Background: High fatty acid concentrations have been shown to stimulate sym
pathetic nervous system activity, which may modify ventricular repolarizati
on and thus the Q-T interval on electrocardiogram recordings.
Objective: The aim of this study was to investigate whether acute elevation
s of plasma fatty acid concentrations influence the corrected Q-T interval
(Q-Tc), Q-Tc dispersion, and sympathetic nervous system activity in healthy
nonobese subjects.
Design: Thirty-two healthy subjects ((x) over bar +/- SD: 48 +/- 7 y of age
) received an infusion of 10% triacylglycerol emulsion plus heparin (a bolu
s of 200 U followed by 0.2 U min(-1). kg body wt(-1) for 180 min); on anoth
er occasion and in random order, the same subjects received a saline infusi
on.
Results: Compared with the saline infusion, infusion of 10% triacylglycerol
emulsion increased plasma fatty acids (P < 0.001) and was associated with
an increase in mean blood pressure (P < 0.05), heart rate (P < 0.05), Q-Tc
(P < 0.01), Q-Tc dispersion (P < 0.01), and plasma epinephrine (P < 0.005).
Further more, individual changes in plasma epinephrine correlated with cha
nges in Q-Tc (r = 0.60, P < 0.001) and Q-Tc dispersion (r = 0.53, P < 0.02)
even after adjustment for age, sex, and body mass index (P < 0.03 for all
correlations). Only changes in plasma fatty acids (P = 0.04) and plasma epi
nephrine (P = 0.006) concentrations were significantly and independently as
sociated with the lengthening of the Q-T interval.
Conclusion: Our study showed that elevated plasma fatty acid concentrations
might affect cardiac repolarization, at least in part because of an increa
se in plasma catecholamines.