Hypertension,Essential
Conditions
Keywords
Sympathetic nervous system, Blood oxygen level dependent, Brainstem, Contrast enhanced ultrasound, Kidney function, Hypertension, Renal denervation
Brief summary
This study will explore the brainstem activity in response to stress in hypertensive patients and normotensive subjects. In addition, it will evaluate if the response in hypertensive patients can be modulated by blocking the afferent signalling of sympathetic nervous system from the kidney to the brain achieved by renal denervation. The investigators hypothesize that the change in BOLD signal intensity in response to stress is higher in hypertensive patients than in normotensive subjects and that in patients responsive to renal denervation the change in BOLD signal intensity in response to stress is decreased compared to non-responders or to non-denervated resistant hypertensive patients.
Detailed description
In hypertension, the overactivity of the sympathetic nervous system (SNS) has been found to be implicated in its initiation, maintenance and adverse consequences. The SNS is composed of an afferent and efferent arm, which brings sensory information to the brain (e.g. brainstem and hypothalamus) and transmits sympathetic outflow from the brain to the peripheral organs, respectively. Selective removal of the afferent renal component of the SNS can modulate central sympathetic outflow to the kidney, heart and vasculature in animals. The specific contribution of afferent nerve signalling in hypertension and in the potential antihypertensive effect of renal denervation has not been studied in humans.
Interventions
DIAGNOSTIC_TESTCold Pressor test
Both feet in icy waterbath alternated with body temperature water
DIAGNOSTIC_TESTPinPrick test
Pricking both feet with a needle using gravity (without penetrating) alternated with cotton swap
Sponsors
Ecole Polytechnique Fédérale de Lausanne
Centre Hospitalier Universitaire Vaudois
Study design
Observational model
CASE_CONTROL
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* signed informed consent * capable of discernment
Exclusion criteria
* having contra-indications for MRI (claustrophobia, cardiac pacemaker or other metallic or mechanical implant or device, etc.) * pregnant women * lower limb sensitive neuropathy * Blood pressure \>180/110 mmHg during washout period (for hypertensive patients) * Intolerance to Sonovue®(ultrasound contrast agent) * Acute or chronic disease other than hypertension that influences renal function * taking medication/drugs, except of calcium channel blockers for resistant hypertensive patients
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in brain BOLD signal intensity | 1.5 hours | Changes in the brain BOLD fMRI signal of the brainstem in response to a cold pressor test |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Functional connectivity (resting state and effective connectivity) | 1.5 hours | Activation patterns in spatially separated brain regions tending to have synchronous activity in resting state and activation pattern changes during a cold pressor test |
| Structural connectivity | 30 minutes | Map of anatomical (neural) connections within the brain in normotensive subjects and hypertensive patients |
| Correlation between brain BOLD fMRI and renal ultrasound | 2 hours | Correlation between changes in brain BOLD signal and renal (contrast-enhanced) ultrasound endpoints |
Countries
Switzerland
Outcome results
None listed