Severe Delirium and Refractory Bradycardia Associated With Uncaria tomentosa Toxicity: A Case Report

Abstract

Uncaria tomentosa (cat’s claw) is an Amazonian medicinal vine widely used for its anti-inflammatory properties. While generally safe at therapeutic doses, its active oxindole alkaloids can precipitate profound cardiovascular and central nervous system (CNS) toxicity in supratherapeutic amounts. We present a case of a 53-year-old female who presented with severe insomnia, anxiety, and gastrointestinal distress following an attempt to self-wean from a high-dose, over-the-counter cat’s claw supplement. Her hospital course was complicated by severe delirium requiring intensive care and persistent, symptomatic sinus bradycardia, 29-40 beats per minute with first-degree atrioventricular (AV) block. Although her neuropsychiatric symptoms resolved with supportive care and benzodiazepines, her bradycardia remained refractory to medical management. Subsequent electrophysiology evaluation was suggestive of sick sinus syndrome, which was successfully treated with the implantation of a permanent dual-chamber pacemaker. This case highlights the potential for unregulated herbal supplements to induce severe neuro-cardiac toxicity and unmask underlying cardiopulmonary disease. Clinicians must maintain a high index of suspicion for toxicological etiologies and underlying structural pathologies when evaluating complex, multisystem presentations.