Canine dynamic left ventricular outflow tract obstruction: assessment of myocardial function and clinical outcome.
OBJECTIVE
The aims of this study were (i) to evaluate echocardiographic findings and myocardial function including pulsed wave tissue Doppler imaging in dogs with naturally occurring dynamic left ventricular outflow tract obstruction and (ii) to investigate the clinical outcome and response to therapy in these dogs.


METHODS
Two cases were retrospectively reviewed and three cases were prospectively evaluated including clinical findings, diagnostic test results (including standard Doppler echocardiography and pulsed wave tissue Doppler imaging), response to treatment and outcome. The two retrospective cases received no treatment. Other cases were treated with a beta-blocker.


RESULTS
All dogs had a variable intensity left apical systolic murmur. Concentric left ventricular hypertrophy, systolic anterior motion of the mitral valve and scimitar-shaped left ventricular outflow tract Doppler flow profile were present in all cases. Pulsed wave tissue Doppler imaging interrogation of the interventricular septum revealed E'/A' reversal in all but one patient. Regression of left ventricular hypertrophy and total resolution of the dynamic left ventricular outflow tract obstruction were observed in all cases.


CONCLUSIONS
Young dogs are affected with a possible terrier breed predisposition. Dynamic left ventricular outflow tract obstruction may be distinguished from canine hypertrophic cardiomyopathy as progressive resolution of echocardiographic abnormalities was documented. Pulsed wave tissue Doppler imaging abnormalities provide further evidence for significant diastolic dysfunction associated with the hypertrophy.
Loureiro
J
J
The Scarsdale Veterinary Hospital, Derby, UK 45/47 Kedleston Road, Derby DE221FN.
Smith
S
S
Fonfara
S
S
Swift
S
S
James
R
R
Dukes-McEwan
J
J
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000818:Animals; D004283:Dog Diseases / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000503:physiopathology; D004285:Dogs; D015150:Echocardiography, Doppler / Q000662:veterinary*; D018619:Echocardiography, Doppler, Pulsed / Q000662:veterinary; D004739:England; D005260:Female; D006321:Heart / Q000503:physiopathology; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging / Q000662:veterinary; D008297:Male; D008943:Mitral Valve / Q000503:physiopathology; D011446:Prospective Studies; D012189:Retrospective Studies; D016896:Treatment Outcome; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*
D000319:Adrenergic beta-Antagonists