title: Transmyocardial revascularization ameliorates ischemia by attenuating paradoxical catecholamine-induced vasoconstriction.
abstract: BACKGROUND
  The mechanism by which transmyocardial revascularization (TMR) offers clinical benefit is controversial. We hypothesized that TMR ameliorates ischemia by reversing paradoxical catecholamine-induced vasoconstriction.
  
  
  RESULTS
  Chronic ischemic cardiomyopathy was created in 11 dogs by placing ameroid constrictors on the proximal coronary arteries and their major branches. Six weeks later, 35 channels were created percutaneously in the left circumflex artery region, with the left anterior descending artery region serving as control. At rest, wall thickening and myocardial blood flow did not change in the treated region, whereas they deteriorated in the control bed. Contractile and myocardial blood flow reserve increased in the treated region but deteriorated in the control region. There was diminished iodine 123 metaiodobenzylguanidine uptake and a significant reduction in noradrenergic nerves in the treated region compared with the control region, with a corresponding reduction in tissue tyrosine hydroxylase activity.
  
  
  CONCLUSIONS
  We conclude that the absence of a catecholamine-induced reduction in MBF reserve and contractile reserve in the TMR-treated region with associated evidence of neuronal injury indicates that the relief of exercise-induced ischemia after TMR most likely results from reversal of paradoxical catecholamine-induced vasoconstriction. These findings may have implications in selecting patients who would benefit from TMR.
authors: Division of Cardiology, University of Virginia, Charlottesville, Va, USA.
authors: D Elizabeth
authors: DE
authors: Le
authors: Eric R
authors: ER
authors: Powers
authors: Jian-Ping
authors: JP
authors: Bin
authors: Howard
authors: H
authors: Leong-Poi
authors: N Craig
authors: NC
authors: Goodman
authors: Sanjiv
authors: S
authors: Kaul
mesh_terms: D000818:Animals; D002395:Catecholamines / Q000378:metabolism*; D003326:Coronary Circulation; D004285:Dogs; D017202:Myocardial Ischemia / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D009204:Myocardial Revascularization / Q000379:methods*; D016896:Treatment Outcome; D014661:Vasoconstriction; D018487:Ventricular Dysfunction, Left / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery*
chemical_list: D002395:Catecholamines