Moderate-dose dobutamine maximizes left ventricular contractile response during dobutamine stress echocardiography in children

Background. Assessment of ventricular contractile reserve by dobutamine stress echocardiography (DSE) may be a powerful tool for detection of subclinical ventricular dysfunction, however, the hemodynamic dose-response relationship during DSE in children has not been established. Methods: To characterize changes in hemodynamics and ventricular contractility during DSE in children, 26 participants (age 8.3 +/- 4.8 years; 17 male/9 female) with normal resting left-ventricular function underwent DSE. Participants with abnormal wall motion at rest or during DSE, or rejection were excluded. Left ventricular M-mode echocardiography and carotid pulse tracings were obtained at each stage for calculation of shortening fraction, velocity of circumferential fiber shortening (VCFc), and end-systolic wall stress (WS). Contractility was expressed as the difference between actual and predicted VCFc for measured WS. Dose-response curves for shortening fraction, VCFc, WS, and contractility (the difference between actual and predicted VCFc for measured WS) were obtained. Results: Stepwise changes in contractility, systolic blood pressure, WS, and left ventricular shortening fraction were observed at doses up to, but not beyond, 20 mug/kg/min. Increases in double product were observed at doses up to 30 mug/kg/min. Conclusions: DSE at a dobutamine dose of 20 mug/kg/min is optimal to fully assess contractile reserve in children. Lesser doses may provide insufficient stress, whereas higher doses may incur unnecessary increases in myocardial oxygen consumption and side effects.