Ultrafast four-dimensional imaging of cardiac mechanical wave propagation with sparse optoacoustic sensing

Significance Propagation of electromechanical waves in excitable heart muscles follows complex spatiotemporal patterns holding the key to understanding life-threatening arrhythmias. Despite recent progress, there is a lack of cardiac imaging methods capable of transmural visualization of fast electromechanical phenomena across the beating heart. Here we introduce a sparse optoacoustic sensing technique for ultrafast four-dimensional imaging of cardiac mechanical wave propagation in the entire beating murine heart with high contrast and sub-millisecond temporal resolution. We extract accurate dispersion and phase velocity maps of the cardiac waves and reveal vortex-like patterns associated with mechanical phase singularities that occur during arrhythmic events induced via ventricular stimulation. Our cardiac mapping approach is a bold step toward deciphering the complex mechanisms underlying cardiac arrhythmias.