Renal sympathetic denervation
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]
Synonyms and keywords: RDN, renal denervation
Overview
Renal denervation (RDN) is a minimally invasive, endovascular catheter-based procedure invented to treat patients with severe resistant hypertension.[1] Preliminary data suggest that renal denervation is safe and results in a sustained blood pressure reduction of approximately 30 mm Hg at a three-year follow up.[2][3] However, in light of the negative results from SYMPLICITY HTN–3, the beneficial effect of renal denervation remains uncertain.
Rationale
A treatment catheter is introduced into the renal artery and energy is applied circumferentially at several ablation points within each renal artery to target the sympathetic endings in the adventitia of the vessel wall.[4][5] The drop in blood pressure presumably results from a reduction in norepinephrine release from the nerve endings and an overall decrease in sympathetic activity, which culminates in diminished renin secretion, vasoconstriction, and sodium reabsorption.[5][1] Renal denervation might also be beneficial in comorbidities of hypertension such as congestive heart failure, chronic kidney disease, and metabolic syndrome.[6]
Device
As of today, several percutaneous renal sympathetic nerve ablation systems are being studied and tested, 6 of them have already received CE marking to be used for renal nerve ablation. So far, no renal denervation device has been approved by the FDA.[1][5]
- Medtronic's Simplicity™ System - produced by Medtronic (formerly Ardian), was the first device to be used in humans, receiving market approval in 2010. It uses a radio frequency catheter (6F) inserted percutaneously through a femoral sheath, under fluoroscopic control. Despite being easily used, it has a tendency to create lesions with a less predictable pattern. This device now has over 5 years of clinical experience and 3 years of follow up data. The device has received favourable reviews on WhichMedicalDevice™, but concerns have been reported regarding availability and financial reimbursement for the procedure.
- St. Jude's EnligHTN system - also uses a radio frequency catheter inserted percutaneously through a femoral sheath, under fluoroscopic control, however, it is equipped with 4 electrodes on a basket structure. This allows it to create lesions in a more circumferential pattern, being able to create thermal injury and fiber interruption in a more predictable way.
- Vessix's V2 system - also uses a radio frequency catheter inserted percutaneously through a femoral sheath, under fluoroscopic control, however, the electrodes are mounted in a balloon, allowing for a good distribution of the energy.
- Covidien's One Shot system - also uses a radio frequency catheter inserted percutaneously through a femoral sheath, under fluoroscopic control, however, the electrodes are mounted in a balloon, allowing for a good distribution of the energy.
- Iberis system - also uses a radio frequency catheter and a 4-French shaft, enabling radial access.
- Recor's Paradise system - uses an ultrasound technology catheter inserted percutaneously through a femoral sheath.
Procedure
Overview
Considering the factors: drug-resistant hypertension, sympathetic nervous system (SNS) involvement in hypertension, importance of renal nerves for the overall sympathetic activity of the body, along with the ease of approach of the renal nerves through catheter techniques, hypertension was thought to be a good candidate for a catheter-based interventional approach. Knowing that sympathetic nerve fibers are located in the adventitia of the renal arteries, they can be easily reached by a catheter through a transvascular approach and interrupted using thermal energy. However, considering that sympathetic nerves share their location with C-pain fibers, analgesia and sedation, but not anesthesia, are mandatory for this procedure.[1][5][7]
Pre-procedure
- This technique must take place in a well equipped catheterization lab center, with skilled operators, experienced in handling possible surgical complications.
- Preprocedural examinations require the exclusion of secondary hypertension, as a "hidden cause" of resistance, as well as confirmation of uncontrolled blood pressure, while on medical treatment. This last criterion may involve the testimonial of a third party, confirming that the patient took the medication, since a common cause of "resistance" is noncompliance with the regimen.[6]
- Renal artery suitability must be assessed, which is done with a duplex ultrasound or MRI, and adequate anticoagulation should be attained and confirmed by activated clotting time test (with a target of 200-250 seconds). Ideally the renal artery must be >20 mm in length and >4 mm in diameter.
- Renal function tests are also required to confirm kidney's ability to sustain preprocedural contrast medium exposure.[6][8][9]
During procedure
- Vital signs such as blood pressure, heart rate and oxygen saturation must be monitored and continuous transcutaneous oxygen should be provided.[8]
- Although not confirmed by clinical trials, it has been suggested the administration of periprocedural anti-platelet therapy, for up to 4 weeks after the procedure, to prevent thrombus formation.[9]
Technique
- Under fluoroscopic guidance, through a femoral sheath, the electrode is positioned in each of the renal arteries.
