This review has outlined a rational approach to the understanding and pharmacologic treatment of low output states after cardiac surgery. There are clearly other reasonable schemes for the use of these agents for management of these difficult patients. However, the principles of management remain the same. Data about the specific effects of these drugs must be applied to specific patients whose particular hemodynamic derangements have been analyzed carefully. However, the complex and changing interactions between the heart and the peripheral vascular system and the effects of these agents on both signify that these analyses must be made continuously during the early hours after cardiac surgery. Rational use of these agents requires careful analysis of the specific hemodynamic disorder in a given patient. Pharmacologic inotropic therapy should then be tailored to these abnormalities and based on what is known about the expected effects of these drugs on the heart and peripheral circulation. Careful and repeated follow-up measurements to document both the effects of the drugs and potential changes in the patient's hemodynamic state are required if successful therapy is to be achieved. A rational approach to the selection of the inotropic agents requires not only an understanding of the effects of the drugs, but continuous monitoring of the patient's hemodynamic state and recognition that the patient's condition and needs may change and dictate alteration in subsequent therapy.