extrasystolic

ex·tra·sys·to·le   (ěk'strə-sĭs'tə-lē)    n.  A premature contraction of the heart, resulting in momentary cardiac arrhythmia. ex'tra·sys·tol'ic (-sĭ-stŏl'ĭk) adj.

Main Entry: ex·tra·sys·to·le
Pronunciation: -'sis-t&-(")lE
Function: noun
: a prematurely occurring beat of one of thechambers of the heart that leads to momentary arrhythmia but leaves the fundamental rhythm unchanged called also premature beat —ex·tra·sys·tol·ic /-sis-'täl-ik/ adjective

extrasystole ex·tra·sys·to·le (ěk'strə-sĭs'tə-lē)
n.
An ectopic, usually premature contraction of the heart, resulting in momentary cardiac arrhythmia. Also called premature systole.