LOW-PRESSURE RADIOFREQUENCY BALLOON ANGIOPLASTY - EVALUATION IN PORCINE PERIPHERAL ARTERIES

Objectives. The purpose of this study was to evaluate the efficacy of radiofrequency-powered thermal balloon angioplasty in an in vivo porci ne model. Background. Various modes of thermal energy used adjunctivel y during balloon angioplasty have demonstrated the potential to enhanc e the results of acute lumen dilation. Methods. In normal pigs, 75 per ipheral arteries were dilated with a newly designed, radiofrequency-po wered, thermal angioplasty balloon. All inflations were performed at 2 -atm pressure for 85 s. Dilations were performed either with (hot) or without (cold) the application of heat. Lumen dimensions and vessel mo rphology were assessed with intravascular ultrasonography. At the end of each study, dilated arterial segments were harvested for histologic examination. Results. Single cold balloon inflations resulted in a 12 .7% increase in arterial cross-sectional area whereas single hot infla tions resulted in a 22.9% increase (p < 0.03). Similarly, when multipl e cold inflations were compared with multiple hot inflations, two, thr ee and four sequential hot inflations resulted in a significantly grea ter increase in cross-sectional area than an equivalent number of cold inflations (p < 0.03). Histologic examination demonstrated a temperat ure-dependent effect on the depth of medial necrosis and extent of art erial wall thinning (p < 0.001) as well as evidence for uniform altera tion of elastic tissue fibers at temperatures of greater-than-or-equal -to 60-degrees-C (p < 0.03). Conclusions. Low pressure radiofrequency thermal balloon angioplasty results in a greater increase in cross-sec tional area in porcine peripheral arteries than does nonheated convent ional balloon angioplasty. The pathologic basis for this enhanced dila tion may be a temperature-dependent effect on medial necrosis, thinnin g of the arterial wall or alteration of vascular elastic fibers, alone or in combination.