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Medical Term:

protective block


an incompletely understood mechanism whereby a pacemaker is protected from being discharged by the impulse from another center; the mechanism, usually conceived as an encircling zone of unidirectionally refractory tissue permitting egress of impulses from the center but preventing access to the center, is seen in operation in ventricular parasystole where the parasystolic center is protected from discharge by the sinus pacemaker and so is able to maintain its intrinsic rhythm undisturbed.

Synonym(s): entrance block, protection

© Copyright 2017 Wolters Kluwer. All Rights Reserved. Review Date: Sep 19, 2016.