title: Functional significance of recruitable collaterals during temporary coronary occlusion evaluated by 99mTc-sestamibi single-photon emission computerized tomography.
abstract: OBJECTIVE
  The present study evaluated the impact of recruitable collaterals on regional myocardial perfusion measured by 99mtechnetium (Tc)-sestamibi single-photon emission computerized tomography (SPECT) during temporary coronary occlusion and related these estimates to the coronary wedge pressure and electrocardiographic (ECG) ST-segment changes.
  
  
  BACKGROUND
  Clinical variables (angina and ECG changes) and intracoronary flow and pressure recordings have indicated a protective role of recruitable collaterals on myocardial perfusion during percutaneous transluminal coronary angioplasty (PTCA).
  
  
  METHODS
  Thirty patients (mean age 55 years, SD 9; 20 men) with stable angina pectoris and proximal nonocluding single-vessel left anterior descending coronary artery (LAD)-stenosis scheduled for PTCA were included. Visualization of recruitable collaterals by ipsilateral and contralateral contrast injection, registration of coronary wedge pressure and injection of 99mTc-sestamibi during 90-s LAD occlusions were undertaken. A rest perfusion study was performed within four days before PTCA. As an estimate of the severity of regional hypoperfusion during occlusion, an occlusion/rest count ratio was calculated (mean defect pixel count during occlusion divided by mean pixel count in identical regions at rest).
  
  
  RESULTS
  The scintigraphic occlusion/rest count ratio was higher in patients with recruitable collaterals (n = 16), 67 +/- 11%, compared to patients without collaterals (n = 14), 60 +/- 6% (p < 0.05). The occlusion/rest count ratio correlated with the coronary wedge pressure (R2 = 0.34; p < 0.001). The occlusion/rest count ratio was lower, 61 +/- 6%, in patients with ST-segment elevation (n = 23) versus 74 +/- 9% in patients without ST-segment elevation (n = 7) (p < 0.0001).
  
  
  CONCLUSIONS
  Using 99mTc-sestamibi SPECT imaging during brief episodes of coronary occlusion, the severity of regional myocardial hypoperfusion was reduced by the presence of recruitable collaterals in a selected patient population with proximal LAD stenoses. Our results demonstrate a protective effect of recruitable collaterals on myocardial perfusion during temporary coronary occlusion.
authors.affiliation: Department of Nuclear Medicine, Aarhus University Hospital, Skejby Sygehus, Denmark.
authors.forename: N P
authors.initials: NP
authors.lastname: Sand
authors.forename: M
authors.initials: M
authors.lastname: Rehling
authors.forename: J P
authors.initials: JP
authors.lastname: Bagger
authors.forename: L
authors.initials: L
authors.lastname: Thuesen
authors.forename: C
authors.initials: C
authors.lastname: Flø
authors.forename: T T
authors.initials: TT
authors.lastname: Nielsen
mesh_terms: D000787:Angina Pectoris / Q000150:complications; D015906:Angioplasty, Balloon, Coronary; D003097:Collateral Circulation / Q000502:physiology*; D003326:Coronary Circulation / Q000502:physiology*; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D015203:Reproducibility of Results; D017256:Technetium Tc 99m Sestamibi / Q000008:administration & dosage; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi