Valerian
Valerian considered if perhaps he had a case of cardiac arrhythmia.
A medical term used to describe an abnormal or irregular heartbeat.
The human heart normally beats in a regular, rhythmic pattern, which is necessary to effectively pump blood throughout the body. However, in the case of arrhythmia, the heart's electrical system, which controls the heartbeat, malfunctions, leading to irregular heart rhythms.
A disconcerting fluttering in his chest had become a recurring presence, sometimes making itself known when he least expected it. As he lay there, his thoughts turned to the possibility of cardiac arrhythmia, a term he had heard before but never truly understood.