[Temperature-directed radiofrequency ablation. A new safer treatment of tachycardia].
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
L Bergfeldt
Publications and source records attributed to L Bergfeldt.
Diagnostic value of programmed ventricular stimulation in patients with bifascicular block: a prospective study of patients with and without syncope.
OBJECTIVES: The aim of this study was to examine the inducibility of ventricular arrhythmias in patients with bifascicular block both with and without a history of syncope and to relate the findings to clinical events during follow-up. BACKGROUND: Patients with bifascicular block have an increased risk of sudden death that is not reduced by pacemaker treatment. This risk could be related to a high incidence of ventricular arrhythmias. METHOD: Programmed ventricular stimulation was performed in 101 patients with bifascicular block: 41 had a history of unexplained syncope, and 60 were asymptomatic. RESULTS: Programmed ventricular stimulation resulted in a sustained ventricular arrhythmia in 18 patients (18%), 8 in the syncope group and 10 in the nonsyncope group (p = NS). Three patients in each group had an inducible sustained monomorphic ventricular tachycardia. During a mean follow-up of 21 months, 10 patients experienced a clinical event defined as sudden death (n = 4), syncope (n = 5) or appropriate discharges from an implantable cardioverter-defibrillator (n = 1). Only one of these patients had an inducible ventricular arrhythmia at baseline. CONCLUSIONS: The inducibility of ventricular arrhythmias is high in patients with bifascicular block and of the same magnitude in patients with and without a history of syncope. Clinical events during follow-up were not predicted by programmed ventricular stimulation in either of the two groups. The finding of inducible ventricular arrhythmia in patients with bifascicular block should therefore be interpreted with caution.
Adolescent↗
"Normal" response of the QT interval and QT dispersion following intravenous injection of the sodium channel blocker disopyramide: methodological aspects.
Measurement of the QT dispersion (the maximal interlead difference) on the surface electrocardiogram has been suggested for assessing the risk for ventricular arrhythmias and for examining drug effects and their proarrhythmic potential. The acute response of QT dispersion was assessed in 10 healthy subjects receiving disopyramide, which is known to delay repolarization and to prolong global measures thereof. The QRS, JT, and QT intervals and their dispersion were assessed at spontaneous rhythm and at atrial pacing at baseline and after an intravenous injection of disopyramide 2 mg/kg over 5 minutes. The short-term (within 30 minutes) and long-term (> or = 2 weeks) variabilities of the QT interval and the QT dispersion, expressed as the coefficient of variation, were also analyzed. At spontaneous rhythm the group average QT interval was between 369 and 375 msec, and the QT dispersion was between 33 and 37 msec; both were relatively stable over time. All subjects responded homogeneously to disopyramide with a significant QT prolongation (p < 0.001), but no consistent response of the QT dispersion was observed. This discrepancy reflects the significant difference in time-dependent variability with a coefficient of variation of spontaneous, paced, and heart rate-corrected QT dispersion between 25% and 42%, 8-42 times greater than the corresponding values of 1-4% for the QT intervals. The individual response of the QT dispersion to drug challenge should therefore be interpreted with caution. Furthermore and as a consequence, QT dispersion is less sensitive for assessing drug effects on ventricular depolarization and repolarization than the QT interval.
Adult↗
Electrophysiological evaluation of the sodium-channel blocker carbamazepine in healthy human subjects.
