Still's-like innocent murmur can be produced by increasing aortic velocity to a threshold value

Still's murmur is a musical or vibratory systolic ejection murmur found in many normal school-aged children and adolescents. Its origin has been attributed to vibration of a cardiac structure during ventricular contraction, turbulent blood flow, or pressure changes across normal valves.¹ We previously related Still's murmur to a small ascending aorta with concomitant high aortic velocity.² Functional murmurs are accentuated in high cardiac output states such as fever, exercise and anemia. Dobutamine, a β₁ agonist with primarily inotropic action at low doses, allows study of high cardiac output states. We investigated whether dobutamine infusion could produce a Stills-like murmur in subjects without murmurs at rest and evaluated those factors correlating best with murmur presence.