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In an eight-choice reaction task, the influence of erroneous responses upon the temporary changes in the level of heart rate (HR) was studied. It was shown that after errors there was a short-term deceleration of the HR-level, while after correct responses an accelerating tendency was found. This phenomenon has to be regarded as an additional source of fluctuations of the HR-level. Therefore, it has to be taken into account when suppression of sinus arrhythmia is used for assessing the level of mental load.

Onehundred andseventy-five patients withatrial fibrillation treated forthefirst timewithDC shock weredivided into twogroupsaccording toyearofbirth. GroupIreceived a long-acting quinidine bisulphate preparation, thedosage ofwhich was adjusted togive serumlevels of1-3mg./l. Side-effects wererarewiththis dosage. Group 2received noquinidine. Ofthe88patients ofgroup I,sinus rhythm was restored in75(85%). Whenleaving thehospital 64(73%) still hadsinus rhythm, andafter 3 months 52(59%). Thecorresponding figures forthe87patients ofGroup2 were 73(84%), 54(62%), and30(34%). Thedifference at3 months isstatistically highly significant. Because ofthese results itisconcluded thatelectric conversion ofatrial fibrillation should beperformed forthefirst timewithout quinidine prophylaxis. Ifthere isfailure orearly recurrence,however, a second electric conversion withsubsequent quinidine treatmentshould be considered.

1.1. The P-R interval often shows an inverse relationship to the R-R interval in sinus arrhythmia. 2.2. When this phenomenon was first observed, it was thought possibly to be specific for active rheumatic fever. Further study, however, showed that it occurred in many individuals with normal hearts. 3.3. Four possible explanations for this P-R phenomenon are discussed. 4.4. It is suggested that the Wenckebach phenomenon may be due to a pathologic exaggeration of the fatigability of the conducting tissue frequently found even under normal conditions.

General inspection of an electrocardiogram shows whether a cardiac arrhythmia is benign or serious, but a specific diagnosis requires more thorough analysis. A systematic approach, such as the one described here, will aid the clinician in making an accurate diagnosis.

Marked symptomatic sinus bradycardia was treated by permanent pervenous Bifocal (sequential atrioventricular) demand pacemaker (BFD) implantation in four patients. The specific mode of operation and the complications encountered are analyzed. In the group of implants, six different BFD pulse generators were used; two of these generators underwent premature battery failure, one developed runaway and a fourth, premature circuit instability. Improper position or later displacement of the J-shaped atrial electrode prompted a special problem—ventricular stimulator inhibition. This self-inhibition is unique to this variety of generator and requires repositioning of the atrial electrode. The longterm high drain of energy and the electrical instability of the pulse generator are problems remaining to be solved before this mode of pacing can reach its full potential use.

In one area of Sweden interest has been directed towards the improved detection of patients with symptomatic bradyarrhythmias. Monitoring facilities were increased and indications for monitoring were expanded. In particular, patients with cerebral ischaemic episodes were included, introducing the concept of "cardiogenic neurology". This has resulted in a significantly increased frequency of recognition and treatment of patients requiring permanent pacemakers.

The vectorcardiograms of 5 cases of wandering pacemaker was recorded during sinus rhythm and during the various phases of the arrhythmia. The analysis of the P loops allowed us to distinguish two basi

A technique for long-term atrial pacing is described. It uses the system whereby power from an external pulse-generator (including battery) is transferred through the intact skin by inductive-coupling. Once installed, there is no requirement for further surgery to effect battery changes, and the patient can control his heart rate over a wide range to suit his needs. It is suggested that pacing by such means may offer a preferable alternative to drug therapy in the treatment of low cardiac output due to pathological sinus bradycardia. Two patients successfully treated in this way are reported.

On the basis of the four present case reports and analysis of previous cases from theliterature, two distinct clinical forms of atrial flutter in infancy are recognized. One is a chronic congenital arrhythmia, which is refractory to treatment; it usually subsides spontaneously during the first year of life. The second is paroxysmal and occurs several weeks or months after birth; it is usually responsive to treatment but tends to recur.

Three cases are reported in which early premature ventricular beats were followed by ventricular fibrillation (2 cases) and repetitive ventricular responses (1 case). The relationship of these findings to the vulnerable phase is discussed.

The logic for the contour analysis programs and the results of a comparison of computer and physician diagnosis for over two thousand cases are described. A detailed breakdown of the patient population and nature of the errors made by the program is given. The effectiveness of the program as a screening tool is also considered.

An examination of respiratory sinus arrhythmia is presented. Sinusoidal breathing was varied over a wide frequency range and the amplitude and phase of the accompanying fluctuations of heart rate were observed. These data show that heart rate is not necessarily in phase with respiration as previously described, but rather that the phase angle between heart rate fluctuations and respiration varies with frequency of breathing in a characteristic fashion. The usual descriptions of respiratory sinus arrhythmia are judged to be inadequate since they are shown to represent only a single point on the entire frequency response curve correlating breathing rate with sinus arrhythmia. heart rate fluctuation and respiratory frequency in man; frequency amplitude analysis of respiration-heart rate relationship; heart rate versus breathing: amplitude and phase angle; breathing-induced heart rate changes: phase angle; respiration-induced heart rate changes: phase angle respiratory sinus arrhythmia; respiration versus heart rate: amplitude and phase angle; sinus arrythmia and respiration: amplitude and phase angle Submitted on July 22, 1963