preexcitation

noun

pre·​ex·​ci·​ta·​tion -ˌek-ˌsī-ˈtā-shən, -ˌek-sə- 

: premature activation of part or all of the cardiac ventricle by an electrical impulse from the atrium that typically is conducted along an anomalous pathway (as muscle fibers on the heart surface) bypassing the atrioventricular node, that may produce arrhythmias, and that is characteristic of LGL syndrome and Wolff-Parkinson-White syndrome

preexcited

-ik-ˈsīt-əd 

adjective