isometric period of cardiac cycle

n.
  1. The period in the cardiac cycle, extending from the closing of the atrioventricular valves to the opening of the semilunar valves, in which the muscle fibers do not shorten.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.