Chronic Metabolic Syndrome develops a frailty of cardiac rhythm similar to aging in rats

Abstract

Heart rhythm decreases and alterations depend on aging and correlate with lifestyle and metabolic alterations like obesity, dyslipidemia, and chronic inflammation; these alterations may also produce ventricular hypertrophy and atrial fibrillation, increasing lethal arrhythmias. The high sucrose diet in young adult Wistar rats produces metabolic syndrome from the eighth week that continues twenty-six weeks later. In this work, we analyzed the changes presented by the heart during six months of metabolic syndrome. After this period, the rats were anesthetized, and the electrocardiogram was recorded. We observed that metabolic syndrome produced bradycardia and arrhythmias. The electrocardiogram showed an 18 % decrease in the heart rate in rats with metabolic syndrome and a decreased ability to regulate heart rate variability using the p-p interval Poincare graph. The electrical activity recorded in the sinus node showed alteration in the morphology and propagation of the action potential, therefore, a dysfunction in the pacemaker and supraventricular arrhythmias. This data correlated with the increase in the collagen and lipid area in the pacemaker that produced unexcitable segments, which induced lethal arrhythmias by alterations in electrical activity and premature aging and frailty, like those described in humans. We proposed that the changes in electrical and morphological alterations in the sinus node that are associated with metabolic syndrome are the cause of cardiovascular frailty and premature aging of the heart.