Carbamazepine (CBZ) is a sodium-channel blocker used mainly for the treatment of epileptic seizures and neuralgias. It may impair the function of the cardiac conduction system in susceptible patients, but its electrophysiological effects have not been thoroughly assessed in the normal heart, which was the aim of the present study. Ten healthy volunteers, mean age 32 years, underwent two electrophysiological investigations at baseline and three at different dose levels of CBZ. The transesophageal atrial stimulation technique was used to evaluate sinus node function, refractoriness of the atrial myocardium, atrioventricular conduction, and ventricular depolarization and repolarization (as reflected by the QRS, JT, and QT intervals) at spontaneous rhythm and after atrial pacing. Atropine was administered to facilitate 1:1 conduction and assessment of rate-dependent effects. At the highest CBZ dose (800 mg/day), which gave plasma concentrations within the upper therapeutic range, the PQ interval was mildly prolonged (151 vs. 159 msec; p < 0.01). In addition, the shortening of the JT interval normally seen at higher pacing rates was counteracted by high-dose CBZ, as demonstrated by a lower mean slope of the regression line after atropine and CBZ than after atropine alone (0.17 vs. 0.20; p < 0.05). No other effects were detected. At therapeutic levels CBZ had minimal effects on the healthy conduction system, supporting its safe use in the absence of cardiac disease.
Administration, Oral↗
Screening for sinus node dysfunction by analysis of short-term sinus cycle variations on the surface electrocardiogram.
A new noninvasive screening method for diagnosing sinus node dysfunction (SND) was evaluated. Sinus cycle variations from 1-minute electrocardiograms (ECG) were described by two variables: the variation range around the mean cycle length (percentage) and the maximal change between any two consecutive cycles (milliseconds). SND was diagnosed when both variables were increased. Part 1: Validation of this method against Holter and sinus node recovery time assessment in 69 patients with proven or possible sick sinus syndrome (SSS). Part 2: Application of the method to 60 patients with clinically significant cardiovascular and pulmonary disorders (group 3), but without any pretest suspicion of SND. Part 1: Sinus cycle variations and sinus node recovery times were abnormal in similar proportions, 55% and 63%, respectively. The sensitivities in proven SSS were 72% and 71%, respectively. Sinus node function was concordantly classified in 80% of 64 patients undergoing both tests. When sinus cycle variations were abnormal the probability of a prolonged recovery time was 89%. Part 2: Asymptomatic SND was found in 12% of patients in group 3. Thus, analysis of short-term beat-to-beat variations in the surface ECG has a sensitivity of approximately 70% and a specificity of 100% for diagnosing SND.
Adolescent↗
Use of signal-averaged electrocardiography for predicting inducible sustained monomorphic ventricular tachycardia in patients with bundle branch block with and without a history of syncope.
The aim of this study was to examine the utility of signal-averaged electrocardiography in relation to inducible sustained monomorphic ventricular tachycardia in patients with bundle branch block. One hundred fourteen patients with bundle branch block underwent signal-averaged electrocardiography in the time domain and programmed ventricular stimulation. Sustained monomorphic ventricular tachycardia was induced in 17 patients. The mean values of the three signal-averaged electrocardiographic variables analyzed differed significantly between the inducible and the noninducible group. The filtered QRS duration showed the most prominent difference between the two groups, and a filtered QRS duration > or = 155 msec had a sensitivity of approximately 80%, a specificity of 60%, and a total predictive value of 65%. In the subgroup of patients with syncope, a combination of these criteria with a history of coronary artery disease had a sensitivity of 100% and a specificity of 90%.
Aged↗
Long-term follow-up of patients treated by radiofrequency ablation of the atrioventricular junction.
Radiofrequency ablation of the AV conduction tissue (His-bundle ablation) is an accepted treatment for therapy resistant atrial fibrillation/flutter. However, data on the long-term effects of the procedure are limited. We followed 50 patients for a mean of 17 months after AV junction ablation. The indication was treatment resistant atrial fibrillation or flutter. The patients underwent a standardized interview performed by two nurses. Health care was studied via the in-patient register. Subjective improvement was reported by 88% and the number of days in hospital per year was reduced from 17 to 7. The use of antiarrhythmic drugs was reduced by 75%. If the reduction in costs of drugs and days in hospital is compared with the cost of the ablation and the pacemaker implantation, breaking even is achieved after 2.6 years. We could not confirm that patients with paroxysmal atrial fibrillation note less improvement than those with chronic fibrillation. CONCLUSION: Ablation of the AV junction is a cost effective treatment with good long-term results and relatively few complications. RECOMMENDATIONS: Chronic atrial fibrillation: If sinus rhythm cannot be established and in cases in which heart rate regulating drugs have been ineffective, ablation of the AV junction with implantation of a VVIR pacemaker is recommended. PAROXYSMAL ATRIAL FIBRILLATION: If the patient despite treatment with antiarrhythmic drugs continues to have symptomatic episodes of atrial fibrillation, then AV junction ablation with implantation of a permanent pacemaker is recommended. Patients who have self-limiting episodes of atrial fibrillation should be given a DDDR pacemaker with an automatic mode switch. Patients who do not have self-limiting attacks and require DC conversion, should receive a VVIR pacemaker.
