[Clinico-electrocardiographic findings in 3 cases of blocked atrial tachycardia].

Through the clinical and ECG description of three cases of atrial tachycardia with 2:1 block (T.A.B.) not linked to hypopotassaemia or intake of digitalis, attention is called to the following points: 1) T.A.B. is frequently preceded by other atrial arrhythmias (F. A., common T.P.S.V. etc.); 2) Amiodarone is useful in many cases in restoring sinus rhythm; 3) At surface ECG, T.A.B. can be distinguished, with a few exceptions, from atrial flutter with which it is often confused, essentially owing to the morphology of the P wave in normal practice, a finding that suggests the pathogenesis of the two arrhythmias is different (return arrhythmia the flutter, arrhythmia due to ectopic focus te T.A.B.); 4) the PR segment of the P wave is lengthened even without digitalis intake (as in 2 of the 3 cases described): this might be not a straightforward, chance association but an integral part of T.A.B. owing to simultaneous disturbance of A-V conduction.