| 1. |
- Gunnarsson, Gunnar, 1965, et al.
(författare)
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Continuous ST-segment monitoring of patients with right bundle branch block and suspicion of acute myocardial Infarction
- 2005
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Ingår i: Ann Noninvasive Electrocardiol. - 1082-720X. ; 10:2, s. 161-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Patients with right bundle branch block comprise 5-9% of all patients with acute myocardial infarction. In spite of this, limited data exist on early diagnosis or the usefulness of continuous electrocardiographic monitoring in these patients. METHODS: A prospective multicenter study with 14 Swedish coronary care units. Patients with right bundle branch block and suspicion of acute myocardial infarction with less than 6 hours symptom duration were included. All patients were monitored with continuous vectorcardiography for 12-24 hours. RESULTS: Seventy-nine patients were included, 43% had acute myocardial infarction. Patients with acute myocardial infarction had significantly higher initial ST-vector magnitude values (P = 0.0014) compared to patients without acute myocardial infarction. Patients with acute myocardial infarction also showed gradual regression of ST-vector magnitude over time that was not seen for patients without acute myocardial infarction (P = 0.005). ST-vector magnitude measured at the J-point differentiated best between patients with and without acute myocardial infarction. A cutoff value of 125 microV for initial ST-vector magnitude resulted in 55% sensitivity and 87% specificity for the diagnosis of acute myocardial infarction. Over time, patients with acute myocardial infarction showed greater changes in QRS-vector difference compared to patients without acute myocardial infarction (P = 0.052). CONCLUSION: Vectorcardiographic monitoring shows good diagnostic abilities for patients with right bundle branch block and clinical suspicion of acute myocardial infarction and could be useful for continuous monitoring of these patients.
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| 2. |
- 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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| 3. |
- Holmqvist, Fredrik, et al.
(författare)
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Altered interatrial conduction detected in MADIT II patients bound to develop atrial fibrillation.
- 2009
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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 14:3, s. 268-275
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Changes in P-wave morphology have recently been shown to be associated with interatrial conduction route used, without noticeable changes of P-wave duration. This study aimed at exploring the association between P-wave morphology and future atrial fibrillation (AF) development in the Multicenter Automatic Defibrillator Trial II (MADIT II) population. METHODS: Patients included in MADIT-II without a history of AF with sinus rhythm at baseline who developed AF during the study ("Pre-AF") were compared to matched controls without AF development ("No-AF"). Patients were followed for a mean of 20 months. A 10-minute high-resolution bipolar ECG recording was obtained at baseline. Signal-averaged P waves were analyzed to determine orthogonal P-wave morphology, P-wave duration, and RMS20. The P-wave morphology was subsequently classified into one of three predefined types using an automated algorithm. RESULTS: Thirty patients (age 68 +/- 7 years) who developed AF during MADIT-II were compared with 60 patients (age 68 +/- 8 years) who did not. P-wave duration and RMS20 in the Pre-AF group was not significantly different from the No-AF group (143 +/- 21 vs 139 +/- 30 ms, P=0.26, and 2.0 +/- 1.3 vs 2.1 +/- 1.0 muV, P=0.90). The distribution of P-wave morphologies was shifted away from Type 1 in the Pre-AF group when compared to the No-AF group (Type 1/2/3/atypical; 25/60/0/15% vs 10/63/10/17%, P=0.04). CONCLUSIONS: This study is the first to describe changes in P-wave morphology in patients prior to AF development. The results indicate that abnormal interatrial conduction may play a role in AF development in patients with prior myocardial infarction and congestive heart failure.
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| 4. |
- Holmqvist, Fredrik, et al.
(författare)
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Detailed ECG analysis of atrial repolarization in humans.
- 2009
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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 14:1, s. 13-18
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Data on human atrial repolarization are scarce since the QRS complex normally obscures its ECG trace. In the present study, consecutive patients with third-degree AV block were studied to better describe the human Ta wave. METHODS AND RESULTS: Forty patients (mean age 75 years, 17 men) were included. All anti-arrhythmic drugs were discontinued before ECG recording. Standard 12-lead ECGs were recorded, transformed to orthogonal leads and studied using signal-averaged P wave analysis. The average P wave duration was 124 +/- 16 ms. The PTa duration was 449 +/- 55 ms (corrected PTa 512 +/- 60 ms) and the Ta duration (P wave end to Ta wave end) was 323 +/- 56 ms. The polarity of the Ta wave was opposite to that of the P wave in all leads. The Ta peaks were located at 196 +/- 55 ms in Lead Y, 216 +/- 50 ms in Lead X, and 335 +/- 92 in Lead Z. No correlation was found between P wave duration and Ta duration, or between Ta peak amplitude and Ta duration. The morphology of the Ta wave was similar regardless of the interatrial conduction. CONCLUSIONS: The Ta wave has the opposite polarity, and the duration is generally two to three times that, of the P wave. Although the Ta peak may occasionally be located in the PQ interval during normal AV conduction, it is unlikely that enough information can be obtained from analysis of this segment to differentiate normal from abnormal atrial repolarization. Hence, an algorithm for QRST cancellation during sinus rhythm is needed to further improve analysis.
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| 5. |
- 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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| 6. |
- Husser, D, et al.
(författare)
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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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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 10:2, s. 206-210
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Tidskriftsartikel (refereegranskat)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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