Assessment of ECG interval and restitution parameters in the canine model of short QT syndrome

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• 作者：Anusak Kijtawornrat ; Yaowalak Panyasing ; Carlos del Rio ; Robert L. Hamlin
• 关键词：Dog ; QT ; QTc ; Restitution ; Short QT ; Sling-trained
• 刊名：Journal of Pharmacological and Toxicological Methods
• 出版年：2010
• 出版时间：May-June 2010
• 年：2010
• 卷：61
• 期：3
• 页码：231-237
• 全文大小：729 K

文摘

Introduction

The short QT syndrome (SQTS) is characterized by a short QT interval resulting from accelerated ventricular repolarization, and may be associated with ventricular fibrillation but not torsades de pointes. There are abundant data on the adverse effects of long QT, but knowledge of SQTS is sparse. The aim of this study was to examine whether analyses of several ECG biomarkers (QT, QTcB, QTcF, QTcV, QT_btb, and QT_RR1000) and dynamic restitution of the beat-to-beat QT–TQ relationship (TQ_min, % QT/TQ ratio > 1, QT/TQ ratio_max) can be used to assess ECG changes in conscious dogs.

Methods

Sling-trained dogs were infused with escalating concentration of levcromakalim (0, 1.0, 3.3, and 10.0 µg/kg/min), pinacidil (0, 3.3, 10.0, and 33.3 µg/kg/min), and nicorandil (0, 0.03, 0.1, and 0.3 mg/kg/min), drugs known to shorten QT. The RR, QT, QTcB, QTcF, QTcV, QT_RR1000, and TQ were measured before and after each concentration of the QT shortening test compounds.

Results

Levcromakalim, pinacidil, and nicorandil but not vehicle significantly shortened RR, QT, QT_btb, QT_RR1000, and TQ but not QTc(B,F,V). The QT–RR cloud also shifted to the lower bounds of the normal QT–RR boundary by the test compounds. The percentage of beats with a QT/TQ ratio > 1 was significantly increased in a dose response manner with levcromakalim and pinacidil and the lower TQ interval boundary (5th percentile) was decreased when compared to baseline or vehicle.

Discussion

QT_btb, QT_RR1000, and dynamic beat-to-beat measurements of restitution constitute clinically applicable ECG biomarkers for assessment of changes associated with arrhythmogenic risk of ventricular fibrillation due to QT abbreviation.