Role ascribed by some authorities to ordinary growth in production of organic cardiac conditions, notably hypertrophy, cannot be demonstrated. Potain and Vaques (La Semaine MC,d., Sept. 25, '95).
High tension in the systemic arteries, aortic stenosis, and aortic regurgitation cause a predominant change in the left ventricle as compared with the other cavities.
Results of examinations of 139 vessels of all sizes. In smaller arteries thicken ing affecting both muscular and fibrous coats. Thickening greater in small ves sels than in larger. With chronic granu lar kidney hypertrophy of the muscle and of the fibrous tissue of whole arterial system connected with left side of the heart and of muscles of the heart. W. Howsbip Dickinson (Lancet, July 20, Aug. 3, '95).
In certain grave states of cardiac dila tation, and in advanced valvular disease, the blood-pressure ft S tested by Hill's instrument may be enormously high: a fact accounted for by admitting that the ventricle is called upon to work at its highest pressure. :.\.Ticholson (Brit. Med. Jour., Apr. 13, 1901).
In aortic regurgitation the dilatation is beneficial with certain limits. Inas much as a certain portion of the blood pressed into the aorta with each systole is at once allowed to return to the ven tricle, the total amount of blood pressed out with the systole must be greater than in health, or there will inevitably be a diminution in the normal amount in the arterial system. In its final development aortic insufficiency presents dilatation of all the cavities of the heart. In case of mitral regurgitation there is also dilata tion of the left ventricle, because a leak in the mitral valve during systole over distends the left auricle, and during d.ias tole the blood rushes into the left ven tricle under more than normal tension, enlarging its cavity. The usual and chief effect of mitral lesions, however, is en largement of the right side of the heart: at first of the right ventricle, and, when it begins to fail, also of the right auricle. The right auricle seldom undergoes much hypertrophy; any increase in its size is apt to be a pure dilatation.
Hypertrophy is never primary in a hard-working heart, whether increased labor be due to resistance from within, from without, or to nervous stimulation and augmented action. Primary dila tation is a compensatory element. Re
sidual blood dilates the cavities, and diminishes the extent to which each fibre is called upon to contract. J. G. Adami (Montreal Med. Jour., May, '95).
The stress of initial stenosis, pulmo nary stenosis, and chronic pulmonary disease falls upon the right side of the heart. Predominant dilatation of the right ventricle makes the heart globular in shape.
Temporary dilatation of the heart may occur under both physiological and pathological conditions. It cannot be explained as only apparent and ascribed to the action of respiration, for ordinary respiration does not sensibly modify the area of the cardiac dullness, and may occur four or five times in a minute. The phenomenon may be explained by suddenly increased intracardiac pressure or by diminished tonicity of the ventric ular wall. G. SGe (La MG(1. Mod., June 4, '91).
Reticulated condition of the myocar dium observed in the case of a woman afflicted with mitral obstruction and re gurgitation, who died, at the age of 40, after eighteen months of chronic asys tole. The interstitial spaces of the myo cardium were found to be dilated with out signs of an inflammatory process. The author's explanation is that a chronic interstitial cedema had stretched apart the muscular fibres, and that the condition was a result of venous and lymphatic stasis. Maurice Letulle (Bull. de la Soc. Anat., No. 25, '93).
Acute dilatation of the heart occur ring in the course of cancrum oris. The area of cardiac dullness had rapidly ex tended, the apex was beating an inch and a half external to the nipple, and over area there was heard for the first time a loud, blowing, systolic murmur. The principal point of interest in the case is the rapidity with which the heart dilated. When the patient came under observation it was noted that her heart was healthy and its area of per cussion normal. In the course of the illness the apex of the heart could be seen getting carried farther and farther daily, and all at once a mitral systolic murmur developed, and the pulse be came rapid and irregular. The heart dilated owing to malnutrition of the myocardium, either from fever or from the poisoned blood, and the mitral sys tolic murmur that developed was ady namie rather than endocarditic. Thomas Oliver (Edinburgh Med. Jour., Mar., '93).