Biomedical subjects

C Blomström-Lundqvist

Publications and source records attributed to C Blomström-Lundqvist.

At least 19 recordsLinked to original sources

PubMed2001

ACC/AHA/ESC Guidelines for the Management of Patients With Atrial Fibrillation: Executive Summary A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines and Policy Conferences (Committee to Develop Guidelines for the Management of Patients With Atrial Fibrillation) Developed in Collaboration With the North American Society of Pacing and Electrophysiology.

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Aged↗

PubMed2001

Thoracic epidural anesthesia does not influence the occurrence of postoperative sustained atrial fibrillation.

BACKGROUND: To evaluate whether thoracic epidural anesthesia (TEA) can reduce the incidence of atrial fibrillation (AF) after coronary artery bypass grafting (CABG). METHODS: Forty-one patients undergoing CABG were treated with TEA intraoperatively and postoperatively. Another 80 patients served as the control group. The sympathetic and parasympathetic activities were evaluated by analysis of neuropeptides, catecholamines and heart rate variability (HRV), preoperatively and postoperatively. RESULTS: Postoperative AF occurred in 31.7% of the TEA-treated patients and in 36.3% of the untreated patients (p = 0.77). TEA significantly suppressed sympathetic activity, as indicated by a less pronounced increase of norepinephrine and epinephrine (p = 0.03, p = 0.02) and a significant decrease of neuropeptide Y (p = 0.01) postoperatively in TEA-treated patients compared to untreated patients. The HRV variable expressing sympathetic activity was significantly lower and the postoperative increase in heart rate was significantly less in the TEA group than in the control group after surgery (p = 0.01, p < 0.001). Among patients developing AF, the maximal number of supraventricular premature beats per minute increased significantly in untreated patients postoperatively but remained unchanged in TEA-treated patients (p = 0.004 versus p = 0.86). CONCLUSIONS: TEA has no effect on the incidence of postoperative sustained AF, despite a significant reduction in sympathetic activity.

Aged↗

PubMed2001

ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation: executive summary. A Report of the American College of Cardiology/ American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines and Policy Conferences (Committee to Develop Guidelines for the Management of Patients With Atrial Fibrillation): developed in Collaboration With the North American Society of Pacing and Electrophysiology.

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Algorithms↗

PubMed2001

Diminished circadian variation in heart rate variability before surgery in patients developing postoperative atrial fibrillation.

OBJECTIVE: To evaluate the role of the autonomic nervous system for the development of atrial fibrillation (AF) after coronary artery bypass surgery. DESIGN: Eighty patients without a previous history of AF were included. The sympathetic and parasympathetic activity were evaluated by the analysis of heart rate variability (HRV) in the frequency domain from 24-h Holter recordings and by measuring neuropeptides (neuropeptide Y, chromogranin A, chromogranin B, and pancreatic polypeptide (PP)) and catecholamines, obtained pre- and postoperatively. RESULTS: Preoperatively, patients (36.3%) developing AF postoperatively showed a statistically significant less circadian variation in the HRV variables, the high-frequency (HF) component (p = 0.013) and the low-frequency (LF)/HF ratio (p = 0.007), than patients remaining in sinus rhythm. The HF component and PP. both reflecting parasympathetic activity, and all other variables in the frequency domain, decreased significantly after surgery in both patient groups (p < 0.0001). Although catecholamines increased significantly postoperatively in both patient groups, neither catecholamines nor neuropeptides expressing sympathetic activity, differed between the two groups. PP was, however, significantly higher in patients with postoperative AF than in those with sinus rhythm postoperatively on day 1. CONCLUSION: The diminished circadian variation in HRV before surgery and the indirect signs of a higher parasympathetic activity in patients developing postoperative AF compared with patients remaining in sinus rhythm, may indicate a propensity for AF.

Aged↗

PubMed2000

Effects of the maze operation on health-related quality of life in patients with atrial fibrillation.

