Prophylactic catheter ablation for the prevention of defibrillator therapy.

BACKGROUND: For patients who have a ventricular tachyarrhythmic event, implantable cardioverter-defibrillators (ICDs) are a mainstay of therapy to prevent sudden death. However, ICD shocks are painful, can result in clinical depression, and do not offer complete protection against death from arrhythmia. We designed this randomized trial to examine whether prophylactic radiofrequency catheter ablation of arrhythmogenic ventricular tissue would reduce the incidence of ICD therapy. METHODS: Eligible patients with a history of a myocardial infarction underwent defibrillator implantation for spontaneous ventricular tachycardia or fibrillation. The patients did not receive antiarrhythmic drugs. Patients were randomly assigned to defibrillator implantation alone or defibrillator implantation with adjunctive catheter ablation (64 patients in each group). Ablation was performed with the use of a substrate-based approach in which the myocardial scar is mapped and ablated while the heart remains predominantly in sinus rhythm. The primary end point was survival free from any appropriate ICD therapy. RESULTS: The mortality rate 30 days after ablation was zero, and there were no significant changes in ventricular function or functional class during the mean (+/-SD) follow-up period of 22.5+/-5.5 months. Twenty-one patients assigned to defibrillator implantation alone (33%) and eight patients assigned to defibrillator implantation plus ablation (12%) received appropriate ICD therapy (antitachycardia pacing or shocks) (hazard ratio in the ablation group, 0.35; 95% confidence interval, 0.15 to 0.78, P=0.007). Among these patients, 20 in the control group (31%) and 6 in the ablation group (9%) received shocks (P=0.003). Mortality was not increased in the group assigned to ablation as compared with the control group (9% vs. 17%, P=0.29). CONCLUSIONS: In this randomized trial, prophylactic substrate-based catheter ablation reduced the incidence of ICD therapy in patients with a history of myocardial infarction who received ICDs for the secondary prevention of sudden death. (Current Controlled Trials number, ISRCTN62488166 [controlled-trials.com].).

Atrioventricular nodal reentrant tachycardia associated with idiopathic ventricular tachycardia: clinical and electrophysiologic characteristics.

BACKGROUND: Case reports have described the coexistence of ventricular tachycardia (VT) and supraventricular tachycardia in the same patient. This study examines the frequency of dual atrioventricular nodal (AVN) physiology, AVN echo beats, and atrioventricular nodal reentrant tachycardia (AVNRT) in patients with VT. METHODS: Programmed atrial and ventricular stimulation was performed in 132 consecutive patients referred for electrophysiologic study of symptomatic VT. Of the 132, 99 patients had structural heart disease, and 33 patients had idiopathic ventricular tachycardia (IVT). RESULTS: Among the 33 patients with IVT, 23 had dual AVN physiology. Compared with patients with structural heart disease undergoing VT ablation, dual AVN pathways (70% vs 27%, P < .0001), dual AVN pathways with echo beats (24% vs 8%, P = 0.03), and AVNRT (21% vs 1%, P = .0002) were more common in patients with IVT. CONCLUSION: Dual AVN physiology and AVNRT appear to be associated with IVT. This finding suggests that patients with IVT should undergo a complete electrophysiologic evaluation, and the diagnosis of coexistent AVNRT should be considered in this population.

Bi-directional electrical pulmonary vein isolation as an endpoint for ablation of paroxysmal atrial fibrillation.

OBJECTIVE: Various approaches to pulmonary vein (PV) isolation have shown variable efficacy in patients with paroxysmal atrial fibrillation (AF). The purpose of this study is to report the efficacy and safety of routine isolation of all PVs using an endpoint of bi-directional electrical block. MATERIALS AND METHODS: This study included 85 consecutive patients who underwent PV isolation for symptomatic paroxysmal AF. Complete isolation of all PVs was confirmed by demonstration of bi-directional block: (a) loss of all PV potentials, and (b) failure to capture the left atrium by pacing 10-14 bipolar pairs of electrodes on a circumferential catheter placed at the entrance of the PV at 10 mA with 2 ms pulse width. Induction of AF by burst pacing was attempted after PV isolation. RESULTS: Freedom from symptomatic or asymptomatic AF (detected by event recorder or Holter monitor) was present in 85% and 76% of patients at 6 and 12 months. Additional mitral isthmus or posterior left atrial lines were performed in seven patients with inducible atrial arrhythmias after PV isolation. Atrial tachycardia occurred in three of these patients during long-term follow-up and in two of the 78 patients without additional ablation. CONCLUSION: The use of bi-directional block circumferentially across all PV ostia as an electrophysiological endpoint may improve results of PV isolation for paroxysmal AF. Avoidance of routine additional left atrial ablation lines may decrease the risk of atrial tachycardia and esophageal fistula.

A phenomenologic study of fatigue in adolescents receiving treatment for cancer.

PURPOSE/OBJECTIVES: To generate a detailed description of how adolescents with cancer manage their daily lives and the way in which fatigue affects this. DESIGN: Phenomenologic. SETTING: A pediatric oncology unit at a regional cancer center in the United Kingdom. SAMPLE: A convenience sample of adolescents (N = 8), aged 16-19 years and with hematologic or solid tumors, who currently were undergoing primary treatment. METHODS: Semistructured interviews were conducted using 11 open-ended questions. MAIN RESEARCH VARIABLES: Adolescents' perceptions of fatigue, well-being, and ability to maintain normal activities. FINDINGS: Adolescents reported fatigue as overwhelming and embedded in a syndrome of symptoms and emotions associated with the illness itself and with treatment. Fatigue had a significant effect on physical, psychological, and social well-being, placing an extra burden on adolescents who were striving for normality. CONCLUSIONS: Equipped with a rich description of fatigue, clinicians will be better prepared to initiate strategies congruent with their own work settings and particular patients. IMPLICATIONS FOR NURSING: The findings should enable healthcare professionals to construct a more accurate and perceptive picture of the needs of particular individuals, highlighting those that may be amenable to intervention.

Variable electrocardiographic characteristics of isthmus-dependent atrial flutter.

OBJECTIVES: The purpose of this study was to characterize variations in flutter-wave (F-wave) morphology among patients with clockwise isthmus-dependent (CWID) and counterclockwise isthmus-dependent (CCWID) right atrial flutter (AFL) and to attempt to correlate F-wave morphology with echocardiographic data and clinical patient characteristics. BACKGROUND: Variations in F-wave morphology on surface electrocardiogram (ECG) during CCWID and CWID flutter have been reported but never systematically characterized. METHODS: Over a four-year period, 139 patients with AFL on ECG underwent electrophysiologic study and echocardiography at our institution. Electrocardiographic data, intracardiac recordings, echocardiographic data, and patient characteristics were reviewed retrospectively. RESULTS: Of 156 AFLs evaluated, 130 were CCWID, 26 were CWID. Three types of CCWID flutter were observed: type 1 had purely negative F-waves inferiorly, types 2 and 3 had F-waves inferiorly with small (type 2) or broad (type 3) positive terminal deflections; CCWID flutter types 2 and 3 were associated with higher incidence of left atrial (LA) enlargement, heart disease, and atrial fibrillation (Afib) than type 1. Two types of CWID flutter were observed: type 1 had notched positive F-waves with a distinct isoelectric segment inferiorly. Type 2 had broader F-waves inferiorly with positive and negative components and a short isoelectric segment. CONCLUSIONS: Variable ECG patterns for CCWID and CWID AFL exist. A positive component of the F-wave in the inferior leads during CCWID flutter is associated with an increased likelihood of heart disease, Afib, and LA enlargement.