Causation. During the development of pericarditis the foreign body perforates the reticulum and diaphragm, passing along the middle line of the body, without which it would not come in contact with the pericardium. If the perforation, however, occurs to the right or left of the median plane, the foreign body moves forward just as easily, but it misses the pericardium and passes either into the lung, where it causes fatal pneumonia; or the pleura, where either it sets up septic pleurisy in the subpleural connective tissue or produces an abscess.
The abscess is generally lateral, situated in the right subpleural region, or it may develop below the pericardium. These are the two varieties of pseudo-pericarditis seen by Moussu.
There is, however, a third variety, which might be called “parasitic pseudo-pericarditis.” It is extremely rare, and Moussu has only seen one case. It was due to the presence of an enormous hydatid cyst of the right lung as large as a man’s head, which was situated towards the mediastinal plane of the lung and pressed on the supero-posterior surface of the heart and pericardium. In consequence of the permanent downward pressure which it exercised it interfered seriously with the heart’s action and caused symptoms of pseudo-pericarditis.
Symptoms. The general and external symptoms are those of pericarditis—viz., dulness, diminution in appetite, irregular rumination, wasting, œdema of the dewlap, distension of the jugulars, marked venous pulse, great anxiety and dyspnœa when the patients are forced to move, etc.
But the cardiac symptoms differ notably, and moreover vary, according to the nature of the lesions. Speaking generally percussion reveals complete dulness on one or both sides, and auscultation always indicates the absence of sounds due to extravasated fluid in the pericardial sac.
When the abscess is situated below the pericardium, a condition difficult to diagnose, the dulness seldom extends very high on either side of the chest, and the sounds heard over the cardiac area, while much weaker than usual, are audible above the normal points.
An abscess developing beneath the pleura on one side displaces the heart in the opposite direction. The cardiac beat is weakened by the compression, but, nevertheless, transmits an impulse to the purulent fluid, which in its turn conveys it outwards through the intercostal spaces in the form of movements corresponding in rhythm with the beating of the heart, so that at first glance one might imagine an aneurism existed at the base of the large arterial trunks. The lower pulmonary lobe is thrust upwards, and over the area of dulness pulmonary sounds completely disappear.
When the heart is compressed by a large hydatid cyst or other lesion, the general and external symptoms are similar to those above described.
Finally, one last symptom, which appears of some importance, may be mentioned. When animals suffering from pericarditis due to a foreign body are forced to move, the heating of the heart becomes so tumultuous that it can no longer be counted, and even in a state of rest it may rise to 140 or 150 beats per minute. In cases of pseudo-pericarditis it rarely rises above 90 or 110.
