Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: QT Interval Variability and Sudden Death. Introduction: Recent studies have implicated repolarization lability in the genesis of malignant ventricular arrhythmias. However, few data exist on assessment of temporal QT interval variability and its relation to arrhythmogenesis. We tested the ability of the QT variability index (QTVI), a measure of beat-to-beat QT interval fluctuations measured on a single ECG lead, to identify patients presenting with malignant ventricular arrhythmias and predict their subsequent occurrences. Methods and Results: We measured the QTVI in 95 patients presenting for electrophysiologic study (EPS). The ability of the QTVI to identify patients with sudden cardiac death (SCD) or sustained monomorphic ventricular tachycardia (MVT) on presentation and during follow-up of 23.7 ± 14.3 months was compared with spatial QT dispersion, T wave alternans ratio during atrial pacing, MVT inducibility at EPS, signal-averaged ECG, heart rate variability, and ejection fraction. The QTVI was higher in patients with heart disease than in controls (-0.7 ± 0.7 vs −1.1 ± 0.5, P 〈 0.05), and higher in patients presenting with SCD than in other patients with heart disease (0.0 ± 0.6 vs −0.8 ± 0.5, P 〈 0.05). The QTVI was the only clinical variable that identified patients who presented with SCD (P= 0.004, odds ratio = 12.5) on stepwise, logistic multiple regression. Fourteen patients had arrhythmic events during follow-up. In a Kaplan-Meier analysis of arrhythmic events, QTVI ≥ 0.1 was a discriminator for higher risk of arrhythmic events (P 〈 0.05). Conclusions: (1) This noninvasive measure of temporal repolarization lability identified patients with SCD and predicted arrhythmia-free survival. (2) Further studies are needed to determine the mechanisms that mediate beat-to-beat QT interval variability.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    350 Main Street , Malden , MA 02148 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Arrhythmogenic right ventricular dysplasia (ARVD) is characterized by progressive replacement of RV myocardium with fibro-adipose tissue thought to be responsible for the presence of late potentials (LP) detected by SAECG. The general consensus on the role of SAECG in the diagnosis and prognosis of patients with ARVD is lacking. The purpose of this systematic review was to better define the role of SAECG in ARVD. Methods: An extensive review of literature was done to specifically describe the prevalence of LP in ARVD and its determinants, explore the various options available to improve the diagnostic ability of SAECG, and provide recommendations for proper utilization of this technique. Results: LPs are frequent in ARVD (47–100%), and more prevalent in severe disease and in patients with documented spontaneous VT. SAECG is a useful test in following the characteristic evolutivity of the disease. 4–16% of normal family members of patients with ARVD also have abnormal SAECG results. Detection of LP in ARVD can be improved by employing a high-pass filter of 25 Hz and specifically looking for changes in the Z leads. Conclusions: SAECG testing should be considered a standard part of the evaluation of patients with known or suspected ARVD. Further research is needed to confirm the value of SAECG testing in predicting arrhythmia risk and assessing the rate of disease progression, as well as to determine if greater prevalence of SAECG abnormalities in family members of patients with ARVD represents early detection of ARVD. The ongoing multidisciplinary study of right ventricular dysplasia will hopefully answer some of these questions.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    350 Main Street , Malden , MA 02148 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Initiation of Sustained Ventricular Arrhythmias. Introduction: The purpose of this study was to analyze the pattern of initiation of sustained ventricular arrhythmias in patients with varying types of underlying structural heart disease. Methods and Results: The study group consisted of 90 patients with an implantable cardioverter defibrillator. Cardiovascular diagnoses included coronary artery disease in 64 patients (71%). The patients were divided into four groups based on the type and severity of structural heart disease. Two hundred sixty episodes of sustained ventricular arrhythmias were analyzed. The mean coupling interval of the initiating heat of all ventricular arrhythmias was 523 ± 171 msec. The coupling interval of the initiating beat was longer in patients with impaired ventricular function, particularly those with nonischemic dilated cardiomyopathy. The prematurity index was similar regardless of the type of underlying structural heart disease. However, the prematurity index was shorter in patients with polymorphic ventricular tachycardia (VT) compared to those with monomorphic VT. A pause was observed more commonly before the onset of polymorphic VT/ventricular fibrillation than sustained monomorphic VT. Two hundred twenty-two (85%) of the arrhythmia episodes were initiated by a late-coupled premature beat, 33 (13%) were initiated by an early-coupled premature beat, and 5 episodes (2%) were initiated with a short-long-short sequence. The patttern of initiation of the ventricular arrhythmias was similar in all patient groups and for both monomorphic and polymorphic tachycardias. Conclusion: These findings demonstrate that sustained ventricular arrhythmias typically are initiated by late-coupled ventricular premature depolarizations, regardless of the type or severity of underlying structural heart disease or resultant arrhythmia.