title: Response of myocardial oxygenation to breathing manoeuvres and adenosine infusion.
abstract: OBJECTIVE
  Testing for inducible myocardial ischaemia is one of the most important diagnostic procedures and has a strong impact on clinical decision-making. Current standard protocols are typically limited by the required infusion of vasodilatory substances. Recent data indicate that changes of myocardial oxygenation induced by hyperventilation and breath-holds can be monitored by oxygenation-sensitive (OS) cardiovascular magnetic resonance (CMR) and may be useful for assessing coronary vascular function. As tests using breathing manoeuvres may be safer, easier, and more comfortable than vasodilator stress agent infusion, we compared its impact on myocardial oxygenation with that of a standard adenosine infusion protocol.
  
  
  RESULTS
  In 20 healthy volunteers, we assessed changes of myocardial oxygenation using OS-CMR at 3 T during adenosine infusion (140 µg/kg/min, i.v.) and during voluntary breathing manoeuvres: a maximal breath-hold following normal breathing and a maximal breath-hold following 60 s of hyperventilation. The study was successfully completed in 19 subjects. There was a significantly stronger myocardial response for hyperventilation (decrease of -10.6 ± 7.8%) and the following breath-hold (increase of 14.8 ± 6.6%) than adenosine (3.9 ± 6.5%), whereas a simple maximal voluntary breath-hold yielded a similar signal intensity increase (3.1 ± 3.9%). Subjective side effects occurred significantly more often with adenosine, especially in females.
  
  
  CONCLUSIONS
  Hyperventilation combined with a subsequent long breath-hold and hyperventilation alone both have a greater impact on myocardial oxygenation changes than an intravenous administration of a standard dose of adenosine, as assessed by OS-CMR. Breathing manoeuvres may be more efficient, safer, and more comfortable than adenosine for the assessment of the coronary vasomotor response.
authors.affiliation: Philippa and Marvin Carsley CMR Centre at the Montreal Heart Institute, 5000 Belanger Street, Montreal, QC, Canada H1 T 1C8.
authors.forename: Kady
authors.initials: K
authors.lastname: Fischer
authors.affiliation: Philippa and Marvin Carsley CMR Centre at the Montreal Heart Institute, 5000 Belanger Street, Montreal, QC, Canada H1 T 1C8 Department Anesthesiology and Pain Therapy, Bern University Hospital, Bern, Switzerland.
authors.forename: Dominik P
authors.initials: DP
authors.lastname: Guensch
authors.affiliation: Philippa and Marvin Carsley CMR Centre at the Montreal Heart Institute, 5000 Belanger Street, Montreal, QC, Canada H1 T 1C8 Departments of Cardiology and Radiology, Université de Montréal, Montreal, QC, Canada mgwfriedrich@gmail.com.
authors.forename: Matthias G
authors.initials: MG
authors.lastname: Friedrich
mesh_terms: D000241:Adenosine / Q000008:administration & dosage*; D000293:Adolescent; D000328:Adult; D001945:Breathing Exercises / Q000379:methods; D003326:Coronary Circulation / Q000187:drug effects; D005260:Female; D006801:Humans; D007260:Infusion Pumps; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D017202:Myocardial Ischemia / Q000175:diagnosis; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine; D010100:Oxygen
keywords: Adenosine; Blood oxygen level-dependent; CMR; Oxygenation-sensitive; Vasoconstriction; Vasodilation