- In patients with single renal arteries, 4 ablation points are recommended. The catheter should be placed at the periphery of the second order renal artery branch point, with the help of a guide wire. The lesions made in the artery wall should have a circumferential pattern, to decrease the risk of artery stenosis, which can be achieved by rotating the catheter while pulling it back to the ostium of the artery, at the same time that the energy is being delivered. For a successive and safe ablation, the points of lesion should be distanced by >5 mm. In areas of atherosclerotic plaque, the ablation should be avoided.[9] The energy used for the ablation also generates heat within the vessels, yet the system is cooled by the high rate of blood flow.[6] The procedure lasts for about 30 to 60 minutes.[9]
- Up until now, the devices used for this procedure have used either a single-tip electrode catheter, or a multielectrode system. The multielectrode systems have simplified this process by making it less painful and faster than the single-tip electrode version.[5][1]
Post-procedure
- After the procedure, the patient should be monitored until the sedation wears off, and closely followed to access the safety and efficacy of the procedure. Some studies also recommend the evaluation of the renal arteries, using duplex ultrasound, in order to exclude renal artery stenosis. Despite having been reported in single cases, this complication might not be due to the technique itself, but to pre-existing atherosclerotic plaques.[6]
Outcomes
SYMPLICITY HTN–1
- The safety and efficacy of renal denervation were first investigated in a proof-of-concept study on 45 patients with resistant hypertension.[10] Office blood pressures after procedure were reduced by –14/–10, –21/–10, –22/–11, –24/–11, and –27/–17 mm Hg at 1, 3, 6, 9, and 12 months, respectively. Three-year follow-up data demonstrated an average blood pressure reduction of 33/19 mm Hg.
- This trial confirmed the durability of the procedure, contradicting the hypothesis that sympathetic nerve regrowth would nullify the effect. It has also noted a reduction of 47% in renal norepinephrine spillover, accompanied by a decrease in overall body norepinephrine spillover, confirming a reduction in central sympathetic activity after the renal denervation.[2][6]
- In terms of safety, follow-up renal angiography was performed at the 14th and 30th day and MRI angiography at the 6th month, which showed no sign of renal artery aneurysm or stenosis.[9]
SYMPLICITY HTN–2
In SYMPLICITY HTN–2, a total of 106 patients from Australia and Europe were enrolled and randomized into two balanced groups. Six month follow-up data demonstrated a blood pressure reduction of –32/12mm Hg in the treatment group compared with a change of 1/0 mm Hg in the control group.
- Office-based blood pressure measurements at 6 months were as follows:
- Active treatment group: 147/84 mm Hg, from 178/96 mm Hg at baseline (p<0.0001)
- Control group: 179/96 mm Hg, from 178/97 mm Hg at baseline (p=0.77 systolic and p=0.83 diastolic)
SYMPLICITY HTN–3
SYMPLICITY HTN–3 is a multi-center, prospective, single-blind, randomized, sham-controlled study on the efficacy and safety of renal sympathetic denervation in patients with severe resistant hypertension (Clinical Trial No. NCT01418261).[11][12] A total of 535 patients were randomized in a 2:1 ratio to receive renal denervation or sham procedure. There was no significant reduction in office and ambulatory systolic blood pressure or differences in safety between the two groups.