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Magnesium and Arrhythmias. Introduction: Magnesium deficiency has been implicated in the pathogenesis of sudden death, but the investigation of arrhythmic mechanisms has been hindered by difficulties in measuring cellular tissue magnesium stores. Methods and Results: To see if magnesium deficiency is associated with a propensity toward triggered arrhythmias, we measured tissue magnesium levels and QT interval dispersion (as an index of repolarization dispersion) in 40 patients with arrhythmic complaints. Magnesium was measured in sublingual epithelium using X-ray dispersive analysis. QT interval dispersion was assessed on 12-lead surface F-XCs in all patients, and programmed stimulation was performed in 28. The sublingual epithelial magnesium level ([Mg]i), but the not the serum level, correlated Inversely with QT interval dispersion in 40 patients (r = 0.58, P 〈 0.0.5); in 12 patients undergoing repeat testing on therapy, the change in magnesium also correlated inversely with the change in QT dispersion (r = 0.61, P 〈 0.05). Patients with left ventricular ejection fractions 〉 40% had significantly higher tissue magnesium and lower QT dispersion (34.5 ± 0.5 mEq/L, 81 ± 8 msec) than those with left ventricular ejection fractious 〈 40% (32.7 ± 0.5 mEq/L, P 〈 0.01, and 114 ± 9 msec, P 〈 0.05). There was no difference in either [Mg]i, or QT dispersion in the 16 patients with inducible monomorphic ventricular tachycardia versus the 12 noninducible patients. Conclusion: Reduced tissue magnesium stores may represent a significant risk factor for arrhythmias associated with abnormal repolarization, particularly in patients with poor left ventricular systolic function, but may not represent a risk for excitable gap arrhythmias associated with a fixed anatomic substrate (e.g., monomorphic ventricular tachycardia).
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Typical atrial flutter (AFL) can be cured by catheter ablation of the cavotricuspid isthmus (CTI). The surface electrocardiogram (ECG) is not always diagnostic of isthmus dependence of AFL. The aim of this study was to evaluate clinical parameters for the prediction of isthmus-dependent AFL. Methods and Results: Sixty consecutive adult patients without suspected atriotomy-related AFL, congenital heart disease, or previous AFL ablation, referred for catheter ablation of presumed typical AFL were studied. All patients had distinct flutter waves in the inferior leads, suggestive of CTI-dependent AFL, either on presentation to the electrophysiology (EP) lab or documented on prior ECG. Electrophysiology study was performed in the standard fashion. Patients who presented to the EP laboratory not in AFL underwent arrhythmia induction with a burst pacing protocol.A clinical history of persistent AFL (P = 0.0001) and existence of AFL on presentation to the EP laboratory (P = 0.0001) were strong predictors of CTI dependence. History of atrial fibrillation (P = 0.19), structural heart disease (P = 0.6), hypertension (P = 0.4), and previous cardiac surgery (P = 0.5), as well as the nature of AFL-related symptoms (P = 0.5), were not predictors of CTI-dependent AFL documented during EP study. Conclusion: In patients with ECG suggestive of typical AFL, the presence of persistent rather than paroxysmal AFL and presentation to the EP laboratory in AFL are strong predictors of CTI-dependent AFL. A paroxysmal pattern of AFL predicts noninducibility of CTI-dependent AFL during EP study. CTI ablation may therefore be less effective in these patients.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: ATIGA, W.L., et al.: Prospective Randomized Comparison of Cooled Radiofrequency Versus Standard Radiofrequency Energy for Ablation of Typical Atrial Flutter. In patients with atrial flutter, conventional RF ablation may not result in complete isthmus block. This prospective, randomized study tested the hypothesis that the cooled RF ablation is safe and facilitates the achievement of isthmus block with fewer RF applications than with standard ablation for typical atrial flutter. Isthmus ablation was performed in 59 patients (40 men, 64 ± 14 years) with type I atrial flutter using standard RF (n = 31) or cooled RF (n = 28) catheters with crossover after 12 unsuccessful RF applications. The endpoint was bidirectional isthmus block or a total of 24 unsuccessful RF applications. After the first 12 RF applications, 17 (55%) of 