BACKGROUND: Maze surgery for atrial fibrillation (AF) is a curative therapy, but its effect on health-related quality of life has not been studied. METHODS AND RESULTS: Maze operations were performed in 48 patients with drug-refractory AF. The majority of patients (80%) had lone AF, and the primary indication for surgery in all patients was AF. The SF-36 Health Survey was used to assess quality of life before operation and at 6 months and 1 year after surgery. Twenty-five patients were available for the 1-year follow-up and completed all questionnaires. Before maze surgery, the SF-36 scores were significantly lower than in the general Swedish population, reflecting significant impairment in well-being, physical and social functioning, and mental health. After maze surgery, the quality of life was significantly improved at 6 months and at 1 year on all scales except for bodily pain, which, however, was not significantly decreased before surgery. At both 6 months and 1 year after maze surgery, quality of life, measured by the SF-36, reached the levels of the general Swedish population. CONCLUSIONS: The maze operation can significantly improve the health-related quality of life in selected groups of patients with both paroxysmal and chronic AF refractory to antiarrhythmic therapy.

Adult↗

PubMed2000

Tachyarrhythmias and triggering factors for atrial fibrillation after coronary artery bypass operations.

BACKGROUND: We evaluated the role of supraventricular arrhythmias and assessed clinical predictors of atrial fibrillation (AF) that developed after coronary artery bypass operations. METHODS: Eighty patients, with a mean age of 65.8 years, underwent 24-hour Holter monitoring preoperatively and for 4 consecutive days postoperatively, or until clinically documented AF, for analysis of the number of premature beats and tachyarrhythmias. Atrial areas and atrial peptides were measured preoperatively and postoperatively. RESULTS: Twenty-nine of 80 (36.3%) patients had postoperative AF. Preoperatively, the maximal supraventricular premature beats per minute were higher in the AF group (p = 0.02). The body mass index and total amount of cardioplegia were lower (p = 0.02 and p = 0.006, respectively), and withdrawal of beta-blockers postoperatively more frequent (p = 0.001) in the AF group, but atrial areas and atrial peptides did not differ. CONCLUSIONS: Frequent supraventricular premature beats preoperatively may indicate a propensity for AF. A larger amount of cardioplegia during the cross-clamp period may reduce the risk of postoperative AF. Further studies are mandatory to clarify why patients with lower body mass index were more prone to AF.

Aged↗

PubMed2000

The value of predischarge ICD tests in patients with a successful peroperative test.

An internal cardioverter defibrillator (ICD) is normally extensively tested during implantation. The necessity of retesting prior to discharge of the patient is a matter of debate. In our material of 30 patients undergoing first-time implantation of a transvenous internal defibrillator system, we retrospectively compare the predischarge defibrillation test with the peroperative test. A successful peroperative defibrillation test with no failed shocks at 10 J below maximal energy level was followed by a successful predischarge test with the same safety margin in 18/19 patients, while one patient required a maximal energy ICD shock for conversion at the predischarge test. We conclude that the predischarge defibrillation test can be omitted if the peroperative test was successful, with no failed shocks at 10 J below maximal energy level and if the shock therapy is set to maximal energy level.

Defibrillators, Implantable↗

PubMed1999

Autosomal dominant myofibrillar myopathy with arrhythmogenic right ventricular cardiomyopathy linked to chromosome 10q.

