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This research was financially supported by the Ministry of Health subvention (No. STM.A280.20.107 from the IT Simple system of Wroclaw Medical University).

Functional and structural changes in atrial muscle constitute a substrate for atrial fibrillation. The pathological changes in the left atrium decrease conduction velocity and result in prolongation of the P wave duration. The aim of the study was to assess the duration of the P wave in patients with paroxysmal and persistent atrial fibrillation. The study group consisted of 119 patients diagnosed with atrial fibrillation, 57 women and 62 men, aged 65.3+/-9.4 years. There were 65 patients with paroxysmal AF and 54 with persistent AF. In this group the electrical cardioversion was performed. The P wave duration, was measured using electrophysiological system in all leads at paper speed of 200 mm/s. The studied patients did not differ in term of age, gender and comorbidities. The patients with persistent AF had longer P wave duration (159.9+/-22.3 vs 144.6+/-17.2 ms, p<0.001), higher glucose concentration (119.4+/-33.4 vs 108.0+/-24.6 mg/dL, p=0.015). Those results were not influenced by the anti-arrhythmic treatment. The persistent atrial fibrillation shows prolongation of the P wave duration over the paroxysmal form of the arrhythmia, independently to age, gender and anti-arrhythmic medication. The prolongation of the P wave related to persistent arrhythmia should force the physicians to earlier restoration of the sinus rhythm in order to its more successful long term maintenance.

Background The P wave dispersion concept was created to describe the non-uniform atrial conduction as a separate AF factor. However the major assumptions of the theory are inconsistent with the main principle of electrocardiography, which assumes that 12 leads of ECG, recorded simultaneously, register the same events at the same time. The presence of dispersion suggests the presence of a P wave in one lead, while in the other one it has ended and no longer exists. This observation per se could be considered as a methodological artifact. Objective The major objective is to present that the P wave dispersion descends from imprecise measurements in various ECG leads. We intend to demonstrate that more accurate measurements make this parameter disappear. Methods Our study included 150 patients (89F, 61M) assessed using the electrophysiological system, which allowed to assess the sinus P waves. The P wave duration was measured by 3 independent researchers in all leads twice: 1. paper speed=50 mm/s, enhancement 16x (basic measurement) 2. paper speed=200 mm/s, enhancement 128–256x, simultaneously measuring the P wave dispersion. All measurements were repeated 3 times. Results The results are presented in Table 1 Conclusion 1. The P wave dispersion is the artifact of measurement. It is clear that after using much more accurate tools, the parameter disappears. 2. The P-wave dispersion is connected with Pmax, therefore may be apparently clinically useful but as a matter of fact, doesn't carry any meaning itself. 3.The significant P wave duration parameter should be a total atrial activation time, from the beginning of the earliest recorded P wave, till the end of the last Pwave recorded in any lead. Funding Acknowledgement Type of funding source: None

Introduction: A dual-chamber pacemaker (DDD/R) for a sinus node disease is sometimes referred to as a physiological pacemaker as it maintains atrioventricular synchrony, however several clinical trials have proved its inferiority to a nonphysiological single-chamber ventricular back-up pacing. Patient concerns: A subject of the study is a 74-year-old woman with a sick sinus syndrome (SSS) and a previously implanted physiological DDD/R pacemaker. The SSS was diagnosed because of patient's very slow sinus rhythm of about 36 bpm, and due to several episodes of dizziness. After the DDD/R implantation the percentage of atrial pacing approached 100%, with almost none ventricular pacing. Diagnoses: Sick sinus syndrome, complete Bachmann's bundle block, atrial fibrillation, atrial flutter. Interventions: The patient was previously implanted with a physiological DDD/R pacemaker. Several years after the implantation, the atrial fibrillation was diagnosed and the pulmonary vein isolation was then performed by cryoablation. During the follow-up after pulmonary vein isolation, the improvement of mitral filling parameters was assessed using echocardiography. Shortly thereafter the patient developed the persistent paroxysm of a typical atrial flutter which was successfully terminated using a radiofrequency ablation. No recurrence thereof has been observed ever since (24 months). Outcomes: The atrial electrode of the pacing system was implanted within the low interatrial septal region that resulted in a reduced P-wave duration compared to native sinus rhythm P-waves. The said morphology was deformed because of the complete Bachmann bundle block. That approach, despite a nonphysiological direction of an atrial activation, yielded relatively short P-waves (paced P-wave: 179 ms vs intrinsic sinus P-wave: 237 ms). It also contributed to a significantly shorter PR interval (paced PR: 204 ms vs sinus rhythm PR: 254 ms). Conclusions: The authors took into consideration different aspects of alternative right atrial pacing sites. This report has shown that in some patients with a sinus node disease, low interatrial septal pacing can reduce the P-wave duration but does not prevent from the development of atrial arrhythmias.