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May 24, 1965

Diving Reflex Slows Heart Rate; May Be Key to Unexplained Deaths

JAMA. 1965;192(8):25-27. doi:10.1001/jama.1965.03080210089047

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A n exaggerated physiologic reflex may be the key to sudden heart failure in apparently healthy persons and may play a role in some heart disease, according to scientists at the University of Oklahoma.

The reflex is a saving of oxygen for the brain whenever the body's air supply is threatened. For example, when a person puts his face into a bowl of water, his heart rate immediately slows— sometimes as much as 25 or 30 beats a minute. Vigorous arterial constriction occurs cooling the skin by 3 or 4 degrees, cutting off the blood supply to the visceral organs, and greatly increasing diastolic pressure.

Metabolic changes accompany the circulatory changes. Lactic acid accumulates in the blood and blood pH drops. Potassium levels sharply increase. Metabolism is essentially anaerobic. If the reaction is severe or accentuated by fear, death may result.

Stewart Wolf, MD, of the University of Oklahoma Medical

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