| 1. |
- Carlson, Jonas, et al.
(författare)
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Can Orthogonal Lead Indicators of Propensity to Atrial Fibrillation be Accurately Assessed from the 12-Lead ECG?
- 2005
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092. ; 7:Suppl 2, s. 39-48
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Tidskriftsartikel (refereegranskat)abstract
- Aims: When analyzing P-wave morphology, the vectorcardiogram(VCG) has been shown useful to identify indicators of propensity to atrial fibrillation (AF). Since VCG is rarely used in the clinical routine, we wanted to investigate if these indicators could be accurately determined in VCG derived from standard 12-lead ECG (dVCG).Methods: ECG and VCG recordings from 21 healthy subjects and 20 patients with a history of AF were studied. dVCG was calculated from ECG using the inverse Dower transform. Following signal averaging of P-waves, comparisons were madebetween VCG and dVCG, where three parameters characterizing signal shape and 15 parameters describing the P-wave morphology were used to assess the compatibility of the two recording techniques. The latter parameters were alsoused to compare the healthy and the AF groups.Results: After transformation, P-wave shape was convincingly preserved. P-wave morphology parameters were consistent within the respective groups when comparing VCG and dVCG, with better preservation observed in the healthy group.Conclusion VCG derived from routine 12-lead ECG may be a useful alternate method for studying orthogonal P-wave morphology.
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| 2. |
- Havmöller, Rasmus, et al.
(författare)
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Age-related changes in P wave morphology in healthy subjects.
- 2007
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 7:22
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Tidskriftsartikel (refereegranskat)abstract
- Background We have previously documented significant differences in orthogonal P wave morphology between patients with and without paroxysmal atrial fibrillation (PAF). However, there exists little data concerning normal P wave morphology. This study was aimed at exploring orthogonal P wave morphology and its variations in healthy subjects. Methods 120 healthy volunteers were included, evenly distributed in decades from 20–80 years of age; 60 men (age 50+/-17) and 60 women (50+/-16). Six-minute long 12-lead ECG registrations were acquired and transformed into orthogonal leads. Using a previously described P wave triggered P wave signal averaging method we were able to compare similarities and differences in P wave morphologies. Results Orthogonal P wave morphology in healthy individuals was predominately positive in Leads X and Y. In Lead Z, one third had negative morphology and two-thirds a biphasic one with a transition from negative to positive. The latter P wave morphology type was significantly more common after the age of 50 (P < 0.01). P wave duration (PWD) increased with age being slightly longer in subjects older than 50 (121+/-13 ms vs. 128+/-12 ms, P < 0.005). Minimal intraindividual variation of P wave morphology was observed. Conclusion Changes of signal averaged orthogonal P wave morphology (biphasic signal in Lead Z), earlier reported in PAF patients, are common in healthy subjects and appear predominantly after the age of 50. Subtle age-related prolongation of PWD is unlikely to be sufficient as a sole explanation of this finding that is thought to represent interatrial conduction disturbances. To serve as future reference, P wave morphology parameters of the healthy subjects are provided.
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| 3. |
- Havmöller, Rasmus, et al.
(författare)
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Evolution of P-wave morphology in healthy individuals: a 3-year follow-up study.
- 2009
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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 14:3, s. 226-233
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Orthogonal P-wave morphology in healthy men and women has been described using unfiltered signal-averaged technique and holds information on interatrial conduction. The stability of P-wave morphology in healthy subjects over time is not fully known. METHODS: Sixty-seven healthy volunteers were investigated (29 males, aged 63 +/- 14 years, 48 females, 60 +/- 13 years). Orthogonal lead data (X, Y, and Z) were derived from standard 12-lead ECGs (recording length 6 minutes, sampling rate 1kHz, resolution 0.625 muV) recorded at baseline (BL), and 3 years later at follow-up (FU). P waves were then signal-averaged and analyzed regarding P-wave morphology, locations of maxima, minima, zero-crossings, and P-wave duration (PWD). RESULTS: No differences of P-wave variables were observed at FU compared to BL, including PWD (127 +/- 12 vs 125 +/- 14 ms at BL and FU, respectively, n.s.). In 59 of the 67 subjects (88%), the P-wave morphology was unaltered at FU. However, in the remaining eight cases a distinctively different morphology was observed. The most common change (P=0.030) was from negative polarity to biphasic (-/+) in Lead Z (n=5). In one case the opposite change was observed and in two cases transition into advanced interatrial block morphology was evident at FU. CONCLUSIONS: In the majority of healthy subjects, P-wave morphology is stable at 3-year FU. Subtle morphological changes, observed principally in Lead Z, suggest variation of interatrial conduction. These changes could not be detected by measuring conventional PWD that remained unchanged in the total population.
