Sympathoexcitation Increases the QT/RR Slope in Healthy Men: Differential Effects of Hypoxia, Dobutamine, and Phenylephrine

Abstract

Beta-adrenergic stimulation induces comparable increases in the QT/RR slopes than hypoxia, but in the presence of a larger cardiac vagal activity. Vagal cardiac activation by phenylephrine does not change the QT slopes. This reveals that the sympathetic system is an important determinant of QT/RR dynamicity in healthy men.