Alan Thicke died of a “ruptured aorta,” according to his death certificate which was just recently released.

Alan had the heart attack around 11:15 a.m. on December 13 and sadly died three hours later, at 2:15 p.m., while in surgery in Burbank, Calif.

According to TMZ, the document says doctors tried to save Alan by performing a median sternotomy, a surgery that creates a vertical incision is made along the sternum to allow access to the heart and lungs for further surgery.

Alan was 69-years-old when he passed away.  We are sending love to his entire family!