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Nils Edvardsson

Publications and source records attributed to Nils Edvardsson.

13 recordsLinked to original sources
PubMed2006

New insights into the initiation of atrial fibrillation: a detailed intraindividual and interindividual analysis of the spontaneous onset of atrial fibrillation using new diagnostic pacemaker features.

BACKGROUND: This study investigated onset scenarios of atrial fibrillation (AF), the first phase of the Atrial Fibrillation Therapy (AFT) trial, to determine potential arrhythmogenic triggers as targets for atrial pacing algorithms that have been proposed for prevention of AF. METHODS AND RESULTS: Ninety-eight patients (58 men; age 65+/-11 years) with recurrent, symptomatic, drug-refractory AF and a conventional pacemaker indication in 31 of 98 received a dual-chamber pacemaker. Using novel diagnostic pacemaker features AF onset scenarios were prospectively evaluated in 612 AF episodes during a 2-month monitoring period, with atrial pacing limited to 40 bpm. The most common onset scenario was premature atrial complexes (PACs) before AF (48% onsets per patient), followed by bradycardia (33%), sudden onset (17%), and tachycardia (0%). Combinations of onset scenarios were frequent (median 2 different scenarios per patient). A main study finding was the significance of repetitive AF, with 33% of onsets per patient being initiated within 5 minutes of a previous AF episode. Sudden onsets were more frequent among patients with than without repetitive AF (24% versus 0% onsets per patient, P=0.011), whereas the proportion of PACs before AF was not statistically different (50% versus 37%, P=0.52); however, patients with repetitive AF had more PACs per hour (72 versus 29, P=0.023) and a higher number of AF episodes per day (17 versus 0, P=0.001) and were more likely to have at least 1 PAC-related onset (90% versus 53%, P<0.0001). CONCLUSIONS: Novel diagnostic pacemaker features allowed a detailed individual analysis of rate and rhythm changes before AF and thus uncovered a substantial intraindividual and interindividual variability of AF onset scenarios.

Aged↗
PubMed2006

T wave inversions following ablation of 125 posteroseptal accessory pathways.

BACKGROUND: Cardiac memory, electrophysiological remodeling induced by periods of altered ventricular activation, has been observed after resumption of normal activation following ablation of overt accessory pathways. We studied the occurrence and temporal characteristics of cardiac memory (inferior T wave inversions) after ablation of overt posteroseptal accessory pathways. METHODS: T wave changes were assessed in the frontal plane (leads II, aVF, and III) up to one year after the ablation in 125 consecutive patients. T wave polarity immediately after ablation was compared with the pre ablation delta wave polarity and the dominant QRS force in each lead. The number of inferior leads (0-3) with post ablation T wave changes (estimate of degree of cardiac memory) was analyzed in relation to estimates of the degree of preexcitation (accessory pathway refractoriness and QRS duration) prior to ablation. RESULTS: Electrocardiogram (ECG) signs of cardiac memory were present in 123 (98%) of the patients within one day after ablation. The post ablation T wave vector had the same direction as the vector of the pre-excited QRS complex (and delta wave) creating inferior T wave inversions. There was no correlation between the degree of preexcitation pre ablation and the extent of cardiac memory post ablation. A majority (about 90%) of ECGs recorded 3-6 months after the procedure, showed complete or almost complete normalization. CONCLUSIONS: T wave inversions were present in the vast majority of patients, persisted in some patients beyond 3 months, and might be misinterpreted as inferior wall ischemia.

Catheter Ablation↗
PubMed2004

Genuine effects of ventricular fibrillation upon myocardial blood flow, metabolism and catecholamines in patients with aortic stenosis.

