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- Hnatkova, K, et al.
(författare)
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Computer package generating non-invasive atrial electrograms: Detection and subtraction of QRS and T waves
- 1998
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Ingår i: Computers in Cardiology. - 0780352009 ; 25, s. 533-536
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Konferensbidrag (refereegranskat)abstract
- Computerized systems to localize specific patterns appearing in ECG signal, such as the QRS complex and T wave usually utilize predefined templates. Where the signal is not clean, such as during atrial fibrillation (AF), analysis based on self-similarities of the ECG signal appears to be more stable. The authors describe a software package which uses self-similarity techniques to allow the subtraction of ventricular signals during AF. The dataset used in this study was Holter ECG recorded in 23 patients (11 male, age 61.1±8.7 years) with chronic AF using an Altair 6500 digital Holter (Burdick Inc., 3 channels, 1 kHz sampling). Self-similarities between corresponding QRS and corresponding T windows were assessed using Spearman correlation coefficients, utilising the commercial software derived fiducial point but with shifted windows to overcome possible minor imprecision thereof. A linear order algorithm successfully subtracted 87% of QRS's and 67% of T waves.
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| 4. |
- Pehrson, Steen, et al.
(författare)
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Non-invasive assessment of magnitude and dispersion of atrial cycle length during chronic atrial fibrillation in man
- 1998
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 1522-9645 .- 0195-668X. ; 19:12, s. 1836-1844
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Atrial fibrillation cycle lengths can be assessed from right precordial ECG leads and the unipolar oesophageal ECG using a non-invasive method called Frequency Analysis of Fibrillatory ECG. The purpose of this report is to present the results from application of this method in a large group of patients with long-term atrial fibrillation and to examine the differences between patients with 'coarse' and 'fine' atrial fibrillation. METHODS AND RESULTS: Simultaneous 15 min recordings from V1, V2 and an oesophageal lead at a position behind the posterior atrium were obtained in 28 patients, aged 41 to 78 years, with long-term (> 1 month) atrial fibrillation. In each lead, using the time averaging technique, the QRST complexes were suppressed. Thereafter, the frequency distribution of the residual ECG was estimated by means of Fast Fourier Transform. In the 3-12 Hz range of each lead, the dominant atrial cycle length, the power maximum and the spectral width were calculated. In 26 patients (93%), frequency spectra in the 3-12 Hz range could be obtained. The dominant atrial cycle length ranged from 120 to 175 ms, mean 150+/-16 (SD) ms in V1, and from 120 to 190 ms, mean 150+/-16 in an oesophageal lead (ns). The absolute difference in the dominant atrial cycle length between V1 and the oesophageal lead was 10.4+/-7.7 ms. There was no significant difference in the dominant atrial cycle length in V1 between patients with coarse and fine atrial fibrillation. The power maximum in V1 was significantly greater in patients with coarse compared to fine atrial fibrillation (P=0.01). The spectral widths ranged from 10 to 55 ms and demonstrated significantly higher mean values in lead V2 compared to V1 (P=0.001). Compared to V1, the mean values tended to be smaller in the oesophageal lead (P=0.05). CONCLUSIONS: Using the Frequency Analysis of Fibrillatory ECG method, the dominant atrial cycle length, power maximum and spectral width can be estimated from the frequency spectra in the majority of patients with atrial fibrillation. Spatial dispersion of the dominant atrial cycle length occurs in some patients and may be an important proarrhythmic marker. The distinction between coarse and fine atrial fibrillation cannot be used as a marker of the atrial cycle length.
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