At the present time, physicians often treat patients with
atrial fibrillation (AF) using radiofrequency (RF)
catheter systems to ablate conducting tissue in the wall of the
Left Atrium of the heart around the
ostium of the pulmonary veins. These systems are expensive and take
time consuming to use. The present invention circular
ablation system CAS includes a multiplicity of expandable needles that can be expanded around a central axis and positioned to inject a fluid like
ethanol to ablate conductive tissue in a ring around the
ostium of a
pulmonary vein quickly and without the need for expensive
capital equipment. The expansion of the needles is accomplished by self-expanding or
balloon expandable structures. The invention includes centering means so that the needles will be situated in a pattern surrounding the outside of the
ostium of a
vein. Also included are members that limit the distance of penetration of the needles into the wall of the
left atrium, or the
aortic wall. The present invention also has an important application to ablate tissue around the ostium of one or both renal arteries, for the
ablation of the
sympathetic nerve fibers and / or other
afferent or
efferent nerves going to or from each
kidney in order to treat hypertension.