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- Ahlsson, Anders, 1962-
(author)
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Atrial fibrillation in cardiac surgery
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Atrial fibrillation (AF) is the most common arrhythmia seen in clinical practice. In cardiac surgery, one-third of the patients experience episodes of AF during the first postoperative days (postoperative AF), and patients with preoperative AF (concomitant AF) can be offered ablation procedures in conjunction with surgery, in order to restore ordinary sinus rhythm (SR). The aim of this work was to study the relation between postoperative AF and inflammation; the long-term consequences of postoperative AF on mortality and late arrhythmia; and atrial function after concomitant surgical ablation for AF. In 524 open-heart surgery patients, C-reactive protein (CRP) serum concentrations were measured before and on the third day after surgery. There was no correlation between levels of CRP and the development of postoperative AF. All 1,419 patients with no history of AF, undergoing primary aortocoronary bypass surgery (CABG) in the years 1997–2000 were followed up after 8.0 years. The mortality rate was 191 deaths/1,000 patients (19.1%) in patients with no AF and 140 deaths/419 patients (33.4%) in patients with postoperative AF. Postoperative AF was an age-independent risk factor for late mortality, with a hazard ratio (HR) of 1.56 (95% CI 1.23–1.98). Postoperative AF patients had a more than doubled risk of death due to cerebral ischaemia, myocardial infarction, sudden death, and heart failure compared with patients without AF. All 571 consecutive patients undergoing primary CABG during the years 1999–2000 were followed-up after 6 years. Questionnaires were obtained from 91.6% of surviving patients and an electrocardiogram (ECG) from 88.3% of all patients. In postoperative AF patients, 14.1% had AF at follow-up, compared with 2.8% of patients with no AF at surgery (p<.001). An episode of postoperative AF was found to be an independent risk factor for development of late AF, with an adjusted risk ratio (RR) of 3.11 (95% CI 1.41–6.87). Epicardial microwave ablation was performed in 20 open-heart surgery patients with concomitant AF. Transthoracic echocardiography was performed preoperatively and at 6 months postoperatively. At 12 months postoperatively 14/19 patients (74%) were in SR with no anti-arrhythmic drugs. All patients in SR had preserved left and right atrial filling waves (A-waves) and Tissue velocity echocardiography (TVE) showed preserved atrial wall velocities and atrial strain. In conclusion, postoperative AF is an independent risk factor for late mortality and later development of AF. There is no correlation between the inflammatory marker CRP and postoperative AF. Epicardial microwave ablation of concomitant AF results in SR in the majority of patients and seems to preserve atrial mechanical function.
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| 2. |
- Ågren, Henrik, 1968-
(author)
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Tidigmodern tid : Den sociala tidens roll i fyra lokalsamhällen 1650-1730
- 1998
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Doctoral thesis (other academic/artistic)abstract
- This dissertation examines how time-reckoning was used in Swedish courts in the early modem period. The theoretical foundation is that the need for people to coordinate in time becomes more important the larger and more complicated the social context is. Therefore, it is more important that one part in a communication is clear in its indication of time the less the other part shares its everyday life. A time-indication is formed by the situation of both sender and receiver, within the context of a society's system of measuring time.During the seventeenth and eighteenth centuries, contacts between local communities and central state institutions intensified through the state's increasing demands of influence over local authorities.Thereby, a situation arose in which it became more important for ordinary courts to be careful in theirrecord keeping with, among other things, time-reckoning. Terms for time are also formed by the context in which they are reckoned. As life is different in different types of local communities, there are also differences in the use of time in different courts. Therefore, the empirical study is a comparison of the Lagunda district court, the Uppsala city courts, and the Sala mining court, circa 1650 and circa 1730. Lagunda represents a rural environment, while Uppsala represents a preindustrial urban area. Sala silver mine is included in the study as an industrial environment. Also, the city courts of Sala have been studied to gain perspective on the comparison between Uppsala and Sala silver mine.The results show that both the chronological differences and differences in areas of investigation were important. During the 1730's, all courts were considerably more careful in time-reckoning than they had been in the 1650's. Also, the similarities between the areas were greater, which must be seen as a result of the fact that time-reckoning primarily was made for the sake of the central institution towhich the records were to be sent. The more interactive the state, the greater the precision of courtrecords and uniformity of local communities. The time-indications used are thus more a reflection ofthe need for understanding in communication between separate institutions than of organisation in thelocal community.The manifest differences between the areas are that while time in Lagunda and at Sala silver mine in different ways reflected the areas' economic foundation, time-reckoning in the towns was of a more varied nature. The results for the towns of Sala and Uppsala are more similar than those of the townof Sala and Sala silver mine, although the selection of people was practically the same at the mine andin the town. This indicates that the environment and the type of court played a greater role in deter-mining which results we obtain, than did the people's own concept of time. However, there were somesimilarities between the town of Sala and the silver mine. Therefore, one cannot rule out that the results also reflect peoples' relation to time, irrespective of the situation they are in.
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| 3. |
- Kesek, Milos, 1957-
(author)
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Traces of Repolarization Inhomogeneity in the ECG
- 2005
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Doctoral thesis (other academic/artistic)abstract
- Repolarization inhomogeneity is arrhythmogenic. QT dispersion (QTd) is an easily accessible ECG-variable, related to the repolarization and shown to carry prognostic information. It was originally thought to reflect repolarization inhomogeneity. Lately, arguments have been risen against this hypothesis. Other measures of inhomogeneity are being investigated, such as nondipolar components from principal component analysis (PCA) of the T-wave. In all here described populations, continuous 12-lead ECG was collected during the initial hours of observation and secondary parameters used for description of a large number of ECG-recordings.Paper I studied QTd in 548 patients with chest pain with a median number of 985 ECG-recordings per patient. Paper II explored a spatial aspect of QTd in 276 patients with unstable coronary artery disease. QTd and a derived localized ECG-parameter were compared to angiographical measures. QTd, expressed as the mean value during the observation was a powerful marker of risk. It was however not effective in identifying high-risk patients. Variations in QTd contained no additional prognostic information. In unstable coronary artery disease, QTd was increased by a mechanism unrelated to localization of the disease.Two relevant conditions for observing repolarization inhomogeneity might occur with conduction disturbances and during initial course of ST-elevation myocardial infarction (STEMI). Paper III compared the PCA-parameters of the T-wave in 135 patients with chest pain and conduction disturbance to 665 patients with normal conduction. Nondipolar components were quantified by medians of the nondipolar residue (TWRabsMedian) and ratio of this residue to the total power of the T-wave (TWRrelMedian). Paper IV described the changes in the nondipolar components of the T-wave in 211 patients with thrombolyzed STEMI. TWRabsMedian increased with increasing conduction disturbance and contained a moderate amount of prognostic information. In thrombolyzed STEMI, TWRabsMedian was elevated and has an increased variability. A greater decrease in absolute TWR during initial observation was seen in patients with early ST-resolution. Nondipolar components do however not reflect identical ECG-properties as the ST-elevation and their change does not occur at the same time.
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