title: Perfusion-contraction mismatch during inotropic stimulation in hibernating myocardium.
abstract: The aims of this study were to assess the value of dobutamine echocardiography in identifying myocardial hibernation versus stunning and to elucidate the underlying pathophysiological mechanism of the contractile impairment.
  
  
  METHODS
  Twenty-one patients with isolated stenosis of the left anterior descending artery were evaluated 1 mo after thrombolysed acute anterior infarction. Regional function and blood flow were measured using echocardiography and PET at rest and during dobutamine administration (10 microg/kg/min).
  
  
  RESULTS
  Defined by [18F]fluorodeoxyglucose uptake, 36 of 102 dyssynergic segments were necrotic, and 66 were viable. The latter segments were subdivided according to their [13N]ammonia flow distribution: 30 hibernating regions with perfusion defects (flow of <80% of maximum) and 36 stunned areas with preserved resting perfusion (flow of > or =80% of maximum). Resting flows were similar in necrosis and hibernation (0.43 +/- 0.18 versus 0.47 +/- 0.16 ml x min(-1) x g(-1); not significant), and both resting values were lower than those seen in stunning (0.79 +/- 0.24; p < 0.05). Flow response to dobutamine was markedly reduced in necrosis (dobutamine/resting flow = 1.16 +/- 0.27), whereas it was maintained in hibernation (1.65 +/- 0.54) and stunning (1.42 +/- 0.57). Dobutamine improved function in a higher number of stunned (55%) than hibernating (16%) or necrotic (11%) segments.
  
  
  CONCLUSIONS
  Dobutamine improves function mainly in stunned myocardium and does not reliably identify hibernation. The lack of functional response in hibernation is not related to an exhausted vasodilating capacity.
authors.affiliation: Consiglio Nazionale delle Ricerche Institute of Clinical Physiology, Pisa, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Sambuceti
authors.forename: A
authors.initials: A
authors.lastname: Giorgetti
authors.forename: L
authors.initials: L
authors.lastname: Corsiglia
authors.forename: C
authors.initials: C
authors.lastname: Marini
authors.forename: J
authors.initials: J
authors.lastname: Schneider-Eicke
authors.forename: C
authors.initials: C
authors.lastname: Brunelli
authors.forename: P
authors.initials: P
authors.lastname: Marzullo
authors.forename: A
authors.initials: A
authors.lastname: L'Abbate
authors.forename: S
authors.initials: S
authors.lastname: Capponnetto
authors.forename: O
authors.initials: O
authors.lastname: Parodi
mesh_terms: D002316:Cardiotonic Agents / Q000494:pharmacology; D017023:Coronary Angiography; D003326:Coronary Circulation / Q000187:drug effects; D004280:Dobutamine / Q000494:pharmacology; D004452:Echocardiography / Q000379:methods*; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects*; D017682:Myocardial Stunning / Q000000981:diagnostic imaging / Q000503:physiopathology*; D019275:Radiopharmaceuticals; D014055:Tomography, Emission-Computed
chemical_list: D002316:Cardiotonic Agents; D005462:Fluorine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D004280:Dobutamine