Renal nerve stimulation: complete versus incomplete renal sympathetic denervation.

PURPOSE: Blood pressure (BP) reduction after renal sympathetic denervation (RDN) is highly variable. Renal nerve stimulation (RNS) can localize sympathetic nerves. The RNS trial aimed to investigate the medium-term BP-lowering effects of the use of RNS during RDN, and explore if RNS can check the completeness of the denervation. MATERIAL AND METHODS: Forty-four treatment-resistant hypertensive patients were included in the prospective, single-center RNS trial. The primary study endpoint was change in 24-h BP at 6- to 12-month follow-up after RDN. The secondary study endpoints were the acute procedural RNS-induced BP response before and after RDN; number of antihypertensive drugs at follow-up; and the correlation between the RNS-induced BP increase before versus after RDN (delta [Δ] RNS-induced BP). RESULTS: Before RDN, the RNS-induced systolic BP rise was 43(±21) mmHg, and decreased to 9(±12) mmHg after RDN (p < 0.001). Mean 24-h systolic/diastolic BP decreased from 147(±12)/82(±11) mmHg at baseline to 135(±11)/76(±10) mmHg (p < 0.001/<0.001) at follow-up (10 [6-12] months), with 1 antihypertensive drug less compared to baseline. The Δ RNS-induced BP and the 24-h BP decrease at follow-up were correlated for systolic (R = 0.44, p = 0.004) and diastolic (R = 0.48, p = 0.003) BP. Patients with ≤0 mmHg residual RNS-induced BP response after RDN had a significant lower mean 24-h systolic BP at follow-up compared to the patients with >0 mmHg residual RNS-induced BP response (126 ± 4 mmHg versus 135 ± 10 mmHg, p = 0.04). 83% of the patients with ≤0 mmHg residual RNS-induced BP response had normal 24-h BP at follow-up, compared to 33% in the patients with >0 mmHg residual RNS-induced BP response (p = 0.023). CONCLUSION: The use of RNS during RDN leads to clinically significant and sustained lowering of 24-h BP with fewer antihypertensive drugs at follow-up. RNS-induced BP changes were correlated with 24-h BP changes at follow-up. Moreover, patients with complete denervation had significant lower BP compared to the patients with incomplete denervation.

Renal nerve stimulation identifies aorticorenal innervation and prevents inadvertent ablation of vagal nerves during renal denervation.

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.

Integrated cardiovascular risk management programme versus usual care in patients at high cardiovascular risk: an observational study in general practice.

BACKGROUND: Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Despite the impact of CVDs, risk factors are often insufficiently controlled in patients at high risk. Recently, integrated multidisciplinary cardiovascular risk management (CVRM) programmes have been introduced in primary care. AIM: To investigate the effects of a CVRM programme on systolic blood pressure (SBP) and low-density lipoprotein (LDL)-cholesterol. DESIGN & SETTING: A prospective observational study was undertaken in patients at high cardiovascular (CV) risk who were aged 40-80 years. Integrated CVRM care was compared with usual care in general practice in the Netherlands. METHOD: Intervention and usual care patients were matched at baseline on age, sex, and presence of CVD. During 1 year of follow-up, patients received integrated or usual CVRM care in general practice. Primary outcomes were SBP and LDL-cholesterol. Secondary outcomes included calculated 10-year CV risk, body mass index (BMI), lifestyle (smoking, physical activity, and dietary habits), medication use, patient satisfaction, healthcare consumption, morbidity, comorbidity, and mortality. Mixed-model analyses were used to assess the outcomes. RESULTS: Totals of 372 and 317 patients were included in the intervention and usual care group, respectively. Mean age at baseline was 65.1 years and 66.2 years, respectively, and 42% were female in both groups. After 1 year, no differences were observed in: SBP (137.2 mmHg versus 139.0 mmHg in the intervention and usual care group, respectively); LDL-cholesterol (2.6 mmol/l in both groups); or in any of the secondary outcomes. CONCLUSION: Integrated CVRM care in general practice did not lead to a lower SBP or LDL-cholesterol in patients at high CV risk. Further research is needed to improve CVRM.

