C07 - Incidence of Clinically Relevant Pulmonary Restenosis in Dogs and Cats Following High-pressure vs. Low-pressure Balloon-valvuloplasty

Abstract: Introduction/

Objectives: Pulmonic stenosis (PS) is a common congenital heart disease, and balloon valvuloplasty (BVP) is considered a standard treatment for severely affected patients. We evaluated restenosis incidence in dogs and cats following high-pressure (HP) vs. low-pressure (LP) BVP. It was hypothesized that no difference in restenosis rates between groups would occur, but a higher incidence may correlate with annular hypoplasia.

Animals, Materials, and

Methods: Medical records of 109 animals (106 dogs, 3 cats) with severe PS were reviewed retrospectively. Patients were stratified into HP (burst pressure > 6 atm) and LP (≤ 6 atm) groups. Restenosis was defined as a > 30% increase in trans-pulmonic pressure gradient (PG) at recheck vs. 1-day post-operative measurements. Cardiac complications, angiographic vs. echocardiographic annular measurements, and atenolol impact were also assessed.

Results: Restenosis occurred in 39.4% (43 / 109). Incidence did not differ between HP and LP groups (P > 0.05). Mean PG decreased 60.1% post-operatively and remained 50.6% lower than baseline at follow-up (P < 0.001). Complications were rare and comparable between groups.

Conclusions: HP balloons did not reduce restenosis risk compared to LP balloons. While ~ 40% of patients developed restenosis, BVP provided significant, sustained PG reduction. The higher restenosis rate compared to previous reports (10 – 27%) likely reflects this study's stricter definition (> 30% increase from nadir) rather than clinical failure (> 75 mmHg). Despite restenosis, balloon valvuloplasty conveyed a significant reduction in the trans-pulmonary pressure gradient compared to baseline.