Atrial Tachysystole with Block

Two patients are reported who demonstrated bouts of rapid atrial activity with associated AV block at times unrelated to the administration of digitalis. The criteria of Lown and Levine for the differentiation of PAT with block from atrial flutter are examined. The application of atrial rate in the region of the arbitrary borderline is not a useful criterion. Determination of P-wave direction in leads II and III cannot be made in the presence of an undulating baseline. Identification, when possible, is not sufficient evidence for distinguishing the two arrhythmias. The appearance of the baseline may not warrant the decisive weight commonly given to it. A combination of recording instrument characteristics, the appearance of atrial repolarization at critical rates, as well as subjective factors may explain the undulatory baseline rather than denote a special electrocardiographic entity. Alternation of the P-P cycle length in PAT with block occurs inconstantly and is not an intrinsic property of the arrhythmia. Digitalis, which has a vagal effect, may contribute to the presence of this [see figure in the PDF file] phenomenon. The occurrence of ventricular premature contractions, response to carotid sinus pressure, and the AV ratio are nonspecific findings. The mode of termination of the arrhythmia may also lack specificity. Restoration of sinus rhythm following potassium administration will be, at times, coincidental. Moreover, the successful outcome of such a therapeutic trial is evidence of digitalis intoxication not proof of a specific arrhythmia.

Experimental and clinical evidence has firmly established that digitalis is capable of producing an atrial arrhythmia attended by AV block. This report does not contest the observation. A critical review of the contrasting features of atrial flutter and PAT with block and an analysis of the data in the present cases suggest that the electrocardiogram does not provide a means for the clear-cut separation of atrial tachycardia from flutter in certain cases and questions the existence of such a division. The term atrial tachysystole with block is offered as a designation for such tracings.

THE PSYCHIATRIC ASPECTS OF PAROXYSMAL TACHYCARDIA

The nervous origin of paroxysmal tachycardia was stressed by many German-speaking authors (Hering, 1911; Rothberger and Winterberg, 1911a; Rothberger and Winterberg, 1911b; Schlesinger, 1906) at the beginning of the century. Thus Schlesinger (1906) pointed out that many patients who suffered from this disorder had neurasthenic or hysterical personalities. He postulated that there was a mechanism responsible for the attacks of tachycardia which could be set in motion by a stimulus in the nervous system. Somewhat later a French cardiologist (Gallavardin, 1922) described a type of paroxysmal tachycardia which he believed was of nervous origin. In more recent times Stokvis (1947) has given an account of a Jewish patient who was taught to think himself into an attack in order to avoid deportation by the German occupation authorities in Holland. There is some pharmacological support for the central origin of paroxysmal tachycardia. Thus Klein (1940) described a schizophrenic patient who when treated with pentamethylene tetrazol developed supraventricular paroxysmal tachycardia four minutes after the injection of the drug. He suggested that the delay between the injection and the onset of the attack indicated that the attack was due to an effect of the drug on the central nervous system. Several different workers (Evans, 1940; Peters and Penner, 1946) have claimed that intravenous injection of ergotamine tartrate will relieve an attack of supraventricular paroxysmal tachycardia within a few minutes. Rothlin and Cerletti (1949) have shown that the effect of adrenaline on the heart is not altered by ergot alkaloids, so that the effect of ergotamine in paroxysmal tachycardia cannot be due to an unopposed vagal effect and must therefore be due to a direct action on the brain centres which regulate cardiac activity.