title: Evaluation of excitation propagation in the rabbit heart: optical mapping and transmural microelectrode recordings.
abstract: BACKGROUND
  Because of the optical features of heart tissue, optical and electrical action potentials are only moderately associated, especially when near-infrared dyes are used in optical mapping (OM) studies.
  
  
  OBJECTIVE
  By simultaneously recording transmural electrical action potentials (APs) and optical action potentials (OAPs), we aimed to evaluate the contributions of both electrical and optical influences to the shape of the OAP upstroke.
  
  
  RESULTS
  A standard glass microelectrode and OM, using an near-infrared fluorescent dye (di-4-ANBDQBS), were used to simultaneously record transmural APs and OAPs in a Langendorff-perfused rabbit heart during atrial, endocardial, and epicardial pacing. The actual profile of the transmural AP upstroke across the LV wall, together with the OAP upstroke, allowed for calculations of the probing-depth constant (k ~2.1 mm, n = 24) of the fluorescence measurements. In addition, the transmural AP recordings aided the quantitative evaluation of the influences of depth-weighted and lateral-scattering components on the OAP upstroke. These components correspond to the components of the propagating electrical wave that are transmural and parallel to the epicardium. The calculated mean values for the depth-weighted and lateral-scattering components, whose sum comprises the OAP upstroke, were (in ms) 10.18 ± 0.62 and 0.0 ± 0.56 for atrial stimulation, 9.37 ± 1.12 and 3.01 ± 1.30 for endocardial stimulation, and 6.09 ± 0.79 and 8.16 ± 0.98 for epicardial stimulation; (n = 8 for each). For this dye, 90% of the collected fluorescence originated up to 4.83 ± 0.18 mm (n = 24) from the epicardium.
  
  
  CONCLUSIONS
  The co-registration of OM and transmural microelectrode APs enabled the probing depth of fluorescence measurements to be calculated and the OAP upstroke to be divided into two components (depth-weighted and lateral-scattering), and it also allowed the relative strengths of their effects on the shape of the OAP upstroke to be evaluated.
authors.affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Regina
authors.initials: R
authors.lastname: Mačianskienė
authors.affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Irma
authors.initials: I
authors.lastname: Martišienė
authors.affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Antanas
authors.initials: A
authors.lastname: Navalinskas
authors.affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Rūta
authors.initials: R
authors.lastname: Vosyliūtė
authors.affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Rimantas
authors.initials: R
authors.lastname: Treinys
authors.affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Birutė
authors.initials: B
authors.lastname: Vaidelytė
authors.affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Rimantas
authors.initials: R
authors.lastname: Benetis
authors.affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Jonas
authors.initials: J
authors.lastname: Jurevičius
mesh_terms: D015081:2-Naphthylamine / Q000031:analogs & derivatives; D000200:Action Potentials; D000818:Animals; D004699:Endocardium / Q000502:physiology; D005456:Fluorescent Dyes; D006321:Heart / Q000502:physiology*; D008297:Male; D008839:Microelectrodes; D009924:Organ Culture Techniques; D010477:Perfusion; D010496:Pericardium / Q000502:physiology; D011806:Quinolinium Compounds; D011817:Rabbits; D056969:Voltage-Sensitive Dye Imaging / Q000295:instrumentation / Q000379:methods*
chemical_list: C553754:1-(4-sulfanatobutyl)-4-(beta-(2-(di-n-butylamino)-6-naphthyl)butadienyl)quinolinium betaine; D005456:Fluorescent Dyes; D011806:Quinolinium Compounds; D015081:2-Naphthylamine