Effects of Low-Level Tragus Stimulation on Endothelial Function in Heart Failure With Reduced Ejection Fraction.

BACKGROUND: Autonomic dysregulation in heart failure with reduced ejection fraction plays a major role in endothelial dysfunction. Low-level tragus stimulation (LLTS) is a novel, noninvasive method of autonomic modulation. METHODS AND RESULTS: We enrolled 50 patients with heart failure with reduced ejection fraction (left ventricular ejection fraction of ≤40%) in a randomized, double-blinded, crossover study. On day 1, patients underwent 60 minutes of LLTS with a transcutaneous stimulator (20 Hz, 200 µs pulse width) or sham (ear lobule) stimulation. Macrovascular function was assessed using flow-mediated dilatation in the brachial artery and cutaneous microcirculation with laser speckle contrast imaging in the hand and nail bed. On day 2, patients were crossed over to the other study arm and underwent sham or LLTS; vascular tests were repeated before and after stimulation. Compared with the sham, LLTS improved flow-mediated dilatation by increasing the percent change in the brachial artery diameter (from 5.0 to 7.5, LLTS on day 1, P = .02; and from 4.9 to 7.1, LLTS on day 2, P = .003), compared with no significant change in the sham group (from 4.6 to 4.7, P = .84 on day 1; and from 5.6 to 5.9 on day 2, P = .65). Cutaneous microcirculation in the hand showed no improvement and perfusion of the nail bed showed a trend toward improvement. CONCLUSIONS: Our study demonstrated the beneficial effects of acute neuromodulation on macrovascular function. Larger studies to validate these findings and understand mechanistic links are warranted.

Percutaneous Neuromodulation for Atrial Fibrillation.

Percutaneous neuromodulation is emerging as a promising therapeutic approach for atrial fibrillation (AF). This article explores techniques such as ganglionated plexi (GP) ablation, and vagus nerve stimulation, pinpointing their potential in modulating AF triggers and maintenance. Noninvasive methods, such as transcutaneous low-level tragus stimulation, offer innovative treatment pathways, with early trials indicating a significant reduction in AF burden. GP ablation may address autonomic triggers, and the potential for GP ablation in neuromodulation is discussed. The article stresses the necessity for more rigorous clinical trials to validate the safety, reproducibility, and efficacy of these neuromodulation techniques in AF treatment.

Low-Level Tragus Stimulation Attenuates Blood Pressure in Young Individuals With Hypertension: Results From a Small-Scale Single-Blind Controlled Randomized Clinical Trial.

BACKGROUND: Hypertension is a significant risk factor for cardiovascular and chronic kidney diseases. Its management in young people remains limited. Device-based therapies, such as low-level tragus stimulation (LL-TS), a noninvasive method that reduces sympathetic activity, have recently been explored for resistant hypertension. METHODS AND RESULTS: This trial involved patients with Grade 1 hypertension with no other medical history. LL-TS (20 Hz, 1 mA, 1 h/day) was applied for 3 months on the tragus (Intervention group [IG]) or earlobe (Control group [CG]). Blood pressure and outcomes were assessed at the first, second, and third months. Among 40 patients, 21 were in IG and 19 in CG. Baseline systolic blood pressure was similar between IG (142.62±8.18 mm Hg) and CG (143.00±8.61 mm Hg), P=0.89. Post-LL-TS, systolic blood pressure showed significant reductions in IG compared with CG at the first (IG: 134.47±5.95 mm Hg, CG: 141.28±6.78 mm Hg, P=0.002), second (IG: 132.50±7.51 mm Hg, CG: 140.62±7.15 mm Hg, P=0.001), and third months (IG: 128.81±7.13 mm Hg, CG: 136.51±7.96 mm Hg, P=0.003). diastolic blood pressure also differed significantly: first month (IG: 85.34±5.81 mm Hg, CG: 89.74±6.32 mm Hg, P=0.03), second month (IG: 82.12±5.22 mm Hg, CG: 88.57±7.11 mm Hg, P=0.002), and third month (IG: 80.71±5.96 mm Hg, CG: 87.55±5.26 mm Hg, P=0.001). Heart rate was unchanged (P>0.05). Only 0.01% of IG subjects reported site irritation, with no serious adverse events. CONCLUSIONS: LL-TS led to significant blood pressure reductions in young patients with essential hypertension. Further larger trials are needed to confirm the safety and efficacy of LL-TS. REGISTRATION: URL: https://www.chictr.org.cn/; Unique identifier: ChiCTR2000038448.