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 (MCG) mapping, in a rat model of carnitine deficiency. Method: 21 anesthetized Wistar rats (WR), 11 males and 10 females (weight: 545.8 ± 143 gr), were investigated, with an unshielded 36-channel MCG instrumentation used for clinical recordings. After a basal recording at the age of 15 months, 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. Results: A prolongation of all HR-corrected 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 (p <0.05). Although TPH WR values were longer than those of controls the differences were not significant. Discussion: 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 re-evaluation 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