Cold Water Immersion Safety: Arrhythmias and Autonomic Conflict
What are the cardiovascular safety risks of cold water immersion?
Cold water immersion can trigger dangerous cardiac arrhythmias through “autonomic conflict” - simultaneous activation of opposing nervous system responses that can cause fatal heart rhythm disturbances, particularly in individuals with underlying cardiovascular conditions. This mechanism represents a critical but under-recognized cause of sudden death in cold water.
The phenomenon involves competing physiological responses where the diving reflex promotes bradycardia and peripheral vasoconstriction, while cold shock triggers tachycardia and hypertension. This “autonomic conflict” can overwhelm the heart’s electrical system and precipitate life-threatening arrhythmias within minutes of cold water entry.