COMBINED INFLUENCE OF TEMPERATURE AND HYDROSTATIC-PRESSURE ON CARDIAC CONDUCTION

  • 1 January 1980
    • journal article
    • research article
    • Vol. 7  (3) , 211-223
Abstract
Interactions of temperature and hydrostatic pressure were examined in 3 types of cardiac tissue. Decreases in temperature from 37-27.degree. C and increases in pressure from 1-150 ATA [atmospheres of absolute pressure] slowed conduction significantly in rabbit atria, dog atria and dog Purkinje fibers. The combination of lowest temperature and highest pressure produced the greatest decreases in conduction in all 3 tissues. Purkinje fiber action potentials revealed that slowing of conduction was due to depressed excitability, decreased membrane potential and reduced maximum upstroke velocity of the action potential. These action potential variables exhibited the greatest change at the lowest temperature and highest pressure. Cooling or elevations in pressure increased the duration of the action potential. At 27.degree. C the duration was unaffected by increases in pressure. Aberrant conduction developed occasionally at 27.degree. C and 150 ATA. This was explained by changes in action potential variables. The possible development of cardiac arrhythmias in divers exposed to cold hyperbaric stress is discussed.

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