Extended Data Figure 2 : 3D Imaging of electromechanical activity in the heart using simultaneous ultrasound and fluorescence imaging.

From: Electromechanical vortex filaments during cardiac fibrillation

Extended Data Figure 2

af, Reconstruction of the heart shape during simultaneous imaging of electromechanical cardiac activity using ultrasound imaging and panoramic optical mapping. a, Photograph of heart in the Langendorff setup with ultrasound transducer at the bottom of the bath. LA, left atrium. b, 3D optical reconstruction of the surface of the heart obtained by rotating the heart after the experiment. Photorealistic rendering of the surface of the heart on reconstructed 3D surface mesh. c, Rendering (transparent) of 3D volumetric ultrasound speckle data showing the contracting heart from a similar perspective. Fan indicates lateral imaging depth of approximately 6–8 cm that was used for high-speed imaging. d, Optical mapping video images showing a bipolar electrode touching the epicardium of the left ventricle. The electrode is bend at the top, such that the tip is perpendicular to the electrode (only the tip touches the epicardium). The approximate location of the tip is indicated by the white rectangles in a–d, g, i. The 3D reconstruction allows the determination of the position of the electrode’s tip on the heart surface from the two video images. e, Optical calibration target used for optical 3D reconstruction of heart surface. f, Acoustic calibration target for ultrasound imaging used to determine approximate alignment and position of transducer. The inset shows the corresponding ultrasound speckle image of the calibration target at a particular depth. gj, Focal electromechanical activity in a contracting pig heart mapped with optical mapping and ultrasound during pacing. g, Photorealistic rendering of optically reconstructed heart. The heart is rotated towards the left compared to a, b. h, Action potential wave propagating outwards (green arrows) from stimulation (voltage-sensitive mapping using Di-4-ANNEPS, black–white colour code: dark corresponds to depolarizing tissue or the upstroke of the action potential). i, 3D ultrasound speckle movie data showing same part of the heart (opaque and transparent rendering). j, Elastomechanical activation computed from 3D motion of the tissue acquired with ultrasound. The tissue starts to contract first at the stimulation site. The strain rate and its phase representation pattern exhibit a focal point that coincides with the stimulation site and the focal point that is visible in the optical maps. ad, g, i, The region in which electrical pacing (stimulation) was applied to the heart is indicated with a rectangle.