Mechanoelectric feedback (transduction) in heart: concepts and implications.

It seems that one could regard mechanoelectric feedback in normal heart as an intrinsic regulatory process that modulates normal electromechanical interactions (Fig. 6, left loop). Any physiological mechano-electro-mechano perturbation is self-adjusting and homeostatic. This preserves the status quo, or the heart adapts to form a new electro-mechanoelectric situation. The position in cardiac pathology is different (Fig. 6, right loop), particularly if the disease process produces inhomogeneities. A premature ventricular contraction can be mechanically induced by several of the accepted electrophysiological arrhythmic mechanisms. Thereafter, instantaneous feedback develops within and between regional heterogeneous mechanical conditions. These non-linear recovery processes compound interacting non-linear time courses of recovery of restitution and excitability. Changes in initial loading or mechanical conditions could initiate arrhythmia. Both mechanical and electrical inhomogeneities (also diagrammed in Fig. 5) compound the situation in the intact ventricle. This would enable a milieu of altered excitability, arrhythmogenic current flow and re-entry, to sustain the arrhythmia.