exocardiac
/ˌɛksəˈkɑːrdɪæk/Definitions
1. adjective
located or originating outside the heart
“The exocardiac nerves are primarily responsible for controlling the respiratory rate.”
2. adjective
relating to the heart or its function, but originating outside the heart
“The exocardiac system has its roots in cardiac physiology but operates on external stimuli.”