312 MATERIA MEDIC A AND THERAPEUTICS. 



medicinal doses of digitalis ; with a sense of faintness, depres- 

 sion, nausea, or actual sickness. Metabolism is variously in- 

 fluenced by digitalis, according to the length of the different 

 stages and the rapidity of their development. When the 

 pressure and temperature are high, the urea and uric acid may 

 be increased, and certain salts may be diminished in amount. 



The effect of digitalis on the urine is equally uncertain in 

 the healthy individual; the period at which the renal vessels 

 begin to be relaxed, the duration of the second stage, and the 

 relation of the action of the drug on the heart to its action on 

 the vessels, being all vaiiable. As a rule, the urine is not in- 

 creased in bulk in health, but is remarkably increased in some 

 cases of dropsy to be presently referred to. 



3. SPECIFIC USES. 



Digitalis is one of the most valuable of medicinal remedies, 

 and is employed in the following conditions : 



1. Digitalis is indicated in disease of the heart, when the 

 nervo-muscular structures of the cardiac walls fail, so that the 

 circulatory force falls, the cavities are incompletely emptied, the 

 arteries are insufficiently filled, the veins imperfectly drained, 

 and the blood accumulates behind the seat of disease. Such a 

 condition is characterised by cardiac distress and pain ; a small, 

 weak, and often irregular pulse ; distension of the veins, 

 haemorrhage, dropsy, and visceral disorder ; and often by con- 

 gestion of the lungs, and great dyspnoea. It occurs under a 

 variety of circumstances which demand separate consideration. 



The disturbances of the circulation produced by disease of 

 the valves of the heart are removed by a natural process of 

 compensation, consisting of hypertrophy of the muscular walls, 

 with or without dilatation of the cavities. If this compensation 

 do not occur, or fail after having been established, and the 

 circulation be disordered as described, digitalis may give relief, 

 by increasing the force of the cardiac wall ; by lengthening 

 diastole, so that the venous flow and the ventricular rest are 

 both prolonged ; and by sustaining the pressure on the 

 arteries, thus driving the blood in a steady stream into the 

 veins. All the symptoms will be thus removed, including 

 dropsy, the fluid being absorbed by the increased venous flow, 

 and excreted by the kidneys as a profuse diuresis. Mitral 

 1 1 disease, tricuspid incompetence, and aortic obstruction are 

 1 the forms of valvular disease in which imperfect or failing 

 I hypertrophy is relieved by digitalis. In aortic incompetence 

 some authorities forbid the use of the drug, as prolonging 

 diastole, and thus permitting greater reflux, but this practice 

 is not to be carried too far, and digitalis must be given if the 



