# ring model

- in cardiology, a model describing the mechanism of anatomical reentry, based on a circuit that is formed around an impenetrable barrier to propagation and contains a locus of slow conduction. The locus blocks the initial normal impulse but is traversed by later impulses from the opposite direction that reexcite normal cardiac fibers, which can occur repetitively. There must exist either a segment of slow conduction or overall slow conduction with a locus of unidirectional block, and total conduction time in the circuit must exceed the refractory period of the fibers so that an excitable gap exists between a wavefront head and the tail of that preceding. See also
*reentrant mechanism,*under*mechanism.*

*Medical dictionary.
2011.*

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