Adult↗
Prospective study of left ventricular function after radiofrequency ablation of atrioventricular junction in patients with atrial fibrillation.
BACKGROUND: In patients with drug resistant incessant supraventricular tachycardia, radiofrequency induced ablation of the atrioventricular junction and pacemaker implantation have hitherto been considered a treatment of last resort. OBJECTIVE: To assess the short and long term effects of ablation of the atrioventricular junction on systolic and diastolic left ventricular function in patients with atrial fibrillation with and without impaired left ventricular function. PATIENTS: 29 patients (19 men; mean age 65 (SD 7) years (range 50-76)) undergoing ablation of the atrioventricular junction for drug refractory atrial fibrillation were examined a mean of 2, 65, and 216 days after ablation of the bundle of His. MAIN OUTCOME MEASURES: Left ventricular ejection fraction and early filling deceleration times (Edec) were assessed by Doppler echocardiography after 1 to 2 hours of ventricular pacing at a rate of 80 beats/minute. RESULTS: In 14 patients with a left ventricular ejection fraction < 50% left ventricular ejection fraction increased significantly from 32% (11%) to 39% (11%) (65 days) and 45% (11%) (216 days) (P < 0.001); Edec increased from 142 (46) ms to 169 (57) ms (65 days) and 167 (56) ms (216 days) (P < 0.05). In 15 patients with an ejection fraction > or = 50% at the initial examination no significant change in systolic function was observed. CONCLUSIONS: In patients with left ventricular dysfunction long term improvement of systolic and diastolic left ventricular function was seen after ablation of the atrioventricular junction for rate control of atrial fibrillation. This procedure had no adverse effects on normal left ventricular function.
Aged↗
Disopyramide stress test: a sensitive and specific tool for predicting impending high degree atrioventricular block in patients with bifascicular block.
OBJECTIVE: To study the value of intravenous disopyramide as part of an invasive electrophysiological study in predicting impending high degree atrioventricular block in patients with bifascicular block. DESIGN: An invasive electrophysiological study was performed in the basal state and after the infusion of disopyramide (2 mg/kg body weight). The progression to high degree atrioventricular block was assessed by bradycardia-detecting pacemakers or repeated 12-lead electrocardiogram recordings, or both. PATIENTS: 73 patients with bifascicular block were included, of whom 25 had a history of unexplained syncope. The remaining 48 patients had no arrhythmia related symptoms and were included as controls. All patients had an ejection fraction of > 35%. RESULTS: After a mean follow up of 23 months, seven patients in the syncope group and three in the non-syncope group had a documented high degree atrioventricular block or pacemaker-detected bradycardia of < or = 30 beats/min for > or = 6 s. The sensitivity of the disopyramide test was 71% and the specificity 98%. The corresponding figures for an abnormal electrophysiological study in the basal state were 14% and 91%, respectively. CONCLUSIONS: The sensitivity of an invasive electrophysiological study in patients with bifascicular block and syncope can be markedly increased by the use of intravenous disopyramide. A positive test is a highly specific finding and warrants pacemaker implantation.
Adolescent↗
Atrioventricular block progression in patients with bifascicular block assessed by repeated electrocardiography and a bradycardia-detecting pacemaker.
