cardioinhibitory

adjective

car·​dio·​in·​hib·​i·​to·​ry ˌkärd-ē-(ˌ)ō-in-ˈhib-ə-ˌtōr-ē, -ˌtȯr- 

: interfering with or slowing the normal sequence of events in the cardiac cycle

the cardioinhibitory center of the medulla