| 1. |
- Husser, D., et al.
(author)
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A genotype dependent intermediate ECG phenotype in patients with persistent lone atrial fibrillation
- 2009
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In: Circulation: Arrhythmia and Electrophysiology. - 1941-3084. ; 2:1, s. 24-28
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Journal article (peer-reviewed)abstract
- Background— Atrial fibrillation (AF) is heterogeneous at the clinical and molecular levels. Association studies have reported that common single-nucleotide polymorphisms in KCNE1 and SCN5A may predispose to AF. In this study, we tested the hypothesis that specific AF-associated genotypes confer variation on the appearance of AF assessed by analysis of fibrillatory rate of the atria. Methods and Results— Twenty-six nonrelated patients (21 males, mean age 55±12 years) with persistent lone AF (median AF duration 5 weeks) not taking class I or III antiarrhythmic drugs were studied. Fibrillatory rate was obtained by spatiotemporal QRST cancellation and time-frequency analysis of the index surface ECG. Genotypes at the AF-associated loci in KCNE1 (S38G) and SCN5A (H558R) were determined by direct DNA sequencing. The atrial fibrillatory rate was 418±50 fibrillations per minute (range, 336 to 521) in the study cohort. Carriers of the 38GG KCNE1 genotype (n=13) had significantly lower fibrillatory rates (392±36 versus 443±49 fibrillations per minute, P=0.006) compared to those with GS or SS genotype (n=13). Six patients (23%) with fibrillatory rates >450 fibrillations per minute, all had either the GS or SS genotype (χ2 P=0.008). In contrast, both the heterozygeous and homozygeous SCN5A H558R polymorphism had no effect on fibrillatory rate. There were no significant associations between fibrillatory rate and clinical (age, gender, AF duration, drug treatment) or echocardiographic (left atrial diameter, left ventricular ejection fraction) variables. In multivariable regression analysis, the KCNE1 S38G genotype (SS/GS coded 0, GG coded 1) was the only independent predictor of fibrillatory rate (β=−0.437, P=0.006) with a SE of the estimate of 44 fibrillations per minute. Conclusions— This study suggests that atrial fibrillatory rate obtained from the surface ECG is at least in part determined by KCNE1 (S38G) genotype, implying that this variant exerts functional effects on atrial electrophysiology. This intermediate ECG phenotype may be useful for elaborating genetic influences on AF mechanisms and identifying subsets of patients for variability in AF susceptibility or response to therapies.
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| 2. |
- Corino, V. D. A., et al.
(author)
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A Gaussian mixture model for time-frequency analysis during atrial fibrillation electrocardiograms
- 2007
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In: 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS 2007.. - 1557-170X. - 9781424407880 ; , s. 271-274
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Conference paper (peer-reviewed)abstract
- During atrial fibrillation (AF), time-frequency analysis of atrial signal has been applied to describe fibrillatory frequency trends. Recently, temporal changes in spectral shape have been investigated using the spectral profile technique. This profile is computed recursively by fitting each short-time log-spectrum to a spectral template, using amplitude scaling and frequency shifting. The purpose of the present study was to develop a Gaussian mixture model of the spectral profile in order to characterize the shape of AF waveforms. A novel index is introduced, the so-called harmonic index (HI), which reflects properties of the fundamental frequency peak and related harmonics peaks as estimated from the model. The index was tested on recordings from 9 patients with persistent AF, obtained before and after exercise testing. The HI succeeded in monitoring the response to exercise, i.e. change in the spectral profile to a less harmonic pattern, which is consistent with a reduction in AF organization (HI: 0.61±0.11 vs. 0.50±0.19, rest vs. exercise; p≪0.05).
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| 3. |
- Husser, D, et al.
(author)
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Determinants and prognostic significance of immediate atrial fibrillation recurrence following cardioversion in patients undergoing pulmonary vein isolation
- 2005
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In: PACE. - : Wiley. - 1540-8159. ; 28:2, s. 119-125
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Journal article (peer-reviewed)abstract
- Background: Immediate recurrence of atrial fibrillation (IRAF) occurs frequently after electrical cardioversion, its electrophysiological determinants and prognostic significance hove, however, not been studied in detail. This Study aimed to explore (1) the association of IRAF with clinical characteristics, pulmonary vein (PV) arrhythmogenicity as well as atrial electrophysiologic properties and (2) the prognostic significance of IRAF for outcome of PV isolation for atrial fibrillation (AF). Methods and Results: The subjects of this study were 41 consecutive patients (30 males, 11 females) who underwent PV isolation for drug-refroctory AF. Following successful initial cordioversion, 19 patients (46%) had IRAF within 2 minutes. Coupling intervals of AF reinitiating beats arising from PVs were shorter (386 +/- 39 vs 490 +/- 136 ms, P=0.008) and prematurity indices (0.38 +/- 0.06 vs 0.51 +/- 0.12, P=0.01) smaller than those of premature beats not initiating AF Patients with IRAF had more frequently AF duration <1 month, a longer P-wave duration, and a longer mid coronary sinus AF cycle length. Multivariate regression analysis revealed coronary sinus AF cycle length ( beta = 0.186, P=0.049), which was closely correlated with conduction time along the coronary sinus (R = 0.716, P = 0.003) to be independently associated with IRAF While early AF recurrence rate (within the first 5 days) following the procedure was higher in the IRAF group (53 vs 18%, P = 0.02), outcome was not different between the two groups thereafter. Conclusions: (1) IRAF is common in patients undergoing PV isolotion for AF, (2) is initiated by premature atrial beats with short coupling intervals, and (3) seems to be associated with conduction disturbances along the coronary sinus. It reflects susceptibility of arrhythmia recurrence within the first 5 days after the procedure, but not thereafter.
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| 4. |
- Husser, Oliver, et al.
(author)
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Exercise testing for non-invasive assessment of atrial electrophysiological properties in patients with persistent atrial fibrillation
- 2007
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In: Europace. - : Oxford University Press (OUP). - 1532-2092. ; 9:8, s. 627-632
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Journal article (peer-reviewed)abstract
- Aims Experimental studies suggest that the autonomic nervous system modulates atrial refractoriness and conduction velocity in atrial. fibrillation (AF). These modulatory effects are, however, difficult to assess in the clinical setting. This study sought to non-invasively characterize in patients with persistent AF, the influence of autonomic modulation induced by exercise on atrial fibrillatory rate as marker of atrial refractoriness and to identify clinical and electrocardiographic predictors of atrial rate response. Methods and results In 24 patients (16 mates, mean age 60 +/- 13 years) with persistent AF (16 +/- 25 months), continuous ECGs were recorded during bicycle exercise testing. Fibrillatory rate (in fibrillations per minute, fpm) was assessed at baseline and immediately after termination of exercise with spatiotemporal QRST cancellation and time-frequency analysis. Ventricular response was characterized by time-domain HRV indices. Exercise had no influence on mean fibrillatory rate (409 +/- 42 vs. 414 +/- 43 fpm, P = NS). Seven patients responded to exercise with an increase in fibrillatory rate (26 10 fpm, P < 0.001 and three with a decrease (-21 +/- 8 fpm, P < 0.001), while the remaining 14 patients did not show a response. Responders' HRV indices changed in response to exercise similarly to that of non-responders. Their baseline fibrillatory rate was, however, lower than that of non-responders (387 +/- 18 vs. 425 +/- 48 fpm, P = 0.028). No other clinical or echocardiographic variable was associated with fibrillatory rate response. Twelve weeks after cardioverson, responders were more likely to remain in sinus rhythm than non-responders (88 vs. 46 %, P = 0.04). Conclusions Exercise-induced autonomic activation produces changes in atrial. etectrophysiological properties that can be detected by time-frequency analysis. Higher baseline fibrillatory rates are associated with an impaired atrial response to exercise that suggests advanced electrical remodelling and reduced sensitivity to autonomic stimuli.
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| 5. |
- Husser, O., et al.
(author)
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Exercise testing for non-invasive assessment of atrial electrophysiology in patients with persistent atrial fibrillation
- 2006
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In: 2006 Computers in Cardiology, CIC. - 1424425328 - 9781424425327 ; 33, s. 21-24
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Conference paper (peer-reviewed)abstract
- The abstract with its heading should not be more than 75 mm long. This is equivalent to 18 lines of text. Leave 1 line space at the bottom of the abstract before continuing with the next heading. The autonomic nervous system modulates atrial electrophysiology in atrial fibrillation (AF). The purpose of this study was (1) to non-invasively characterize the effects of exercise on atrial fibrillatory rate as marker of atrial refractoriness in patients with persistent AF and (2) to identify clinical and electrocardiographic predictors for rate response. In 15 patients with persistent AF, mean fibrillatory rate assessed by spatiotemporal QRST cancellation and time-frequency analysis remained unchanged with exercise. There were, however, 6 responders (rate change > 2.5%), with either a rate increase (N=5, 25±9 fpm) or decrease (N=1, -13 fpm). Absolute fibrillatory rate change (%) correlated inversely with baseline fibrillatory rate (r= -0.543, p=.045). In conclusion, sympathetic activation by exercise modulates atrial electrophysiology in some patients which can be monitored using time-frequency analysis. Higher baseline fibrillatory rates are associated with less autonomic modulation indicating advanced electrical remodeling.
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| 6. |
- Stridh, Martin, et al.
(author)
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Time-frequency characterization of simultaneous intra-atrial and electrocardiographic recordings during atrial fibrillation
- 2005
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In: Computers in Cardiology 2005. - 0780393376 ; 32, s. 347-350
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Conference paper (peer-reviewed)abstract
- A new method for characterization of simultaneous intra-atrial and ECG recordings during atrial fibrillation (AF) is presented. With different preprocessing, both types of signals are characterized using a logarithmic time-frequency distribution from which trends of frequency, regularity, morphology (only ECG) and signal quality are extracted. The objective of the study is to relate ECG measures of rate and morphology to measures of intra-atrial organisation. The algorithm has been tested on a database with simultaneous ECG and right atrial recordings from 34 patients with drug-refractory AF. The average frequency in lead V1 was 5.91 Hz (std=0.94) and the average exponential decay of harmonic magnitudes (reflecting the morphology) in V1 was 1.31 (std=0.38); their correlation coefficient was 0.53 (p<0.001). The correlation coefficient between spatial frequency dispersion in the right atrium and harmonic decay was 0.53 (p<0.005). More organized AF, observed in patients treated with amiodarone, was reflected by a lower frequency, smaller right atrial frequency dispersion and lower exponential decay
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| 7. |
- Husser, D, et al.
(author)
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Pilot study: Noninvasive monitoring of oral flecainide's effects on atrial electrophysiology during persistent human atrial fibrillation using the surface electrocardiogram
- 2005
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In: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 10:2, s. 206-210
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Journal article (peer-reviewed)abstract
- Background: The relation between flecainide's plasma level and its influence on human atrial electrophysiology during acute and maintenance therapy of atrial fibrillation (AF) is unknown. Therefore, this study determined flecainide plasma levels and atrial fibrillatory rate obtained from the surface ECG during initiation and early maintenance of oral flecainice in patients with persistent lone AF and assessed their relationship. Methods and Results: In 10 patients (5 males, mean age 63 14 years, left atrial diameter 46 +/- 3 mm) with persistent lone AF, flecainide was administered as a single oral bolus (day 1) followed by 200-400 mg/day (days 2-5). The initial 300 mg flecainide bolus resulted in therapeutic plasma levels in all patients (range 288-629 ng/ml) with no side effects. Flecainide plasma levels increased on day 3 and remained stable thereafter. Day 5 plasma levels were lower (508 +/- 135 vs 974 :E 276 ng/ml, P = 0.009) in patients with daily mean flecainide doses of 200 mg compared to patients with higher maintenance doses. Fibrillatory rate obtained from the surface electrocardiogram measuring 378 +/- 17 fpm at baseline was reduced to 270 +/- 18 fpm (P < 0.001) after the flecainice bolus but remained stable thereafter. Fibrillatory rate reduction was independent of flecainide plasma levels or clinical variables. Conclusion: A 300 mg oral flecainide bolus is associated with electrophysio logic effects that are not increased during early maintenance therapy in persistent human lone AF In contrast to drug plasma levels, serial analysis of fibrillatory rate allows monitoring of individual drug effects on atrial electrophysiology.
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| 8. |
- Husser, D, et al.
(author)
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Time-frequency analysis of the surface electrocardiogram for monitoring antiarrhythmic drug effects in atrial fibrillation
- 2005
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In: American Journal of Cardiology. - : Elsevier BV. - 1879-1913 .- 0002-9149. ; 95:4, s. 526-528
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Journal article (peer-reviewed)abstract
- This study explored time-frequency analysis of surface electrocardiograms in patients with persistent atrial fibrillation for monitoring atrial drug action. Drug loading over 3 days with oral flecainide (n = 13) or amiodarone (n = 17) organized the fibrillatory process expressed by decreased atrial fibrillatory rate, increased rate stability, and decreased exponential decay. Effects were more pronounced with flecainide than with amiodarone.
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| 9. |
- Richter, Ulrike, et al.
(author)
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Wavefront detection from intra-atrial recordings
- 2007
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In: Computers in Cardiology. - 0276-6574. - 9781424425334 ; 34, s. 97-100
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Conference paper (peer-reviewed)abstract
- The present study deals with detection of intra-atrial wavefronts from atrial activation times in adjacent bipolar electrograms. A statistic of the delays within each wave-front was calculated and served as a basis for quantifying the wavefront consistency as well as the propagation of the electrical activity along the catheter. The database consisted of 19 patients for which five electrograms were recorded simultaneously during 10 s. The analysis resulted in 38plusmn2 complete wavefronts per patient, i.e., wavefronts consisting of one activation from each recording site. Two parameters were evaluated for quantifying wavefront consistency, which together with the propagation profile well reflect the overall wavefront timing. In most cases, electrical activity was observed first in the high septal right atrium, and then spread along the catheter.
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| 10. |
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