More precisely this system consists of the bundle of His, the left and right bundle branch and the fascicles of the left bundle branch ( Figure 1). The intraventricular conduction system is composed of the His-Purkinje system. Normal and abnormal intraventricular impulse conduction Note that the terms intranventricular conduction delay and intranventricular conduction defect are used interchangeably. These concepts will be discussed in detail in this and the subsequent articles.
The primary ECG manifestations of conduction defects are prolonged QRS complexes and altered QRS appearance. This is due to the fact that the left ventricle pumps against greater resistance and any disturbance in ventricular activation will reduce the efficiency of the pumping function. In general, a conduction defect in the left ventricle is more significant, as compared with a defect affecting the right ventricle. The significance of this will depend on the severity of the conduction defect and the affected ventricle. In this chapter we will discuss intraventricular conduction delays (defects), which are caused by functional or anatomical defects in the components of the intraventricular conduction system. Because the conduction system is crucial for rapid and synchronized activation of the ventricles, conduction defects will typically cause abnormal ventricular activation (contraction). Intraventricular conduction delay (defect): constellations of bundle branch blocks and fascicular blocks (hemiblocks)
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