Condition B: Patients in need of semi-urgent coronary bypass surgery, allowing interrupting the administration of ticagrelor 3 days before surgery. A nasogastric tube is inserted during surgery. On intensive care the patients will receive crushed tablets of ticagrelor with 10 ml water and a flush of 20 ml water via gastric tube, the first dose will be a loading dose. The first blood sample is taken just before surgery (weak effect of ticagrelor because administration has stopped 3 days). The following samples are taken at 30minutes, 1, 2, 4, 8, 12, and 24h. The ninth sample is taken 24 hours after stopping sedation and 4h after administration of ticagrelor with 10 ml water and a flush of 20 ml water via nasogastric tube. The tenth sample is taken 4 days and 4hours after first intake of ticagrelor, this last sample is mostly after a non-crushed intake of ticagrelor (this depends on the neurological condition of the patient). Only the first dose is a loading dose of 180mg, hereafter a normal dose of 90mg is given.