Syncope may be due to intermittent high-degree atrioventricular (AV) block, but a cause-relation is sometimes difficult to prove. Diagnostic methods with high predictive value proven by instruments for safe and sensitive follow-up are needed. A bradycardia-detecting pacemaker was used in patients with bifascicular block, who had been the subjects of pharmacologic stress testing of the His-Purkinje system. Thirty-seven patients were included, of whom 26 had experienced at least 1 syncopal episode of suspected bradycardia origin, and 11 had previously documented transient high-degree AV block. The electrophysiologic study included injection of disopyramide 2 mg/kg (up to 150 mg) over 5 minutes. A positive test result was defined as spontaneous or pacing-induced His-Purkinje high-degree AV block after drug or a drug-induced HV prolongation of > or = 50%. Patients were followed an average 63 months with repeated electrocardiography and a diagnostic pacemaker (n = 23). Altogether, 24 patients had a significant bradycardia diagnosed by either or both methods. The sensitivity and positive predictive values were: HV interval > or = 70 ms at baseline, 47% and 88%; a positive disopyramide test result, 75% and 80%; and HV interval > or = 70 ms or a positive disopyramide test result, 93% and 74%, respectively. Thus, the diagnostic pacemaker is a safe and sensitive tool for evaluating the information obtained at electrophysiologic study, and pharmacologic stress testing with disopyramide has an informative value in patients with bifascicular block and syncope when results at baseline are inconclusive.
Aged↗
[Long-term follow-up after removal of the bundle of His. Radiofrequency ablation is effective against fibrillation].
Explore the source record for details and available documents.
Adult↗
Sinus node dysfunction during long-term lithium treatment.
BACKGROUND AND OBJECTIVE: Lithium has occasionally been reported to cause symptomatic sinus node bradyarrhythmias. The prevalence and mechanism of these arrhythmias during long-term treatment are unknown. The aims of this study were (a) to evaluate the systemic effects of lithium treatment on cardiac conduction in individuals who were free from cardiovascular disorders; (b) to assess the prevalence of lithium treatment in a group of patients with pacemakers; and (c) to evaluate the interaction between the parasympathetic limb of the autonomous nervous system and the sinus node cells during long-term lithium treatment. PATIENTS AND METHODS: 45 patients who had been treated with lithium for > 12 months were investigated in a long-term electrocardiography study. Only patients without cardiovascular disease, or concomitant chronotropic medication, or metabolic disorders known to cause rhythm disturbances were included. An age-stratified population was used as a reference group. 21 patients also underwent analysis of carotid sinus pressure and sinus cycle length before and after atropine to clarify whether neural mechanisms were involved. The prevalence of lithium treated patients was determined in 650 patients with pacemakers. RESULTS: (a) Signs of moderate sinus node dysfunction (sinus arrest > 1.5 s, minimum heart rate < 50 beats/min) were found in 56% and 78% respectively in the lithium-treated group compared with 30% and 30% respectively in the reference group (p < 0.01). Severe sinus node dysfunction was equally common in both groups. (b) The prevalence of chronic lithium treatment in the pacemaker population was 0.46%. (c) Sinus cycle variations were abnormal in the basal state in three (14%) patients and in 11 (52%) patients after atropine despite signs of intact and normal parasympathetic innervation. CONCLUSIONS: Depressed sinus node function was significantly more common in a lithium-treated population than in an age-stratified reference group. Clinically significant dysfunction, however, was uncommon. The effect of lithium on the sinus node seemed to be intrinsic and was not caused by increased parasympathetic tone.
Aged↗
[Radiofrequency ablation--promising treatment in supraventricular arrhythmia].
Explore the source record for details and available documents.
Adult↗
Comparative class 1 electrophysiologic and anticholinergic effects of disopyramide and its main metabolite (mono-N-dealkylated disopyramide) in healthy humans.