Renal sympathetic denervation induces changes in heart rate variability and is associated with a lower sympathetic tone.

BACKGROUND: 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. METHODS AND RESULTS: 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 < 0.001) after RDN. RNS before RDN decreased the sinus cycle length from 1210 (± 201) ms to 1170 (± 203) ms (p = 0.03), after RDN this effect was blunted (p = 0.59). The LF/HF ratio in response to RNS changed from ∆ + 0.448 (± 0.550) before RDN to ∆ - 0.656 (± 0.252) after RDN (p = 0.02). Selecting patients off beta-blockade (n = 11), the RNS-induced changes in HRV components before versus after RDN were more pronounced (LF/HF ratio ∆ + 0.900 ± 1.171 versus ∆ - 0.828 ± 0.519, p = 0.01), whereas changes in HRV parameters in patients on beta-blockade (n = 19) were no longer significant. In patients with diabetes mellitus (n = 7), RNS induced no changes in HRV parameters (LF/HF ratio ∆ - 0.039 ± 0.103 versus ∆ - 0.460 ± 0.491, p = 0.92). CONCLUSION: RNS induces changes in HRV suggesting increased sympathetic activity. Conversely, after RDN, the RNS-induced changes in HRV suggesting a lower sympathetic autonomic balance. These changes were most pronounced in beta-blocker naïve patients and not present in patients with diabetes mellitus. These findings could support RNS-guided RDN to optimize results.

Changes in arterial pressure hemodynamics in response to renal nerve stimulation both before and after renal denervation.

BACKGROUND: Renal nerve denervation (RDN) is developed as a potential treatment for hypertension. Recently, we reported the use of renal nerve stimulation (RNS) to localize sympathetic nerve tissue for subsequent selective RDN. The effects of RNS on arterial pressure dynamics remain unknown. The current study aimed to describe the acute changes in arterial pressure dynamics response to RNS before and after RDN. METHODS AND RESULTS: Twenty six patients with drug-resistant hypertension referred for RDN were included. RNS was performed under general anesthesia before and after RDN. We continuously monitored heart rate (HR) and invasive femoral blood pressure (BP). Augmentation pressure (AP) and index (Aix), pulse pressure (PP), time to reflected wave, maximum systolic BP and dicrotic notch were calculated. Systolic and diastolic BP at site of maximum response significantly increased in response to RNS (120 ± 16/62 ± 9 to 150 ± 22/75 ± 15 mmHg) (p < 0.001/< 0.001), whereas after RDN no RNS-induced BP change was observed (p > 0.10). RNS increased Aix (29 ± 11 to 32 ± 13%, p = 0.005), PP (59 ± 14 to 75 ± 17 mmHg, p < 0.001), time to reflected wave (63 ± 18 to 71 ± 25 ms, p = 0.004) and time to maximum systolic pressure (167 ± 36 to 181 ± 46 ms, p = 0.004) before RDN, whereas no changes were observed after RDN (p > 0.18). All changes were BP dependent. RNS had no influence on HR or the time to dicrotic notch (p > 0.12).   CONCLUSION: RNS induces temporary rises in Aix, PP, time to maximum systolic pressure and time to reflected wave. These changes are BP dependent and were completely blunted after RDN.

Treatment of atrial fibrillation in patients with enhanced sympathetic tone by pulmonary vein isolation or pulmonary vein isolation and renal artery denervation: clinical background and study design : The ASAF trial: ablation of sympathetic atrial fibrillation.

