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Doppler echocardiographic effects of medetomidine on dynamic left ventricular outflow tract obstruction in cats

Leigh A. Lamont DVM, MS1,2, Barret J. Bulmer DVM3, David D. Sisson DVM, DACVIM4, Kurt A. Grimm DVM, MS, DACVA, DACVCP5, and William J. Tranquilli DVM, MS, DACVA6
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  • 1 Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61801.
  • | 2 Present address is the Department of Companion Animals, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3.
  • | 3 Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61801.
  • | 4 Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61801.
  • | 5 Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61801.
  • | 6 Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61801.

Abstract

Objective—To evaluate the effects of medetomidine on dynamic left ventricular outflow tract (LVOT) obstruction in cats with left ventricular hypertrophy.

Design—Clinical trial.

Animals—6 domestic shorthair cats with echocardiographic evidence of dynamic LVOT obstruction.

Procedure—Cats were restrained in lateral recumbency, and baseline M-mode and Doppler echocardiographic examinations were performed. An ECG was recorded continuously, and blood pressure was measured indirectly with Doppler instrumentation. Medetomidine (20 µg/kg [9.1 µg/lb]) was then administered IM, and examinations were repeated 15 minutes later.

Results—Significant decreases in heart rate, LVOT velocity, and the LVOT pressure gradient were documented following medetomidine administration. After adjusting for the effects of heart rate by ANCOVA, there were no significant differences in any other systolic or diastolic indices of left ventricular function.

Conclusions and Clinical Relevance—Results suggest that administration of medetomidine to cats with dynamic LVOT obstruction may result in elimination of outflow tract obstruction; medetomidine may be a suitable sedative and analgesic agent in this subpopulation of cats. (J Am Vet Med Assoc 2002;221:1276–1281)

Abstract

Objective—To evaluate the effects of medetomidine on dynamic left ventricular outflow tract (LVOT) obstruction in cats with left ventricular hypertrophy.

Design—Clinical trial.

Animals—6 domestic shorthair cats with echocardiographic evidence of dynamic LVOT obstruction.

Procedure—Cats were restrained in lateral recumbency, and baseline M-mode and Doppler echocardiographic examinations were performed. An ECG was recorded continuously, and blood pressure was measured indirectly with Doppler instrumentation. Medetomidine (20 µg/kg [9.1 µg/lb]) was then administered IM, and examinations were repeated 15 minutes later.

Results—Significant decreases in heart rate, LVOT velocity, and the LVOT pressure gradient were documented following medetomidine administration. After adjusting for the effects of heart rate by ANCOVA, there were no significant differences in any other systolic or diastolic indices of left ventricular function.

Conclusions and Clinical Relevance—Results suggest that administration of medetomidine to cats with dynamic LVOT obstruction may result in elimination of outflow tract obstruction; medetomidine may be a suitable sedative and analgesic agent in this subpopulation of cats. (J Am Vet Med Assoc 2002;221:1276–1281)