Outcomes after combined percutaneous balloon valvuloplasty and external beam radiation therapy for the treatment of congenital pulmonic stenosis in four dogs.

Valve restenosis after percutaneous balloon pulmonary valvuloplasty (BPV) for the treatment of congenital pulmonic stenosis (PS) may occur in up to 17% of canine cases. Outcomes in dogs with PS that are treated with repeat BPV after restenosis have not been described. The present report details the clinical courses of four dogs with congenital PS, previously treated with conventional BPV and atenolol (n = 4) or atenolol alone (n = 1), two with anomalous, circumpulmonary coronary artery anatomy, which underwent BPV followed immediately by external beam radiation therapy (BPV + EBRT) to prevent valve restenosis. External beam radiation therapy involved five daily fractions of 3.6 Gray to the pulmonic valve. Echocardiographic and clinical follow-up information for 2-4 years after BPV + EBRT is presented. Three dogs experienced long-term reduction in transpulmonic pressure gradient. In one dog, which was treated with conservative BPV + EBRT as first-line therapy, return of transpulmonic pressure gradient to pretreatment levels was noted by 7 months after BPV + EBRT. Although clinical benefit remains unproven, the addition of EBRT to conventional BPV may be a treatment option for dogs experiencing restenosis after BPV or those in which restenosis is considered likely. Further study to evaluate the efficacy and safety of this approach is needed.