Prospective Evaluation of the Balloon-to-Annulus Ratio for Valvuloplasty in the Treatment of Pulmonic Stenosis in the Dog

BACKGROUND: In dogs, treatment of pulmonic valve stenosis (PS) with pulmonary balloon valvuloplasty (PBV) is a viable method to decrease the pressure gradient across the valve. However, to the authors' knowledge, the variables that influence the selection of the correct balloon size for the procedure have not been explored. Moreover, the lesions caused by the procedure have not been detailed. HYPOTHESIS: Variables that influence the measurement of the annulus could affect selection of the balloon size. We sought to determine the effects of treatment when the balloon-to-annulus ratio (BAR) was or > 1.3, but within the recommended range of 1.2-1.5, regardless of whether dilation was performed with single or double balloon technique. ANIMALS: Twenty-five Beagles with PS were studied. METHODS: Inter- and intra-observer variability, echocardiography versus angiocardiography, and systolic versus diastolic timing were evaluated for the BAR. Assessment of right ventricular (RV) pressure, Doppler gradient, stenotic valve area, and RV wall thickness were compared before and 1, 90, and 180 days after treatment. Postmortem examination of the heart was done. RESULTS: Significant correlations existed in measurement of the annulus; however, variation existed that would change balloon size. Improvement in the degree of PS was significant regardless of the BAR or single or double ballooning. In the most severely affected dogs, continued improvement was noted on day 90. Postmortem examination revealed tears in the commissures and the valve leaflets. CONCLUSIONS: Multiple factors influenced determination of the BAR and a range of 1.2-1.5 was effective without detrimental consequences. Dogs with severe PS had continued decrease in RV pressure 3 months after treatment.