Cardiac chaotic attractors of ultrasound echo signals

We found a human cardiac chaotic attractor in ultrasound RF echo signals of an ultrasound diagnostic system. Proof of these kinds of cardiac chaos was obtained by the reconstruction of the dynamics in phase space and confirmation of the evidence of the validity of Lyapunov exponents. The goal of our study is to develop novel diagnostic indices using chaotic echo signals. We calculated the correlation dimension of attractors, the dimension of which increased linearly with time as determined by stress echocardiography.