Pacing and clinical electrophysiology : PACE
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Pacing Clin Electrophysiol · Dec 1997
Comparative StudySteroid-eluting epicardial pacing electrodes: six year experience of pacing thresholds in a growing pediatric population.
Indications for pacemaker implantation in the pediatric population often include sinus or atrioventricular node dysfunction following surgery for congenital heart defects. However, patient size, cardiac defects, and vascular and valvular concerns may limit transvenous lead utilization. Since the epicardial surface of these patients often exhibits variable degrees of fibrosis from scar tissue formation or pericardial adhesions, chronic low output (2.5/1.6 V, 0.3 ms) epicardial pacing from implant is not currently recommended in children due to frequent threshold changes and electrode exit block. ⋯ Mean ventricular pulse width thresholds (0.12 ms +/- 0.05 ms) were significantly higher (P < 0.001) than atrial thresholds (0.06 ms +/- 0.03 ms) at implant and throughout the study period. The thresholds in the patients following cardiac surgery were comparable to those without previous cardiac surgery (P = NS). Stable low thresholds may be chronically maintained for up to 6 years for epicardial steroid-eluting electrodes irrespective of pacing site or associated cardiac surgery.
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Pacing Clin Electrophysiol · Dec 1997
Relation between left atrial size and secondary atrial arrhythmias after successful catheter ablation of common atrial flutter.
Catheter ablation provides an effective cure for patients with typical atrial flutter. However, these patients may have the potential to develop atrial tachyarrhythmias other than common atrial flutter. This study examines clinical and echocardiographic predictors for the occurrence of uncommon atrial flutter or atrial fibrillation after abolition of common atrial flutter. ⋯ On Kaplan-Meier analysis, time to occurrence of postablation atrial arrhythmias was significantly shorter in patients with enlarged left atrium (P < 0.02). In conclusion, symptomatic uncommon atrial flutter and atrial fibrillation develops in a substantial proportion of patients after successful ablation of common atrial flutter. Out of a series of clinical and echocardiographic parameters, preablation left atrial size is the best predictor for the occurrence of these postablation atrial arrhythmias.
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Pacing Clin Electrophysiol · Nov 1997
Case ReportsLong QTc and torsades de pointes in human immunodeficiency virus disease.
Three patients with human immunodeficiency virus (HIV) infection presented with QT, prolongation (> 440 ms) and torsades de pointes. We sought to evaluate the etiology of the long QT syndrome in these patients without previously identified causes for QT, prolongation, and determine the prevalence among patients with HIV infection. The three index patients underwent: (1) left stellate ganglion block; (2) beta-blocker challenge; and (3) electrocardiographic stress testing. ⋯ We observed a 7.0% prevalence of QT, prolongation among all patients screened. Hospitalized patients with HIV disease (n = 42) during this same period, demonstrated an increased prevalence of QT, prolongation (28.6%, P = 0.002). Patients with HIV disease have a significantly higher prevalence of QTc prolongation than a general hospital-based population, may have an unrecognized acquired form of the long QT syndrome, and are at risk for torsades de pointes.
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Pacing Clin Electrophysiol · Nov 1997
Comparative StudyEfficacy and safety of a new protocol for continuous infusion of midazolam and fentanyl and its effects on patient distress during electrophysiological studies.
Electrophysiological studies are often distressing for patients. We devised a regime of continuous infusion of midazolam and fentanyl during electrophysiological studies without the presence of a specialist anaesthetist. The effects on key hemodynamic and respiratory variables and level of sedation were evaluated in detail in the first 775 patients. ⋯ The amount of distress experienced by sedated patients (n = 775) was significantly less compared to a previous series of nonsedated patients (n = 775) undergoing electrophysiological studies (P < 0.001). The degree of distress experienced by patients during electrophysiological studies can be reduced significantly by sedation with intravenous midazolam and fentanyl. Continuous infusion is an efficient, safe, and effective way of administering midazolam and fentanyl.
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Supraventricular and ventricular arrhythmias, particularly nonsustained ventricular tachycardia, and ventricular premature beats are a common finding in patients with hypertrophic cardiomyopathy. Several investigations have demonstrated that nonsustained ventricular tachycardia on Holter monitoring is associated with an increased risk of sudden cardiac death. It has been a long lasting controversial discussion whether suppression of these arrhythmias with drugs, such as amiodarone is capable to reduce the incidence of sudden cardiac death. ⋯ The implantation of an ICD in asymptomatic patients should be limited to those who have several risk factors for sudden cardiac death. It is questionable whether other risk stratifiers, such as programmed electrical stimulation may be helpful to identify asymptomatic patients who are at risk to die suddenly. Moreover, whether the demonstration of electrocardiogram fractionation during electrophysiological study is superior to the induction of sustained ventricular arrhythmias for risk stratification, needs further investigation.