Decreased systolic function and inadequate hypertrophy in large and small breed dogs with chronic mitral valve insufficiency.
BACKGROUND
Systolic dysfunction associated with chronic mitral valve insufficiency (CMVI) has been demonstrated in experimental animal models and large breed (LB) dogs but has been reported as an uncommon finding in small breed (SB) dogs with naturally occurring disease. It has been suggested the myocardial failure could be, in part, because of an insufficient increase in left ventricular mass.


OBJECTIVE
To test if SB and LB dogs with CMVI and moderate heart failure have systolic dysfunction and if they have adequate eccentric hypertrophy.


METHODS
Data from 38 SB and 18 LB dogs affected with CMVI were compared retrospectively with results from 2 groups of normal dogs (17 SB and 32 LB).


METHODS
Systolic function was investigated echocardiographically by using percentage fractional shortening (FS), the ratio between observed and expected end-systolic diameter (ESD/ESDe), and end-systolic volume index (ESVI). Left ventricular hypertrophy was estimated by using the ratio between the thickness of the left ventricular free wall and the radius in diastole (h/R).


RESULTS
Both affected SB and LB dogs had a significantly increased FS and ESVI (FS% SB 45.6 + 8.04 versus 40.06 + 8.9, P < .05; FS% LB 33.64 + 8.61 versus 27.3 + 7.3 P < .05; ESVI SB 30.0 +/- 2.3 mL/m2 versus 21.18 +/- 13.9 mL/m2, P < .05; ESVI LB 83.22 +/- 43.84 mL/m2 versus 36.43 +/- 13.30 mL/m2 versus P < .001). The h/R in affected animals was decreased (0.53 +/- 0.11 versus 0.41 +/- 0.12, P < .05 SB; 0.47 +/- 0.11 versus 0.38 +/- 0.09, P < .05, LB).


CONCLUSIONS
Data from this study indicate that dogs with moderate heart failure caused by CMVI have systolic dysfunction. Inadequate hypertrophy of the left ventricle may be, in part, responsible for this finding.
Borgarelli
Michele
M
Department Patologia Animale, Faculty Veterinary Medicine, Via L. da Vinci 44, Grugliasco, Italy. michele.borgarelli@unito.it
Tarducci
Alberto
A
Zanatta
Renato
R
Haggstrom
Jens
J
D000818:Animals; D049628:Body Size; D002908:Chronic Disease; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005260:Female; D017379:Hypertrophy, Left Ventricular / Q000473:pathology / Q000662:veterinary*; D008297:Male; D008944:Mitral Valve Insufficiency / Q000473:pathology / Q000662:veterinary*; D020257:Ventricular Remodeling