Reversible Dynamic Left Ventricular Outflow Tract Obstruction in Two Young Dogs Managed with β1-Blockers

초록

Dynamic left ventricular outflow tract obstruction (DLVOTO) is commonly observed in feline patients with hypertrophic cardiomyopathy, but it is less frequent in dogs. DLVOTO observed in young dogs often resolves after β1-adrenergic antagonist treatment. However, due to the lack of reported cases and the absence of a control group, it is difficult to determine whether improvements are due to aging-related changes in ventricular architecture or treatment itself. Thus, we report two cases of DLVOTO confirmed via echocardiography. Case 1 was an 8-month-old female Spitz and Case 2 was a 5-month-old female Cocker Spaniel. A prophylactic β1-adrenergic antagonist was prescribed to reduce the outflow gradient, and echocardiographic changes associated with DLVOTO and consequent left ventricular concentric hypertrophy resolved after β1 blocker prescription. This is the first report to discuss echocardiographic changes in relation to changes in β-blocker dose in canine DLVOTO.

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