24


Renal denervation


How to negotiate tortuous arteries in renal denervation


ERWIN BLESSING COMMENT & ANALYSIS


Renal denervation offers an attractive interventional option for patients with treatment-resistant arterial hypertension. Although it is a rather straightforward procedure in the vast majority of patients, challenging anatomic variations, such as tortuous anatomies, accessory arteries etc. can make the procedure challenging in some cases.1


and tricks” for performing renal denervation in patients with tortuous arteries


S Erwin Blessing provides some “tips


everal new devices have recently been approved and are available in many countries, and most of them are currently being evaluated within clini- cal trials. Most devices use radiofrequen- cy (with or without irrigation) to ablate renal nerves, but alternative approaches include using high-energy ultrasound or installation of chemical substances into the adventitia. Although some of the fol- lowing tips and tricks may apply for all devices, they focus on the specifics of the by far most frequently used device—the Symplicity Flex catheter (Medtronic). The most common challenge with all renal denervation devices arises in pa- tients with tortuous anatomy of the renal arteries, compromising safe insertion of the guide catheter and/or proper wall contact of the ablation catheter. Pre- procedural imaging such as CT or MRI, although not mandatory, can help you to choose the ideal guiding catheter. Since most renal arteries show a


August 2013


slightly inferior take-off, a left internal mammary artery (LIMA) guide catheter will work best for most renal arteries. Alternatively, a renal double curve or renal long guide might be suitable as well. If tortuosity involves iliac arteries and/or the aorta, the use of a long sheath straightens the aortic/iliac vasculature and helps to improve handling of the guide and ablation catheter. In case of a very steep inferior take-off of the renal artery, use of a 0.014” buddy wire will also help engaging the ablation catheter. Removal of the wire is crucial prior application of radiofrequency energy. Alternatively, a transbrachial access with a 90cm sheath or guide catheter might also be consid- ered. Next-generation ablation devices are most probably going to enable a transra- dial approach as well.


Whether challenging anatomies compromise safety and efficacy of renal denervation therapy is one of several interesting aspects that are currently being evaluated in a large scale global Symplic- ity registry.2


Results of our own registry


suggest that renal denervation is feasible, safe, and effective also in patients with challenging anatomies, such as tortuous arteries, small calibre vessels, previous stent placement, mild vascular patholo- gies etc.3


References 1. Bertog et al. Eurointervention 2013; 9:R83-8. 2. Mahfoud et at. Eurointervention 2013 3. Kirchberger et al. JACC 2012;60:B61.


Figure 1: Example of a challenging anatomy, where the right renal artery originates just above the iliac bifurcation


Figure 2: Stable insertion of the guide cath- eter was achieved by the use of a 0.014’’ guidewire (“buddy” wire technique)


Figure 3: Position of the Symplicity ablation catheter in the right renal artery. The buddy wire has to be removed prior delivery of radiofrequency energy


Erwin Blessing is at Medizinische Klinik III, University of Heidelberg, Heidelberg, Germany. He spoke about this issue at EuroPCR (21–24 May, Paris, France)


Renal denervation is safe and effective for patients with moderate resistant hypertension


Christian Ott (Department of Nephrology and Hypertension, University of Erlangen-Nuremberg, Erlangen, Germany) and others have reported in the Journal of American College of Cardiology that the use of renal denervation in patients with moderate true treatment- resistant hypertension is associated with substantial reductions in both office and 24-hour ambulatory blood pressure


O


tt et al commented that while studies have shown that catheter-


based renal denervation produc- es “substantial and sustained” reductions in blood pressure in patients with severe treatment- resistant hypertension, only one small retrospective study has assessed the role of renal dener- vation in patients with moderate hypertension. They added: “We therefore initiated a prospec- tive, multicentre open-label pilot study, aimed to assess the efficacy of renal denervation in true moderate treatment-resistant hypertension.”


The authors included patients in the study if their office blood pressure was between ≥140/90mmHg and <160/100mmHg, commenting: “True resistant hypertension was confirmed by initial 24-hour ambulatory blood pressure monitoring, thereby excluding white coat-


or pseudo-resistant hyperten- sion.” All patients eligible for treatment underwent renal denervation with Medtronic’s Symplicity catheter, and were treated between February 2011 and March 2012.


Of the 54 patients in the


study, most were middle-aged, male, and overweight. The mean office blood pressure was 151/83mmHg and mean 24-hour ambulatory blood pressure was ≥130/80mg mmHg. Ott et al reported that no adverse


events were observed with the procedure.


Office blood pressure was significantly reduced at three months (p=0.011) with further significant reductions at six months (p<0.001). The authors noted: “In 51% of patients, office blood pressure was controlled after renal denerva- tion—defined as office blood pressure <140/90mmHg. 61.1% of patients had an office systolic blood reduction of ≥10mmHg six months after renal dener- vation (defined as treatment response).” They added that they also observed significant reductions in 24-hour ambu- latory blood pressure at six months (p<0.001), and that renal denervation reduced both day- and night-time ambulatory blood pressure.


Roland E Schmieder


The investigators stated: “The major finding of our prospective, multicentre study is that renal denervation resulted in signifi-


cant reduction in office systolic and diastolic blood pressure as well as 24-hour ambulatory blood pressure in moderate true treatment-resistant hyperten- sion.” They added that “not surprisingly” the reductions in office blood pressure observed were less than observed in previ- ous reports because “entry blood pressure criteria were lower and pre-treatment blood pressure is the major determinant of the magnitude of blood pressure fall”. However, according to Ott et al, even modest blood pres- sure reductions are “accompa- nied by significant attenuation of cardiovascular morbidity and mortality.”


Calling their data “encourag- ing”, the authors stated that their results potentially indicated “an innovative interventional approach to treat patients with moderate treatment-resistant hypertension.”


Study author Roland E


Schmieder, Department of Nephrology and Hypertension, University of Erlangen-Nurem- berg, Erlangen, Germany, told Cardiovascular News that more data on this area was needed. He said: “Firstly, a randomised preoperative trial in these pa- tients with moderate treatment- resistant needs to be conducted. Indeed, on 7 March this year, Medtronic submitted an investi- gational device exemption to the FDA to assess in a randomised, controlled trial, the safety and efficacy for renal denerva- tion in patients with moderate treatment-resistant hypertension. Second, our results challenge the common practice to up titrate the medication with all available drugs, irrespective how many there are. Renal denervation (depending on the results of the randomised trial) may represent an alternative treatment strategy, with better compliance and fewer side effects.”


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40