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Several studies have shown that high amplification and averaging of the electrocardiographic P wave may soon enable better identification of people at high risk of paroxysmal atrial fibrillation. The results of this technique are closely dependent on the conditions of recording and analysis of the atrial signal but this factor has not been widely appreciated. The authors, therefore, undertook a study of the reliability of the manual method of measuring P wave duration, the influence of the filters used and the level of background noise on the 3 parameters of analysis: the duration of the P wave (DUR), the root mean square of the amplitude of the terminal 20 milliseconds (RMS20) and the integral under the P curve (IN). The recorder was a Predictor II 5.0 (Corazonix) with a special programme to identify and analyse the P wave in 3 bipolar non-orthogonal leads. DUR was determined manually after amplification and averaging; RMS20 and IN were calculated automatically. In order to assess the reliability of manual determination of the P wave, 48 consecutive patients were studied: two analyses were made with a least a 2 months' interval by entering the data through two filters (unidirectional and FIR). The role of the filters was then studied by passing the preceding 48 recordings to an analysis with three filters: unidirectional, bidirectional and FIR, and comparing the results.(ABSTRACT TRUNCATED AT 250 WORDS)

Signal averaging of the ECG P wave is a recent technique used for obtaining predictive and prognostic information in atrial arrhythmias. There have been few publications of its evaluation in this setting. The authors report their results of temporal analysis of the P wave of patients who had undergone electrical cardioversion of atrial fibrillation (group 3, n = 22 patients) and compared them with those of a control group without atrial arrhythmias (group 1, n = 25 patients). After recording signals in three bipolar leads (Predictor 5.0 II Corazonix recorder-analyser), the total duration of the P wave, the root mean square of the P wave amplitude (RMSt) and of the last 20 milliseconds (RMS 20) and the integral under the curve of the P waves (IN) were determined. The comparison was continued with data obtained from a population of patients with paroxysmal atrial fibrillation (group 2, n = 22). All patients had normal left atria on echocardiography, had no valvular heart disease, had no myocardial infarction or signs of cardiac failure. Results showed that the most discriminating parameter was the P wave duration (Group 3: 159.45 +/- 15.1 ms; group 1: 123 +/- 8.5 ms; group 2: 144.6 +/- 12.03 ms; group 1 versus group 2, p < 0.001, group 2 versus group 3, p < 0.01; group 1 versus group 3, p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Many in vitro and animal experimental studies seem to support the hypothesis of reentry as the physiopathological mechanism of atrial flutter. Clinically, these studies are much more difficult because of problems in determining the different sequences of atrial depolarisation. In this study, the authors attempted to improve the technique of endocavitary atrial mapping. Three or four multi-recording electrodes were positioned in the atria using biplane 30 degrees RAO and 60 degrees LAO incidences. Right atrial angiocardiography showed up the atrial borders and enabled the recording catheters to be more accurately positioned. Thirty to 47 recordings points were thereby determined within the atrial cavities, the left atrium being studied via the coronary sinus, right pulmonary artery, patent foramen ovale or by the endooesophageal approach. This method of spatial orientation of the catheters associated with recording of the endocavitary potentials allowed the construction of an isochronic map of atrial depolarisation, which was then analysed for each case of flutter. The study confirmed two hypotheses: the asynchronism of right and left atrial depolarisation, and the circus motion of depolarisation. Three types of flutter were observed: --The first two types were similar with cirus motion within the right atrium. The wave front ascended in part or all of the septum and descended in the external free wall of the right atrium. There was a transitional zone, possibly reentrant, in the groove located anterior to the inferior vena cava. --The third type of flutter was atypical and was associated with cirus motion in the left atrium. Two transitional zones, similar to those encountered in the right atrium, were detected in one patient between the orifices of the pulmonary veins, and, in another patient, on the anterior part of the roof of the left atrium. These transitional zones seem to be at the basis of the physiopathological mechanism of flutter. Unfortunately, their small size makes their analysis by endocavitary mapping difficult.

The introduction of data processing techniques into the interpretation of electrocardiograms and the rapid progress towards automatization require a multiplication of the criteria of decision and an exact evaluation of their performance. The ECG diagnosis of left ventricular hypertrophy depends on a large number of parameters. Only the aVR lead has not been fully exploited to date. This study proposes a corrected measurement of S in aVR, with an amplitude of S aVRc greater than or equal to 11 mm being the parameter with the best performance and the best predictability.

The interpretation of a continuous electrocardiographic recording according to Holter's method is valid only in terms of well defined standard criteria. These criteria are beginning to become more specific, in spite of uncertainties linked especially to study protocols. Finally, if these criteria were established among healthy populations, their application to pathological situations comes up against the notion of physical condition which may modify all norms.