Abstract
Dyssynchrony of cardiac contraction is an important factor in development of heart failure. It is caused by surrogate conduction of action potential by working myocardium in case of conduction system dysfunction.
In children and adolescent, this situation is often caused by damage to conduction system by cardiac surgery for congenital heart defect leading to bundle branch block or by inappropriate cardiostimulation. Activation of ventricle via working myocardium is much slower and vector of spreading is abnormal.
It leads to significantdelay of free wall activation in contrast to early activation of interventricular septum. This disrupts synchrony of ventricular activation which is mandatory for effective ventricular contraction.
There is an inhomogeneity in the distribution of myocardial work, leading to redistribution of perfusion, oxygen consumption and levels of metabolism in favor of more loaded segments, there are also changes at the subcellular level. Asymmetric hypertrophy of the affected ventricle develops together with its dilatation and reduced function - so called dyssynchronopathy.
The development of dyssynchronopathy can be prevented by careful selection of the site of long-term stimulation or it can be treated by resynchronization therapy of the left, resp. right ventricle.