tachycardia

antonym: bradycardia
https://doi.org/10.1351/goldbook.12117
Abnormally fast heartbeat.
Compare: bradycardia
Source:
PAC, 2015, 87, 841. (IUPAC Glossary of terms used in neurotoxicology (IUPAC Recommendations 2015)) on page 909 [Terms] [Paper]