Effects of adrenaline and potassium on QTc interval and QT dispersion in man

Eur J Clin Invest. 2003 Feb;33(2):93-8. doi: 10.1046/j.1365-2362.2003.01123.x.

Abstract

Background: Hypoglycaemia alters cardiac repolarization acutely, with increases in rate-corrected QT (QTc) interval and QT dispersion (QTd) on the electrocardiogram (ECG); such changes are related to the counterregulatory sympatho-adrenal response. Adrenaline produces both QTc lengthening and a fall in plasma potassium (K+) when infused into healthy volunteers. Hypokalaemia prolongs cardiac repolarization independently however, and therefore our aim was to determine whether adrenaline-induced repolarization changes are mediated directly or through lowered plasma K+.

Materials and methods: Ten healthy males were studied on two occasions. At both visits they received similar l-adrenaline infusions but on one occasion potassium was also administered; infusion rates were adjusted to maintain circulating K+ at baseline. The QTc interval, QTd, peripheral physiological responses and plasma adrenaline and potassium concentrations were measured during both visits.

Results: The QTc interval and QTd increased both with and without potassium clamping. Without K+ replacement, mean (SE) QTc lengthened from 378 (5) ms to a final maximum value of 433 (10) ms, and QTd increased from 36 (5) ms to 69 (8) ms (both P < 0.001). During K+ replacement, QTc duration at baseline and study end was 385 (7) ms and 423 (11) ms, respectively (P < 0.001), and QTd 38 was (4) ms and 63 (5) ms (P = 0.001).

Conclusions: These data suggest that disturbed cardiac repolarization as a result of increases in circulating adrenaline occurs independently of extracellular potassium. A direct effect of adrenaline upon the myocardium appears the most likely mechanism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Dose-Response Relationship, Drug
  • Electrocardiography / drug effects*
  • Epinephrine / blood
  • Epinephrine / pharmacology*
  • Heart Conduction System / drug effects
  • Hemodynamics / drug effects
  • Humans
  • Hypoglycemia / physiopathology
  • Long QT Syndrome / blood
  • Long QT Syndrome / physiopathology*
  • Male
  • Potassium / blood
  • Potassium / pharmacology
  • Potassium / physiology*

Substances

  • Potassium
  • Epinephrine