Twenty-one members of a Swedish family suffering from myopathy and cardiomyopathy underwent neurological and cardiological investigations. Medical charts of 2 affected deceased patients were reviewed. Twelve patients had myopathy. The distribution of weakness was axial in mildly affected, axial and predominantly distal in moderately affected, and generalized in severely affected patients. The electromyogram showed signs of myopathy in 10 patients. Muscle biopsy specimens showed myopathic changes, rimmed vacuoles, and accumulation of desmin, dystrophin, and other proteins. Electron microscopy revealed granulofilamentous changes and disorganization of myofibrils. Several patients had episodes of chest pain or palpitations. Three men had arrhythmogenic right ventribular cardiomyopathy. Nonsustained ventribular tachycardia, atrial flutter, and dilatation of the ventricles mainly affecting the right ventricle were documented. Two of them had a pacemaker implanted because of atrioventricular block and sick sinus syndrome. Inheritance is autosomal dominant with variable onset and severity of skeletal muscle and cardiac involvement. Linkage analysis of candidate chromosomal regions showed a maximum 2-point LOD score of 2.76 for marker locus D10S1752 on chromosome 10q. A multipoint peak LOD score of 3.06 between markers D10S605 and D10S215 suggests linkage to chromosome 10q22.3, and this region may harbor a genetic defect for myofibrillar myopathy with arrhythmogenic right ventricular cardiomyopahty.

Adult↗

PubMed1998

The safety of reusing ablation catheters with temperature control and the need for a validation protocol and guidelines for reprocessing.

The objective of this study was to evaluate the safety of reusing ablation catheters with temperature control, which has not previously been reported. A review of previously conducted studies on the feasibility of reusing electrode catheters is also presented. From September 1994 to December 1997, 74 deflectable ablation catheters with temperature control (Cordis-Websters and Osypkas) were used during mean 7.6 +/- 8.0 ablation sessions. The catheter tests included visual inspection for surface defects using a magnification glass, impedance measurements, evaluation of the catheter deflection capability, and the integrity of the thermistor and thermocouple. The catheters were sterilized by Sterrad after each use. A total of 41 catheters were rejected after an average 9.1 +/- 8.8 uses (range 1-31). The main reasons for rejection were inaccurate temperature measurements by the thermistor or thermocouple (19%), breakage of or defect in the internal pulling wire (12%), loss or disturbance of electrogram (9%), and loss of deflection capability (8%). The reuse of the catheters has not resulted in any major catheter failures or any major adverse clinical complications. There were no local or systemic infections. It can be concluded that these types of ablation catheters will sustain repeated uses and resterilizations without untoward harm to the patient provided that a thorough validation protocol and guidelines for quality control and rejection of catheters are used. There seems to be no rational for setting a limit for the number of reuses, since most failures occurred at any time of reuse.

Catheter Ablation↗

PubMed1997

Signed value of monophasic action potential duration difference. A useful measure in evaluation of dispersion of repolarization in patients with ventricular arrhythmias.

AIMS: To evaluate the usefulness of the signed value of monophasic action potential duration difference in analysing the cause of dispersion of ventricular repolarization. METHODS AND RESULTS: Monophasic action potentials were simultaneously recorded from the right ventricular apex and outflow tract during programmed stimulation in 36 patients with ventricular arrhythmias. The time difference between the ends of repolarization on the two monophasic action potentials was used as a measure of the dispersion of ventricular repolarization, and the signed value of the monophasic action potential duration difference was used to specify the contributions of the activation time difference and the monophasic action potential duration difference to the dispersion of ventricular repolarization. During right ventricular pacing, single and double programmed stimulation and at the induction of ventricular arrhythmias, the dispersion of ventricular repolarization and the signed value of monophasic action potential duration difference were markedly greater in the 11 patients with polymorphic ventricular tachycardia/ventricular fibrillation induced than in the 13 patients with monomorphic ventricular tachycardia induced, and in the 10 patients with clinical polymorphic ventricular tachycardia/ventricular fibrillation/cardiac arrest than in the 12 patients with sustained monomorphic ventricular tachycardia. This disclosed that the increased dispersion of ventricular repolarization was caused by increases in both the activation time difference and the monophasic action potential duration difference in the former, but mainly by an increased activation time difference in the latter groups. CONCLUSION: The signed value of monophasic action potential duration difference can specify whether an increased dispersion of ventricular repolarization is caused by inhomogeneous repolarization, inhomogeneous conduction or both, and thereby it is useful in study of the mechanism of ventricular arrhythmias.