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| 4. |
- Havmöller, Rasmus
(författare)
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Observations of Interatrial Conduction in Healthy Individuals Using Signal-averaged P-wave ECG: A Clinical Perspective
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Disturbances of interatrial conduction are linked to supraventricular arrhythmias. Previous studies have shown that these disturbances can be detected non-invasively as distinctive appearances of the orthogonal P wave using signal-averaged P-wave analysis (PSAECG). Orthogonal recordings (VCG) are however scarce in clinical practice for practical reasons. The aim of the presented study was to explore the possibility of mathematically transforming conventional 12-lead ECGs into orthogonal P-wave data with preserved information content regarding P-wave morphology. If feasible, the method would then be used to analyse P-wave data from healthy adult men and women of all ages in order to provide a first reference material of the “normal” P wave for future studies. Study I evaluated the feasibility of lead conversion (ECG into VCG) in both healthy individuals and arrhythmia patients. The study compared P waves from recorded and derived VCG and it was found that information of interatrial conduction disturbances is preserved. Study II further evaluated this method in a similar material. Different variations of ECG data mimicking true clinical conditions were explored regarding the preservation of P-wave data. It was found that PSAECG is a robust analysis method also in a proposed clinical setting. Study III and IV were devoted to the analysis of P-wave data retrieved from a large material of healthy individuals using the previously validated method. The main finding of Study III was that P-wave morphologies previously observed in arrhythmia patients were commonly observed also in this normal population. The changes were, however, mostly found in the higher age groups, which is in keeping with the known fact that many arrhythmias are more common with increasing age. In Study IV, a long-term follow-up of the “normal” P-wave morphology was conducted, where it was found that P-wave morphology is mostly unaltered after three years. However, in a small number of individuals, discrete changes were observed that support the theory that age-related changes influence interatrial conduction and may implore susceptibility for developing arrhythmias. The presented study adds to the increasing knowledge about interatrial conduction. It provides a validated method for non-invasive exploration of he impulse propagation and also a reference material of the “normal” signal-averaged P-wave morphology.
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| 5. |
- Holmqvist, Fredrik, et al.
(författare)
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Abnormal atrial activation in young patients with lone atrial fibrillation.
- 2011
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092 .- 1099-5129. ; Okt, s. 188-192
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Tidskriftsartikel (refereegranskat)abstract
- Aims Patients with a history of atrial fibrillation (AF) have previously been shown to have altered atrial conduction, as seen non-invasively using signal-averaged P-wave analysis. However, little is known about the P-wave morphology in patients in the early phases of AF with structurally normal hearts. Methods and results Thirty-six patients with lone AF were included before the age of 40 years (34 ± 4 years, 34 men) and compared with age- and gender-matched control subjects. Standard 12-lead electrocardiogram (ECG) was recorded for at least 10 s. P-wave morphology and duration were estimated using signal-averaged P-wave analysis. Echocardiography was performed in association with the ECG recording. Heart rate (67 ± 13 vs. 65 ± 7 b.p.m., P = 0.800) and PQ-interval (163 ± 16 vs. 164 ± 23 ms, P = 0.629) were similar in AF cases and controls, as was P-wave duration (136 ± 13 vs. 129 ± 13 ms, P = 0.107). The distribution of P-wave morphology differed between the AF cases and controls [33/58/0/8 vs. 75/25/0/0% (Type 1/Type 2/Type 3/atypical), P = 0.001], with a larger proportion of patients with AF exhibiting signs of impaired interatrial conduction. Conclusion A significant difference in P-wave morphology distribution was seen between patients with early-onset, lone paroxysmal AF and age- and gender-matched healthy control subjects. This finding indicates that alterations in atrial electrophysiology are common in the early stage of the arrhythmia, and since it occurs in young patients without co-morbidity may well be the cause rather than the consequence of AF.
