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Evaluation of excitation propagation in the rabbit heart: optical mapping and transmural microelectrode recordings.

Mačianskienė R, Martišienė I, Navalinskas A, Vosyliūtė R, Treinys R, Vaidelytė B, Benetis R, Jurevičius J - PLoS ONE (2015)

Bottom Line: 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.These components correspond to the components of the propagating electrical wave that are transmural and parallel to the epicardium.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.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.

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.

Methods and 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.

No MeSH data available.


Related in: MedlinePlus

Detection of the probing-depth constant.(A) Dependence of LSCATT on the probing-depth constant of the fluorescence measurement for stimulations in the atrium (black line), endocardium (gray line), and epicardium (light gray line; n = 8 for each). The arrow indicates the minimum level of the integrated LSCATT when k = 2.1. The integrated LSCATT is given in units of the fluorescence intensity calculated as a percentage and multiplied by ms. (B) The exponential decay of the dependence of fluorescence probing on the depths under routine experiments was calculated using the formula exp(-z/k), where z is the depth of the myocardium (mm), and k = 2.1. (C) Averaged transmural upstrokes: traces of a calculated TAP (dotted line) versus the DWTAP, when k = 1 (dashed gray line), 2.1 (dashed black line), and 10 (short-dotted line). (D) The data points (from separate measurements of penetration depths) for the weighting function (filled circles) for the red excitation light (660 mm) and the near-infrared emission (735 mm) light are shown, together with a curve (solid line) depicting single exponential decay with a constant k = 2 mm, which was obtained by fitting the data for the weighting function.
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pone.0123050.g005: Detection of the probing-depth constant.(A) Dependence of LSCATT on the probing-depth constant of the fluorescence measurement for stimulations in the atrium (black line), endocardium (gray line), and epicardium (light gray line; n = 8 for each). The arrow indicates the minimum level of the integrated LSCATT when k = 2.1. The integrated LSCATT is given in units of the fluorescence intensity calculated as a percentage and multiplied by ms. (B) The exponential decay of the dependence of fluorescence probing on the depths under routine experiments was calculated using the formula exp(-z/k), where z is the depth of the myocardium (mm), and k = 2.1. (C) Averaged transmural upstrokes: traces of a calculated TAP (dotted line) versus the DWTAP, when k = 1 (dashed gray line), 2.1 (dashed black line), and 10 (short-dotted line). (D) The data points (from separate measurements of penetration depths) for the weighting function (filled circles) for the red excitation light (660 mm) and the near-infrared emission (735 mm) light are shown, together with a curve (solid line) depicting single exponential decay with a constant k = 2 mm, which was obtained by fitting the data for the weighting function.

Mentions: To evaluate the influence of k on the magnitude of LSCATT, we used increasing values of k (from 0.01 to 100 mm) in Eqs (3) and (4), and the interdependence was obtained for changes in the magnitude of LSCATT versus the probing-depth constant (Fig 5A).


Evaluation of excitation propagation in the rabbit heart: optical mapping and transmural microelectrode recordings.

Mačianskienė R, Martišienė I, Navalinskas A, Vosyliūtė R, Treinys R, Vaidelytė B, Benetis R, Jurevičius J - PLoS ONE (2015)

Detection of the probing-depth constant.(A) Dependence of LSCATT on the probing-depth constant of the fluorescence measurement for stimulations in the atrium (black line), endocardium (gray line), and epicardium (light gray line; n = 8 for each). The arrow indicates the minimum level of the integrated LSCATT when k = 2.1. The integrated LSCATT is given in units of the fluorescence intensity calculated as a percentage and multiplied by ms. (B) The exponential decay of the dependence of fluorescence probing on the depths under routine experiments was calculated using the formula exp(-z/k), where z is the depth of the myocardium (mm), and k = 2.1. (C) Averaged transmural upstrokes: traces of a calculated TAP (dotted line) versus the DWTAP, when k = 1 (dashed gray line), 2.1 (dashed black line), and 10 (short-dotted line). (D) The data points (from separate measurements of penetration depths) for the weighting function (filled circles) for the red excitation light (660 mm) and the near-infrared emission (735 mm) light are shown, together with a curve (solid line) depicting single exponential decay with a constant k = 2 mm, which was obtained by fitting the data for the weighting function.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4400155&req=5

pone.0123050.g005: Detection of the probing-depth constant.(A) Dependence of LSCATT on the probing-depth constant of the fluorescence measurement for stimulations in the atrium (black line), endocardium (gray line), and epicardium (light gray line; n = 8 for each). The arrow indicates the minimum level of the integrated LSCATT when k = 2.1. The integrated LSCATT is given in units of the fluorescence intensity calculated as a percentage and multiplied by ms. (B) The exponential decay of the dependence of fluorescence probing on the depths under routine experiments was calculated using the formula exp(-z/k), where z is the depth of the myocardium (mm), and k = 2.1. (C) Averaged transmural upstrokes: traces of a calculated TAP (dotted line) versus the DWTAP, when k = 1 (dashed gray line), 2.1 (dashed black line), and 10 (short-dotted line). (D) The data points (from separate measurements of penetration depths) for the weighting function (filled circles) for the red excitation light (660 mm) and the near-infrared emission (735 mm) light are shown, together with a curve (solid line) depicting single exponential decay with a constant k = 2 mm, which was obtained by fitting the data for the weighting function.
Mentions: To evaluate the influence of k on the magnitude of LSCATT, we used increasing values of k (from 0.01 to 100 mm) in Eqs (3) and (4), and the interdependence was obtained for changes in the magnitude of LSCATT versus the probing-depth constant (Fig 5A).

Bottom Line: 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.These components correspond to the components of the propagating electrical wave that are transmural and parallel to the epicardium.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.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania.

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.

Methods and 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.

No MeSH data available.


Related in: MedlinePlus