CARDIAC ELECTROMECHANICS IN THE HEALTHY HEART

In this chapter, cardiac function is discussed in the context of the healthy heart as part of a system. Anatomy and physiology will be described for each scale, starting with the organ level, and continuing to tissue and cell scales. For each scale, we will have a closer look at both electrical and mechanical functions.

Electrical function in the heart is intimately linked to mechanical function: muscle contraction is generated at the cellular level, and triggered by electrical activity via the flux of calcium ions. Furthermore, cell electrophysiology is modified by feedback from mechanical alterations (mechano-electric feedback or MEF). From a clinical standpoint, understanding these electromechanical interactions is becoming increasingly important because, for example, of regional wall remodeling induced by chronic pacing and the rapidly growing interest in cardiac resynchronization therapy (CRT).

As electrophysiology and mechanics in the heart are virtually inseparable, so are experiment and mathematical models of cardiac bioengineering. Through iterative interactions between experiment and simulation, insight in cardiac physiology is growing. Hence, in this chapter we will refer to examples of bioengineering experiments and simulations that helped in understanding normal cardiac function. The role of mechanics in cardiac disease can be found in Chapter 4.