supranormal excitability

su·pra·nor·mal ex·cit·a·bil·i·ty

at the end of phase three of the cardiac action potential, the successful stimulation threshold falls below (that is, less negative than) the level necessary to produce excitation during the rest of the phase of diastole, so that an ordinary subthreshold stimulus becomes effective. Compare: supranormal conduction.
Farlex Partner Medical Dictionary © Farlex 2012

su·pra·nor·mal ex·ci·ta·bil·i·ty

(sū'pră-nōr'măl ek-sī'tă-bil'i-tē)
At the end of phase 3 of the cardiac action potential, the successful stimulation threshold falls below (i.e., becomes less negative than) the level necessary to produce excitation during the rest of the phase of diastole, so that an ordinary subthreshold stimulus becomes effective.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
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