During steady-state treatment with disopyramide, its main and active metabolite, mono-N-dealkylated disopyramide, was reported to reach concentrations that were equal to or higher than the parent drug in 25% of 70 evaluated patients. This metabolite has been found to have a more pronounced anticholinergic action than the parent drug on in vitro evaluation, but neither its anticholinergic nor its direct electrophysiologic effects on the human heart have been properly assessed. We therefore compared the acute electrophysiologic and anticholinergic effects (the standard being atropine, 0.04 mg/kg) of disopyramide and its main metabolite, given 2 mg/kg body weight intravenously to 10 healthy individuals in a double-blind, randomized, crossover design. The anticholinergic effect of these substances on sinus and atrioventricular node function was unexpectedly found to be of similar magnitude and more pronounced than previously thought (at least one-third the effects of the atropine dose). The class 1 electrophysiologic effects were as follows: intra-atrial and His-Purkinje conduction (the PA and the HV interval, respectively) was prolonged 33% (95% CI: 18-47%) and 27% (21-32%) by disopyramide, and 15% (10-19%) and 13% (10-17%), respectively, by the metabolite. Disopyramide also prolonged the QRS, JT, and QT intervals by 15% (9-21%), 10% (8-13%), and 10% (7-12%), respectively. The metabolite caused a 9% (7-12%) prolongation of the QRS interval (significantly less than disopyramide), but shortened repolarization (as reflected by the JT interval) by -7% (-2 to -11%; p < 0.01), which is similar to the acute effects of lidocaine 2 mg/kg body weight.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Carbamazepine induced bradycardia--a problem in general or only in susceptible patients? A 24-h long-term electrocardiogram study.
Carbamazepine is a first line drug in the treatment of epilepsy and trigeminal neuralgia, but may exert negative chronotropic and dromotropic effects on the cardiac conduction system. Bradyarrhythmias of different types and severity have been described, especially in the elderly, but the prevalence of arrhythmias in a larger group of carbamazepine treated patients is unknown. Forty-eight patients, 40 years of older, on continuous carbamazepine treatment because of various neurologic disorders were investigated by interview, physical examination, 12-lead surface electrocardiogram, and 24-h long-term electrocardiogram recording. The prevalence of bradyarrhythmias was compared with that in an age-stratified reference group. There was no differences between the two groups, either in the number or the duration of pauses or in the type of pauses. In conclusion, carbamazepine does not increase the risk of bradyarrhythmias in the vast majority of patients.
Adult↗
[Catheter ablation--a first choice alternative in supraventricular tachycardias?].
Explore the source record for details and available documents.
Cardiac Catheterization↗
[Bradyarrhythmias induced by antiepileptics increase frequency of epileptic seizures].
Explore the source record for details and available documents.
Aged↗
Electrophysiologic effects and clinical hazards of carbamazepine treatment for neurologic disorders in patients with abnormalities of the cardiac conduction system.
Carbamazepine, a first-line drug for the treatment of epilepsy and neuralgia, may exert hazardous effects on the cardiac conduction system. Standard ECG and long-term ECG monitoring and invasive electrophysiologic testing were carried out in 10 patients who required this drug for neurologic disorders, but in whom its safe use had been questioned because of symptoms of ECG abnormalities. We observed depression of sinus node function and an atrioventricular conduction delay with a significant prolongation of the PQ interval of 16 msec (9%; 95% confidence interval: 1.9% to 16.5%; p less than 0.05), of which the HV interval was significantly prolonged but not the PA and AH intervals. These effects are in accordance with previously shown class 1A properties. However, the lack of effects on QRS, JT, and QT intervals at normal heart rates is a class 1B characteristic. Thus carbamazepine seems to have composite electropharmacologic actions. A cause effect relationship between carbamazepine treatment and significant arrhythmias was established in five patients. Thus the negative chronotropic and dromotropic effects of carbamazepine may, at least in predisposed patients, induce symptoms confusingly similar to the epileptic seizures it is used to prevent.
Aged↗