Two in vivo experiments were designed to study the applicability of a bipolar radiofrequency heating system to perform consistent thermal fusion of vascular tissue and to assess the short-term effects of radiofrequency thermal ballon angioplasty on normal carotid arteries.
Carotid arteries were compressed between a pair of modified bipolar forceps that applied radiofrequency energy, causing occlusive tissue welds between the opposed inner surfaces. The strength of the welds was examined by measuring the perfusion pressure required to reopen the vessel lumen.
1) In the first experiment an effective dose range for vascular tissue fusion was identified by testing the strength of the welds produced at various levels of radiofrequency thermal energy.
2) The second experiment was a preliminary investigation in which a prototype bipolar radiofrequency balloon catheter was used to apply a combination of mechanical pressure (by balloon dilatation) and heat (by energizing the electrodes) to the arterial wall.
Modulation type: CW
A dosimetry range of 0 to 205 joules showed a typical dose-response curve for the relationship between energy applied and bond strength. There was a plateau at approximately 300 mm Hg. A fusion of the inner surfaces of the vessel with preservation of vessel wall architecture was revealed. In addition, inflation of a bipolar radiofrequency balloon catheter in the normal carotid lumen produced an alteration of vessel profile angiographically and histologically. Data of these preliminary experiments indicate that balloon angioplasty with adjunctive radiofrequency energy may have benefits in reducing the factors causing acute failure of conventional percutaneous balloon angioplasty.