Determination of Corrected QT Interval in Kangal Breed Dogs

Abstract

QT interval is one of the important reasons of severe and life threatening ventricular arrhythmias in humans and animals. Many formulas have been developed for correcting the QT interval however the best formula did not define yet by the researchers. For this reason, forty-nine clinically healthy Kangal dogs without cardiac problems other than sinus arrhythmia were included to the study. In this study corrected QT interval was determined by Bazet (QTcB = QT/√RR), Fridericia (QTcF = QT/ 3 √RR), Famingham (QT+0.154(1-RR)), Van der Water (QTcVdW = QT-0.087((60/HR)-1)), Hodges (QT+0.00175(HR-60)), Matsunaga (QTcM = log600 QT/logRR) formulas. As a result, Bazett's formula showed the best consistency because the slope curve of the regression line was closest to zero (-0.00743) in our study.

Evaluation of the Corrected QT Interval with Bazett’s Method in Cavalier King Charles Spaniel Dogs with Myxomatous Mitral Valve Disease

“…Bazett's formula is most applicable in dogs with high heart rates (12,29). In another study (30), a significant prolongation of the QTc value calculated by the Bazett method was observed with the progression of heart failure.…”

“…In dogs, QT>0.25 mm/second is defined as interval prolongation and <0.15 mm/second as interval shortening. QT prolongations may occur as a result of hypocalcemia, hypokalemia, quinidine toxicity, ethylene glycol intoxication, central nervous system problems, hypothermia, myocardial ischemia, left ventricular hypertrophy, right or left bundle branch block, myocarditis, and pericarditis (12). Variations in the heart rate can affect the QT and can lead to misinterpretation.…”