Radiofrequency thermal balloon angioplasty in an experimental model of peripheral arterial stenosis

Rationale: To assess the effect of thermal balloon angioplasty on surgically created peripheral arterial stenoses. Methods: Unilateral femoral arterial stenoses were created in 17 neonatal lambs (Dorset×Suffolk/Mule), using absorbable sutures. Six to 8 weeks later, the stenoses were dilated using either a standard (N=5), or thermal balloon angioplasty (N=9). Immediate angiography, flow and pressure gradient measurements were made to assess the acute result following either procedure. The survivors were followed up for a further period of 4 to 6 weeks, and a terminal angiographic study performed. The thermally treated segments of vessels were removed for qualitative histologic analysis. Results: Thermal angioplasty appeared to be acutely successful in eight of nine animals, compared with one of five successful procedures following standard angioplasty. Higher therapeutic temperatures (≥80°C) were associated with vascular complications. At the terminal study, stenoses had recurred in four of six survivors successfully treated with thermal angioplasty. Histologic studies demonstrated non-uniform effects of thermal dilation on the vessel wall, with variable changes ranging from partial or full-thickness tears, fibroblastic or myocyte proliferation, and disorganization of the vessel wall layers. Conclusion: Thermal angioplasty appears to be acutely more beneficial compared with standard angioplasty. However there is a significant recurrence of stenoses, and non-uniform changes in the vessel wall.