title: Obstructive sleep apnea leads to transient uncoupling of coronary blood flow and myocardial work in humans.
abstract: OBJECTIVE
  Obstructive Sleep Apnea (OSA) is associated with a poor prognosis in patients with coronary artery disease. We hypothesized that abnormalities of coronary blood flow (CBF) associated with obstructive apneas may predispose patients to ischemia. We aimed to determine CBF during respiratory events in patients with OSA.
  
  
  METHODS
  University Hospital.
  
  
  METHODS
  Ten subjects undergoing elective percutaneous coronary intervention
  
  
  METHODS
  We measured CBF and myocardial work (rate-pressure product [RPP]) in a non-culprit coronary artery in patients sleeping in the cardiac catheterization laboratory. Hemodynamic responses were matched to spontaneously occurring respiratory events.
  
  
  RESULTS
  Events comprised a mixture of obstructive apneas, central apneas and hypopneas. RPP increased at the termination of each type of respiratory event. Following the rise in RPP, there was a delay, identified with breakpoint analysis, before CBF began to increase (P<0.001) that differed in duration with event type: 8 sec for obstructive apnea, 5 sec for central apnea, and 4 sec for hypopnea. The delay in CBF with obstructive apnea was associated with an increase in coronary vascular resistance of 16% +/- 4% (P < 0.05). Stepwise multilinear regression analysis showed the increase in CBF was predicted by the rise in RPP (R=0.52, P<0.001) and presence of arousal from sleep (R=0.30, P<0.05), but not the degree of O2 desaturation.
  
  
  CONCLUSIONS
  Following obstructive apneas there is a transient uncoupling of CBF from myocardial work and an increase in CVR. This disturbed flow-metabolic coupling may lead to nocturnal myocardial ischemia in patients with both OSA and coronary artery disease.
authors.affiliation: Department of Medicine, Monash Medical Centre, Clayton, Victoria, Australia.
authors.forename: Garun S
authors.initials: GS
authors.lastname: Hamilton
authors.forename: Ian T
authors.initials: IT
authors.lastname: Meredith
authors.forename: Adrian M
authors.initials: AM
authors.lastname: Walker
authors.forename: Peter
authors.initials: P
authors.lastname: Solin
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D003326:Coronary Circulation / Q000502:physiology*; D003327:Coronary Disease / Q000503:physiopathology* / Q000628:therapy; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology; D015607:Stents; D014655:Vascular Resistance / Q000502:physiology; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology*