How to measure electrocardiographic QT interval in the anaesthetized rabbit.

Abstract

Many drugs prolong QT or QU intervals [QT(U)] in the electrocardiogram (ECG), and this may be associated with the generation of drug-induced torsades de pointes. Therefore, it is essential to assess the ability of the newly developed drugs to prolong QT(U) interval. For this purpose, both in vivo and in vitro rabbit models are frequently used. However, it is very difficult to locate the end of the QT(U) interval in most rabbit ECGs when repolarisation is delayed, as the shape of the T and U waves may be deformed. In addition, as the heart rate of the rabbit is very high, the T (or U) wave may overlap the P wave or even the QRS complex of the following sinoatrial beat. In these circumstances, application of the "extrapolation method" makes it possible to determine the length of the QT(U) interval. This article describes the extrapolation method, shows ECG examples of typical T and U waves in the anaesthetized rabbit, and makes an attempt to provide a useful guide for researchers to measure reliably and reproducibly the duration of the QT(U) interval in rabbit studies.

• Authors: András Farkas, Andrew J Batey, Susan J Coker
• Journal: Journal of pharmacological and toxicological methods (J Pharmacol Toxicol Methods) Vol. 50 Issue 3 Pg. 175-85 ( 2004) ISSN: 1056-8719 [Print] United States
• PMID: 15519904 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Pharmaceutical Preparations

Topics

• Anesthesia
• Animals
• Electrocardiography (methods, veterinary)
• Heart (physiology)
• Humans
• Laboratory Animal Science (methods)
• Long QT Syndrome (chemically induced, physiopathology, veterinary)
• Pharmaceutical Preparations (administration & dosage)
• Rabbits
• Reproducibility of Results