Examining The Effects Of Body Temperature On QT Interval In Non-Naïve Telemetered Göttingen Minipig

By Miri K. Pannu, Joel Baublits, Rebecca M. Smith, Emily M. Griffith, and Theodore J. Baird.

Changes in body temperature (BT) have been shown to influence the QT/QTcH interval, with an established inverse relationship in other species (e.g., dogs and humans). The objective of this study was to propose a correction formula for routine application in miniature swine. Eight male telemetered Göttingen Minipigs® were used to examine the relationship between QT/QTcH interval and BT. The study was conducted in two phases. In Phase 1, animals received a single intramuscular (IM) injection of Zoletil (tiletamine and zolazepam, 9 mg/kg) due to its known effects on heart rate and BT. In Phase 2, the same animals were anesthetized, and manual cooling and heating procedures were used to further investigate the BT and QT/QTcH interval relationship. Following Zoletil administration, significant (p< 0.05) increases in the QT/QTcH interval, along with concomitant (p< 0.05) decreases in BT, were observed. Peak differences in QT/QTcH occurred 2 hours post-dose, with values returning to baseline around 4 hours post-dose.

Similarly, peak differences in BT occurred at 2 hours post-dose, with values returning to baseline at approximately 4 hours. These changes were expected given the known inverse relationship between BT and QT/QTcH. This study established the relationship between BT and the QTcH interval in Göttingen Minipigs® in both conscious and anesthetized states, providing evidence of an inverse, nearly linear relationship. A QTcH correction formula incorporating a BT correction factor (QTcHcT) was derived for both conscious and anesthetized states.