- Mean changes in office systolic blood pressure at 6 months were as follows, for a difference of –2.39 mm Hg:
- Renal denervation group: –14.13±23.93 mm Hg (p<0.001)
- Sham procedure group: –11.74±25.94 mm Hg (p<0.001)
- Mean changes in 24-hour ambulatory systolic blood pressure at 6 months were as follows, for a difference of –1.96 mm Hg:
- Renal denervation group: –6.75±15.11 mm Hg (p<0.001)
- Sham procedure group: –4.79±17.25 mm Hg (p<0.001)
Risks
Data from SYMPLICITY trials suggest a favorable safety profile for catheter-based renal denervation.[10][13][14] Procedure-related complications include small hematomas, renal artery stenosis, vasospasm of the renal artery following the procedure, femoral artery pseudoaneurysm, renal artery dissection, and minor deterioration of renal function.[5] In an animal study, applied radiofrequency energy resulted in morphologic alterations of the renal arteries such as transient loss of endothelium, acute cellular swelling, and thrombus formation.[15] Two case reports described a secondary rise in blood pressure associated with progression of renal artery stenosis. However, it is unclear whether this progression is related to the procedure.[8]
Uses of Renal Denervation Beyond Hypertension
Potential benefits of renal denervation are being investigated in comorbidities of hypertension that are associated with exaggerated sympathetic activity, including:
- Atrial fibrillation[16][17][18][19][20]
- Diabetes mellitus[21]
- Heart failure[22]
- Sleep apnea[23][24][25]
- Polycystic ovary disease[26]
- Ventricular tachycardia[27]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Thukkani, A. K.; Bhatt, D. L. (2013). "Renal Denervation Therapy for Hypertension". Circulation. 128 (20): 2251–2254. doi:10.1161/CIRCULATIONAHA.113.004660. ISSN 0009-7322.
- ↑ 2.0 2.1 SYMPLICITY HTN–1, Investigators (2011 May). "Catheter-based renal sympathetic denervation for resistant hypertension: durability of blood pressure reduction out to 24 months". Hypertension. 57 (5): 911–7. doi:10.1161/HYPERTENSIONAHA.110.163014. PMID 21403086. Check date values in:
|date=(help) - ↑ SYMPLICITY HTN–2, Investigators (2010 Dec 4). "Renal sympathetic denervation in patients with treatment-resistant hypertension (The SYMPLICITY HTN–2 Trial): a randomised controlled trial". Lancet. 376 (9756): 1903–9. doi:10.1016/S0140-6736(10)62039-9. PMID 21093036. Unknown parameter
|coauthors=ignored (help); Check date values in:|date=(help) - ↑ Esler, MC (2010 Dec 4). "Renal sympathetic denervation in patients with treatment-resistant hypertension (The SYMPLICITY HTN–2 Trial): a randomized controlled trial". Lancet. 376 (9756): 1903–9. doi:10.1016/S0140-6736(10)62039-9. PMID 21093036. Unknown parameter
|coauthors=ignored (help); Check date values in:|date=(help) - ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Papademetriou, V.; Rashidi, A. A.; Tsioufis, C.; Doumas, M. (2014). "Renal Nerve Ablation for Resistant Hypertension: How Did We Get Here, Present Status, and Future Directions". Circulation. 129 (13): 1440–1451. doi:10.1161/CIRCULATIONAHA.113.005405. ISSN 0009-7322.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Böhm M, Linz D, Urban D, Mahfoud F, Ukena C (2013). "Renal sympathetic denervation: applications in hypertension and beyond". Nat Rev Cardiol. 10 (8): 465–76. doi:10.1038/nrcardio.2013.89. PMID 23774592.
- ↑ Atherton, Daniel S.; Deep, Nicholas L.; Mendelsohn, Farrell O. (2012). "Micro-anatomy of the renal sympathetic nervous system: A human postmortem histologic study". Clinical Anatomy. 25 (5): 628–633. doi:10.1002/ca.21280. ISSN 0897-3806.
- ↑ 8.0 8.1 8.2 Mahfoud, F.; Luscher, T. F.; Andersson, B.; Baumgartner, I.; Cifkova, R.; DiMario, C.; Doevendans, P.; Fagard, R.; Fajadet, J.; Komajda, M.; LeFevre, T.; Lotan, C.; Sievert, H.; Volpe, M.; Widimsky, P.; Wijns, W.; Williams, B.; Windecker, S.; Witkowski, A.; Zeller, T.; Bohm, M. (2013). "Expert consensus document from the European Society of Cardiology on catheter-based renal denervation". European Heart Journal. 34 (28): 2149–2157. doi:10.1093/eurheartj/eht154. ISSN 0195-668X.
- ↑ 9.0 9.1 9.2 9.3 9.4 Schlaich MP, Schmieder RE, Bakris G, Blankestijn PJ, Böhm M, Campese VM; et al. (2013). "International expert consensus statement: Percutaneous transluminal renal denervation for the treatment of resistant hypertension". J Am Coll Cardiol. 62 (22): 2031–45. doi:10.1016/j.jacc.2013.08.1616. PMID 24021387.
