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Role of Device Therapy
Questions
1
What do we mean by device therapies in hypertension?
Device therapies refers to interventions that are used to reduce blood pressure (BP). These interventions can be surgical, or with interventional angiographic procedures targeting the mechanism of hypertension. The device therapies that have undergone research in this area include
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Renal denervation
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Baroreceptor activation or modulation
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Central arteriovenous fistula (AVF) creation
A brief summary of the effect of these interventions and their current status is presented in Table 40.1 .
Table 40.1
Summary of Device Therapies, Effect on BP, Adverse Effects, and Current Status
| INTERVENTION | EFFECT ON BP | POSSIBLE ADVERSE EFFECTS | CURRENT STATUS |
|---|---|---|---|
| Lumbar sympathectomy | ∼ 70 mm Hg decrease | Paralytic ileus, impotence, loss of sweating, sensation, death | Abandoned |
| Renal denervation | Initial reports 20–30 mm Hg Sham controlled decrease in ABPM ∼ 4/2 mm Hg |
Low risk of procedural complications Potential risk of shock with hypovolemia or hemorrhage |
Approved in Europe and some other countries Not approved in North America as of 2021 |
| Baroreceptor | ∼ 16 mm Hg decrease in office BP compared to 9 mm Hg in control group in pivotal RCT | ∼ 4%–5 % developed facial nerve injury or damage with initial device Dysphagia, paresthesia |
Approved in Europe Barostim Neo being pursued for heart failure MobiusHD in pilot trials |
| Central arteriovenous fistula | ∼ 13 mm Hg decrease in ABPM | 30% risk of procedural complications and venous stenosis (early) Potential late complications include heart failure |
Abandoned |
ABPM, Ambulatory blood pressure monitoring; BP, blood pressure; RCT, randomized controlled trial.
Renal Denervation:
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Catheter based radiofrequency (Simplicity and Spyral catheters, Medtronic Inc, Dublin, Ireland; EnligHTN system, St Jude Medical Inc, St Paul, MN)
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Catheter based ultrasound (Paradise system, ReCor Medical, Palo Alto, CA)
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Catheter based alcohol (Peregrin system, Ablative Solutions, Wakefield, MA)
Baroreceptor:
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Baroreceptor activation: Bilateral multielectrode system (Rheos) and unilateral (CVRx Inc, Minneapolis, MN)
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Baroreceptor modulation: MobiusHD system (Vascular dynamics Inc, Mountain View, CA)
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Central Arteriovenous Fistula: ROX coupler (ROX Medical, San Clemente, CA)
2
What is the history of interventions for hypertension?
In 1923, Bruning had suggested sympathectomy for control of hypertension as the role of the efferent sympathetic system in maintaining BP had already been discovered then. A few years later, following the observation that sympathectomy, performed for peripheral arterial disease, results in prolonged vasodilation, Adson and Brown performed the section of the nerve roots from D6 to L2 and noted a dramatic decrease in BP from 250/180 to 170/120. Over the next few years, this procedure was used in severe cases of hypertension, but it was quickly noted that the impressive BP drop was accompanied by impressive adverse effects, such as loss of sensation, paralytic ileus, problems with ejaculation, loss of sweating, and the occasional mortality. Once effective pharmacological therapy became available, this procedure fell into disfavor and was abandoned.
3
How does renal denervation work?
Renal denervation was rejuvenated by clinical research that demonstrated the role of afferent nerves from the kidney which increase the efferent sympathetic tone. Using catheter-based radiofrequency ablation, it was found that targeting the nerves in the renal artery resulted in a BP decrease. The BP decrease was initially reported to be in the initial case report, and in the first two clinical trials, which were performed in patients with severe, resistant hypertension.
4
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