Vascular Lesions Induced by Renal Nerve Ablation as Assessed by Optical Coherence Tomography: Pre- and Post-Procedural Comparison With the Simplicity Catheter System and the EnligHTN Multi-Electrode Renal Denervation Catheter
What are the morphological features of the endothelial and vascular injury induced by renal nerve ablation (RNA) using optical coherence tomography (OCT)?
In a prospective observational study, 32 renal arteries of patients with treatment-resistant hypertension underwent OCT before and after RNA. All pre- and post-procedural OCT pullbacks were evaluated regarding vascular changes such as vasospasm, edema (notches), dissection, and thrombus formation. Thirty-two renal arteries were evaluated, in which automatic pullbacks were obtained before and after RNA.
Vasospasm was observed more often after RNA than before the procedure (0 vs. 42%, p < 0.001). A significant decrease in mean renal artery diameter after RNA was documented both with the EnligHTN (4.69 ± 0.73 vs. 4.21 ± 0.87 mm; p < 0.001) and with the Simplicity catheter (5.04 ± 0.66 vs. 4.57 ± 0.88 mm; p < 0.001). Endothelial-intimal edema was noted in 96% of cases after RNA. The presence of thrombus formations was significantly higher after the RNA than before ablation (67 vs. 18%, p < 0.001). There was one evidence of arterial dissection after RNA with the Simplicity catheter, while endothelial and intimal disruptions were noted in two patients with the EnligHTN catheter.
The authors concluded that diffuse renal artery constriction and local tissue damage at the ablation site with edema and thrombus formation occur after RNA, and that OCT visualizes vascular lesions not apparent on angiography.
This study reported that using OCT, local tissue damage not apparent with angiography (i.e., local and diffuse vasospasm, edema formation, and endothelial injury with thrombus generation) can be identified after renal nerve ablation. Larger studies with short- and long-term follow-up using advanced imaging are indicated to further document the type and extent of the healing response after RNA and the relation between local injury and the blood pressure response after the procedure. Based on this study finding, it appears reasonable to use effective antiplatelet therapy after RNA, but the safety and efficacy of such therapies need to be prospectively tested.
Keywords: Vascular System Injuries, Renal Artery, Denervation, Thrombosis, Tomography, Optical Coherence, Edema, Blood Pressure, Hypertension, Tunica Intima
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