OBJECTIVE: Ventricular fibrillation (VF) is life-threatening because of its haemodynamic and metabolic effects. The purpose was to examine if VF also has primary effects per se. We therefore investigated the early effects of VF on myocardial blood flow, metabolic characteristics and catecholamine concentrations in patients undergoing surgery for aortic stenosis. DESIGN: The immediate effects of up to 5 min of VF were studied in 21 patients during cardiopulmonary bypass (CPB) before valve replacement. RESULTS: During VF the global myocardial oxygen consumption, coronary blood flow and vascular resistance were unchanged, and the mean arterial pressure (on CPB) decreased from 70 to 51 mmHg (p < 0.02). Fibrillation induced a high myocardial tone and a probable functional aortic insufficiency, which instantly equilibrated left ventricular and aortic pressures. Signs of myocardial ischaemia and acidosis developed after 4 min: a decrease in the pH of coronary sinus blood from 7.38 to 7.32 (p < 0.001), an increased release of lactate from 32 to 137 micromol/min (p < 0.001) and potassium from 29 to 73 micromol/min (p < 0.05). The noradrenaline net release increased from 0.021 to 0.58 nmol/min (p < 0.02) after 1.5 min of VF and then decreased. The adrenaline net uptake remained low and unchanged (17-28%). CONCLUSION: VF in patients with aortic stenosis was rapidly followed by myocardial ischaemia, acidosis and a transient increase in the myocardial noradrenaline net release despite sufficient coronary perfusion and unchanged global myocardial oxygen consumption. The VF instantly induced equilibration of left ventricular and aortic pressure and probably caused a relative underperfusion of the subendocardium. These factors all support persistence of VF.

Adult↗
PubMed2003

Dronedarone for prevention of atrial fibrillation: a dose-ranging study.

AIMS: Dronedarone, a benzofurane derivative without iodine substituents, shares the electrophysiologic properties of amiodarone. This study was designed to determine the most appropriate dose of dronedarone for prevention of atrial fibrillation (AF) after cardioversion. METHODS AND RESULTS: Patients with persistent AF were randomly allocated to 800, 1200, 1600 mg daily doses of dronedarone or placebo. The main analysis was conducted on 199/270 patients, who entered the maintenance phase following pharmacological cardioversion or, if unsuccessful, DC cardioversion. Within 6-month follow-up, the time to AF relapse increased on dronedarone 800 mg, with a median of 60 days vs 5.3 days in the placebo group (relative risk reduction 55% [95% CI, 28 to 72%] P=0.001). No significant effect was seen at higher doses. Spontaneous conversion to sinus rhythm on dronedarone occurred in 5.8 to 14.8% of patients (P=0.026). There were no proarrhythmic reactions. Drug-induced QT prolongation was only noticed in the 1600 mg group. Premature drug discontinuations affected 22.6% of subjects given 1600 mg dronedarone versus 3.9% on 800 mg and were mainly due to gastrointestinal side effects. No evidence of thyroid, ocular or pulmonary toxicity was found. CONCLUSION: Dronedarone, at a 800 mg daily dose, appears to be effective and safe for the prevention of AF relapses after cardioversion. The absence of thyroid side effects and of proarrhythmia are important features of the drug. Further studies are needed to better delineate the antiarrhythmic profile of the drug.

Aged↗
PubMed2003

Inter- and intraday variability in major electrocardiogram intervals and amplitudes in healthy men and women.

The ECG may vary during the day (intra-day), and between days (interday), for the same subject. Variability in ECG characteristic measurements between different investigators is well documented and is often large. During days 1-6 of each placebo period of a two-way crossover Phase I study, digital ECGs were recorded at about 8 and 12 AM in 16 healthy volunteers (8 men, 8 women). Two observers independently analyzed leads V2 and V6 using EClysis software. The durations and amplitudes of major ECG waves and the intervals between major electrocardiographic events were analyzed in a mixed model ANOVA, in which subject, observer, time, and day were treated as random factors. The influence of various corrections for heart rate on the variability of QT intervals was investigated. The difference among subjects explained between 44-81% of the total variability in ECG intervals and amplitudes. Overall, inter- and intraday variability was not statistically significant for any variable. The individualized exponential correction of the QT interval for heart rate eliminated the QT interval dependence on the RR interval in all subjects. Changes in T wave morphology and shortening of the QT interval from morning to noon were observed in ten subjects. The interobserver variability was close to zero (SD < 0.005 ms) for all variables except the PQ interval (SD 1.4 ms). The various sources of variability in determinations of ECG wave characteristics should be considered in the design of clinical studies. The use of EClysis software for ECG measurements is this study made the results highly observer independent.

