Not less important are pain and dyspncea ; but they are often absent, and may be both dependent simply on rheumatism of the intercostal muscles, or even perhaps of the diaphragm. Tenderness between the ribs, pain awe vated by movement, or felt over an extensive surface, and the absence of 816118 of cardiac inflammation, are the evidences on which we base our conclusion that intercostal rheumatism is the cause of the difficult or painful respiration. On the other hand, we must be careful to observe that the tenderness is not really in the pericardium, when it is increased by pressure.
It may seem scarcely possible that enlargement of the heart should be mis taken for pericardial effusion ; but there is a certain similarity when the cavi ties are greatly dilated without thickening of the walls. The simulation of undulatory movement has been already mentioned, and the error has been due to this circumstance, attended as it necessarily is with increased dulness on percussion. The difficulty can only arise when along with the dilatation the sounds are obscured by the existence of valvular murmur, and especially when heard both at base and apex ; in such a case, when pain is complained of, or dyspncea has been recently increased, and any of those conditions are present which may act as causes of pericarditis, the doubt will occur to every observant mind. The quesi-undulatory movement, however, will not long de ceive any one of much experience—though analogous, it is in reality different; but, in addition to this, a very safe guide is to be found in the circumstance that the presence of fluid diminishes the distinctness with which sounds are transmitted to the ear, and that above the region of the dulness the sounds of the heart, whether marked by bruit or not, are heard with much greater distinctness than anywhere in the prrecordial space ; and this is something quite distinct from the difference between the intensity of a bruit as ordinarily made out in the one or in the other situation. For it is to be remembered that we are supposing an advanced stage of pericarditis, and that if there be not much fluid, there must be friction ; if there be much effusion, the bruit or the natural sound can only be heard as distant and obscure.
§ 8. Hypertrophy.—Increased dulness on percussion, heaving impulse, sounds muffled and indistinct though usually loud, a full, firm pulse, and generally throbbing of the arteries, indicate simple hypertrophy : the heart's action is not irregular. Such a
condition, however, is one of comparative rarity ; the increase of muscular power only results from the preservative action of na On the left side of the heart it is much more common than on the right, and this as a necessary result of the primary diseases from which it is derived. Its simplest form is produced by degeneration of the coats of the artery, and by Bright's disease of the kidney ; and it is very constantly found after in flammation and atheromatous disease of the valves. or partial adhesions of the pericardium ; all of these especially affect the left side. On the right, the chief cause of hypertrophy seems to be the impediment offered to the pul monary circulation by an emphysematous condition of lung.
§ 4. Daatation.—Increased dulness without heaving impulse, a quasi-undulatory movement, and irregular action ; sharp, shrill, or feeble, and flapping sounds: a soft, weak pulse, with general dyspncea and depression, indicate a dilated heart. Its signs and symptoms are those of enfeebled power, and hence they have close analogy with those produced by what used to be called a flabby, now very generally believed to be a fatty heart ; the in creased dulness and the undulatory movement are of course ab sent when there is no dilatation. These are the conditions most commonly associated with the pain and distress of angina pec toris, and its allied spasms.
The diagnosis of fatty heart derives much confirmation from observing a premature development of the areas senilis, because the tendency to fatty degeneration in one tissue is not improbably associated with the same ten dency in others ; but it is rather to be inferred from the pathological fact that simple dilatation is exLeedingly rare, and consequently when we cannot dis cover any cause for the symptoms of enfeebled power, we suspect fatty de generation. Dilatation without degeneration belongs especially to aortic regurgitation, mitral insufficiency, and completely adherent pericardium. The valvular lesions produce, complications which have yet to be noticed ; the pericardial adherence tends to increase the appearance of undulatory movemenL In a large number of cases more or less hypertrophy accompanies the dila tation, and thus the physical signs become infinitely varied ; I believe that irregularity of action, accompanying evidence of enlargement, may be almost always t,aken as an indication of the presence of some degree of dilatation.