Potentiels ventriculaires tardifs

The recording of ventricular late potentials is a simple, noninvasive technique for ventricular tachycardia evaluation; it permits also the measurement of the degree of myocardial ischemia or fibrosis in various heart diseases such as right ventricular dysplasia, ischemic heart disease or dilated cardiomyopathies. Today, this technique has a more limited place due to its relatively low diagnosis value, principally for the prediction of sudden cardiac death. Late potentials are detected by the amplification and averaging of QRS complexes that may reveal an electrical activity of low amplitude occurring at the end of the QRS; they are due to the late depolarisation of pathological myocardial fibres and to the possible presence of an intra-ventricular reentry. This examination must be interpreted taking into account the clinical history and other noninvasive investigations undertaken for the evaluation of ventricular tachycardia and fibrillation. The averaged ECG used for the detection of late potentials remains important when measuring QRS duration because this technique is precise and reproducible; actually, this assessment is one of the more simple and potent signs of prognostic evaluation and follow-up of idiopathic or ischemic dilated cardiomyopathies.