SOME PRINCIPLES OF DRUG TREATMENT IN CARDIOVASCULAR CONDITIONS
Journal of the American Medical Association
Therapy as a science has not kept pace with pathology and diagnosis, largely due to a lack of method that will enable us to place it on the same sure footing as the above-named branches. Its scientific basis rests chiefly on experiments on normal animals. The dosage and frequency of repetition has been left largely to clinical experience, which too frequently consists of personal impressions rather than conclusions from recorded facts, and certainly lacks the accuracy of a true science. The
... macologic action of a drug on a normal animal may have reached the certainty of a chemical test and yet give very misleading information as to its action or indications for its use on the diseased human. It now rests with clinicians, in conjunction with pharmacologists and physiologists, to take up this subject, and by experimental work on animals in which the disease has been artificially produced, and by bringing pharmacologic and physiologic methods to the bedside, to clear up this subject as far as the means at hand will permit. With our modern clinical appliances for accurate determination of both systolic and diastolic blood pressure, the field of cardiovascular therapeutics is gradually being placed on a firm basis. In fact, there is no other therapy, except that of the specifics, that at the present time rests on such a scientific foundation. The most important cardiac remedies may be divided into two groups: those which act chiefly on the heartdigitalis and strophantlius; and those whose chief action is on the vessels-the vasoconstrictors, adrenalin, caffein, camphor and strychnin, and the vasodilators, alcohol, nitroglycerin and the nitrites. In making such a subdivision we must bear in "mind that they are all cardiovascular drugs affecting both heart and vessels, however, in varying degrees. It is not my intention to detail the indications for the use of cardiac remedies. In general, however, they are indicated when there is imperfect distribution of blood, due either to cardiac insufficiency or to a lack of the proper vascular tone. THE DIGITALIS GROUP. The digitalis group is, therefore, to be used in cases in which this improper distribution is dependent on heart insufficiency, the result either of valvular or of muscular cbanyps. The idea, that the digitalis group is contraindicated in myocarditis is not well grounded, although we must remember that greater care should be observed in regard to dosage and that the final results of the treatment must, from the nature of the trouble, be less satisfactory than in valvular lesions with good heart muscle. This group is, furthermore, not necessarily contraindicated in cardiac trouble with marked arteriosclerosis, or high blood pressure, as it is rare that in the physiologic doses these drugs increase blood pressure sufficiently to endanger the vessel wall. Sahli1 has shown that cardiac insufficiency may be associated with high blood pressure which has its basis in stimulation of the vasomotor centers by the poorly oxygenated blood ; improve the pulmonary circulation and the blood pressure falls. Heart insufficiency associated with slow pulse is often relieved by digitalis, due to a more complete emptying of the heart in each systole, better circulation in the coronary vessels, with consequently improved nutrition of the heart muscle. There is still considerable difference of opinion as to the value of digitalis in aortic regurgitation on account of its prolonging diastole. It is generally conceded that the prognosis in incompensated aortic regurgitation is bad, probably, as Sahli has suggested, due to the presence of essential passive congestion; that is to say, the leakage is so marked, before evidence of incompensation occurs, that even with complete systole and normal diastole it is impossible to maintain the proper amount of blood in the arterial system, while in mitral lesions, on account of the early passive congestion in the lungs, the individual is conscious of the disturbed compensation before the stage of essential passive congestion is reached. It is well to remember that digitalis increases the systolic output, which compensates in a measure for the greater amount that returns during diastole and, even prolonging the diastole, has its advantage, as it allows the auricle to empty itself more completely. Finally, the recent painstaking work of Stewart2 has shown that, after all, the amount of regurgitating blood is slight and prolonging the diastole is not a serious matter. The action of the various members of the digitalis group of drugs is practically identical; the main difference is one of degree and some slight differences in the amount of vasoconstrictor action. The less well-known members of this groupconvallaria, apocynum and cactus-do not possess any advantage over digitalis, are much less constant in action and will not be discussed. Digitalis.-Since Traube's time it has been a disputed question whether digitalis acts principally on the heart or on the blood vessels, and whether the increase in blood 1 pressure is chiefly of cardiac or of vascular origin. The recent work of Gottlieb and Magnus,3 now generally accepted, shows that the chief action is on the heart, the rise in pressure being due to more complete s}'stole with / a consequently greater flow of blood into the aorta. Its j vascular action is chiefly constriction of the splanchnic 1 arteries with dilatation of the peripheral vessels, includ-| 1.