title: Nitroglycerin-induced coronary vasodilation in cardiac transplant recipients. Evaluation with in vivo intracoronary ultrasound.
abstract: BACKGROUND
  Coronary artery vasomotion is altered after cardiac transplantation. The impact of accelerated transplant coronary atherosclerosis and myocardial rejection on vasomotion is not well understood. Intravascular ultrasound is a new imaging method with the ability to study real-time changes in coronary artery dimensions.
  
  
  RESULTS
  Epicardial coronary artery response to nitroglycerin was studied in 32 cardiac transplant recipients (age, 47 +/- 11 years) 3 weeks to 10 years after transplantation with intracoronary ultrasound. Cross-sectional luminal area and diameter were measured at a fixed position in the left anterior descending artery immediately before and every 30 seconds for 5 minutes after 0.4 mg of sublingual nitroglycerin. Cross-sectional area increased from a baseline of 13.1 +/- 3.9 mm2 to 15.8 +/- 3.9 mm2 at maximal vasodilation; luminal diameter increased from 4.0 +/- 0.6 mm to 4.5 +/- 0.6 mm. This increase reached statistical significance (p less than 0.001) at 1.5 minutes after administration of nitroglycerin; mean maximum increase occurred at 4.5 minutes (24% for cross-sectional area and 11% for luminal diameter). Patients with biopsy-proven mild or moderate concurrent rejection had a significantly blunted vasodilatory response versus the nonrejection group (9% versus 27% for cross-sectional area, p less than 0.04), although a vasodilatory effect was still present. Nitroglycerin response was well preserved in patients up to 10 years after transplantation; however, there was a trend toward a decreased response in patients studied immediately after transplantation (21% versus 29%, p = 0.37). Coronary intimal thickness, as measured by ultrasound, had no impact on the vasodilatory response (R = 0.23, p = 0.34).
  
  
  CONCLUSIONS
  Vasodilatory response to nitroglycerin in cardiac transplant recipients is attenuated during episodes of cardiac rejection. This response is preserved in long-term survivors and is independent of the degree of intimal thickening. Intravascular ultrasound provides a new method to document real-time epicardial coronary vasomotion.
authors.affiliation: Stanford University School of Medicine, Division of Cardiovascular Medicine, CA 94305.
authors.forename: F J
authors.initials: FJ
authors.lastname: Pinto
authors.forename: F G
authors.initials: FG
authors.lastname: St Goar
authors.forename: T A
authors.initials: TA
authors.lastname: Fischell
authors.forename: M L
authors.initials: ML
authors.lastname: Stadius
authors.forename: H A
authors.initials: HA
authors.lastname: Valantine
authors.forename: E L
authors.initials: EL
authors.lastname: Alderman
authors.forename: R L
authors.initials: RL
authors.lastname: Popp
mesh_terms: D000328:Adult; D003326:Coronary Circulation / Q000187:drug effects*; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D005260:Female; D006084:Graft Rejection / Q000502:physiology; D016027:Heart Transplantation; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin / Q000494:pharmacology*; D013997:Time Factors; D014463:Ultrasonography; D014664:Vasodilation
chemical_list: D005996:Nitroglycerin