Adult↗
PubMed2003

Feasibility of spinal cord stimulation in angina pectoris in patients with chronic pacemaker treatment for cardiac arrhythmias.

Spinal cord stimulation (SCS) has been used since 1985 as additional symptom-relieving treatment for patients with severe angina pectoris despite optimal conventional medical and invasive treatment. SCS has antiischemic effects and is safe and effective in long-term use. Several patients with coronary artery disease also suffer from disorders that necessitate the use of a cardiac permanent pacemaker (PPM). The combination of SCS and PPM has previously been considered hazardous because of possible false inhibition of the PPM. To assess if thoracic SCS and PPM can be safely combined in patients with refractory angina pectoris, 18 patients treated with both SCS and PPM were tested. The PPM settings were temporarily modified to increase the probability of interference, while the SCS intensity (used in bipolar mode) was increased to the maximum level tolerated by the patient. Any sign of inhibition of the ventricular pacing was recorded by continuous ECG monitoring. With the aid of a questionnaire, symptoms of interference during long-term treatment were evaluated. No patient had signs of inhibition during the tests. Reprogramming of the pacemaker because of the test results was not needed in any of the patients. The long-term follow-up data revealed no serious events. This study indicates that bipolar SCS and PPM can be safely combined in patients with refractory angina pectoris. However, individual testing is mandatory to ascertain safety in each patient. A testing procedure for patients in need of SCS and PPM is suggested in this article.

Aged↗
PubMed2002

Embolic complications of direct current cardioversion of atrial arrhythmias: association with low intensity of anticoagulation at the time of cardioversion.

OBJECTIVES: The goal of this study was to identify the factors responsible for embolic complications of direct current (DC) cardioversion of atrial arrhythmias. BACKGROUND: Direct current cardioversion of atrial fibrillation (AF) carries a risk of thromboembolism, which is reduced, but not eliminated, by anticoagulation. The risk of embolism after conversion of atrial flutter is believed to be lower. No series to date has included enough patients receiving anticoagulants or enough patients with atrial flutter to estimate the risk in these groups. METHODS: We reviewed the case records of 1,950 patients who underwent 2,639 attempts at DC cardioversion. RESULTS: Cardioversion was performed within two days of the apparent onset of the arrhythmia in 443 episodes, 352 without subsequent prolonged anticoagulation with one embolic complication. Cardioversion was preceded by warfarin therapy for > or = 3 weeks in 1,932 instances. No embolic complication occurred in 779 attempts performed with an international normalized ratio (INR) of > or = 2.5 (95% confidence limits 0% to 0.48%). Of 756 cases in which the INR was <2.5 or was not measured before conversion, nine were complicated by thromboembolism. Embolism was significantly more common at an INR of 1.5 to 2.4 than at an INR > or = 2.5 (0.93% vs. 0%, p = 0.012). The incidence of embolism after conversion of atrial flutter or tachycardia was similar to that after cardioversion of AF (0.72% vs. 0.46%, p = NS). CONCLUSIONS: The INR should be > or = 2.5 at the time of cardioversion if the duration of AF is uncertain or >2 days. Cardioversion of atrial flutter presents similar risks and requires similar anticoagulation.

Anticoagulants↗
PubMed2002

Life situation related to the ICD implantation; self-reported uncertainty and satisfaction in Swedish and US samples.

The aim of the study was to describe changes in the life situation related to the ICD implantation of Swedish and US samples with regard to uncertainty and satisfaction. The life situation was measured by reference to the uncertainty caused by the condition and satisfaction with the life situation. Inferential statistics were used to analyse changes within and between the Swedish and US samples. Uncertainty showed a statistically significant difference between the Swedish and US samples before as well as after the ICD implantation. A higher level of uncertainty was indicated for the US sample prior to the ICD implantation and for the Swedish sample following the implantation. In the Swedish sample, satisfaction with life showed a statistically significant difference within the socio-economic domain, indicating a higher degree of satisfaction 3 months after implantation. Satisfaction within the domains of health and functioning, socio-economics and psychological-spiritual showed a statistically significant difference between the Swedish and US samples both before and after ICD implantation, indicating a higher degree of satisfaction in the US sample. The previous study shows that the ICD-patient's life situation is changed after the implantation and that it is necessary to provide the patient with information and education based on their own preconditions. The fact that US sample was investigated at a later stage after ICD implantation than the Swedish sample may have influenced the results of the study.

