title: Hyperoxia Exacerbates Myocardial Ischemia in the Presence of Acute Coronary Artery Stenosis in Swine.
abstract: BACKGROUND
  Current guidelines limit the use of high oxygen tension after return of spontaneous circulation after cardiac arrest, focusing on neurological outcome and mortality. Little is known about the impact of hyperoxia on the ischemic heart. Oxygen is frequently administered and is generally expected to be beneficial. This study seeks to assess the effects of hyperoxia on myocardia oxygenation in the presence of severe coronary artery stenosis in swine.
  
  
  RESULTS
  In 22 healthy pigs, we surgically attached a magnetic resonance compatible flow probe to the left anterior descending coronary artery (LAD). In 11 pigs, a hydraulic occluder was inflated distal to the flow probe. After increasing PaO2 to >300 mm Hg, LAD flow decreased in all animals. In 8 stenosed animals with a mean fractional flow reserve of 0.64±0.02, hyperoxia resulted in a significant decrease of myocardial signal intensity in oxygenation-sensitive cardiovascular magnetic resonance images of the midapical segments of the LAD territory. This was not seen in remote myocardium or in the other 8 healthy animals. The decreased signal intensity was accompanied by a decrease in circumferential strain in the same segments. Furthermore, ejection fraction, cardiac output, and oxygen extraction ratio declined in these animals. Changing PaCO2 levels did not have a significant effect on any of the parameters; however, hypercapnia seemed to nonsignificantly attenuate the hyperoxia-induced changes.
  
  
  CONCLUSIONS
  Ventilation-induced hyperoxia may decrease myocardial oxygenation and lead to ischemia in myocardium subject to severe coronary artery stenosis.
authors.affiliation: From the Philippa and Marvin Carsley CMR Centre at the Montreal Heart Institute, Montreal, QC, Canada (D.P.G., K.F., N.S., J.L., M.G.F.); Department of Anesthesiology and Pain Therapy, Bern University Hospital, Inselspital, Bern, Switzerland (D.P.G., K.F.); and Department of Cardiology and Radiology, Université de Montréal, Montreal, QC, Canada (M.G.F.). dominik.guensch@gmail.com.
authors.forename: Dominik P
authors.initials: DP
authors.lastname: Guensch
authors.affiliation: From the Philippa and Marvin Carsley CMR Centre at the Montreal Heart Institute, Montreal, QC, Canada (D.P.G., K.F., N.S., J.L., M.G.F.); Department of Anesthesiology and Pain Therapy, Bern University Hospital, Inselspital, Bern, Switzerland (D.P.G., K.F.); and Department of Cardiology and Radiology, Université de Montréal, Montreal, QC, Canada (M.G.F.).
authors.forename: Kady
authors.initials: K
authors.lastname: Fischer
authors.affiliation: From the Philippa and Marvin Carsley CMR Centre at the Montreal Heart Institute, Montreal, QC, Canada (D.P.G., K.F., N.S., J.L., M.G.F.); Department of Anesthesiology and Pain Therapy, Bern University Hospital, Inselspital, Bern, Switzerland (D.P.G., K.F.); and Department of Cardiology and Radiology, Université de Montréal, Montreal, QC, Canada (M.G.F.).
authors.forename: Nancy
authors.initials: N
authors.lastname: Shie
authors.affiliation: From the Philippa and Marvin Carsley CMR Centre at the Montreal Heart Institute, Montreal, QC, Canada (D.P.G., K.F., N.S., J.L., M.G.F.); Department of Anesthesiology and Pain Therapy, Bern University Hospital, Inselspital, Bern, Switzerland (D.P.G., K.F.); and Department of Cardiology and Radiology, Université de Montréal, Montreal, QC, Canada (M.G.F.).
authors.forename: Julie
authors.initials: J
authors.lastname: Lebel
authors.affiliation: From the Philippa and Marvin Carsley CMR Centre at the Montreal Heart Institute, Montreal, QC, Canada (D.P.G., K.F., N.S., J.L., M.G.F.); Department of Anesthesiology and Pain Therapy, Bern University Hospital, Inselspital, Bern, Switzerland (D.P.G., K.F.); and Department of Cardiology and Radiology, Université de Montréal, Montreal, QC, Canada (M.G.F.).
authors.forename: Matthias G
authors.initials: MG
authors.lastname: Friedrich
mesh_terms: D000208:Acute Disease; D000818:Animals; D023921:Coronary Stenosis / Q000150:complications / Q000378:metabolism*; D003331:Coronary Vessels / Q000502:physiology* / Q000601:surgery; D018450:Disease Progression; D006931:Hyperbaric Oxygenation / Q000009:adverse effects; D018496:Hyperoxia / Q000150:complications / Q000378:metabolism*; D023421:Models, Animal; D017202:Myocardial Ischemia / Q000150:complications / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D013552:Swine
chemical_list: D010100:Oxygen
keywords: coronary stenosis; hyperoxia; ischemia; magnetic resonance imaging; oxygen; swine