Treatment methods and devices are provided for percutaneously accessing a patient's thoracic region via a controlled opening in the aorta, so that cardiac procedures, such as a coronary bypass procedure, can be performed in a minimally invasive manner. Advantageously, it may be possible to perform the procedure without placing the patient on cardiopulmonary bypass. The method may include percutaneously delivering at least one catheter into an aorta of a heart, forming a controlled opening in the aorta and pericardium via the at least one catheter to access a thoracic region within the patient's chest, and performing at least one coronary bypass graft procedure through the controlled opening.