title: Variations of coronary hemodynamic responses to intravenous adenosine infusion: implications for fractional flow reserve measurements.
abstract: BACKGROUND
  Continuous intravenous adenosine infusion reportedly produces stable and maximal hyperemia to allow for fractional flow reserve (FFR) measurement; however, several observers have noted variation of the coronary/aortic (Pd/Pa) pressure ratio during the course of an adenosine infusion.
  
  
  METHODS
  Pd/Pa pressure recordings during continuous peripheral intravenous adenosine infusion were examined in 51 patients (68 measurements) with data collected for at least 150 sec and for at least 30 sec after the lowest Pd/Pa reading. The lowest recorded Pd/Pa ratio was used as the true FFR value at maximal hyperemia. The highest subsequent Pd/Pa during the remaining period of adenosine infusion was recorded. A separate cohort of 12 patients had Pd/Pa values measured with both peripheral and central infusion.
  
  
  RESULTS
  The average FFR value was 0.82 ± 0.10 and was recorded 99 ± 33 sec into the infusion. The Pd/Pa value showed a subsequent average increase of 0.08 ± 0.07 at 135 ± 32 sec. From the lowest measurement, Pd/Pa changed from a ratio ≤0.80 to >0.80 in 28% of recordings. In the cohort with matched recordings, central infusion reduced the severity (mean change of 0.08 vs. 0.11, P = 0.09) but not the incidence of Pd/Pa variability compared with peripheral infusion.
  
  
  CONCLUSIONS
  Instability of Pd/Pa measurements is common over the course of a continuous intravenous adenosine infusion. FFR remains valid as the lowest value of Pd/Pa observed, however, Pd/Pa variability may subsequently occur and complicate pullback measurements for serial or multiple lesions.
authors.affiliation: Division of Cardiology, Department of Medicine, Long Beach Veteran's Affairs Medical Center, Salem, Virginia; Division of Cardiology, Department of Medicine, University of California, Irvine, California.
authors.forename: Arnold H
authors.initials: AH
authors.lastname: Seto
authors.forename: David M
authors.initials: DM
authors.lastname: Tehrani
authors.forename: Murtaza I
authors.initials: MI
authors.lastname: Bharmal
authors.forename: Morton J
authors.initials: MJ
authors.lastname: Kern
mesh_terms: D000241:Adenosine / Q000008:administration & dosage*; D000368:Aged; D006328:Cardiac Catheterization; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000503:physiopathology; D003331:Coronary Vessels / Q000187:drug effects / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D053805:Fractional Flow Reserve, Myocardial / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D012189:Retrospective Studies; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine
keywords: adenosine; coronary hemodynamics; fractional flow reserve; hyperemia