A coronary artery check valve includes a stent configured to attach to an inner wall of a coronary artery of a living subject, and a tapered helical coil coupled to the stent and configured to regulate blood flow in the coronary artery. The coronary artery check valve is configured to prevent retrograde flow of the coronary blood supply during diastole by closing during systole of the heart when the tapered helical coil compresses longitudinally, and opening when the tapered helical coil expands longitudinally to permit blood flow into the coronary artery when a coronary pressure of the living subject drops below diastolic blood pressure.