Background
The clarification of atrial fibrillation is the main indication for performing a Holter ECG. According to the guideline of the German Cardiac Society and the European Society of Cardiology (DGK and ESC, 2016), atrial fibrillation is described as follows: "The diagnosis of AF requires an electrocardiogram (ECG) showing irregular RR intervals and no distinct P waves" [1]. The critical duration of an AF episode of at least 30 seconds is an additional criterion mentioned in the in the ESC document [2] as well as in the comment of Eckardt et al. (2017) [3]. Atrial fibrillation is the most frequent, permanent cardiac arrhythmia with more than one million people concerned in Germany [4]. AF diagnostics is of particular significance because it is related to various critical events such as increased mortality, AF-caused strokes (up to 30%) and hospital stays [1].
Detecting atrial fibrillation
From a technical point of view, the detection of AF is a challenge. While the diagnostic criteria are relatively easy to formulate (no existing P wave, R-R not consistent) with a simple decision path leading to the result (s. Fig. 1), the technical analysis is more complicated. Trained specialists in internal medicine as well as cardiologists identify the P wave (almost) always, even in the tachycardic ECG and even if the isoelectric line is superimposed by noise. However, it is especially the latter that is difficult to handle technically. Noise can be reduced by means of filtering but there is the risk that an already "small" P wave (with low amplitude) may be "filtered away" and this may lead to a false-positive result.
Figure 1: Decision path for analysing AF (Source: Dr. med. J. Bott, Berlin)
Therefore it makes sense to base the analysis on all evaluable criteria and incorporate them into the result. This approach has been implemented in the software module AF diagnostics.
The software module AF diagnostics
The software module AF diagnostics is part of the custo diagnostic Holter ECG analysis. It is an easy-to-handle and efficient tool for analysing atrial activity and allows the doubtless and reliable statement whether a patient suffers from atrial fibrillation or not. Detection is based on P wave assessment and rhythm analysis which are visualized in multiple views (screens). These are: the RR trend, the Poincaré plot, a ("signal-averaged") summary complex, a mountain view ECG and the original ECG. By means of these screens AF can be detected in only five steps.
Software Overview
Figure 2: Overview
The RR trend
In the RR trend, i.e. the view showing the distance between two R waves in the ECG or the duration of an electrical heart activity, high-frequency areas can be displayed which possibly deviate from the sinus rhythm.
A mouse click in the trend allows selecting areas specifically.
Figure 3: RR Trend
The Poincaré plot
The Poincaré plot represents the rhythm in the scatterplot. In a healthy person, as shown in Figure 4, the Poincaré plot appears in a "torpedo" shape – which corresponds to a sinus rhythm. It can be clearly seen that the torpedo is longer than wide, that the points within the diagram do not scatter and that they arrange centrally alongside a diagonal. If the Poincaré plot shows another pattern, this can suggest different pathologies. Among other things, the use of the Poincaré plot is helpful for proving atrial fibrillation and atrial flutter, breaks and ectopic beats (VES, SVES).
Figure 4: Poincaré plot, sinus rhythm
The specific patterns in the two-dimensional view improve the detectability of potential tachyarrhythmias [5]. The most frequent form of tachyarrhythmia is atrial fibrillation. By means of the following graphs Esperer et al. (2008) explain further frequent characteristics (s. Fig. 5).
As Figure 5 and Table 1 show, certain patterns in the Poincaré plot are characteristic of certain arrhythmias. The Poincaré plots 1, 2, 3 and 4 require particular attention in connection with atrial fibrillation and atrial flutter.
Figure 5: Different typical Poincaré plot views [5]
Table 1: Explanations as to the Poincaré plot [5]
No | Morphology | Description | Effect |
1 | Hand fan pattern A | Point cloud | Atrial fibrillation |
2 | Hand fan pattern B |
| Atrial fibrillation |
3 | Island pattern A |
| Atrial flutter (with AV block) (or atrial tachycardia with AV block) |
4 | Island pattern B |
| Atrial flutter |
5 | Double-sided cloth pattern Type A | Butterfly | Extrasystoles (SVES / VES) |
6 | Double-sided cloth pattern Type B |
| Extrasystoles (SVES / VES) with recurrent pattern (e.g. bigeminy) |
7 | Three-sided cloth pattern Type A |
| VES (with consistent coupling interval) |
8 | Three-sided cloth pattern Type B | Propeller | SVES (and consistent VES) |
The Poincaré plot patterns shown here are ideal-typical examples. In practice, hybrid forms can often be found in which paroxysmal AF and other arrhythmias occur jointly in a Poincaré plot (see e. g. case study 3).