- ↑ 10.0 10.1 Krum, H.; Schlaich, M.; Whitbourn, R.; Sobotka, PA.; Sadowski, J.; Bartus, K.; Kapelak, B.; Walton, A.; Sievert, H. (2009). "Catheter-based renal sympathetic denervation for resistant hypertension: a multicentre safety and proof-of-principle cohort study". Lancet. 373 (9671): 1275–81. doi:10.1016/S0140-6736(09)60566-3. PMID 19332353. Unknown parameter
|month=ignored (help) - ↑ Bhatt, Deepak L.; Kandzari, David E.; O'Neill, William W.; D'Agostino, Ralph; Flack, John M.; Katzen, Barry T.; Leon, Martin B.; Liu, Minglei; Mauri, Laura; Negoita, Manuela; Cohen, Sidney A.; Oparil, Suzanne; Rocha-Singh, Krishna; Townsend, Raymond R.; Bakris, George L. (2014). "A Controlled Trial of Renal Denervation for Resistant Hypertension". New England Journal of Medicine. 370 (15): 1393–1401. doi:10.1056/NEJMoa1402670. ISSN 0028-4793.
- ↑ Renal Denervation in Patients With Uncontrolled Hypertension (SYMPLICITY HTN–3). ClinicalTrials.gov Identifier: NCT01418261 http://clinicaltrials.gov/ct2/show/NCT01418261
- ↑ Esler, MD.; Krum, H.; Sobotka, PA.; Schlaich, MP.; Schmieder, RE.; Böhm, M.; Böhm, M.; Mahfoud, F.; Sievert, H. (2010). "Renal sympathetic denervation in patients with treatment-resistant hypertension (The SYMPLICITY HTN–2 Trial): a randomised controlled trial". Lancet. 376 (9756): 1903–9. doi:10.1016/S0140-6736(10)62039-9. PMID 21093036. Unknown parameter
|month=ignored (help) - ↑ Krum, H.; Barman, N.; Schlaich, M.; Sobotka, P.; Esler, M.; Mahfoud, F.; Bohm, M.; Dunlap, M.; Sadowski, J. (2011). "Catheter-based renal sympathetic denervation for resistant hypertension: durability of blood pressure reduction out to 24 months". Hypertension. 57 (5): 911–7. doi:10.1161/HYPERTENSIONAHA.110.163014. PMID 21403086. Unknown parameter
|month=ignored (help) - ↑ Steigerwald, K.; Titova, A.; Malle, C.; Kennerknecht, E.; Jilek, C.; Hausleiter, J.; Nährig, JM.; Laugwitz, KL.; Joner, M. (2012). "Morphological assessment of renal arteries after radiofrequency catheter-based sympathetic denervation in a porcine model". J Hypertens. 30 (11): 2230–9. doi:10.1097/HJH.0b013e32835821e5. PMID 22914572. Unknown parameter
|month=ignored (help) - ↑ Scherlag, MA.; Scherlag, BJ. (2013). "A randomized comparison of pulmonary vein isolation with versus without concomitant renal artery denervation in patients with refractory symptomatic atrial fibrillation and resistant hypertension". J Am Coll Cardiol. 62 (12): 1129–30. doi:10.1016/j.jacc.2013.05.068. PMID 23810880. Unknown parameter
|month=ignored (help) - ↑ Linz, D.; Mahfoud, F.; Schotten, U.; Ukena, C.; Neuberger, HR.; Wirth, K.; Böhm, M. (2012). "Renal sympathetic denervation suppresses postapneic blood pressure rises and atrial fibrillation in a model for sleep apnea". Hypertension. 60 (1): 172–8. doi:10.1161/HYPERTENSIONAHA.112.191965. PMID 22585944. Unknown parameter
|month=ignored (help) - ↑ Linz, D.; Mahfoud, F.; Schotten, U.; Ukena, C.; Hohl, M.; Neuberger, HR.; Wirth, K.; Böhm, M. (2013). "Renal sympathetic denervation provides ventricular rate control but does not prevent atrial electrical remodeling during atrial fibrillation". Hypertension. 61 (1): 225–31. doi:10.1161/HYPERTENSIONAHA.111.00182. PMID 23150501. Unknown parameter
|month=ignored (help) - ↑ Pokushalov, Evgeny; Romanov, Alexander; Corbucci, Giorgio; Artyomenko, Sergey; Baranova, Vera; Turov, Alex; Shirokova, Natalya; Karaskov, Alexander; Mittal, Suneet; Steinberg, Jonathan S. (2012). "A Randomized Comparison of Pulmonary Vein Isolation With Versus Without Concomitant Renal Artery Denervation in Patients With Refractory Symptomatic Atrial Fibrillation and Resistant Hypertension". Journal of the American College of Cardiology. 60 (13): 1163–1170. doi:10.1016/j.jacc.2012.05.036. ISSN 0735-1097.
