Anatomic Study of the Renal Sympathetic Nervous System.
Daniel S Atherton, Farrell O Mendelsohn. Princeton Medical Center, Birmingham, AL
Background: Hypertension affects millions of patients worldwide causing an enormous disease burden. Despite extensive pharmacologic therapy, the contribution of hypertension to death, stroke, myocardial infarction, and congestive heart failure remains significant. Despite these many pharmacologic therapies, blood pressure control remains suboptimal. This has prompted novel device therapies for blood pressure control. A renal nerve ablation catheter has been developed that can destroy the innervation of the kidneys using radiofrequency energy, which has been associated with significant decreases in blood pressure. The anatomic substrate for this device has been poorly described even though the therapy holds great promise. We report the first detailed anatomic study of the renovascular wall and nervous system in renal arteries studied at autopsy.
Design: Left and right renal arteries (n=6) were obtained at autopsy from patients who died at our institution from natural causes. Unusual anatomic variants and arteries that demonstrated significant atherosclerosis or other structural compromise due to underlying pathology were excluded. Representative proximal, middle, and distal cross sections were obtained from each artery. The distance of peripheral nerves within the adventitia and surrounding soft tissue were measured relative to the lumen using an Olympus ocular micrometer.
Results: The distance from the lumen to closest nerve assessed was 0.4mm and the distance from the lumen to the farthest nerve assessed was 3.1mm. The average percentage of total nerves existing at increasing intervals from the artery lumen was 43.3±10.4% from 0.4-1.0mm, 28.5±8.3% from 1.0-1.5mm, 14.3±3.7% from 1.5-2.0mm, 7.99±2.3% from 2.0-2.5mm, and 5.80±3.3% at >2.5mm.
Conclusions: Our data shows that individual nerve fibers are more prevalent at closer intervals to the renal artery lumen, which could be due to increasing segmentation of peripheral nerves as they travel into and through the adventitia. If radiofrequency energy is sufficient to ablate nerves up to 1.5mm from the lumen, approximately 70% of nerves within 3mm will likely be affected. Likewise, if radiofrequency energy is sufficient to ablate nerves up to 2.5mm from the lumen, approximately 95% of nerves will be affected. This could suggest that relatively conservative radiofrequency energies could be used to still ablate a significant proportion of nerves.
Wednesday, March 2, 2011 9:30 AM
Poster Session V # 238, Wednesday Morning