Evaluation and Treatment of Resistant or Difficult-to-Control Hypertension

Renal denervation as a management strategy for hypertension: current evidence and recommendations

INTRODUCTION

The concept of targeting the renal sympathetic nerves therapeutically to lower blood pressure (BP) is based on their crucial role in regulating both renal and cardiovascular control. These effects are mainly mediated via three major mechanisms including alteration of renal blood flow, renin-release, and Na⁺ retention. Initial surgical approaches applying crude and unselected sympathectomy, while rendering significant BP lowering and cardiovascular event reducing properties, where plagued by side effects. More modern selective catheter-based denervation approaches selectively targeting the renal nerves have been shown to be safe and effective in reducing BP in various forms of hypertension and multiple comorbidities.

AREAS COVERED

This article covers the background relevant for the concept of renal denervation (RDN), the evidence obtained from relevant randomized controlled trials to substantiate the safety and efficacy of RDN, and recently published clinical recommendations.

EXPERT OPINION

Catheter-based RDN is safe and has now been shown in sham-controlled randomized clinical trials to result in clinically meaningful BP lowering in both drug naïve hypertensive patients and those on concomitant antihypertensive therapy. Real world data from a large global registry further supports the clinical utility of RDN. It now seems time to embed renal denervation into routine clinical care.

Catheter-based renal denervation for treatment of patients with treatment-resistant hypertension: 36 month results from the SYMPLICITY HTN-2 randomized clinical trial

AIM

The aim of this study was to determine long-term results of renal artery denervation for treatment of treatment-resistant hypertension in the SYMPLICITY HTN-2 study.

METHODS

SYMPLICITY HTN-2 randomized 106 subjects with treatment-resistant hypertension to renal denervation or medical therapy alone. At 6 months, 37 control subjects crossed over to renal denervation. Office blood pressure measurements, antihypertensive medication use, and safety events were followed every 6 months through 3 years.

RESULTS

Follow-up was available at 36 months in 40 of 52 subjects in the initial renal denervation group and at 30 months in 30 of 37 subjects who crossed over and received renal denervation at 6 months. Baseline blood pressure was 184 ± 19/99 ± 16 mmHg in all treated subjects. At 30-month post-procedure, systolic blood pressure decreased 34 mmHg (95% CI: -40, -27, P < 0.01) and diastolic blood pressure decreased 13 mmHg (95% CI: -16, -10, P < 0.01). The systolic and diastolic blood pressure reduction at 36 months for the initial renal denervation group was -33 mmHg (95% CI: -40, -25, P < 0.01) and -14 mmHg (95% CI: -17, -10, P < 0.01), respectively. Procedural complications included one haematoma, and one renal artery dissection before energy delivery that was treated successfully. Later complications included two cases of acute renal failure, which fully resolved, 15 hypertensive events requiring hospitalization, and three deaths.

CONCLUSION

Renal denervation resulted in sustained lowering of blood pressure at 3 years in a selected population of subjects with severe, treatment-resistant hypertension without serious safety concerns.

CLINICAL TRIAL REGISTRATION

NCT00888433.

Achieving renal denervation: catheter-based and surgical management for neural ablation in the management of hypertension

Hypertension refractory to conventional management with medication remains a significant cause of cardiovascular morbidity and mortality. Alternative strategies are warranted in this subgroup of patients. The target of these strategies centers around sympathetic neural activity, which is thought to play a key role in hypertension. We will review the historic and current approaches toward altering sympathetic neural activity, specifically discussing surgical sympathectomy, catheter-based renal denervation strategies, and baroreflex activation therapy.

