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Medical Dictionary


noun pace·mak·er \ˈpā-ˌsmā-kər\

Medical Definition of PACEMAKER

:  a group of cells or a body part (as the sinoatrial node of the heart) that serves to establish and maintain a rhythmic activity
:  an electrical device for stimulating or steadying the heartbeat or reestablishing the rhythm of an arrested heart—called also pacer
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