Antihypertensive Effects of a Central Arteriovenous Anastomosis Are Mediated Through Profound Reduction in Systemic Vascular Resistance

Device-Based Therapy for Resistant Hypertension: An Up-to-Date Review

Hypertension is the major risk factor for cardiovascular morbidity and mortality. Matter of fact, untreated hypertension can worsen the overall health, whereas pharmacotherapy can play an important role in lowering the risk of high blood pressure in hypertensive patients. However, persistent uncontrolled hypertension remains an unsolved condition characterized by non-adherence to medication and increased sympathetic activity. This paper will review the non-pharmacological treatments for resistant hypertension (RH) that have emerged in recent years. In addition, the technologies developed in device-based RH therapy, as well as the clinical trials that support their use, will be discussed. Indeed, the novel device-based approaches that target RH present a promising therapy which has been supported by several studies and clinical trials, whereas drug non-adherence and high sympathetic activity are known to be the main causes of RH. Nevertheless, some additional aspects of these RH systems need to be tested in the near future, with a particular focus on the device’s design and availability of randomized controlled trials.

Device Therapy of Hypertension

In the past decade, efforts to improve blood pressure control have looked beyond conventional approaches of lifestyle modification and drug therapy to embrace interventional therapies. Based upon animal and human studies clearly demonstrating a key role for the sympathetic nervous system in the etiology of hypertension, the newer technologies that have emerged are predominantly aimed at neuromodulation of peripheral nervous system targets. These include renal denervation, baroreflex activation therapy, endovascular baroreflex amplification therapy, carotid body ablation, and pacemaker-mediated programmable hypertension control. Of these, renal denervation is the most mature, and with a recent series of proof-of-concept trials demonstrating the safety and efficacy of radiofrequency and more recently ultrasound-based renal denervation, this technology is poised to become available as a viable treatment option for hypertension in the foreseeable future. With regard to baroreflex activation therapy, endovascular baroreflex amplification, carotid body ablation, and programmable hypertension control, these are developing technologies for which more human data are required. Importantly, central nervous system control of the circulation remains a poorly understood yet vital component of the hypertension pathway and mandates further investigation. Technology to improve blood pressure control through deep brain stimulation of key cardiovascular control territories is, therefore, of interest. Furthermore, alternative nonsympathomodulatory intervention targeting the hemodynamics of the circulation may also be worth exploring for patients in whom sympathetic drive is less relevant to hypertension perpetuation. Herein, we review the aforementioned technologies with an emphasis on the preclinical data that underpin their rationale and the human evidence that supports their use.

Application of a central iliac arteriovenous coupler device in severe treatment-resistant hypertension: a 3.5-year follow-up

OBJECTIVE

In patients with resistant hypertension, percutaneous placement of an iliac arteriovenous coupler device leads to a reduction of blood pressure (BP) via decreased total vascular resistance and improved arterial compliance. However, long-term efficacy and safety need to be further explored. We report on the first case of 3.5-year follow-up in a patient who underwent implantation of an iliac arteriovenous coupler device.

RESULTS

A patient with resistant hypertension was admitted to hospital. Despite treatment with six anti-hypertensive drugs, his BP was poorly controlled. Previously, he had undergone renal denervation, which did not cause a significant BP decrease. Therefore, an arteriovenous coupler device was implanted, leading to an immediate and significant BP decrease. The patient was discharged with an office BP of 122/71 mmHg. After 3 months, there was a sustained BP decrease (-14/9 mmHg), whereas later, it was fluctuant (office BP: 147-173/85-95 mmHg, ABPM: 153-166/81-94 mmHg) probably due to medication non-adherence confirmed by a urinary toxicological screening test. Follow-up right heart catheterization showed changes in hemodynamic parameters related to volume congestion, which were accompanied by progressive dyspnea and weight gain. This was controlled by an optimized diuretic therapy. Additionally, an invasive closure maneuver was performed, leading to an immediate BP increase after closure and a similar decrease after re-opening of the anastomosis, verifying its proper long-term function.

CONCLUSION

The implantation of an iliac arteriovenous coupler device appears to be a promising and effective method to decrease BP and therefore reduce cardiovascular risk in patients with severe, treatment-resistant hypertension.

The use of a novel ROX central arteriovenous fistula formation device in a patient with severe drug-resistant hypertension and prior aortic graft

We report a case of the successful use of a central arteriovenous (cAV) coupler device to treat severe drug-resistant primary hypertension in a 46-year-old female. The device is inserted via a femoral approach to create an ateriovenous fistula between the external iliac artery and vein and has shown promise in the treatment of severe hypertension. The patient's 24-hr ambulatory blood pressure (ABP) pre device insertion on eleven anti-hypertensive medications revealed a mean 24-hr ABP of 165/98 mm Hg. The insertion of the cAV coupler resulted in a sustained anti-hypertensive effect nine months post-procedure, with mean 24-hr ABP of 154/91 mm Hg on only two anti-hypertensives. Her significant anti-hypertensive response may be explained by the presence of an inelastic aortic graft that had been inserted due to prior aortic dissection as it allowed the restoration of elasticity in a previously inelastic arterial system. We believe that the ROX cAV coupler device warrants further investigation. © 2017 Wiley Periodicals, Inc.

Effect of Arteriovenous Anastomosis on Blood Pressure Reduction in Patients With Isolated Systolic Hypertension Compared With Combined Hypertension

Background

Options for interventional therapy to lower blood pressure (BP) in patients with treatment‐resistant hypertension include renal denervation and the creation of an arteriovenous anastomosis using the ROX coupler. It has been shown that BP response after renal denervation is greater in patients with combined hypertension (CH) than in patients with isolated systolic hypertension (ISH). We analyzed the effect of ROX coupler implantation in patients with CH as compared with ISH.

Methods and Results

The randomized, controlled, prospective ROX Control Hypertension Study included patients with true treatment‐resistant hypertension (office systolic BP ≥140 mm Hg, average daytime ambulatory BP ≥135/85 mm Hg, and treatment with ≥3 antihypertensive drugs including a diuretic). In a post hoc analysis, we stratified patients with CH (n=31) and ISH (n=11). Baseline office systolic BP (177±18 mm Hg versus 169±17 mm Hg, P=0.163) and 24‐hour ambulatory systolic BP (159±16 mm Hg versus 154±11 mm Hg, P=0.463) did not differ between patients with CH and those with ISH. ROX coupler implementation resulted in a significant reduction in office systolic BP (CH: −29±21 mm Hg versus ISH: −22±31 mm Hg, P=0.445) and 24‐hour ambulatory systolic BP (CH: −14±20 mm Hg versus ISH: −13±15 mm Hg, P=0.672), without significant differences between the two groups. The responder rate (office systolic BP reduction ≥10 mm Hg) after 6 months was not different (CH: 81% versus ISH: 82%, P=0.932).

Conclusions

Our data suggest that creation of an arteriovenous anastomosis using the ROX coupler system leads to a similar reduction of office and 24‐hour ambulatory systolic BP in patients with combined and isolated systolic hypertension.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01642498.