DVM, PhD, Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, 228 Coles Hall, Manhattan, KS 66506-5802; E-mail: firstname.lastname@example.org
Structural and Functional Basis for the Long QT Syndrome: Relevance to Veterinary Patients
Article first published online: 28 JUN 2008
© 2003 American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 17, Issue 4, pages 473–488, July 2003
How to Cite
Finley, M. R.1., Lillich, J. D., Jr, R. F. G. and Freeman, L. C. (2003), Structural and Functional Basis for the Long QT Syndrome: Relevance to Veterinary Patients. Journal of Veterinary Internal Medicine, 17: 473–488. doi: 10.1111/j.1939-1676.2003.tb02468.x
- Issue published online: 28 JUN 2008
- Article first published online: 28 JUN 2008
- Revised August 27, 2002; Accepted September 27, 2002.
- Cardiac repolarization;
- Ether-a-go-go related;
- KCNH channels;
- Torsades de pointes
Long QT syndrome (LQTS) is a condition characterized by prolongation of ventricular repolarization and is manifested clinically by lengthening of the QT interval on the surface ECG. Whereas inherited forms of LQTS associated with mutations in the genes that encode ion channel proteins are identified only in humans, the acquired form of LQTS occurs in humans and companion animal species. Often, acquired LQTS is associated with drug-induced block of the cardiac K+ current designated IKr. However, not all drugs that induce potentially fatal ventricular arrhythmias antagonize IKr, and not all drugs that block IKr are associated with ventricular arrhythmias. In clinical practice, the extent of QT interval prolongation and risk of ventricular arrhythmia associated with antagonism of IKr are modulated by pharmacokinetic and pharmacodynamic variables. Veterinarians can influence some of the potential risk factors (eg, drug dosage, route of drug administration, presence or absence of concurrent drug therapy, and patient electrolyte status) but not all (eg, patient gender/genetic background). Veterinarians need to be aware of the potential for acquired LQTS during therapy with drugs identified as blockers of HERG channels and IKr.