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| 6. |
- Holmqvist, Fredrik, et al.
(författare)
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Interatrial conduction can be accurately determined using standard 12-lead electrocardiography: validation of P-wave morphology using electroanatomic mapping in man.
- 2008
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Ingår i: Heart Rhythm. - : Elsevier BV. - 1547-5271. ; 5:3, s. 413-418
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Different P-wave morphologies during sinus rhythm as displayed on standard ECGs have been postulated to correspond to differences in interatrial conduction. OBJECTIVE: The purpose of this study was to evaluate the hypothesis by comparing P-wave morphologies using left atrial activation maps. METHODS: Twenty-eight patients (mean age 49 +/- 9 years) admitted for ablation of paroxysmal atrial fibrillation were studied. Electroanatomic mapping of left atrial activation was performed at baseline during sinus rhythm with simultaneous recording of standard 12-lead ECG. Unfiltered signal-averaged P waves were analyzed to determine orthogonal P-wave morphology. The morphology was subsequently classified into one of three predefined types. All analyses were blinded. RESULTS: The primary left atrial breakthrough site was the fossa ovalis in 8 patients, Bachmann bundle in 18, and coronary sinus in 2. Type 1 P-wave morphology was observed in 9 patients, type 2 in 17, and type 3 in 2. Seven of eight patients with fossa ovalis breakthrough had type 1 P-wave morphology, 16 of 18 patients with Bachmann bundle breakthrough had type 2 morphology, and both patients with coronary sinus breakthrough had type 3 P-wave morphology. Overall, P-wave morphology criteria correctly identified the site of left atrial breakthrough in 25 (89%) of 28 patients. CONCLUSION: In the vast majority of patients, P-wave morphology derived from standard 12-lead ECG can be used to correctly identify the left atrial breakthrough site and the corresponding route of interatrial conduction.
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| 7. |
- Holmqvist, Fredrik, et al.
(författare)
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Signal-averaged P wave analysis for delineation of interatrial conduction - Further validation of the method
- 2007
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 7:29
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: BACKGROUND: The study was designed to investigate the effect of different measuring methodologies on the estimation of P wave duration. The recording length required to ensure reproducibility in unfiltered, signal-averaged P wave analysis was also investigated. An algorithm for automated classification was designed and its reproducibility of manual P wave morphology classification investigated. METHODS: Twelve-lead ECG recordings (1 kHz sampling frequency, 0.625 muV resolution) from 131 healthy subjects were used. Orthogonal leads were derived using the inverse Dower transform. Magnification (100 times), baseline filtering (0.5 Hz high-pass and 50 Hz bandstop filters), signal averaging (10 seconds) and bandpass filtering (40-250 Hz) were used to investigate the effect of methodology on the estimated P wave duration. Unfiltered, signal averaged P wave analysis was performed to determine the required recording length (6 minutes to 10 s) and the reproducibility of the P wave morphology classification procedure. Manual classification was carried out by two experts on two separate occasions each. The performance of the automated classification algorithm was evaluated using the joint decision of the two experts (i.e., the consensus of the two experts). RESULTS: The estimate of the P wave duration increased in each step as a result of magnification, baseline filtering and averaging (100 +/- 18 vs. 131 +/- 12 ms; P < 0.0001). The estimate of the duration of the bandpass-filtered P wave was dependent on the noise cut-off value: 119 +/- 15 ms (0.2 muV), 138 +/- 13 ms (0.1 muV) and 143 +/- 18 ms (0.05 muV). (P = 0.01 for all comparisons).The mean errors associated with the P wave morphology parameters were comparable in all segments analysed regardless of recording length (95% limits of agreement within 0 +/- 20% (mean +/- SD)). The results of the 6-min analyses were comparable to those obtained at the other recording lengths (6 min to 10 s).The intra-rater classification reproducibility was 96%, while the interrater reproducibility was 94%. The automated classification algorithm agreed with the manual classification in 90% of the cases. CONCLUSION: The methodology used has profound effects on the estimation of P wave duration, and the method used must therefore be validated before any inferences can be made about P wave duration. This has implications in the interpretation of multiple studies where P wave duration is assessed, and conclusions with respect to normal values are drawn.P wave morphology and duration assessed using unfiltered, signal-averaged P wave analysis have high reproducibility, which is unaffected by the length of the recording. In the present study, the performance of the proposed automated classification algorithm, providing total reproducibility, showed excellent agreement with manually defined P wave morphologies.