31 standard RF and 22 (79%) of 28 cooled RF patients had bidirectional isthmus block (P 〈 0.05). After the remaining patients crossed over to the alternate RF ablation system and underwent up to 12 more RF applications, bidirectional isthmus block had been demonstrated in 27 (87%) of 31 standard RF and 25 (89%) of 28 cooled RF patients (P = NS). Isthmus block was not achieved within 24 RF applications in four standard and three cooled RF patients. Mean measured tip temperatures for cooled RF were lower than for standard RF (38.5°C ± 6.98°C vs 57.2°C ± 7.42°C, P 〈 0.0001). Peak temperatures were also lower for cooled RF compared to standard RF (45.7°C ± 22.7°C vs 63.4°C ± 9.87°C, P 〈 0.0001). Importantly, mean power delivered was significantly higher for cooled than for standard RF (42.3 ± 9.48 vs 34.0 ± 14.0 W, P 〈 0.0001). There were no serious complications for either ablation system. During a 12.8 ± 3.76-month follow-up, there were two atrial flutter recurrences in the cooled RF group and four in the standard RF group (P = NS). In patients with type I atrial flutter, ablation with the cooled RF catheter is as safe as, and facilitates creation of bidirectional isthmus block more rapidly than, standard RF ablation.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Treatment of arrhythmogenic right ventricular dysplasia (ARVD) is mostly based on the prevention of sudden cardiac death that results from arrhythmias. A clinical history suggestive of ARVD requires careful evaluation including electrophysiological study. The potential ability to identify those patients who will have inducible VT with electrophysiological study will enable better risk stratification and selection of vulnerable patients for electrophysiologically guided therapy. The purpose of the study was to evaluate the predictive ability of signal-averaged electrocardiography (SAECG) to predict inducibility of VT in patients with ARVD. The patient population consisted of 31 ARVD patients diagnosed with McKenna's criteria who underwent electrophysiological study. Electrophysiological study was considered positive if sustained monomorphic VT was induced. The sensitivity, specificity, and predictive accuracy of various SAECG criteria for inducibility of sustained monomorphic VT were also calculated. Twenty-one patients had inducible VT. The filtered QRS duration (fQRS), duration of signal 〈40 uV (LAS40), and root mean square voltage in the last 40 ms of QRS duration (RMS40) in ARVD patients induced versus noninduced were 122 ± 21 and 103 ± 8 ms (P = 0.007), 45 ± 20 and 28 ± 14 ms (P = 0.02), 19 ± 19 and 32 ± 22 uV (0.03), respectively. The ejection fractions were comparable in both groups. fQRS duration ≥110 ms had sensitivity of 91%, specificity of 90%, and a total predictive accuracy of 90% in predicting inducibility of VT in these patients. Filtered QRS duration on SAECG is predictive of electrophysiological study outcome in ARVD. Further studies will be needed to determine if SAECG results can predict the development of ventricular arrhythmias during follow-up. (PACE 2003; 26:1955–1960)
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: CALKINS, H., et al.: Prospective Randomized Comparison of the Safety and Effectiveness of Placement of Endocardial Pacemaker and Defibrillator Leads Using the Extrathoracic Subclavian Vein Guided by Contrast Venography Versus the Cephalic Approach. The purpose of this prospective randomized study was to compare the safety and efficacy of the cephalic approach versus a contrast-guided extrathoracic approach for placement of endocardial leads. Despite an increased incidence of lead fracture, the intrathoracic subclavian approach remains the dominant approach for placement of pacemaker and implantable defibrillator leads. Although this complication can be prevented by lead placement in the cephalic vein or by lead placement in the extrathoracic subclavian or axillary vein, these approaches have not gained acceptance. A total of 200 patients were randomized to undergo placement of pacemaker or implantable defibrillator leads via the contrast-guided extrathoracic subclavian vein approach or the cephalic approach. Lead placement was accomplished in 99 of the 100 patients randomized to the extrathoracic subclavian vein approach as compared to 64 of 100 patients using the cephalic approach. In addition to a higher initial success rate, the extrathoracic subclavian vein medial approach was determined to be preferable as evidenced by a shorter procedure time and less blood loss. There was no difference in the incidence of complications. In conclusion, these results demonstrate that lead placement in the extrathoracic subclavian vein guided by contrast venography is effective and safe. It was also associated with no increased risk of complications as compared with the cephalic approach. These findings suggest that the contrast-guided approach to the extrathoracic portion of the subclavian vein should be considered as an alternative to the cephalic approach.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...