A disadvantage of the needle is that its point may scratch the surface of the heart as it moves with systole and dias tole. The trocar and cannula is not open to this objection, and is, on the whole, preferable. Moreover, a cannula can be moved about in order to loosen any adhe sions. If there is strong reason to feel that fluid has collected, more than one effort to find it should be made.
While it is important to avoid puncture of the heart itself, this has occurred re peatedly without special damage, and in only one recorded case has such an acci dent proved fatal. Sloan saved a mori bund patient suffering from pericarditis by unexpectedly drawing ten ounces of blood from the right ventricle.
Etiology. — Pericarditis is never an idiopathic affection. It may be due to infectious germs, or to toxic conditions of the blood, or to inflammation extend ing from contiguous organs. It is very frequently associated with acute articular rheumatism, and it may precede the joint symptoms, especially in children. It may also complicate scarlet fever, measles, small-pox, and typhoid fever.
Statistics of 100 eases of pericarditis. Of these, 50 were dry, 41 serous, 4 hmm orrhagic, and 5 purulent. Seventy-four were males and twenty-six females. The majority of cases occurred in January. Acute rheumatism was cause in 51 cases; pneumonia in IS; chronic nephritis in 7; pleurisy in 5; chronic rheumatism in 2; gonorrhoea in 2; and various causes in the others, 9 cases being classed as idiopathic. G. G. Sears (Boston Med. and Surg. Jour., Apr. 22, '97).
Rheumatic pericarditis is, in the adult, more rare than endocarditis, but in chil dren rheumatic pericarditis is the more common lesion of the two. Plicque (La Presse Mad., June 4, '98).
Among 45,000 cases of diseases in chil dren 66 instances of pericarditis-20 dur ing the first year of life—observed. In 24 cases the cause of the disease was rheumatic polyarthritis, with or without chorea. Next in frequency were tuber culosis and pleuro-pneumonia. The forms of pericarditis in childhood cor respond anatomically to those seen in the adult, though there is a marked tendency in early life to the formation of purulent exudates and to circumscribed or extensive adhesion of the pericardial layers. Serous pericarditis was seen 13
times. In young children the pericardial sac had the shape of a cone with convex walls; as the child grows older, the sac assumes more and more the form of an ovoid pointed toward the apex of the heart. In pericarditis of young children an area of dullness was generally found in the posterior wall of the thorax. This dullness might lead to the diagnosis of pleural effusion, but the fact that re spiratory sounds become distinct during deep exploratory puncture serve to de cide. Friction-sounds are usually audi ble, but are finer than in the pericarditis of adults. A. Baginsky (Berl. klin. Woch., Nov. 25, '98).
It sometimes occurs in diphtheria, and not so very seldom in association with pneumonia. Septic processes may give rise to it, such as acute osteomyelitis, puerperal fever, and gonorrhoeal infec tion. It has been known to occur after tonsillitis. Tuberculosis is a very im portant cause.
Baginsky has shown that in 9 per cent. (six cases out of sixty-six) of a series of cases of pericarditis in children the dis ease was tuberculous. It is, however, in only a small proportion of these cases of tuberculous pericarditis that the peri carditis gives rise to any important symptoms, and in most instances the tuberculous disease is only discovered at the necropsy.
Tuberculosis of the pericardium may present itself under three different con ditions: (1) as a part of acute general tuberculosis miliary tubercles may be present in the pericardium [these do not, as a rule, produce symptoms during life]; (2) as the result of a local extension from a tuberculous focus in the adjoining structures, the lungs, mediastinal glands, etc.; and (3) as a form of pericarditis which is probably secondary to a tuber culous deposit in some part of the body, but where the pericarditis is the promi nent feature of the illness and the tuber culous disease elsewhere remains latent, often unsuspected. By some a very large amount of exudation is regarded as a characteristic sign of tuberculous peri carditis. C. A. Sutherland (Lancet, Apr. S, '99).