Difficult-to-Treat or Resistant Hypertension: Etiology, Pathophysiology, and Innovative Therapies

Despite the many therapeutic options available today for the treatment of hypertension, a sizable number of patients still remain resistant to treatment. The prevalence of resistant hypertension in the general population under optimal conditions is about 3–5%. Although several factors and conditions can be identified and corrected a percentage of hypertensive patients remain with unacceptably high blood pressure levels. The high prevalence of hypertension in the general population renders this small percentage significant, in terms of actual patient numbers. This special issue of the journal expoars a whole spectrum of topics related to resistant hypertension: several articles address pathophysiolog and secondary causes of resistant hypertension and modern approaches to therapy. Of interest is the referance to the newer interventional approaches, that is, Baroreceptor stimulation therapy and catheter based sympathetic renal denervation.

Renal Sympathetic Denervation for the Treatment of Difficult-to-Control or Resistant Hypertension

Hypertension represents a major health problem with an appalling annual toll. Despite the plethora of antihypertensive drugs, hypertension remains resistant in a considerable number of patients, thus creating the need for alternative strategies, including interventional approaches. Recently, catheter-based renal sympathetic denervation has been shown to be fairly safe and effective in patients with resistant hypertension. Pathophysiology of kidney function, interaction and crosstalk between the kidney and the brain, justifies the use of renal sympathetic denervation in the treatment of hypertension. Data from older studies have shown that sympathectomy has effectively lowered blood pressure and prolonged life expectancy of hypertensive patients, but at considerable cost. Renal sympathetic denervation is devoid of the adverse effects of surgical sympathectomy, due to its localized nature, is minimally invasive, and provides short procedural and recovery times. This paper outlines the pathophysiological background for renal sympathetic denervation, describes the past and the present of this interventional approach, and considers several future potential applications.

Mobile telemonitoring for achieving tighter targets of blood pressure control in patients with complicated diabetes: a pilot study

BACKGROUND

Hypertension is a major risk factor for the long-term complications of diabetes. Mobile, self-measurement of blood pressure is emerging as a method to manage blood pressure in general, but its impact in patients with diabetes is unclear.

METHODS

We randomized 137 patients with diabetes and hypertension to either mobile telemonitoring (n = 72) or usual care (n = 65). Clinic blood pressure was recorded at baseline and after 6 months. Patients in the intervention arm transmitted weekly blood pressure readings wirelessly, using adapted sensors via mobile phones to a central server. Clinicians received the data in real-time and using a web-based application provided management advice to the patient and their physicians.

RESULTS

Systolic blood pressure fell significantly in the patients in the intervention group (mean [95% confidence interval], -6.5 [-0.8 to -12.2] mm Hg; P = 0.027) and remained unchanged in the control group (2.1 [9.3 to -5.0] mm Hg; P = 0.57). Patients within the intervention arm of African origin seemed to benefit more from the intervention. In addition, those who achieved a systolic blood pressure of <120 mm Hg had lower average blood sugars than those with higher readings (7.8 [SD 1.6] vs. 8.9 [SD 2.2] mmol/L; P = 0.02).

CONCLUSIONS

In patients with diabetes, mobile telemonitoring has potential for delivering intensified care to improve blood pressure control, and its use may be associated with reduced exposure to hyperglycemia.

Renal sympathetic denervation and systemic hypertension

Hypertension represents a major health problem, with an appalling annual toll. Despite the plethora of antihypertensive drugs, hypertension remains resistant in a considerable number of patients, thus creating the need for alternative strategies, including interventional approaches. Recently, renal sympathetic denervation (RSD) using a very elegant, state-of-the-art technique (percutaneous, catheter-based radiofrequency ablation) was shown to be beneficial in patients with resistant hypertension. The pathophysiology of kidney function justifies the use of RSD in the treatment of hypertension. Data from older studies have shown that sympathectomy has efficiently lowered blood pressure and prolonged the life expectancy of patients with hypertension, but at considerable cost. RSD is devoid of the adverse effects of sympathectomy because of its localized nature, is minimally invasive, and provides short procedural and recovery times. In conclusion, this review outlines the pathophysiologic background of RSD, describes the past and the present of this interventional approach, and considers several future potential applications.