The cardiac impulse is often extensive in cases of dilatation, although giving the impression of feebleness and irritability, and the area of dullness is rather more quadrilateral than pyramidal, although, it must be confessed, too much stress can not be laid on this distinction.
The importance of dullness in the fifth right intercostal space in the diagnosis of early pericardial effusion, as pointed out by Rotch, confirmed by clinical ob servations on forty-nine cases of peri carditis. Pericardial effusion, as a rule, can be first detected by the appearance of dullness at the right edge of the ster num in the fifth intercostal space. The dullness is more marked than the partial liver-dullness which is met with in health in the fifth right interspace; the dullness due to the effusion is absolute or almost absolute. Ebstein (Virchow's Archiv, B. 130, H. 3, '92).
Experiments on the cadaver tend to show that a pericardial effusion cannot be diagnosed by percussion except it be more than 150 to 200 cubic centimetres. The maximum amount of fluid that can be accommodated in the pericardium varies from G50 to 700 cubic centimetres. In the horizontal position with peri cardial effusions the cardiac area is in creased in all directions more or less, ac cording to the quantity of fluid. On the other hand, in the upright posture the increase is mainly at the lateral limits and particularly in the cardio-hepatic angle. In the former case the anterior surface of the heart is not always covered by fluid, while in the latter, as a rule, it is. In the horizontal position fluid accumulates about the large vessels, even when the effusion is slight; in the verti cal position the vessels are free, even in the presence of large effusions. Aporti and Figaroli (Gaz. degli Osped., May 20, 1900).
A rough systolic murmur simulating that of pericarditis may be heard at the base in case of chlorosis, but usually the two diseases can be distinguished without difficulty.
Considerable stress in point of diag nosis has been laid upon the fact that pericardial murmurs become more dis tinct when the patient sits up in bed, but it should be borne in mind that similar changes are not infrequently demon strable in the case of endocardial mur murs.
In pneumonia, and in pleurisy accom panied by pericarditis, the diagnosis of the latter is sometimes impossible. Of 57 cases of pneumonia under personal care during the past three years, 20 have come to autopsy. In 13 of these peri carditis was found; in 5 the pericarditis was detected during life; in the other 8 it was carefully sought for, and the ab sence of its signs was recorded.
Hydropericardium, with or without in flammation of the sac, in nephritis and cardiac insufficiency, may be masked by hydrothorax, ascites, passive congestion of the liver, and other results of hydrx mia and stasis.
In pericarditis pain in the cardiac re gion is very frequently absent, often it is slight; it is most marked in the rela tively vigorous persons suffering from a mild primary disease. The less severe the original disease, the more likely are symptoms suggestive of secondary peri carditis to be present.
The diagnosis must rest mainly on physical signs, but these may be entirely absent. Friction is often evanescent, and may come and go between examinations which are separated by too long an in terval. Another source of fallacy is the pleuro-pericardial friction. If there is no other evidence of disease in the lungs with which pleurisy is apt to be asso ciated, and no other evidence of pleurisy than friction within the pericardial limits, the chances are in favor of the pericardial origin of the friction, espe cially in the rheumatic cases.
Conversely, with other evidences of pleurisy, or of a cause for it, a friction in the above area is probably pleural. Change of the percussion-sound upward or laterally, with change in the position of the patient, is a valuable sign. Pulsus paradoxicus observed in 5 out of 8 cases. F. Shattuck (Boston Med. and Surg. Jour., July S, '97).
Diagnosis is difficult in those cases in which a friction-murmur has never been detected. If, however, the patient's dition becomes threatening, and the sibility of a considerable effusion exists, it is a proper and comparatively safe measure to insert an hypodermic needle, with aseptic precautions, so as to see whether fluid can be obtained. Perhaps the best point to choose for this purpose is the fifth left intercostal space, an inch and a half from the edge of the sternum. Shattuck, and also Striimpell, recom mend the lower left part of the pericar dial sac, a little way inward from the margin of dullness. Another place is the left costo-xiphoid angle: a spot which is probably perfectly safe when there is a large effusion, but otherwise renders one liable to perforation of the liver and dia phragm. If a sharp-pointed needle is employed suction may be begun as soon as the point of the needle is engaged in the tissues, and the needle then pushed cautiously forward until fluid begins to run.