Action Potentials↗

PubMed1996

Dispersion of repolarization following double and triple programmed stimulation. A clinical study using the monophasic action potential recording technique.

To study the dispersion of ventricular repolarization following double and triple programmed stimulation and its correlation with the inducibility of ventricular arrhythmias, monophasic action potentials were simultaneously recorded from the right ventricular apex and outflow tract during programmed stimulation in 12 patients with ventricular arrhythmias and a normal QT interval. The time difference between the ends of the two monophasic action potentials were used as a measure of the dispersion of ventricular repolarization, which consists of the activation time difference and the monophasic action potential duration difference. During double and triple programmed stimulation, the dispersion of ventricular repolarization increased significantly with the shortening of the coupling interval but decreased slightly with the shortening of the preceding interval. The induction of the ventricular arrhythmias in these patients was invariably associated with a marked increase in the dispersion of ventricular repolarization. The maximal dispersion of ventricular repolarization was significantly larger in the seven patients with polymorphic ventricular tachycardia and/or ventricular flutter/fibrillation induced than in the four patients with monomorphic ventricular tachycardia induced. Analysis of the two components of the dispersion of ventricular repolarization revealed that the increased dispersion of ventricular repolarization was mainly caused by an increase in the activation time difference in the monomorphic ventricular tachycardia subgroup, and by increases in both the activation time difference and monophasic action potential duration difference in the polymorphic ventricular tachycardia/fibrillation subgroup. These findings suggest that increased dispersion of ventricular repolarization is one of the underlying mechanisms accounting for the myocardial vulnerability to ventricular arrhythmias and that repolarization disturbance is important for the genesis of polymorphic ventricular tachycardia/fibrillation.

Action Potentials↗

PubMed1996

Clinical application of a microcomputer system for analysis of monophasic action potentials.

UNLABELLED: Computerized analysis of monophasic action potentials (MAPs) has rarely been reported in clinical setting. We developed a computer system featuring on-line acquisition and user-monitored automatic measurement of multichannel MAPs with the capability of manual corrections. This system has been used in 34 patients in whom two-channel MAPs and 1-lead ECG were digitized during sinus rhythm, pacing, and programmed stimulation (PS). In total, 41, 413 MAPs in 212 data files were measured. The correct determination rate was 100% for MAP onset and plateau, 99.78% (95.76% during PS) for MAP baseline, and 99.96% (54.29% during PS) for QRS onset. The comparison between the computerized and manual measurements in 292 MAPs showed that the former highly agreed with the latter, with the limits of agreement, defined as mean difference +/- 2 SD, being from -4.8-4.9 ms for activation time and from -4.1-6.0 ms for MAP duration measurements. Using this system, two-channel MAPs of more than 300 consecutive beats can be measured in a few minutes, which made it possible to determine the steady state of MAP duration individually, and evaluate the MAP changes during intervention in detail. The clinical routine procedure for testing the effective refractory period and several new MAP parameters were also evaluated using this system. CONCLUSION: The MAP measurement using this computer system is reliable, rapid and accurate; it can therefore replace the manual method and provide more useful information for clinical research.

Action Potentials↗

PubMed1995

The dispersion of repolarization in patients with ventricular tachycardia. A study using simultaneous monophasic action potential recordings from two sites in the right ventricle.

The role of increased dispersion of repolarization in the genesis of torsade de pointes and ventricular fibrillation has been well recognized generally, but not in the genesis of monomorphic ventricular tachycardia (VT). Monophasic action potentials (MAP) were therefore recorded simultaneously from the right ventricular (RV) apex (RVA) and outflow tract (RVOT) during sinus rhythm, RV pacing and programmed extra stimulation (PES) in 24 patients with VT. The activation time (AT), MAP duration at 90% repolarization (MAPd), and repolarization time (RT) were measured and their dispersions, defined as the differences in these parameters between RVA and RVOT, were calculated. During sinus rhythm and RV pacing, the dispersions of AT, MAPd and RT (dispersions) were significantly larger in the 17 patients with a VT induced than in those without. During PES, the dispersions were further augmented in the S2 beats in the seven patients with a sustained VT induced, the maximal dispersion of RT being 85 +/- 22 ms. Both the dispersion of AT and that of MAPd contributed to the dispersion of RT. In both of our two patients with a sustained VT induced during MAP recording, a marked increase in dispersions of RT (140 and 190 ms, respectively) was observed immediately before the initiation of the VT. A link between the dispersions and the inducibility of a monomorphic VT was found in our patients, which suggests that the increased dispersions play an important role in the genesis of a monomorphic VT.

