Extended Data Figure 4 : Mapping and signal analysis of electromechanical rotor patterns during ventricular fibrillation and tachycardia in isolated Langendorff-perfused hearts.

From: Electromechanical vortex filaments during cardiac fibrillation

Extended Data Figure 4

a, Mapping of epicardial electrical (voltage) rotor activity during ventricular fibrillation on the contracting surface of a rabbit heart. Left, the time-series (black) obtained from the unstabilized fluorescence maps shows substantial motion artefacts, whereas the time-series of the motion-stabilized maps (green) shows a series of action potentials. Right, from the stabilized time-series, it is possible to compute the phase (black), that is, introducing phase jumps at the upstroke of the action potentials. Bottom, the upper image series shows a counter-clockwise-rotating action potential rotor (green) on the contracting heart surface (Supplementary Video 6). The lower image series shows the corresponding phase representation of the rotor and a phase singularity at the tip of the spiral. b, Left, time-series of strain rate obtained from the displacement field. Middle, normalized strain rate (see Methods). Right, zero-crossings of strain rate are used to obtain phase representation. Bottom, rotating wave of dilating (blue) and contracting (red) tissue regions rotating around each other and corresponding phase representation. A circle indicates the position of the mechanical phase singularity. Electrical and mechanical phase singularities are co-localized (Supplementary Video 6). c, Electrocardiogram during ventricular fibrillation (same heart as shown in a, b). Frequency spectra of electrocardiogram (black) and electrical (voltage, green) and elastomechanical (red) patterns measured optically on the epicardial surface of the left ventricular wall (a, b), showing matching dominant frequencies (9 ± 1 Hz). Frequency spectra of the patterns are cumulative spectra of all measurement sites (Supplementary Video 6). d, Electromechanical activity in isolated pig heart during ventricular tachycardia (Fig. 1 and Extended Data Fig. 1b). Top, time-series of action potential activity measured optically using voltage-sensitive optical mapping on anterior left ventricular surface. Middle, time-series of strain rate measured optically in same location as in the top panel on left ventricular surface using fluorescence imaging. Bottom, time-series of strain rate measured within the anterior left ventricular wall using 4D ultrasound imaging. n.u., normalized units. e, Electrocardiogram acquired in the isolated rabbit heart during ventricular fibrillation (Fig. 4i). The arrhythmic episode ended by self-termination of arrhythmic activity and transition into sinus rhythm. Frequency spectra of electrocardiogram and electrical (voltage, green) and elastomechanical (red) patterns measured optically on the epicardial surface and elastomechanical (red) patterns measured using ultrasound at midwall inside the left ventricular wall during arrhythmic episode (including data within 2.0 s before self-termination). The dominant frequencies are 9 ± 1Hz for voltage, calcium and strain. Frequency spectra of the patterns are cumulative spectra of all measurement sites.