- ↑ Ukena, Christian; Bauer, Axel; Mahfoud, Felix; Schreieck, Jürgen; Neuberger, Hans-Ruprecht; Eick, Christian; Sobotka, Paul A.; Gawaz, Meinrad; Böhm, Michael (2011). "Renal sympathetic denervation for treatment of electrical storm: first-in-man experience". Clinical Research in Cardiology. 101 (1): 63–67. doi:10.1007/s00392-011-0365-5. ISSN 1861-0684.
- ↑ Mahfoud, F.; Schlaich, M.; Kindermann, I.; Ukena, C.; Cremers, B.; Brandt, MC.; Hoppe, UC.; Vonend, O.; Rump, LC. (2011). "Effect of renal sympathetic denervation on glucose metabolism in patients with resistant hypertension: a pilot study". Circulation. 123 (18): 1940–6. doi:10.1161/CIRCULATIONAHA.110.991869. PMID 21518978. Unknown parameter
|month=ignored (help) - ↑ Davies, JE.; Manisty, CH.; Petraco, R.; Barron, AJ.; Unsworth, B.; Mayet, J.; Hamady, M.; Hughes, AD.; Sever, PS. (2013). "First-in-man safety evaluation of renal denervation for chronic systolic heart failure: primary outcome from REACH-Pilot study". Int J Cardiol. 162 (3): 189–92. doi:10.1016/j.ijcard.2012.09.019. PMID 23031283. Unknown parameter
|month=ignored (help) - ↑ Witkowski, A.; Prejbisz, A.; Florczak, E.; Kądziela, J.; Śliwiński, P.; Bieleń, P.; Michałowska, I.; Kabat, M.; Warchoł, E. (2011). "Effects of renal sympathetic denervation on blood pressure, sleep apnea course, and glycemic control in patients with resistant hypertension and sleep apnea". Hypertension. 58 (4): 559–65. doi:10.1161/HYPERTENSIONAHA.111.173799. PMID 21844482. Unknown parameter
|month=ignored (help) - ↑ Fisher, James P.; Young, Colin N.; Fadel, Paul J. (2009). "Central sympathetic overactivity: Maladies and mechanisms". Autonomic Neuroscience. 148 (1–2): 5–15. doi:10.1016/j.autneu.2009.02.003. ISSN 1566-0702.
- ↑ Witkowski, A.; Prejbisz, A.; Florczak, E.; Kadziela, J.; Sliwinski, P.; Bielen, P.; Michalowska, I.; Kabat, M.; Warchol, E.; Januszewicz, M.; Narkiewicz, K.; Somers, V. K.; Sobotka, P. A.; Januszewicz, A. (2011). "Effects of Renal Sympathetic Denervation on Blood Pressure, Sleep Apnea Course, and Glycemic Control in Patients With Resistant Hypertension and Sleep Apnea". Hypertension. 58 (4): 559–565. doi:10.1161/HYPERTENSIONAHA.111.173799. ISSN 0194-911X.
- ↑ Schlaich, MP.; Straznicky, N.; Grima, M.; Ika-Sari, C.; Dawood, T.; Mahfoud, F.; Lambert, E.; Chopra, R.; Socratous, F. (2011). "Renal denervation: a potential new treatment modality for polycystic ovary syndrome?". J Hypertens. 29 (5): 991–6. doi:10.1097/HJH.0b013e328344db3a. PMID 21358414. Unknown parameter
|month=ignored (help) - ↑ Ukena, C.; Bauer, A.; Mahfoud, F.; Schreieck, J.; Neuberger, HR.; Eick, C.; Sobotka, PA.; Gawaz, M.; Böhm, M. (2012). "Renal sympathetic denervation for treatment of electrical storm: first-in-man experience". Clin Res Cardiol. 101 (1): 63–7. doi:10.1007/s00392-011-0365-5. PMID 21960416. Unknown parameter
|month=ignored (help)