Radiofrequency catheter ablation (RF-ABL) of the renal arteries decreases blood pressure in patients with drug-resistant hypertension. This study investigated whether RF-ABL of the renal arteries alters blood pressure (BP) in an animal model of essential hypertension, the spontaneously hypertensive rat (SHR).
Methods
Nineteen-week old male SHR were instrumented with radio-telemetry probes for chronic measurement of BP (Systolic, SBP; Diastolic, DBP). After 1-week, control BP was measured in rats for 3 days. The next day SHR were anesthetized and randomly received either bilateral Sham-ABL (n=5) or RF-ABL (n=6) of the renal arteries (Biosense Webster Stockert 70 generator and RF-probe). The tip of the RF-probe was applied externally to a small dissected segment of each renal artery and stimulated circumferentially (10 Watts). BP was then measured three times a week for 8 weeks.
Results
In anesthetized hypertensive SHR, RF-ABL of a single renal artery did not alter BP. In contrast, subsequent RF-ABL of the contralateral renal artery produced an immediate (<15 seconds) decrease in mean arterial blood pressure (MAP, range Δ -60 to -100 mmHg). BP in hypertensive SHR was not altered during or after the Sham-RF procedure. In conscious SHR, BP was significantly decreased the day after RF-ABL (153±8/102±4 mmHg) and throughout the post-ABL study (4-week SBP/DBP, 173±7/120±5; 8-weeks, 171±6/116±4 mmHg) compared to pre-ABL control levels (SBP/DBP, 187±9/130±5 mmHg). At the end of week-1 the peak increase in MAP to cage switch stress was significantly blunted and the time to return to basal BP was shortened in RF-ABL (peak Δ 18±5 mmHg; 30-min to basal) vs. Sham-ABL (peak Δ 32±3 mmHg; 70-min to basal). At the end of week-8, the hypotensive response to i.p. chlorisondamine was blunted in RF-ABL (Δ -39±4 mmHg) vs. Sham-ABL rats (Δ -53±2 mmHg).
Conclusions
These data demonstrate that in hypertensive SHR, bilateral RF-ABL of the renal arteries produces, presumably via blockade of renal sympathetic afferent/efferent neural pathways, a reduction in BP, which by 4-weeks is reset to a lower basal level. These findings indicate that RF-ABL can be used in rodents to investigate the therapeutic mechanisms by which endovascular renal denervation reduces blood pressure in hypertension.
TCT-410 Evaluation of the Acute and Long Term Renal Artery Re-Innervation Attempt Response Following Radiofrequency Catheter-Based Renal Nerve Ablation in a Swine Model: A Immunohistochemical Characterization
