The term<unk>  or<unk><unk>  disturbances <unk> s) refers to disturbances in the<unk>  propagation of supraventricular impulses resulting in changes in the QRS complex  either in morphology or duration, or both.  The QRS complex represents electrical activation of the ventricle and normally the entire process of ventricular depolarization in adults is completed within about 0.1 sec (100 msec).  An<unk>  is the result of abnormal activation of the ventricles caused by<unk><unk>  or block in one or more parts of the specialized<unk>  system (bundle of His, bundle branch or purkinje<unk>  system) resulting in widening of QRS complex.  Abnormalities of local myocardial activation can further alter the specific pattern of venticular activation.
Intraventricular conduction delay
Deviated septum
Premature ventricular contraction
Arrhythmogenic right ventricular dysplasia
Right ventricular outflow tract tachycardia
Premature atrial contraction
Respiratory sinus arrhythmia
Echogenic intracardiac focus