How is the Renal Denervation Procedure Performed
The endovascular renal denervation procedure is similar to an angiography or angioplasty procedure and uses a 6F or larger guide catheter to place the RDN catheter (electrode) in the renal artery. An arterial access is achieved with needle puncture in to the arterial system and a 6 F or larger sheath (plastic cannula) is placed to secure the arterial access.
A pigtail or similar catheter is advanced and an abdnominal aortogram is performed to define the anatomy of aorta and renal artery origin and sizes.
The RDN catheter is then advanced through the guide catheter in to the renal artery. The electrode of the RDN catheter is positioned to have intimate contact with the intima of the renal artery which senses the impedence and temperature. When adequate impedance and temperature is sensed and appropriate position is confirmed on angiography, a low powered radiofequency energy is delivered The energy delivered has minimal effect on the renal artery intima (minimal intimial thickening and internal elastic lamina injury), but it disrupts the perineurium of the renal nerve traveling in the adventia of the renal artery, thus ablating the renal nerve (making the renal nerves dysfunctional)1.
Guided by the aortogram and fluoroscopy, a guide catheter is advanced to the renal artery and is selectively engaged. Selective renal artery angiogram is performed and suitability of the renal artery anatomy for renal denervation procedure is confirmed. Absence of flow-limiting obstructions and significant disease, absence of prior renal intervention and Diameter â‰¥4 mmin targeted area is considered suitable.
Energy is delivered at 4-6 different sites in a longitudinal and rotational manner in each renal artery with a goal to achieve circumferential nerve ablation. Without effecting the circumferential intima at the same level, 10-20 mm of the proximal renal artery is targeted with the treatment .
Multielectrode RDN devices allow for 4-6 sites being ablated without much manipulation of the catheter, in contrast to a single electrode. The complications of this procedure included
- Femoral artery access site complications (pesudoaneurysm/hematoma)
- Renal artery dissection by the guide catheter (without any sequel)
- Progression of a pre-existing renal artery stenosis
- Renal artery intimal edema/hematoma, charring
- Symptomatic hypotension requiring medication dose reduction
Multiple different devices are escribed in detail below that offer shorter and less painful procedure