Complex intracardiac nervous system.
The heart is an organ with continuous activity, which must satisfy demands of an organism on various conditions. Therefore, heart activity is modulated at many levels, including intrinsic regulatory mechanisms, humoral factors and autonomic nervous system. The regulation of heart activity by sympathetic and parasympathetic nervous system is well known. Accumulated evidence in recent decades indicates that intracardiac neurons can also significantly regulate heart activity. These neurons are concentrated in multiple heart ganglia. Interactions between neurons within intracardiac ganglia together with interconnections between individual ganglia provide anatomical and functional basis of complex nervous network of the heart. This complex intracardiac nervous system together with extracardiac autonomic neurons, innervating heart, provides modulation of heart activity during both physiological and pathological conditions. This review article summarizes recent knowledge about the role of heart neurons in physiological conditions and in etiopathogenesis of selected diseases. Effect of pharmacological and surgical interventions on heart neurons is also discussed (Fig. 2, Ref. 70).