Effects of supplemental oxygen administration on coronary blood flow in patients undergoing cardiac catheterization

Effects of supplemental oxygen administration on coronary blood flow in patients undergoing cardiac catheterization. Am J Physiol Heart Circ Physiol 288: H1057 - H1062, 2005; doi: 10.1152/ ajpheart. 00625.2004. Patients with heart disease are frequently treated with supplemental oxygen. Although oxygen can exhibit vasoactive properties in many vascular beds, its effects on the coronary circulation have not been fully characterized. To examine whether supplemental oxygen administration affects coronary blood flow ( CBF) in a clinical setting, we measured in 18 patients with stable coronary heart disease the effects of breathing 100% oxygen by face mask for 15 min on CBF ( via coronary Doppler flow wire), conduit coronary diameter, CBF response to intracoronary infusion of the endothelium- dependent dilator ACh and to the endothelium- independent dilator adenosine, as well as arterial and coronary venous concentrations of the nitric oxide ( NO) metabolites nitrotyrosine, NO2-, and NO3-. Relative to breathing room air, breathing of 100% oxygen increased coronary resistance by similar to 40%, decreased CBF by similar to 30%, increased the appearance of nitrotyrosine in coronary venous plasma, and significantly blunted the CBF response to ACh. Oxygen breathing elicited these changes without affecting the diameter of large- conduit coronary arteries, coronary venous concentrations of NO2- and NO3-, or the coronary vasodilator response to adenosine. Administering supplemental oxygen to patients undergoing cardiac catheterization substantially increases coronary vascular resistance by a mechanism that may involve oxidative quenching of NO within the coronary microcirculation.