes upwards and to the right, on the right side of the pulmo

nary artery. It measures approximately 5 to 5.5 cm., in length and about 2.7 cm., in diameter. It ascends near the anterior thoracic wall as high as the second right chondrosternal articulation. It then turns backward and to the left forming an arch which reaches the posterior thoracic wall at the left side of the fourth thoracic vertebra. Sobotta writes that according to the individual breadth of the sternum the ascending aorta is situated either completely behind that bone or extends slightly beyond its right margin, but qualifies his statement by claiming that the latter condition obtains especially in the second intercostal space, particularly in advanced life, as a result of a distinct dilatation of the aorta at a point where the impact of the blood stream coming from the heart is received. Piersol states that upper border of the arch of the aorta reaches about 1 inch from the suprasternal notch, and that in small chests it may reach as far as the angle of Ludovici. Gray says that the height to which the aorta rises in the chest is usually about 1 inch below the upper border of the sternum; but that it may ascend nearly to the top of that bone. Occasionally it is found 1 inches, more rarely 2 or even 3 inches, below this point.

PERCUSSION

the

The aorta can be percussed accurately, its course, size and position can be delineated with a great degree of precision. Unfortunately but very little mention is made in our text books of percussion of the aorta, and slight attention is paid to the art in our medi

cal colleges. Equally as good results may be obtained from percussion of the anterior aspect of the aorta and the great blood vessels, as is possible with teleroentgenography. I have em

ployed the following technic to compare the two methods on the same skiagram. The aorta and the superior vena cava are first percussed, the borders determined and marked with fuse wire fastened to the skin with adhesive plaster, and the chest roentgenographed. The results from the two methods may be compared on the same film.

The method employed is Lerch's drop percussion. This method of percussion is the easiest learned, the most mechanical, and eliminates all personal factors; it has the advantages also of the combination of three essentials: the sounds are heard, the resistance is felt, and the vibrations of the hammer may be seen. This method differs from others in principle. A drop is used instead of a stroke. A hammer and pleximeter are necessary to obtain good results, The method is mechanical, easy to learn, and gives uniform results in everybody's hands because a drop is passive and cannot be changed, and the sound produced is the same; no matter who allows the hammer to drop.

The best proof of accuracy and of perfection of technic is to percuss the patient at different times and obtain the same size, shape and position of the organs examined. The elimination of all personal factors and individual differences of technic may be shown by the fact that different observers skilled in the method will have the same results. Once the drop method

of percussion is mastered, precision may be acquired irrespective of the method employed, in fact, the tactile appreciation of the slightest resistance can be so developed that approximately accurate results may be had by means of light and gentle palpation.

An absolute, exact comparison of the percussed image with that of the roentgen-rays is difficult. The patient must be roentgenographed in the same posture in which he was percussed. Another significant source of error is that percussion is practiced on patients breathing normally and without exaggeration; but, these persons when roentgenographed will invariably breathe deeply, thereby changing the position of the percussion figure traced upon the chest. The lowered position of the percussed outlines of the aorta and the superior vena cava in figures 1 and 3 compared to those of the roentgen-rays may be caused by two important factors. The first, because these persons were percussed in the reclining posture and were roentgenographed standing. The second, for the reason that these subjects were visceroptotics with elongated thoraces, especially the one in figure 3 who has a pronounced cardioptosis and unusual lengthening of the blood vessels at the base of the heart, which elongation was further exaggerated by the divergence of the rays. The length of the great blood vessels and the heart measuring over 20 cm., in a six foot plate will be increased by approximatively 1.5 to over 2 cm. In figure 2 the roentgen and percussion outlines of the aortic arch are about at the same height. In this case the individual was percussed and roentgenographed

standing; and besides, the thorax was short and the diaphragm high. These three plates were made consecutively for the purpose of illustrating this article. The subjects were chosen because of the normality of the great blood vessels and also because of the difference in their statures. It is obvious that the slightest change in posture or any movement by the subject roentgenographed makes extremely difficult an absolutely exact comparison of the percussed image with that of the skiagram. The subject must be roentgenographed in the same posture in which he has been percussed. The blood vessels at the base of the heart are more easily percussed on a person in the recumbent position. The movability of the skin over the thorax on the slightest movement of the individual will alter the position of the percussed lines. The facilities for roentgenographing these subjects were inadequate in so far that the percussion and the skiagram were not made in the same posture.

The right border of the superior vena cava is first percussed, the dulness is clear and the resistance plainly perceptible, then continuing along the same plane over the sternum the more distinct line of dulness of the ascending aorta is reached. The upper portion of the arch is made out by percussing downwards from the suprasternal arch. On light percussion the changes in resonance and resistance are easily discernible, and the whole contour of the arch of the aorta can thus be mapped out. The deeply-rooted opinion of the impossibility of accurately percussing over bony structures is