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Metabolic and structural abnormalities in dogs with early left ventricular dysfunction induced by incessant tachycardia

Kathleen Mc EnteeDepartment of Small Animal Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Thierry FlandreDepartment of Pathology of Domestic Animals, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Cécile DessyDepartment of Histology of Domestic Animals, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Daniel DesmechtDepartment of Pathology of Domestic Animals, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Cécile ClercxDepartment of Small Animal Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Marc BalligandDepartment of Small Animal Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Charles MichauxDepartment of Genetics, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Eva JonvilleDepartment of Small Animal Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Nathalie MiserqueDepartment of Small Animal Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Marc HenroteauxDepartment of Small Animal Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.

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Bruce KeeneDepartment of Medical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606.

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Abstract

Objective—To assess morphologic and metabolic abnormalities in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP).

Animals—7 Beagles.

Procedure—Plasma carnitine concentrations were measured before and after development of ELVD induced by RRVP. At the same times, transvenous endomyocardial biopsy was performed, and specimens were submitted for determination of myocardial carnitine concentrations and histologic, morphometric, and ultrastructural examination.

Results—In 4 dogs in which baseline plasma total carnitine concentration was normal, RRVP induced a decrease in myocardial total and free carnitine concentrations and an increase in myocardial esterified carnitine concentration. In 3 dogs in which baseline plasma total carnitine concentration was low, plasma and myocardial carnitine concentrations were unchanged after pacing. Structural changes associated with pacing included perinuclear vacuolization in 3 dogs. Morphometric analyses indicated there was a decrease in myofiber cross-sectional diameter and area following pacing. Electron microscopy revealed changes in myofibrils and mitochondria following pacing.

Conclusions and Clinical Relevance—Results indicated that moderate to severe alterations in myocyte cytoarchitecture are present in dogs with ELVD induced by RRVP and that in dogs with normal plasma carnitine concentrations, myocardial carnitine deficiency may be a biochemical marker of ELVD. Results also indicated that transvenous endomyocardial biopsy can be used to evaluate biochemical and structural myocardial changes in dogs with cardiac disease. (Am J Vet Res 2001;62:889–894)

Abstract

Objective—To assess morphologic and metabolic abnormalities in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP).

Animals—7 Beagles.

Procedure—Plasma carnitine concentrations were measured before and after development of ELVD induced by RRVP. At the same times, transvenous endomyocardial biopsy was performed, and specimens were submitted for determination of myocardial carnitine concentrations and histologic, morphometric, and ultrastructural examination.

Results—In 4 dogs in which baseline plasma total carnitine concentration was normal, RRVP induced a decrease in myocardial total and free carnitine concentrations and an increase in myocardial esterified carnitine concentration. In 3 dogs in which baseline plasma total carnitine concentration was low, plasma and myocardial carnitine concentrations were unchanged after pacing. Structural changes associated with pacing included perinuclear vacuolization in 3 dogs. Morphometric analyses indicated there was a decrease in myofiber cross-sectional diameter and area following pacing. Electron microscopy revealed changes in myofibrils and mitochondria following pacing.

Conclusions and Clinical Relevance—Results indicated that moderate to severe alterations in myocyte cytoarchitecture are present in dogs with ELVD induced by RRVP and that in dogs with normal plasma carnitine concentrations, myocardial carnitine deficiency may be a biochemical marker of ELVD. Results also indicated that transvenous endomyocardial biopsy can be used to evaluate biochemical and structural myocardial changes in dogs with cardiac disease. (Am J Vet Res 2001;62:889–894)