title: Dipyridamole-induced reversible thallium-201 defect in patients with vasospastic angina and nearly normal coronary arteries.
abstract: BACKGROUND
  Dipyridamole is a vasodilator of resistance vessels and has no vasoconstrictive effect on large coronary arteries.
  
  
  OBJECTIVE
  The present study used dipyridamole thallium-201 (201Tl) scintigraphy to clarify the role of microvasculature in coronary flow limitation in patients with vasospastic angina and normal coronary arteries.
  
  
  METHODS
  Sixteen patients underwent dipyridamole and exercise 201Tl scintigraphy and provocative coronary angiography with acetylcholine. All patients showed coronary spasm (> 90% vasoconstriction concomitant with ST change) in at least one vessel.
  
  
  RESULTS
  Dipyridamole or exercise caused only ST depression despite the ST elevation observed at spontaneous attack. Dipyridamole 201Tl scintigraphy demonstrated the reversible defects (11 cases), as did exercise 201Tl scintigraphy (13 cases). The region of 201Tl defect was not always consistent with the territories of angiographically depicted vasospastic arteries. Basal coronary tone, assessed by percentage of diameter change of epicardial arteries from baseline to isosorbide dinitrate administration, did not differ between the positive and the negative defect regions.
  
  
  CONCLUSIONS
  These results support the hypothesis that, in addition to epicardial coronary spasm, the dysfunction of microvasculature is responsible for abnormal coronary perfusion in the subgroup of patients with vasospastic angina and normal coronary arteries.
authors.affiliation: First Department of Internal Medicine, Kobe University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Fujita
authors.forename: H
authors.initials: H
authors.lastname: Yamabe
authors.forename: M
authors.initials: M
authors.lastname: Yokoyama
mesh_terms: D000787:Angina Pectoris / Q000209:etiology*; D016022:Case-Control Studies; D015986:Confounding Factors, Epidemiologic; D017023:Coronary Angiography; D003326:Coronary Circulation / Q000187:drug effects; D003329:Coronary Vasospasm / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000187:drug effects* / Q000473:pathology; D004176:Dipyridamole; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon; D014665:Vasodilator Agents
chemical_list: D013794:Thallium Radioisotopes; D014665:Vasodilator Agents; D004176:Dipyridamole