Aortic-Radial Pressure Gradients Post CPB

This study will examine whether pre-operative, non-invasive arterial stiffness measurements can be used to predict which patients will develop an aortic-to-radial pressure gradient after coronary artery bypass graft (CABG) surgery. A previous small study by Kanazawa, et al. demonstrated in patients who developed an aortic-to-radial pressure gradient after CABG surgery, the pulse wave velocity (PWV) was higher in the aorta and decreased when moving toward the radial artery. In the patients who did not develop a pressure gradient, the PWV started lower in the aorta and increased when moving towards the periphery. The purpose of this investigation is to examine whether pre-operative PWV measurements can be used to identify patients who will develop an aortic to radial pressure gradient after CABG surgery. Applanation tonometry will be performed on the right carotid and femoral arteries to assess carotid-femoral pulse wave velocity, a surrogate for aortic stiffness. (SphygmoCor system, AtCor Medical, Sydney, Australia). The measurement will be obtained before induction of general anesthesia in the presurgical area. Also in the presurgical area, a non-invasive cardiac output (CO) measurement will be obtained by using the ICON Device (Osypka Medical, La Jolla, California). This CO value will be used to compare to the CO values obtained invasively in the operating room.