Spinal Cord Stimulation for Blood Pressure Control in Hypertension

Overview

High blood pressure, also called hypertension, raises the risk of heart disease, stroke, and kidney disease. Medications work well for many people, but some people still have blood pressure that stays too high, or they have side effects from their medications. Researchers are looking for treatments that do not involve taking more medication. Nerves help control blood pressure by changing how blood vessels tighten and how hard the heart pumps. Because of this, treatments that act on nerves may be able to lower blood pressure. Spinal cord stimulation is a treatment already used to manage long-term pain. It uses a small device, placed under the skin during a standard operation, that sends mild electrical signals to the spine. Laboratory studies suggest that stimulating the lower part of the mid-back may also lower blood pressure, but this has not been carefully studied in people who already use these devices. This study will look at whether changing the settings on a spinal cord stimulator affects blood pressure. About 11 adults who have high blood pressure and who already have a spinal cord stimulator for long-term pain. No new device will be placed, and no surgery or other invasive procedure will be done for this study. Participants attend a series of study visits. At each visit, trained staff record blood pressure and heart rate while the stimulator is turned on, turned off, and set to other settings that the person's care team has approved and that the person finds comfortable. There are rest breaks between each setting. Over successive visits, the study team works to identify the settings that best lower blood pressure. Participants can stop at any time, and their usual settings are restored at the end of each visit. The study will also look at whether this kind of testing is practical and comfortable for participants. The results will help researchers decide whether larger studies of spinal cord stimulation for blood pressure control are worth doing.

Hypertension is a major modifiable risk factor for cardiovascular disease, stroke, heart failure, and chronic kidney disease. Although effective antihypertensive medications are available, a proportion of individuals have inadequately controlled blood pressure, experience adverse medication effects, or require multiple agents to reach target. This has sustained interest in adjunctive, non-pharmacological approaches to blood pressure management. The autonomic nervous system regulates blood pressure through modulation of vascular tone, cardiac output, and reflex control mechanisms, and elevated sympathetic activity is implicated in the pathogenesis and maintenance of hypertension. Device-based therapies including renal denervation and baroreflex activation therapy provide proof of concept that targeted neuromodulation can lower arterial pressure. Spinal cord stimulation is an established clinical therapy for chronic pain. Individuals with implanted lower thoracic spinal cord stimulators represent a population in which the cardiovascular effects of spinal neuromodulation can be examined without exposing participants to a new implantation procedure. Preclinical work indicates that stimulation of lower thoracic spinal segments can acutely reduce arterial blood pressure through modulation of autonomic pathways; these effects have not been well characterized in humans with existing systems. Study procedures: Participants attend a series of study visits conducted in a monitored clinical or research setting. Stimulation parameters are iteratively optimized across visits to identify settings that reduce blood pressure. Baseline assessment includes demographic information, relevant medical history, medication review (including antihypertensive and analgesic medications), and resting blood pressure and heart rate. Continuous or repeated non-invasive blood pressure monitoring is performed throughout the session; additional monitoring may include electrocardiography and pulse oximetry. Stimulation testing is performed using the participant's own implanted system by personnel qualified in spinal cord stimulator programming. Adjustments remain within clinically approved device parameters and within participant tolerance. Rest periods are provided between conditions to allow return toward baseline. Predefined stopping criteria apply: testing is discontinued if a participant reports discomfort, anxiety, worsening pain, dizziness, or symptomatic hypotension, or requests to stop for any reason. Usual clinical stimulator settings are restored at the conclusion of testing, and participants are observed until stable before discharge. Because the design is within-subject, each participant serves as their own control across stimulation conditions, which improves efficiency in a small sample. The study is powered for estimation rather than hypothesis testing; emphasis is placed on effect sizes, variance estimates, and confidence intervals to inform protocol refinement and formal sample size calculation for future controlled trials. Safety monitoring: Blood pressure, heart rate, and oxygen saturation are monitored continuously throughout all stimulation. Stimulation is stopped immediately for any of the following: a fall in systolic blood pressure greater than 40 mmHg from baseline, or an absolute systolic blood pressure below 85 mmHg; a rise in systolic blood pressure greater than 30 mmHg above baseline; new-onset bradycardia (heart rate below 45 bpm) or tachycardia (heart rate above 130 bpm); participant request, for any reason; or new unexpected neurological symptoms, including limb weakness or paralysis, new bladder urgency or incontinence, or spreading numbness or dysesthesia beyond the expected trunk sensory field. Trunk muscle contractions at the amplitudes used are anticipated and are not a stopping criterion. Testing is also discontinued if a participant reports discomfort, anxiety, worsening pain, or dizziness. Usual clinical stimulator settings are restored at the conclusion of testing, and participants are observed until stable before discharge.