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Catheter-based renal artery denervation has successfully been introduced as alternative treatment for patients suffering drug resistant essential hypertension. however, the precise mechanisms underlying this technique remain elusive.
Methods and Results
Seven pigs underwent renal artery denervation utilizing the Simplicity® radiofrequency catheter. both renal arteries were treated in 5 animals, while 2 were treated unilaterally. in bilaterally treated animals, one renal artery was treated at the index procedure, while the contra-lateral artery was treated 10 days later. renal arteries were assigned to either the acute (n=6), sub-acute (10-day follow-up, n=6) or control (untreated, n=2) group. at follow-up blood analysis, final angiography and oct-imaging of the treated arteries was performed. renal arteries and kidneys were processed for histopathology and immunohistochemistry.
Radiofrequency derived energy application to the vessel wall induced transmural tissue coagulation and loss of endothelium resulting in local thrombus formation also detectable by OCT. At 10 days, the luminal surface was almost completely re-endothelialized. Mural wall damage was replaced by fibrotic tissue and the adventitial layer showed strong inflammatory infiltration including vasculogenesis. Remnant nerve fascicles within the lesion segments of the sub-acute group displayed enhanced vacuolic degeneration, thickening of the perineurium and an altered neurofilament protein immunostaining pattern. Examination of the kidneys revealed no abnormalities and blood parameters remained within the physiological range.
Catheter-based application of radiofrequency energy resulted in circumscribed transmural injury within the arterial wall also affecting nerve fascicles in a deferred manner. acute loss of endothelialization resulted in thrombus formation leaving kidney perfusion apparently unimpaired.
- 2013 American College of Cardiology Foundation