Comparison of the cardiocirculatory effects of exercise and isoproterenol in children with pulmonary or aortic valve stenosis.

Isoproterenol infusion during cardiac catheterization as a simulator of exercise was evaluated with hemodynamic studies in children with pulmonary (15) or aortic (8) valve stenosis. Cardiac function was monitored during rest, mild exercise and isoproterenol infusion. Similar heart rates were maintained in both procedures. Peak pulmonary and aortic valve gradients as well as right and left ventricular dp/dt/p were significantly higher and cardiac index significantly lower with isoproterenol as compared to exercise. Isoproterenol induced a significantly greater decrease in systemic vascular resistance, and systemic blood pressure than did exercise. Left ventricular systolic pressure rose to similar levels and this resulted in substantially higher peak aortic gradients with isoproterenol. A consistent correlation was observed for peak valvular gradients measured during exercise and isoproterenol in both groups of patients. Accordingly, regression equations were obtained allowing reasonably accurate prediction of exercise valvular gradients on the basis of the isoproterenol data.