Action Potentials↗

PubMed1995

Reproducibility of the signal-averaged electrocardiogram using individual lead analysis.

The aim of the study was to evaluate the immediate reproducibility of time domain parameters in the signal averaged electrocardiogram using a new method for endpoint determination in individual Frank leads. The method is based on a statistical model of the electrocardiogram (ECG) in which maximum likelihood (ML) estimation is employed. The reproducibility of the ML method was compared to that of conventional time domain analysis using the vector magnitude (VM) of Frank leads. Fifty-nine patients were included in the study and two consecutive ECGs were recorded for signal averaging. The results showed that the mean of the absolute difference of the filtered QRS duration (QRSD) between two consecutive recordings was significantly lower for the ML method than the conventional method when employing 60 Hz highpass filtering (2.1 +/- 2.2 ms vs 5.9 +/- 10.2 ms, P < 0.05). Moreover, the ML method resulted in a significantly longer QRSD compared to the VM-based method (P < 0.05). The terminal amplitude of the QRS complex (RMS40) showed a greater variability than the QRSD for both methods, although the ML method was associated with a higher reproducibility than the VM method for the 60 Hz filter. These findings may contribute to a better identification of patients at high risk of ventricular arrhythmias. A reduction in the number of measurement errors has important implications when QRS changes are analysed over time.

Adult↗

PubMed1994

Clinical value of transesophageal atrial stimulation and recording in patients with arrhythmia-related symptoms or documented supraventricular tachycardia--correlation to clinical history and invasive studies.

The main objective of the present study was to evaluate the clinical applicability of transesophageal atrial stimulation (TAS) and recording with regard to inducibility of supraventricular tachycardia (SVT) in patients with either an ECG-documented paroxysmal SVT or a clinical history of palpitations suggesting this disease. A further objective was to assess the inducibility of SVT and to compare the inducibility by TAS with that obtained by an invasive electrophysiologic study (EPS). A total of 64 patients (aged 13-74 years) with ECG-documented paroxysmal SVT (n = 50) or only a history of palpitations (n = 14) was referred for TAS. Preexcitation was present in 35 patients. The study protocol included single and double extrastimuli delivered at a basic paced interval of 500 ms, and incremental atrial stimulation until a cycle length of 275 ms or a second-degree AV block appeared. In 10 patients atropine intravenously was required for induction. The same protocol was used in 34 of the patients who also underwent invasive EPS. TAS was completed in 56 of 64 patients (88%). In this group SVT was induced during TAS in 84% (47/56). Of patients with ECG-documented tachycardia, clinical tachycardia was induced in 90% (35/39) with ECG-documented regular paroxysmal SVT and in 67% of patients (4/6) with ECG-documented atrial fibrillation. In patients without ECG-documented atrial fibrillation. In patients without ECG-documented tachycardia, clinically relevant arrhythmia was induced in 73% (8/11). In 30 of 32 patients (94%) with an inducible tachycardia during invasive EPS, it was also possible to induce the tachycardia by TAS.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Effect of dofetilide on cardiac repolarization in patients with ventricular tachycardia. A study using simultaneous monophasic action potential recordings from two sites in the right ventricle.

