GENERAL CARDIOLOGY

Catheter-based treatment of hypertension shows promise

Renal sympathetic efferent and afferent nerves are crucial for the initiation and maintenance of systemic hypertension, and as such renal sympathetic denervation is a potential therapeutic target for hypertension. Krum et al describe the development of a novel, percutaneous, catheter-based approach to renal sympathetic denervation. The lumen of the main renal artery is cannulated and the surrounding sympathetic nerves destroyed by radiofrequency waves, and in a swine model this technique has been show to reduce noradrenaline content in the kidney by as much as 85%.

Fifty patients received percutaneous radiofrequency catheter-based treatment between June 2007 and November 2008, with subsequent follow-up to 1 year. The primary end points were office blood pressure and safety data at 1, 3, 6, 9 and 12 months after the procedure. Both renal and magnetic resonance angiography were performed to ensure no anatomical damage from the procedure, and the effectiveness of blood pressure lowering was assessed by repeated measures analysis of variance. Five patients were excluded from treatment for anatomical reasons (such as the presence of dual renal artery systems).

After the procedure, a significant and progressive reduction in blood pressure was seen over the 12 months since treatment (fig 1); by comparison the five patients not treated showed a mean rise in blood pressure. Baseline and 6-month glomerular filtration rate data were available for 25 patients, and showed a mean increase from 79 to 83 m/min/1.73 m². One intraprocedural renal artery dissection occurred before radiofrequency energy delivery, without further sequelae, and there were no other renovascular complications.

This was a proof-of-concept study, and as such lacks a control group. Furthermore, in an age of advanced pharmacotherapy for hypertension, can an invasive approach ever be completely justifiable? …