Investigating the Efficacy of Radiofrequency Renal Artery Denervation: From Bench to Bedside

Abstract

Hypertension is a prevalent condition affecting one third of the adult population worldwide. Medications alone have failed to control the blood pressure (BP) in a large proportion of the hypertensive population. Therefore, renal artery denervation (RAD) was developed for the management of resistant hypertension. However, its efficacy was found to be inconsistent in clinical trials. Delivery of effective ablation that results in sufficient nerve injury is one important criterion for a successful procedure. This thesis focuses on evaluation of various commercially available RAD devices and understanding their unique properties and limitations. Using an in-house built renal artery phantom model, we demonstrated that single electrode Symplicity Flex produced larger lesions, in depth and width compared to multi-electrode EnligHTN when both systems were used under identical experimental conditions, and with optimal vessel wall contact. Clinically, in a small cohort of patients who underwent RAD using either systems, we found no significant difference in office BP reduction between the two systems and both groups had a significant reduction in office BP, which persisted up to 4 years. When the new generation multi-electrode Symplicity Spyral and multi-electrode EnligHTN systems were assessed in the same model, EnligHTN lesions were larger in depth. However, lesion depth of the new generation devices was reduced by 30-40% compared to older generation devices. In a phantom model of branch renal artery, Symplicity Spyral produced lesion that were of similar size and with bigger circumferential coverage compared to main vessel phantom model. No overheating at the electrode-tissue interface occurred during branch ablation. Overall, this thesis broadens our knowledge in the field of RAD with respect to information regarding properties and limitation of different RAD systems and it aids in refining the procedure in order to achieve the best clinical outcome.