Monophasic action potentials (MAP) were simultaneously recorded from the right ventricular (RV) apex (RVA) and the outflow tract (RVOT) before and after an infusion of dofetilide in 10 patients with documented ventricular tachycardia. After the drug infusion, the MAP duration (MAPd), repolarization time, and corrected QT interval were significantly prolonged during sinus rhythm, RV pacing, and RV extra stimulation. The prolongation of MAPd at 90% repolarization during RV pacing at a cycle length of 500 ms was 31 +/- 6 ms (13%) and 26 +/- 7 ms (11%) at RVA and RVOT, respectively. The ventricular effective refractory period was significantly prolonged by 33 +/- 9 ms (13%) and 22 +/- 7 ms (9%) at driving cycle lengths 600 and 500 ms, respectively. The MAPd shortening with decreasing diastolic time intervals was significantly diminished by dofetilide in early extra beats during RV extra stimulation, suggesting a relatively more pronounced effect of this drug at the early diastolic phase. The dispersion of repolarization, defined as the difference in MAPd between RVA and RVOT, and the activation time were not significantly changed. In conclusion, acute administration of dofetilide in patients with ventricular tachycardia significantly prolonged the time intervals of ventricular repolarization and refractoriness in a parallel fashion, without affecting intraventricular conduction. The effect of dofetilide on MAPd prolongation appeared not to be reverse use-dependent in this study in humans. These results verify the selective class III antiarrhythmic property of dofetilide and warrant further studies in patients.

Action Potentials↗

PubMed1994

Monophasic action potentials: concepts to practical applications.

Monophasic action potential (MAP) recordings reproduce the repolarization time course of intracellular action potentials with high accuracy and provide precise information on the local activation time. With the advantage of in vivo application and the development of the safer and simpler contact catheter technique, MAP recording has become the method of choice for evaluating myocardial repolarization changes. This review aims to provide information on practical application of MAP recording in the clinical setting. MAPs can easily be recorded from the endocardium with the contact catheter technique in the electrophysiology laboratory and from the epicardium with electrode probes during open heart surgery. The technical aspects are described in detail. The rate dependence of myocardial excitability and repolarization and the effect of antiarrhythmic drugs on MAP duration and effective refractory period are thoroughly reviewed. The use of MAPs in detecting myocardial ischemia, in studying early afterdepolarization and triggered arrhythmias, in measuring dispersion of repolarization, in identifying intracardiac conduction and the development of the T wave, and in verifying the arrhythmogenic effect of mechanoelectric feedback are presented. Computerized automatic analysis of MAPs and the limitations of the MAP technique are also discussed.

Action Potentials↗

PubMed1993

Safety of transvenous right ventricular endomyocardial biopsy guided by two-dimensional echocardiography.

A total of 231 endomyocardial biopsy procedures performed in 74 consecutive patients were evaluated to compare the incidence and nature of complications in procedures guided by fluoroscopy versus those guided by echocardiography. Sixty biopsy procedures were guided by fluoroscopy and 171 by two-dimensional echocardiography. The right interventricular septum was the target site for biopsy sampling in all patients. Clinical signs of myocardial perforation occurred during one (1.7%) procedure guided by fluoroscopy versus two (1.2%) procedures guided by echocardiography. Two cases of interventricular septal perforation were visualized during the echo-guided procedures. The biopsy specimens were judged to be inadequate for diagnosis in 2.2% of the biopsy procedures, all of which were guided by fluoroscopy. The number of samples obtained during a procedure guided by fluoroscopy was lower (mean 2.3 +/- 1.6) (mean +/- 1 SD) than that taken during a procedure guided by echocardiography (mean 4.0 +/- 1.2). Epicardial or pericardial tissue was present in 5.8% of the samples obtained under fluoroscopic guidance, versus 0.7% of the samples obtained using echocardiography (p = 0.0003). It is concluded that although echocardiography seems to provide more accurate and safer guidance for the positioning of the bioptome toward the septum, the presence of epicardium or pericardium in 0.7% of the samples indicates that inadvertent sampling from the right ventricular free wall cannot be avoided.

Adolescent↗