This clinical trial is focused on preventing delirium and cognitive decline in patients undergoing open heart surgery. Delirium is a sudden change in mental status that can cause confusion and reduced awareness of the environment. The study will use two medications, dexmedetomidine and clonidine hydrochloride, which are known as alpha-2 adrenergic receptor agonists. These medications are being tested to see if they can help prevent delirium after surgery. Some participants will receive a placebo, which is a substance with no active medication, to compare the effects.

The purpose of the study is to explore whether these medications can effectively prevent delirium in patients who are 70 years or older and are undergoing heart surgery with the use of a heart-lung machine. The study will involve administering the medications through an intravenous infusion, which means they will be given directly into a vein. The treatment period will last for a maximum of two days. Participants will be monitored for any changes in their mental status and overall health before and after the surgery.

Throughout the study, researchers will assess various factors, including the number of days participants experience delirium, the severity of delirium, and any changes in cognitive function. They will also look at the overall health status of participants over time. The study aims to provide valuable insights into the potential benefits of using these medications to improve recovery and mental health outcomes after heart surgery.