Copyright © 2006, European Society of Cardiology
Dietary n-3 fatty acids promote arrhythmias during acute regional myocardial ischemia in isolated pig hearts
aDepartment of Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
bThe Interuniversity Cardiology Institute, The Netherlands
cThe Department of Medical Physiology, University Medical Center Utrecht, The Netherlands
dThe Department of Animal Science and Society, Faculty of Veterinary Medicine, Utrecht University, NL, The Netherlands
eThe Wageningen Centre for Food Sciences, and the Department of Human Nutrition, Wageningen University, Wageningen, NL, The Netherlands
* Corresponding author. Department of Experimental Cardiology, Experimental and Molecular Cardiology Groups, Academic Medical Center, M0-53, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands. Tel.: +31 205663267; fax: +31 206975458. Email address: r.coronel{at}amc.uva.nl
Objective: Dietary supplementation with fish oil-derived n-3 fatty acids reduces mortality in patients with myocardial infarction, but may have adverse effects in angina patients. The underlying electrophysiologic mechanisms are poorly understood. We studied the arrhythmias and the electrophysiologic changes during regional ischemia in hearts from pigs fed a diet rich in fish oil.
Methods: Pigs received diets rich in fish oil, in sunflower oil, or a control diet for 8 weeks. Hearts were isolated and perfused. Ischemia was created by occluding the left anterior descending artery. Diastolic stimulation threshold, refractory period, conduction velocity, activation recovery intervals and the maximum downstroke velocity of 176 electrograms were measured in the ischemic zone. Spontaneous arrhythmias during 75 min of regional ischemia were counted.
Results: More episodes of spontaneous ischemia-induced sustained ventricular tachycardia and ventricular fibrillation occurred in the fish oil and sunflower oil group than in the control group. More inexcitable myocardium was present in the ischemic zone in the group fed fish oil or sunflower oil than in the control group after 20 min of ischemia. After 40 min of ischemia, more block occurred in the control group than in the other groups. The downstroke velocity of the electrograms in the ischemic border zone was lower in the fish oil group and sunflower oil group than in the control after 20 min.
Conclusions: A diet rich in fish oil results in proarrhythmia compared to a control diet during regional ischemia in pigs. Myocardial excitability is reduced in the fish oil and sunflower oil group during the early phase of arrhythmogenesis. In the late phase of arrhythmogenesis, excitability is more reduced in the control group than in the fish oil and sunflower oil group.
KEYWORDS Arrhythmias (mechanisms); Lipid metabolism; Diet; Nutrition; Fish oil; Excitability
This study was funded by a) the Wageningen Centre for Food Sciences, an alliance of major Dutch food industries, Maastricht University, TNO Nutrition and Food Research, and Wageningen University and Research Centre, and the Dutch government, and b) de Nederlandse Hartstichting (nr. 2003B079) and c) the SEAFOODplus program of the European Union (nr. 506359).