The averaged sum complex
By means of the averaged sum complex the existence of a P wave can be identified.
Figure 6: Sumy complex with P wave |
Figure 7: Sum complex without P wave |
If no P wave can be detected, atrial fibrillation has to be assumed.
The mountain view ECG
In the mountain view ECG, for example the beginning of a paroxysmal fibrillation episode can be detected quickly and easily. The mountain view ECG represents (here in Fig. 8) one minute of the ECG in which three beats, each averaged to the R wave, are placed one after another. This extract can be arbitrarily configured. By double-clicking on the ECG curve, the original ECG is called up.
Figure 8: The mountain view ECG
The trend view / The original ECG
The original ECG allows for further verification of the assessment (steps 1 to 4). Using the arrow keys, you can fast-forward or fast-backward in the ECG recording. With the F2 key the dialogue box for marking is called up and the concerned area can be marked for documentation purposes.
Figure 9: The trend view
Use of software & hints for evaluation
In order to assess if there is atrial fibrillation or not, the following steps are recommended:
- Identification of critical areas in the RR trend
The curve of the RR trend directs as a clearly defined, demarcated line without AF. If AF occurs, the RR trend becomes wider, more dense and a frequency increase can be identified. - Check Poincaré plot
The Poincaré plot is shows whether or not there is a deviation from sinus rhythm. - Check summary complex
If the P wave cannot be identified, atrial fibrillation could be existent. - Delimitation of area in the mountain view ECG
Beside extrasystoles and frequency fluctuations, arrhythmias can be viewed in detail by means of the mountain view ECG - Verification in the trend view
The corresponding original ECG confirms the results of the previous analysis steps.
The individual parameters and this procedure help improve diagnostic speed, accuracy and effeciency in ECG evaluation by means of a complex view of the most important aspects.
Case studies
Case study 1: Male patient, 69 years, with paroxysmal, long-lasting atrial fibrillation
A) Area with regular sinus rhythm
Identification:
(1) The RR trend appears as a defined, clearly demarcated line
(2) The summary complex shows a P wave with QRS-T configuration
(3) The Poincaré plot is cigar-shaped which indicates a regular sinus rhythm
Verification:
(4) The ECG mountain view shows a sinus rhythm with regular frequency
(5) The original ECG confirms the above-mentioned result
Figure 10: Sinus rhythm
B) Transition zone sinus rhythm - atrial fibrillation
Identification:
(1) The RR trend is widened
(2) The Poincaré plot passes from the cigar shape to a "hand fan shape"
(3) The summary complex still shows a P wave with QRS-T configuration
Verification:
(4) The ECG mountain view clearly shows the transition from sinus rhythm to arrhythmia.
(5) The original ECG confirms the result: beginning of AF.
Figure 11: Transition sinus rhythm - atrial fibrillation
C) Atrial fibrillation
Identification:
(1) The RR trend is widened
(2) The Poincaré plot shows the characteristic shape for AF / atrial flutter
(3) The summary complex does not indicate a P wave
Verification:
(4) The ECG mountain view clearly shows the arrhythmia
(5) The original ECG confirms the result: AF
Figure 12: Atrial fibrillation
Case study 2: Male patient, 33 years, no known pre-existing diseases
A) Area with regular sinus rhythm
Identification:
(1) The RR trend shows a defined, clearly demarcated line. Suspicious facts with sudden frequency increase are marked in red
(2) The Poincaré plot is cigar-shaped which indicates a regular sinus rhythm
(3) The summary complex shows a P wave with QRS-T configuration
Verification:
(4) The ECG mountain view shows sinus rhythm with regular frequency
(5) The original ECG confirms the above-mentioned result
Figure 13: Sinus rhythm
B) Area with tachycardic basic rhythm
Identification:
(1) The RR trend shows a significant frequency increase which is however regular
(2) The Poincaré plot is cigar-shaped which indicates a regular sinus rhythm
(3) The summary complex shows a P wave with QRS configuration and ascending T wave
Verification:
(4) The ECG mountain view shows a sinus rhythm with regular frequency
(5) The original ECG confirms the above-mentioned result
Figure 14: Tachycardic basic rhythm
The areas marked above all show the same pattern, consisting of tachycardic sinus rhythm without signs of atrial disorders.
