Rationale for the use of drugs in the treatment of cardiovascular disease - 3. Positive inotropes

THE quest for the ideal positive inotrope has led to the development of many agents, to the extent that even a limited review of the literature can be a bewildering experience. Most of these drugs have been developed for use in human heart failure patients, but some have 'crossed over' to be used in veterinary patients. A number of recent long-term clinical studies in human heart failure patients receiving positive inotropes have produced some unexpected results which have led to many questions being posed about the rationale behind the use of such drugs. This article discusses the reasoning behind inotrope administration as well as some of the controversies in this area. The inotropes most widely used in veterinary medicine are reviewed and some guidelines are given for when these agents should be administered according to current understanding. The use of diuretics and vasodilators in the treatment of heart failure patients was discussed in earlier articles (Boswood 1996, 1998).