Aged↗
PubMed2002

QRS aberration during atrial fibrillation at rest and during exercise. Effect of a selective potassium channel blocking agent.

This study assesses the occurrence of and identifies clinical characteristics associated with the development of aberrant conduction during infusion of the I(kr)-blocker almokalant. Class III drugs may induce aberrant conduction by prolongation of cardiac repolarization, especially during atrial fibrillation (AF). Ninety-two patients with AF received a 6-hour almokalant infusion, aiming at conversion to sinus rhythm (SR). Fiftyfive of the patients received an identical infusion during SR. During almokalant infusion, the number of patients with intermittent QRS aberration during AF increased, from 21% to 80% at rest, and was further increased to 89% during exercise, with predominantly left, and sequential bilateral, bundle branch aberrancy. Patients with aberrant conduction showed signs of more advanced myocardial disease. Predictors of the development of QRS aberration were female gender, arrhythmia duration, and decreased left ventricular ejection fraction, while use of calcium antagonists decreased the probability. No patient showed aberration during regular SR. Twenty-one patients experienced aberrantly conducted supraventricular premature beats. In conclusion, aberrant conduction is common during infusion of the I(kr)-blocker almokalant during AF, and seems to be more frequent in females and in patients with more advanced myocardial disease.

Anti-Arrhythmia Agents↗
PubMed2002

Computer-based analysis of dynamic QT changes: toward high precision and individual rate correction.

BACKGROUND: New strategies are needed to improve the results of automatic measurement of the various parts of the ECG signal and their dynamic changes. METHODS: The EClysis software processes digitally-recorded ECGs from up to 12 leads at 500 Hz, using strictly defined algorithms to detect the PQRSTU points and to measure ECG intervals and amplitudes. Calculations are made on the averaged curve of each sampling period (beat group) or as means +/- SD for beat groups, after being analyzed at the individual beat level in each lead. Resulting data sets can be exported for further statistical analyses. Using QT and R-R measured on beat level, an individual correction for the R-R dependence can be performed. RESULTS: EClysis assigns PQRSTU points and intervals in a sensitive and highly reproducible manner, with coefficients of variation in ECG intervals corresponding to ca. 2 ms in the simulated ECG. In the normal ECG, the CVs are 2% for QRS, 0.8% for QT, and almost 6% for PQ intervals. EClysis highlights the increase in QT intervals and the decrease of T-wave amplitudes during almokalant infusion versus placebo. Using the observed linear or exponential relationships to adjust QT for R-R dependence in healthy subjects, one can eliminate this dependence almost completely by individualized correction. CONCLUSIONS: The EClysis system provides a precise and reproducible method to analyze ECGs.

Adult↗
PubMedDate not supplied

Long-term quality of life and uncertainty in patients living with an implantable cardioverter defibrillator.

PURPOSE: This study describes the quality of life (QOL) and uncertainty in patients who have an implantable cardioverter defibrillator (ICD) and predicts QOL at long-term follow-up. METHODS: Long-term follow-up was defined as 6.9 years +/- 1 year (range 4.11-8.7 years). QOL was measured with the Quality of Life Index, and uncertainty was measured with the Mishel Uncertainty in Illness Scale. RESULTS: The overall QOL and health/functioning were unchanged over time. QOL in the socioeconomic (P = .002) and psychologic/spiritual domains (P = .012) decreased in the first year. From baseline to long-term follow-up, the QOL in the family domain (P = .011) and uncertainty (P = .002) decreased. Uncertainty was a predictor of low QOL. CONCLUSION: QOL was reasonably good 6.9 years post-ICD implantation. Patients felt less uncertain once they had passed the first year of their illness.

Arrhythmias, Cardiac↗