title: Real-time visualization and quantification of retrograde cardioplegia delivery using near infrared fluorescent imaging.
abstract: OBJECTIVE
  Homogeneous delivery of cardioplegia is essential for myocardial protection during cardiac surgery. Presently, there exist no established methods to quantitatively assess cardioplegia distribution intraoperatively and determine when retrograde cardioplegia is required. In this study, we evaluate the feasibility of near infrared (NIR) imaging for real-time visualization of cardioplegia distribution in a porcine model.
  
  
  METHODS
  A portable, intraoperative, real-time NIR imaging system was utilized. NIR fluorescent cardioplegia solution was developed by incorporating indocyanine green (ICG) into crystalloid cardioplegia solution. Real-time NIR imaging was performed while the fluorescent cardioplegia solution was infused via the retrograde route in five ex vivo normal porcine hearts and in five ex vivo porcine hearts status post left anterior descending (LAD) coronary artery ligation. Horizontal cross-sections of the hearts were obtained at proximal, middle, and distal LAD levels. Videodensitometry was performed to quantify distribution of fluorophore content.
  
  
  RESULTS
  The progressive distribution of cardioplegia was clearly visualized with NIR imaging. Complete visualization of retrograde distribution occurred within 4 minutes of infusion. Videodensitometry revealed retrograde cardioplegia, primarily distributed to the left ventricle (LV) and anterior septum. In hearts with LAD ligation, antegrade cardioplegia did not distribute to the anterior LV. This deficiency was compensated for with retrograde cardioplegia supplementation.
  
  
  CONCLUSIONS
  Incorporation of ICG into cardioplegia allows real-time visualization of cardioplegia delivery via NIR imaging. This technology may prove useful in guiding intraoperative decisions pertaining to when retrograde cardioplegia is mandated.
authors.affiliation: Division of Cardiac Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Aravind T
authors.initials: AT
authors.lastname: Rangaraj
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Ghanta
authors.forename: Ramanan
authors.initials: R
authors.lastname: Umakanthan
authors.forename: Edward G
authors.initials: EG
authors.lastname: Soltesz
authors.forename: Rita G
authors.initials: RG
authors.lastname: Laurence
authors.forename: John
authors.initials: J
authors.lastname: Fox
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Cohn
authors.forename: R M
authors.initials: RM
authors.lastname: Bolman
authors.forename: John V
authors.initials: JV
authors.lastname: Frangioni
authors.forename: Frederick Y
authors.initials: FY
authors.lastname: Chen
mesh_terms: D000818:Animals; D002314:Cardioplegic Solutions; D005240:Feasibility Studies; D006324:Heart Arrest, Induced / Q000379:methods*; D006346:Heart Septum / Q000601:surgery; D006352:Heart Ventricles / Q000601:surgery; D013050:Spectrometry, Fluorescence; D019265:Spectroscopy, Near-Infrared; D013552:Swine; D013903:Thoracic Surgery / Q000379:methods*; D013997:Time Factors
chemical_list: D002314:Cardioplegic Solutions