To make sure that no episodes have been overlooked, the "Poincaré plot" view is selected over the total evaluation time. The cigar-shaped structure does not reveal any of the typical signs of atrial fibrillation or flutter.
Conclusion: there is no AF.
Figure 15: Poincaré plot, total evaluation time
Case study 3: Male patient, 47 years, no known pre-existing diseases, frequent SVES, paroxysmal AF
A) Area with sinus rhythm and numerous SVES
Identification:
(1) The RR trend shows a dense central stripe lined with a range of low point density above and below. A clear frequency increase can be identified from approx. 11:20 to approx. 13:10.
(2) The Poincaré plot is centrally cigar-shaped which indicates a regular sinus rhythm. From the central area one wing-shaped point cloud with low density spreads to the top and two such clouds to the bottom. In the left bottom corner (area of high HR) a slight, circle-shaped point cloud can be seen.
(3) The summary complex shows a P wave with QRS-T configuration in the marked area
Verification:
(4) The ECG mountain view shows sinus rhythm with irregular frequency and occasional supraventricular extra beats
(5) The original ECG confirms the above-mentioned result
Figure 16: Sinus rhythm with SVES
B) Area with AF and atrial flutter
Identification:
(1) The RR trend shows a broad stripe with unclear border
(2) The point cloud in the Poincaré plot is round to circle segment-shaped. There are no signs of sinus rhythm.
(3) In the summary complex no clearly defined P wave can be identified.
Verification:
(4) The ECG mountain view shows a completely irregular frequency and no identifiable sinus rhythm
(5) The original ECG confirms the above-mentioned result, there is atrial fibrillation/atrial flutter.
Figure 17: Atrial fibrillation & flutter
The Poincaré plot over the complete assessment time of this day backs the suspicion. The patient suffers from sinus rhythm with a distinct supraventricular extrasystole which is interrupted by paroxysmal atrial fibrillation from 11:20 to 13:10.
Figure 18: Poincaré plot with SVES and identifiable atrial fibrillation episode
Conclusion
With the new analysing tool "AF Diagnostics" (atrial diagnostics) of custo med GmbH it is possible to detect atrial fibrillation and atrial flutter easily, quickly and reliably.
In addition, the new atrial analysis of custo med completes the offers for AF diagnostics. Beside this module it is equally important to check blood pressure, blood glucose and the existence of coronary heart diseases. An explicit connection between these parameters is described by the ESC in its paper of 2016 [2]. custo diagnostic now offers a complete package and with the module described herein, unclear and uncertain diagnostic results regarding atrial fibrillation will be a thing of the past.
Literature
[1] DGK - Deutsche Gesellschaft für Kardiologie(2016) (Hrsg.). ESC Pocket Guidelines: Management von Vorhofflimmern. Version 201. http://leitlinien.dgk.org/2017/pocket-leitlinie-management-von-vorhofflimmern-version-2016/ (23.11.2017).
[2] ESC (2016) (Hrsg.).Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. The Task Force for the management of atrial fibrillation of the European Society of Cardiology. European Heart Journal (2016) 37, 2893–2962. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Atrial-Fibrillation-Management (25.10.2017).
[3] L. Eckardt, L., Deneke, T., Diener, H.C., Hindricks, G., Hoffmeister, H.M., Hohnloser, S.H., Kirchhof, P. & C. Stellbrink (2017): Kommentar zu den 2016 Leitlinien der Europäischen Gesellschaft für Kardiologie (ESC) zum Management von Vorhofflimmern. Der Kardiologe 2017: 193-204. http://leitlinien.dgk.org/files/2017_Kommentar_Vorhofflimmern.pdf (25.10.2017).
[4] G., Breithardt; F., de Haan; W., Hacke (2013). Schlaganfallprävention und Vorhofflimmern. Stuttgart: Georg Thieme Verlag.
[5] H. D., Esperer; Ch., Esperer; R., Cohnen (2008). Cardiac Arrhythmias Imprint Specific Signatures on Lorenz Plots. In: Annals of Noninvasive Electrocardiology, 13 (1), S. 1-95.
List of abbreviations:
AF Atrial Fibrillation
AV Atrioventricular
DGK Deutsche Gesellschaft für Kardiologie (German Cardiac Society)
ESC European Society of Cardiology
VES Ventricular Extrasystole
SR Sinus Rhythm
Important hint:
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