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

Carnitine deficiency can be associated with cardiomyopathy and life-threatening 7 arrhythmias. The aim of this study was to assess changes of ventricular repolarization (VR) 8 intervals by contactless magnetocardiographic mapping (MCG), in a rat model of carnitine 9 deficiency. 21 anesthetized Wistar rats (WR), 11 males and 10 females, were investigated, with an 10 unshielded 36-channel MCG instrumentation. After a basal recording 10 animals were randomized 11 to carnitine-deprivation induced by a 3-weeks diet containing N-trimethyl-hydrazine-3-propionate 12 (THP). All WR were restudied 1 week after the end of THP treatment. RR, QRS, QTpeak, QTend, 13 JTpeak, JTend and Tpeak-end intervals were measured from MCG waveforms. A prolongation of all HR- 14 corrected VR intervals was observed in THP-treated animals (range 7.6 12.8%), as compared to 15 their basal values. However, only the lengthening of QTend and Tpeak-end was statistically significant 16 (pb0.05). Compared to untreated age-matched controls, the cardiac intervals of TPH-treated WR 17 values were longer, but the differences were not significant. After 3 weeks of THP-induced reduction 18 of cardiac and plasma levels of carnitine, abnormalities in myocardial function are expected. In this 19 study we have found only a prolongation of HR-corrected QTend and Tpeak-end in THP-treated 20 animals. The lack of significance versus age-matched controls could be either due to too early re- 21 evaluation after deprivation, or to the effect of aging. In fact, age-related prolongation of VR 22 intervals has been reported in WR at the age of 14 months.