Description

Approximately 30 million people in the US have chronic kidney disease (CKD) and are at 5-15 fold greater risk of cardiovascular (CV) disease and mortality. A major factor contributing to increased CV risk in these patients is chronic elevation of sympathetic nervous system (SNS) activity.

Patients with even minimal decrements in kidney function have significant and substantial increases in SNS activity and reactivity that are independently linked to adverse CV events. The mechanisms underlying SNS overactivity in CKD are multifactorial, and include chronic inflammation and blunted arterial baroreflex sensitivity (BRS). SNS overactivity, in turn, leads to downstream deleterious effects on ambulatory BP profiles characterized by higher daytime BP, and lack of normal reductions in nocturnal BP (i.e. nocturnal nondipping), both of which are independently linked to increased CV risk. Current treatments to combat SNS overactivity are limited to sympatholytic medications such as β-blockers, α-blockers, and clonidine; however, these pharmacologic agents are associated with long-term adverse metabolic consequences such as insulin resistance and hyperlipidemia, and often intolerable side effects such as fatigue, orthostatic hypotension, and rebound hypertension. New therapeutic strategies to safely and effectively ameliorate SNS over-activity are of paramount importance to improve clinical outcomes in this highly prevalent and high-risk patient population.

Mindfulness meditation (MM) may be one such novel, safe, and effective approach at improving hemodynamics and autonomic function in CKD. Prior studies have shown that 8 weeks of mindfulness-based stress reduction (MBSR) lowers BP in a variety of patient groups. Although the mechanisms are poorly understood, studies using indirect measures of SNS activity such as heart rate variability suggest that MM may exert its hemodynamic effects via autonomic modulation.

This study tests whether mindfulness meditation (MM) improves sympathetic function in chronic kidney disease (CKD) and whether transcutaneous vagus nerve stimulation (tVNS) optimizes the sympatho-inhibitory effects of mindfulness meditation (MM) and restores autonomic balance in CKD patients. These study aims are tested with two separate protocols.

Protocol 1 tests the sustained effects of MBSR on SNS function and BP profiles in CKD. Participants will be randomized to 8 weeks of MBSR or a health enhancement program (HEP).

Protocol 2 tests an optimization strategy to enhance the sympatho-inhibitory effects of MM and restore autonomic balance using transcutaneous vagus nerve stimulation (tVNS) in CKD. The vagus nerve, the major effector of the parasympathetic nervous system (PNS), is composed of afferent nerve fibers that connect to the nucleus tractus solitarii (NTS) and other brainstem regions that influence central SNS output and baroreflexes, and efferent nerve fibers that activate the cholinergic anti-inflammatory pathway. Both experimental and human studies have shown promising results that stimulation of the vagus nerve lowers BP reduces SNS activity, improves BRS, and lowers inflammation. Participants with Stage III and IV CKD will be randomized into one of four study arms: MBSR with tVNS, MBSR with sham-tVNS, HEP with tVNS, and HEP with sham-tVNS. Participants will self-administer tVNS or sham-tVNS twice per day for 8 weeks.