Tonic and phasic components of heart action

Right at the beginning of 1998, the monography ?Analyis of Cardiovascular Dynamics? appeared (Drzewiecki and Li, 1998). In this monography, the article about the shape of the left ventricle was printed (Juznic et al., 1998). The cooperation with our laboratory of cardiovascular dynamics is well reflected in this monography. The reactivity of different myocardial fibres came to the appearance. The aim of the current project is to investigate the mechanism of how the circular and longitudinal myocardial fibres enable the most economical pump function at different heart rates. At a low heart rate the circumferential strong fibres cause a narrowing of the small diameter of the LV; at a higher heart rate the spiral fibres come into action. We can call the slowly reacting fibres the tonic component, the quickly reacting the phasic component of heart action. It is expected that 3-D contrast echo could perhaps distinguish the tonic and phasic fibres.