[The electrode-myocardium interface at the cellular level and prospects of the use of implantable pacemakers]

The interaction of the autonomic nervous system (ANS) and the heart is the subject-matter of new investigations of the interdisciplinary science neurocardiology which represents the newest strategy in cardiac pacing. In this connection the priorities are both the renewal of chronotropy with physiological cardiac pacing of the closed circuit and the prevention and treatment of malignant arrhythmias through ANS modulation. To achieve this requires adequate monitoring the balance of autonomic influences and stimulation and hence neuromodulation of cardiac afferents. Under these conditions, the electrode which is both deflecting and stimulating, and its interface with the body at the cellular level gain prime importance. The physical, electrochemical and physiological properties of the electrode-myocardium interface (boundary) are determined by the structure of the Helmholz bilayer. Translayer electron transport and electrochemical reactions which determine the biological compatibility of the interface may be optimized via the microstructure of the surface of a solid-state component by covering this surface with titanium or iridium nitride with so-called fractal geometry. Experimental and clinical findings have demonstrated that the fractal surface structure ensures extremely low polarization and improvement deflection, hence this deflection of an evoked myocardial cell response monitors a myocardial nervous response as a result of increased chronotropic excitement. The stimulating electrode also monitors the sympathetic activity determined from intracardiac impedance measurements, thus providing a new principle of rhythm adaptation when the pacemaker is an integral part of ANS, recovering normal chronotropy. These benefits of the electrode interface open new avenues for the treatment and prevention of tachyarrhythmias and for the long-term management of the grafted heart to prevent its rejecting processes.