Study of ventricular repolarization changes after carnitine deprivation in rats by contactless magnetocardiography

Carnitine deficiency can be associated with cardiomyopathy and life-threatening arrhythmias. The aim of this study was to assess changes of ventricular repolarization (VR) intervals by contactless magnetocardiographic mapping (MCG), in a rat model of carnitine deficiency. 21 anesthetized Wistar rats (WR), 11 males and 10 females, were investigated, with an unshielded 36-channel MCG instrumentation. After a basal recording 10 animals were randomized to carnitine-deprivation induced by a 3-weeks diet containing N-trimethyl-hydrazine-3-propionate (THP). All WR were restudied 1 week after the end of THP treatment. RR, QRS, QTpeak, QTend, JTpeak, JTend and Tpeak-end intervals were measured from MCG waveforms. A prolongation of all HRcorrected VR intervals was observed in THP-treated animals (range 7.6–12.8%), as compared to their basal values. However, only the lengthening of QTend and Tpeak-end was statistically significant (pb0.05). Compared to untreated age-matched controls, the cardiac intervals of TPH-treated WR values were longer, but the differences were not significant. After 3 weeks of THP-induced reduction of cardiac and plasma levels of carnitine, abnormalities in myocardial function are expected. In this study we have found only a prolongation of HR-corrected QTend and Tpeak-end in THP-treated animals. The lack of significance versus age-matched controls could be either due to too early reevaluation after deprivation, or to the effect of aging. In fact, age-related prolongation of VR intervals has been reported in WR at the age of 14 months