Mechanical triggers of long-term ventricular electrical remodelling

Abstract

Ventricular electrical remodelling (VER) is a persistent change in the electrophysiological properties of myocardium in response to a variety of physiological or pathological perturbations such as altered electrical activation, heart rate and mechanical or chemical stimuli. This chapter focuses on VER triggered by altered electrical activation, which is commonly associated with heart disease or therapeutic ventricular pacing. Pathological changes in the structure and/or function of the cardiac conduction system are a common manifestation of a wide variety of disease processes including ischaemia, hypertrophy and heart failure. Further, therapy for major disorders of the conduction system, i.e. external pacing, is also an important cause of altered activation. It has been known for several decades that changing the rate or sequence of ventricular activation triggers remarkable changes in the polarity of the T-wave. This was initially described as ‘T-wave memory’ by Mauricio Rosenbaum. These profound changes in the T-wave polarity are indicative of remodelling of myocardial repolarization and illustrate dynamic changes in repolarization triggered by abnormal depolarization. In this chapter we aim to provide an overview of pathophysiological implications, cellular electrophysiological changes and mechanisms that drive the remodelling response.