Optical mapping of the pig heart in situ under artificial blood circulation

Figures

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  Figure 1. Overall setup for optical mapping of the whole pig heart in situ. (a) Whole optical mapping setup adapted for registration of the cardiac electrical activity of the pig heart in situ during open-heart surgery. (b) Heart with inserted cannulas. (c) Hand-made frame for heart immobilization. Arrow indicates the bar. (d) Octopus tissue stabilizer used for heart immobilization. (e) Wheel with 8 positions for excitation LEDs (four 660 nm and four 780 nm).

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  Figure 2. Electrical activity in the pig heart immobilized by the frame in situ and recorded by optical mapping using di-4-ANBDQBS under physiological blood circulation. Atrial pacing with a 500-ms period was applied. The metal frame was fixed to the heart surface, mostly on the right ventricle. Maps of the activation time, OAPD50 and repolarization time are presented in (a–c). The numbers near the isochrones show the activation time, OAPD50 and repolarization time in ms. The interval between isochrones is 5 ms for the activation time and 10 ms for the OAPD50 and repolarization time. Optical action potentials (OAPs) were obtained from 5 × 5 pixels at different locations of the right ventricle (RV1, RV2), as indicated by asterisks in map (a) and presented in (d). The amplitude of the OAPs is given as a percentage with respect to the background (ΔF/F). The mapping area was 40 × 40 mm.

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  Figure 3. Electrical activity in the pig heart recorded by optical mapping in situ using the fluorescent dye di-4-ANBDQBS under artificial blood circulation. Activation time, conduction velocity and vector maps were obtained during pacing at four different locations, i.e., the septum (a), left ventricular endocardium (LV endo) (b), left ventricular epicardium (LV epi) (c), and right ventricular epicardium (RV epi) (d), with a 500-ms period. The numbers near the isochrones show the activation time in ms in the activation maps and the conduction velocity in m/s in the conduction velocity maps. The interval between isochrones is 10 ms for the activation time and 0.2 m/s for the conduction velocity.

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  Figure 4. Correlation between the optical and electrical signals of the pig heart. Optical signals were recorded by optical mapping in situ using di-4-ANBDQBS and electrical signals via electrography under artificial blood circulation. (a) Experimental recordings of optical action potentials obtained using di-4-ANBDQBS and electrograms during spontaneous rhythm and under applied stimulation with a period of 500 ms under the control condition and after the injection of a 50-mL bolus containing nifedipine (100 µmol/L). (b) The correlation between the duration of the optical signal at 60% repolarization (OAPD) and electrical signal (RTpeak) obtained under normal-physiological (n = 4, open red dots) or artificial blood perfusion, including with nifedipine (n = 4, closed red and blue dots, respectively). The presented data were obtained during spontaneous activity and a pacing period of 200–500 ms. The solid line indicates the theoretical linear dependence of OAPD and RTpeak, and the dashed lines indicate the boundaries of 5% deviation from the absolute values of the line points. (c) Effect of blebbistatin (bolus concentration 600 µmol/L) on the RT (blue points) and QRS (red points) intervals…

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  Figure 5. Electrical activity in the pig heart in situ recorded by optical mapping using the fluorescent dye Cardiogreen at various excitation and emission wavelengths during apex pacing with a 500-ms period under artificial blood circulation. The maps of the activation time and OAPs from the sites indicated by asterisks in the activation map in the regions of the right ventricle (RV), artery (Ar), and left ventricle (LV), obtained at λex = 660 nm and λem = 775 nm, are presented in the top row. The maps of the activation time, OAPD50 and repolarization time and the OAPs from the sites indicated by asterisks in the activation maps obtained at λex = 780 nm and λem = 808 nm are presented in the middle row. The activation time, OAPD50 and repolarization time maps and the OAPs constructed from the OAPs calculated as the ratio of the two OSs obtained at λex = 660 nm/λem = 720 nm and λex = 780 nm/λem = 808 nm are presented in the bottom row. The numbers near the isochrones show the activation time, OAPD50 and repolarization time in ms. The interval between isochrones is 5 ms for the activation time and 10 ms for the OAPD50 and repolarization time. The amplitude of the OAPs is given as a…

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  Figure 6. Ventricular reentrant arrhythmias with possible functional obstacles (a,b) and with possible stable anatomical obstacles (c,d) recorded by optical mapping of the pig heart in situ using di-4-ANBDQBS under physiological (a,b) or artificial blood circulation(c,d). (a) Activation time maps. The numbers near the isochrones show the activation time in ms. The interval between isochrones is 10 ms. The mapping area was 40 × 40 mm. The excitation period was approximately 500 ms (42 excitations per 20 s). The dominant frequency in the right ventricle (RV) was 9.3 Hz. (b) Recordings of raw optical traces from the regions of the RV, coronary artery (Ar), and left ventricle (LV), indicated by asterisks in the activation maps. The OAPs are labelled with letters (a’-f’) corresponding to the labelling of the activation time maps. (c) Activation time and OAPD50 maps (left and right columns, respectively). The numbers near the isochrones show the activation time and OAPD50 in ms. The interval between isochrones is 10 ms. The mapping area was 55 × 55 mm. The dominant frequency in the LV was 15.6 Hz. (d) Recordings of raw optical traces from the sites indicated by asterisks in the activation maps…