title: Effect of repeated episodes of reversible myocardial ischemia on myocardial blood flow and function in humans.
abstract: Nine patients with coronary artery disease and normal left ventricular (LV) function underwent two episodes of dobutamine-induced ischemia to determine whether repeated episodes of ischemia lead to cumulative stunning. Positron emission tomography (PET) and oxygen 15-labeled H(2)O was used to assess myocardial blood flow (MBF) at baseline, peak stress, and after stress for each ischemic episode. Quantitative echocardiographic assessment of global ejection fraction (EF) and regional systolic function (SF) was performed at rest and regular intervals after dobutamine. SF was assessed for regions subtended by a coronary artery with a >70% diameter stenosis. Both EF and SF were more severely impaired 45 min after the second episode of stress compared with 45 min after the first (both P < 0.01), despite no difference in duration of the two dobutamine infusions or MBF at peak stress (1.72 vs. 1.69). After both episodes of ischemia, when LV function was impaired but subsequently recovered, MBF (1.15 +/- 0.39 and 1.20 +/- 0.43, respectively) was no different to baseline MBF (1.02 +/- 0.35), confirming that repeated episodes of dobutamine-induced ischemia lead to cumulative myocardial stunning.
authors.affiliation: Division of Cardiology and Medical Research Council, National Heart and Lung Institute, Faculty of Medicine, Imperial College of Science, Technology and Medicine, Hammersmith Hospital, London, United Kingdom. ebarnes@doctors.org.uk
authors.forename: Edward
authors.initials: E
authors.lastname: Barnes
authors.forename: David P
authors.initials: DP
authors.lastname: Dutka
authors.forename: Masood
authors.initials: M
authors.lastname: Khan
authors.forename: Paolo G
authors.initials: PG
authors.lastname: Camici
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Hall
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D003326:Coronary Circulation; D003327:Coronary Disease / Q000503:physiopathology; D004280:Dobutamine; D025401:Echocardiography, Stress; D015444:Exercise; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications / Q000209:etiology / Q000503:physiopathology*; D017682:Myocardial Stunning / Q000209:etiology; D010104:Oxygen Radioisotopes; D012008:Recurrence; D014055:Tomography, Emission-Computed; D016277:Ventricular Function, Left
chemical_list: D010104:Oxygen Radioisotopes; D004280:Dobutamine