During recent years cardiac re-synchronization has become an important tool in the treatment of patients with signs and symptoms of heart failure and de-synchronized contraction of the heart. This article describes the pathophysiological basis of de-synchronized contraction due to left bundle branch block and the use of conventional echocardiography to unmask whether the electrical abnormality is accompanied by an asynchronous contraction in the individual patient. The altered contraction in the de-synchronized heart is analysed on different levels: atrioventricular dyssynchrony describes the disturbed mechanical coupling of the ventricles and atria, interventricular dyssynchrony describes the disturbed mechanical coupling of the left and right ventricle, and intraventricular dyssynchrony describes the uncoordinated contraction of the left ventricle. Since tissue Doppler imaging is implemented only in the top level echo machines of the respective manufacturers, this article uses parameters derived from standard echo techniques to analyse the different aspects of dyssynchrony.