We have not emphasized the traditional approaches to the treatment of congestive heart failure, because there is abundant literature detailing the importance of rest and comfort for the patient, reduction of solute load, and administration of digitalis and diuretics. Instead, we have sought to emphasize the therapeutic interventions that are aimed at changing the mechanical loading conditions of the heart. Treatment expectations must be viewed within an age- or maturity-dependent framework. Thus, when a preterm or full-term newborn infant requires cardiocirculatory support, diminished cardiac reserve limits the benefits derived from diverse treatment methods. This unique fragility of the developing heart and circulation places a premium on the astute manipulation of all of the factors that determine optimum cardiovascular adaptation to stress. Beyond infancy, although cardiovascular reserve increases, it remains imperative to modify therapy by using cardioactive drugs that deal specifically with the separate mechanical and contractile variables to assure optimum survival.