20 Sep 2024
Case report: Renal denervation using radiofrequency energy (rRDN)
In this case report, we examine an advanced technique for renal denervation (RDN)—radiofrequency energy—employed to manage severe hypertension in patients with complex medical histories.
Case Report : Renal Denervation Using Radiofrequency Energy (rRDN)
Patient Profile
A 58-year-old male with a 12-year history of hypertension presented with uncontrolled blood pressure despite being on four antihypertensive medications (ACE inhibitor, calcium channel blocker, diuretic, and beta-blocker). His office blood pressure consistently measured around 180/110 mmHg, with 24-hour ambulatory blood pressure monitoring (ABPM) recording 163/105 mmHg. Due to inadequate response to medication and elevated cardiovascular risk, he was referred for renal denervation using radiofrequency energy.
Procedure Overview
The procedure was performed utilizing the Symplicity Spyral™ radiofrequency catheter. The patient received light sedation, and a local anesthetic was administered at the right groin puncture site. Heparin (80-100 IU/ kg) was given to achieve an activated clotting time (ACT) of at least 250 seconds.
Renal Denervation Using Radiofrequency Energy (rRDN)
Steps and Tips
- Accessing the renal arteries:
The common femoral artery was accessed using the Seldinger technique, followed by the introduction of a guidewire and insertion of a 6F sheath for vascular access. Proper sheath placement is crucial to prevent vessel trauma during catheter manipulation. A pigtail catheter was placed in the abdominal aorta to evenly distribute contrast dye and visualize the renal arteries by minimizing vascular injury. The renal arteries typically originate from the abdominal aorta at the level of the L1-L2 vertebral bodies. The pigtail catheter should be placed slightly above or at this level. Prolonged cine-angiographic imaging was recommended to visualize the contrast nephrogram and to identify any accessory renal arteries. - Imaging and navigation:
Fluoroscopy was employed to guide the IMA guiding catheter (without side holes) into the renal artery. Initial angiography confirmed the absence of significant stenosis or anatomical anomalies. Proper positioning under the fluoroscopic image intensifier was essential to minimize radiation exposure and optimize image quality. - Catheter placement:
Nitroglycerine (100-200 µg) was administered to reduce arterial spasm. The Symplicity Spyral™ ablation catheter, featuring four electrodes in a spiral configuration, was carefully advanced over a 0.014” guidewire. The catheter is designed for vessels 3-8 mm in diameter. Correct placement in a distal segment of the artery, ensuring alignment parallel to the vessel wall, was critical for optimal contact with nerve fibers. - Ablation process:
Each electrode was activated for 60 seconds, delivering radiofrequency energy. Real-time monitoring of temperature, impedance, and energy delivery was crucial to prevent overheating and arterial damage. - Multiple ablations:
The catheter was repositioned slightly after each ablation (from distal to proximal), typically applying 16-24 ablation points per renal artery, focusing on significant branches (3-8 mm) and the main renal artery. Consistent fluoroscopic monitoring and careful manipulation were key to avoiding arterial dissection or spasm. After completing the right side, the guiding catheter was moved to the ostium of the left renal artery, and the procedure was repeated as described. - Post-procedure and follow-Up:
Upon completing bilateral ablations, the catheter and sheath were removed, and the puncture site was closed with a closure device (AngioSeal™). The patient was monitored for several hours and discharged the following day with instructions for regular follow-up. At three months, his office blood pressure had decreased to 141/89 mmHg, with 24-hour ABPM showing 133/88 mmHg. The patient reported improved physical activity tolerance and quality of life.
Key tips and tricks
- Ensure proper placement of the dispersive electrode on the patient’s thigh and confirm its connection to the generator.
- Align the catheter correctly within the artery for optimal energy delivery and to minimize the risk of arterial damage.
- Use guidewires with a flexible, soft distal tip that are not hydrophilic-coated to avoid renal arterial perforation.
- In challenging anatomies, the buddy-wire technique may be useful, but always remove the second wire before ablation.
- If any electrode is deployed in an unsuitable location (e.g., ostium of a small vessel, bifurcation, or adrenal gland artery), deselect the electrode via the remote control or generator touchscreen.
