Concealed atrial electrical activity

In the following paragraphs we describe a case diagnosed clinically and haemodynamically as a cardiomyopathy. Atrial flutter which was not in evidence in the standard ECG was diagnosed by the use of a new technique of amplification and filtering of special surface leads (T.A.F.). The diagnosis was later confirmed by means of special internal techniques (intra-atrial ECG and His bundle recording). The existence of a subpraventricular rhythm, probably sinusal, and also unapparent in the standard ECG, was observed by using the same method after electrical defibrillation. We comment on the extreme rareness of discovering concealed atrial rhythms and their possible explanation, and we emphasize the usefulness of the T.A.F. technique in their diagnosis.