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| 8. |
- Holmqvist, Fredrik, et al.
(författare)
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Variable interatrial conduction illustrated in a hypertrophic cardiomyopathy population
- 2007
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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 12:3, s. 227-236
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with hypertrophic cardiomyopathy (HCM) have a high incidence of atrial fibrillation. They also have a longer P-wave duration than healthy controls, indicating conduction alterations. Previous studies have demonstrated orthogonal P-wave morphology alterations in patients with paroxysmal atrial fibrillation. In the present study, the P-wave morphology of patients with HCM was compared with that of matched controls in order to explore the nature of the atrial conduction alterations. Methods and Results: A total of 65 patients (45 men, mean age 49 +/- 15) with HCM were included. The control population (n = 65) was age and gender matched (45 men, mean age 49 +/- 15). Five minutes of 12-lead ECG was recorded. The data were subsequently transformed to orthogonal lead data, and unfiltered signal-averaged P-wave analysis was performed. The P-wave duration was longer in the HCM patients compared to the controls (149 +/- 22 vs 130 +/- 16 ms, P < 0.0001). Examination of the P-wave morphology demonstrated changes in conduction patterns compatible with interatrial conduction block of varying severity in both groups, but a higher degree of interatrial block seen in the HCM population. These changes were most prominent in the Leads Y and Z. Conclusion: The present study suggests that the longer P-wave duration observed in HCM patients may be explained by a higher prevalence of block in one or more of the interatrial conduction routes.
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| 9. |
- Thilén, Ulf, et al.
(författare)
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Prolonged P wave duration in adults with secundum atrial septal defect: a marker of delayed conduction rather than increased atrial size?
- 2007
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092 .- 1099-5129. ; 9:Suppl 6, s. 105-108
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Although atrial fibrillation is a frequent complication of an atrial septal defect (ASD) of the secundum type, the underlying mechanisms are poorly understood. Atrial conduction disturbances, manifested as a prolonged P-wave duration, have been suggested as a substrate for arrhythmia. Prolongation of the P-wave in unrepaired ASD has been demonstrated by means of the conventional ECG, but not by more sophisticated methods. The aim of the study was to analyse P-wave duration and morphology by high-resolution P-wave signal-averaged ECG (PSA-ECG) and to investigate potential atrial mechano-electrical interactions in adults with an unrepaired ASD. METHODS AND RESULTS: P-wave signal-averaged-ECG was obtained in 35 adult patients (age 53 +/- 15 years) with ASD and compared with an equal number of sex- and age-matched healthy controls. Right and left atrial sizes were assessed by echocardiography in the ASD group. P wave duration was significantly longer in the ASD group than in control subjects (148 +/- 16 vs. 128 +/- 15 ms, P < 0.0001). P-wave morphology did not differ significantly between patients and controls. There was no clear relation between P-wave duration and atrial size. CONCLUSION: Atrial septal defect in the adult is characterized by a prolonged P-wave duration, indicating delayed atrial conduction, which is not related to the enlargement of the atria but rather to conduction delay. The nature and potential reversibility of this warrant further investigation.
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