Hypertension (sustained blood pressure in excess of 140/90 mm Hg) is a very large and common problem- it, along with diabetes, is the primary precursor to kidney failure. Risk factors for hypertension include lack of exercise, diabetes, and obesity. This condition is complicated because it often involves no overt symptoms and half the sufferers fail to maintain “good” control with drug administration. Admittedly, this is because many sufferers are not “religious”about taking drugs, but some 20% of the patients have recalcitrant hypertension (uncontrollable with drug regimens).
Ardian has developed a catheterization system (Symplicity) that selectively severs nerves (in the kidney) that are the primary blood pressure regulators in the body. This catheter, a long piece of tubing, is threaded into a groin artery and manipulated to reach the kidney. (Diagram of the site and catheter here.) Once the catheter is in place, the nerves that line renal arteries are severed by a radiofrequency energy.
This device is currently undergoing clinical trials (though 2012), but the first phase of the study has been documented in the Lancet. Dr. Murray Esler is the principal investigator (Baker IDI Heart and Diabetes Institute) for this multicenter (24), multipatient (106 chosen from 190 candidates) prospective study.
The criteria for inclusion in the trial were adults (less than 85 y) persistent high systolic blood pressure (> 160 mm Hg), with treatment via 3 or more drugs. All patients must be capable of undergoing MRI (no pacemakers or metal implants), no renal abnormalities, and no type 1 diabetes (among others).
The first phase (9 June 2009 through 15 January 2010) was evaluated by office based measurement (seated) of systolic blood pressure. At the end of this phase, those patients (52) who underwent enervation had a drop in blood pressure of 32/12 mm Hg, compared to 1/0 for the control (54) patients. The baseline for the patients was 178/96, with no measurable difference between the two groups. Moreover, 41 of the denervated patients demonstrated a drop in systolic pressure > 10 mm Hg (84%) versus only 18 (35%) from the control group. The catheterized group demonstrated adverse effects.