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Renal nerve stimulation (RNS) is used to localize sympathetic nerve tissue for selective renal nerve sympathetic denervation (RDN). Examination of heart rate variability (HRV) provides a way to assess the state of the autonomic nervous system. The current study aimed to examine the acute changes in HRV caused by RNS before and after RDN. 30 patients with hypertension referred for RDN were included. RNS was performed under general anesthesia before and after RDN. Heart rate (HR) and blood pressure (BP) were continuously monitored. HRV characteristics were assessed 1 min before and after RNS and RDN. RNS before RDN elicited a maximum increase in systolic BP of 45 (± 22) mmHg which was attenuated to 13 (± 12) mmHg (p

Blood pressure response to renal denervation is highly variable, and the proportion of responders is disappointing. This may be partly because of accessory renal arteries too small for denervation, causing incomplete ablation. Renal nerve stimulation before and after renal denervation is a promising approach to assess completeness of renal denervation and may predict blood pressure response to renal denervation. The objective of the current study was to assess renal nerve stimulation–induced blood pressure increase before and after renal sympathetic denervation in main and accessory renal arteries of anaesthetized patients with drug-resistant hypertension. The study included 21 patients. Nine patients had at least 1 accessory renal artery in which renal denervation was not feasible. Renal nerve stimulation was performed in the main arteries of all patients and in accessory renal arteries of 6 of 9 patients with accessory arteries, both before and after renal sympathetic denervation. Renal nerve stimulation before renal denervation elicited a substantial increase in systolic blood pressure, both in main (25.6±2.9 mm Hg; P P =0.047) renal arteries. After renal denervation, renal nerve stimulation–induced systolic blood pressure increase was blunted in the main renal arteries (Δ systolic blood pressure, 8.6±3.7 mm Hg; P =0.020), but not in the nondenervated renal accessory renal arteries (Δ systolic blood pressure, 27.1±7.6 mm Hg; P =0.917). This residual source of renal sympathetic tone may result in persistent hypertension after ablation and partly account for the large response variability.

Purpose Recently we reported the use of renal nerve stimulation (RNS) during renal denervation (RDN) procedures. RNS induced changes in blood pressure (BP) and heart rate are not fully delineated yet. We hypothesized that electrical stimulation of the sympathetic nerve tissue in the renal artery would lead to an increase in BP and vagal stimulation would cause a decrease in BP. We report the different patterns of BP and heart rate responses elicited by RNS prior to RDN. Methods 35 patients with drug-resistant hypertension were included. RNS was performed under general anesthesia at four sites in the right and left renal arteries, both before and immediately after RDN. RNS-induced BP and heart rate changes were monitored. Results A total of 289 RNS sites in 35 patients were analyzed. An increase in systolic BP of >10 mmHg was regarded as a positive BP response to RNS. This pattern of response was observed in 180 sites (62%). 86 RNS sites (30%) showed an indifferent response with BP changes ≤10 mmHg. At 13 sites (4.5%) RNS elicited a decrease in BP up to -8 mmHg. However, 10 RNS sites (3.5%) showed a pronounced vagal response with hypotension and sinus cycle lengths ranging between 4224-10272 milliseconds. These sites were distributed among two patients. Conclusion RNS identified sympathetic and parasympathetic nerve tissue in the renal arteries. RNS can be potentially used to map nerve bundles and guide selective ablation of sympathetic nerve fibers and prevent inadvertent ablation of parasympathetic nerve tissue during RDN.

Renal sympathetic nerve denervation (RDN) is accepted as a treatment option for patients with resistant hypertension. However, results on decline in ambulatory blood pressure (BP) measurement (ABPM) are conflicting. The high rate of nonresponders may be related to increased systemic vascular stiffness rather than sympathetic overdrive. A single center, prospective registry including 26 patients with treatment resistant hypertension who underwent RDN at the Isala Hospital in the Netherlands. Renal perivascular calcium scores were obtained from noncontrast computed tomography scans. Patients were divided into 3 groups based on their calcium scores (group I: low 0–50, group II: intermediate 50–1000, and group III: high >1000). The primary end point was change in 24-hour ABPM at 6 months follow-up post-RDN compared to baseline. Seven patients had low calcium scores (group I), 13 patients intermediate (group II), and 6 patients had high calcium scores (group III). The groups differed significantly at baseline in age and baseline diastolic 24-hour ABPM. At 6-month follow-up, no difference in 24-hour systolic ABPM response was observed between the 3 groups; a systolic ABPM decline of respectively −9 ± 12, −6 ± 12, −12 ± 10 mm Hg was found. Also the decline in diastolic ambulatory and office systolic and diastolic BP was not significantly different between the 3 groups at follow-up. Our preliminary data showed that the extent of renal perivascular calcification is not associated with the ABPM response to RDN in patients with resistant hypertension.

Renal denervation may be more effective if performed distal in the renal artery because of smaller distances between the lumen and perivascular nerves. The authors reviewed the angiographic results of 97 patients and compared blood pressure reduction in relation to the location of the denervation. No significant differences in blood pressure reduction or complications were found between patient groups divided according to their spatial distribution of the ablations (proximal to the bifurcation in both arteries, distal to the bifurcation in one artery and distal in the other artery, or distal to the bifurcation in both arteries), but systolic ambulatory blood pressure reduction was significantly related to the number of distal ablations. No differences in adverse events were observed. In conclusion, we found no reason to believe that renal denervation distal to the bifurcation poses additional risks over the currently advised approach of proximal denervation, but improved efficacy remains to be conclusively established.

Blood pressure (BP) response to renal denervation (RDN) is highly variable and its effectiveness debated. A procedural end point for RDN may improve consistency of response. The objective of the current analysis was to look for the association between renal nerve stimulation (RNS)–induced BP increase before and after RDN and changes in ambulatory BP monitoring (ABPM) after RDN. Fourteen patients with drug-resistant hypertension referred for RDN were included. RNS was performed under general anesthesia at 4 sites in the right and left renal arteries, both before and immediately after RDN. RNS-induced BP changes were monitored and correlated to changes in ambulatory BP at a follow-up of 3 to 6 months after RDN. RNS resulted in a systolic BP increase of 50±27 mm Hg before RDN and systolic BP increase of 13±16 mm Hg after RDN ( P P =0.003). Changes in RNS-induced BP increase before versus immediately after RDN and changes in ABPM before versus 3 to 6 months after RDN were correlated, both for systolic BP ( R =0.77, P =0.001) and diastolic BP ( R =0.79, P =0.001). RNS-induced maximum BP increase before RDN had a correlation of R =0.61 ( P =0.020) for systolic and R =0.71 ( P =0.004) for diastolic ABPM changes. RNS-induced BP changes before versus after RDN were correlated with changes in 24-hour ABPM 3 to 6 months after RDN. RNS should be tested as an acute end point to assess the efficacy of RDN and predict BP response to RDN.