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definitions

subsidiary atrial pacemaker

[səb-sĭd′ē-ĕr′ē]
n.
  1. A secondary source for rhythmic control of the heart, available for controlling cardiac activity if the sinoatrial pacemaker fails.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.