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return extrasystole

[rĭ-tûrn′]
n.
  1. A form of reciprocal rhythm in which the impulse, having arisen in the ventricle, ascends toward the atria but before reaching the atria is reflected back to the ventricles to produce a second ventricular contraction.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.