BACKGROUND: Hypertension is an important, modifiable risk factor for the development of atrial fibrillation (AF). Even after pulmonary vein isolation (PVI), 20-40% experience recurrent AF. Animal studies have shown that renal denervation (RDN) reduces AF inducibility. One clinical study with important limitations suggested that RDN additional to PVI could reduce recurrent AF. OBJECTIVE: The goal of this multicenter randomized controlled study is to investigate whether RDN added to PVI reduces AF recurrence. METHODS: The main end point is the time until first AF recurrence according to EHRA guidelines after a blanking period of 3 months. Assuming a 12-month accrual period and 12 months of follow-up, a power of 0.80, a two-sided alpha of 0.05 and an expected drop-out of 10% per group, 69 patients per group are required. We plan to randomize a total of 138 hypertensive patients with AF and signs of sympathetic overdrive in a 1:1 fashion. Patients should use at least two antihypertensive drugs. Sympathetic overdrive includes obesity, exercise-induced excessive blood pressure (BP) increase, significant white coat hypertension, hospital admission or fever induced AF, tachycardia induced AF and diabetes mellitus. The interventional group will undergo PVI + RDN and the control group will undergo PVI. RESULTS: Patients will have follow-up for 1 year, and continuous loop monitoring is advocated. CONCLUSION: This randomized, controlled study will elucidate if RDN on top of PVI reduces AF recurrence.

Renal denervation beyond the bifurcation: The effect of distal ablation placement on safety and blood pressure.

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.

Renal vascular calcification and response to renal nerve denervation in resistant hypertension.

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 ±â€Š12, -6 ±â€Š12, -12 ±â€Š10 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 Nerve Stimulation-Induced Blood Pressure Changes Predict Ambulatory Blood Pressure Response After Renal Denervation.

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<0.001). Average systolic ABPM was 153±11 mm Hg before RDN and decreased to 137±10 mm Hg at 3- to 6-month follow-up (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.

Persistent Increase in Blood Pressure After Renal Nerve Stimulation in Accessory Renal Arteries After Sympathetic Renal Denervation.

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<0.001) and accessory (24.3±7.4 mm Hg; 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.

Insulin detemir offers improved glycemic control compared with NPH insulin in people with type 1 diabetes: a randomized clinical trial.

OBJECTIVE: Insulin detemir is a soluble long-acting basal insulin analog designed to overcome the limitations of conventional basal insulin formulations. Accordingly, insulin detemir has been compared with NPH insulin with respect to glycemic control (HbA1c, prebreakfast glucose levels and variability, and hypoglycemia) and timing of administration. RESEARCH DESIGN AND METHODS: People with type 1 diabetes (n = 408) were randomized in an open-label, parallel-group trial of 16-week treatment duration using either insulin detemir or NPH insulin. Insulin detemir was administered twice daily using two different regimens, either before breakfast and at bedtime (IDet(morn+bed)) or at a 12-h interval (IDet(12h)). NPH insulin was administered before breakfast and at bedtime. Mealtime insulin was given as the rapid-acting insulin analog insulin aspart. RESULTS: With both insulin detemir groups, clinic fasting plasma glucose was lower than with NPH insulin (IDet(12h) vs. NPH, -1.5 mmol/l [95% CI -2.51 to -0.48], P = 0.004; IDet(morn+bed) vs. NPH, -2.3 mmol/l (-3.32 to -1.29), P < 0.001), as was self-measured prebreakfast plasma glucose (P = 0.006 and P = 0.004, respectively). The risk of minor hypoglycemia was lower in both insulin detemir groups (25%, P = 0.046; 32%, P = 0.002; respectively) compared with NPH insulin in the last 12 weeks of treatment, this being mainly attributable to a 53% reduction in nocturnal hypoglycemia in the IDet(morn+bed) group (P < 0.001). Although HbA1c for each insulin detemir group was not different from the NPH group, HbA1c for the pooled insulin detemir groups was significantly lower than for the NPH group (mean difference -0.18% [-0.34 to -0.02], P = 0.027). Within-person between-day variation in self-measured prebreakfast plasma glucose was lower for both detemir groups (both P < 0.001). The NPH group gained weight during the study, but there was no change in weight in either of the insulin detemir groups (IDet(12h) vs. NPH, -0.8 kg [-1.44 to -0.24], P = 0.006; IDet(morn+bed) vs. NPH, -0.6 kg [-1.23 to -0.03], P = 0.040). CONCLUSIONS: Overall glycemic control with insulin detemir was improved compared with NPH insulin. The data provide a basis for tailoring the timing of administration of insulin detemir to the individual person's needs.