To determined the safety and efficacy of a bladed balloon in the treatment of branch pulmonary artery stenosis, a model of left pulmonary artery stenosis was surgically created in two-week-old pigs. Seven pigs underwent angioplasty, five with the bladed balloon and two with conventional balloons. Overall, acute results showed a fall in the peak systolic pressure gradients from 8.3 +/- 2.3 mmHg to 3.2 +/- 3.1 mmHg and an increase in the minimum stenotic diameters from 4.5 +/- 2mm to 5.6 +/- mm. Acute pathological examination after cutting angioplasty showed regular luminal cuts that healed completely by four to six weeks in chronically surviving animals. Two of three surviving animals had persistent vessel enlargement at follow-up with one showing little overall change. Cutting balloons are effective in branch pulmonary artery angioplasty and may have clinical applications.