entrance block [Fr, entrer, to enter; AS, blok] , a theoretic zone that surrounds a pacemaker focus and protects it from discharge by an extraneous impulse that might trigger ectopic ventricular contractions.
entrance block [Fr, entrer, to enter; AS, blok] , a theoretic zone that surrounds a pacemaker focus and protects it from discharge by an extraneous impulse that might trigger ectopic ventricular contractions.