title: [Measurement of coronary flow reserve by pressure/temperature sensor guide wire-based thermodilution in experimental models].
abstract: OBJECTIVE
  Recently, a combined 0.014 pressure/temperature sensor-mounted guide wire has been developed to simultaneously measure fractional flow reserve and coronary flow reserve (CFR) by thermodilution (CFR-thermo). The accuracy of CFR-thermo was compared with CFR obtained by flow rate (CFR-flow) in experimental models.
  
  
  METHODS
  Using an experimental model made from a straight-rigid tube (4 mm diameter) filled with 36 degrees C water, CFR-thermo and CFR-flow were measured under different conditions of sensor position and injected water temperature (0-40 degrees C). A side branch (2 mm diameter) was then placed at 4, 6, 8 and 10 cm from the injected site just proximal to the stenosis. The degree of stenosis ranged from 0 to 75% (0%, 25%, 50%, 75%). CFR-thermo and CFR-flow were calculated from the inverse ratio of the mean transit time and the flow ratio during high flow to low flow rates.
  
  
  RESULTS
  Under the conditions without the side branch, there were good correlations between CFR-thermo and CFR-flow if the temperature of the injected water was under 28 degrees C and the sensor was not placed within 4 cm from the injection site. With the side branch, CFR-thermo was smaller than CFR-flow although there were good correlations between CFR-thermo and CFR-flow. The value of CFR-thermo increased with more distal positions of the side branch to the injected site.
  
  
  CONCLUSIONS
  Temperature of the injected water, and the position of the sensor, the side branch and the stenotic lesion may influence measurements of CFR-thermo. These effects should be considered when CFR is measured by the thermodilution method.
authors.affiliation: Division of Cardiology, Kawasaki Medical School, Okayama.
authors.forename: Yoji
authors.initials: Y
authors.lastname: Neishi
authors.forename: Takashi
authors.initials: T
authors.lastname: Akasaka
authors.forename: Yuji
authors.initials: Y
authors.lastname: Koyama
authors.forename: Maki
authors.initials: M
authors.lastname: Akiyama
authors.forename: Nozomi
authors.initials: N
authors.lastname: Watanabe
authors.forename: Norio
authors.initials: N
authors.lastname: Kamiyama
authors.forename: Shuichiro
authors.initials: S
authors.lastname: Kaji
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Saito
authors.forename: Ryoji
authors.initials: R
authors.lastname: Suetsuna
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Yoshida
mesh_terms: D001783:Blood Flow Velocity; D001831:Body Temperature; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000503:physiopathology; D003331:Coronary Vessels / Q000502:physiology*; D008955:Models, Cardiovascular; D013696:Temperature; D013815:Thermodilution; D014160:Transducers, Pressure