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  • 1
    ISSN: 1540-8167
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Slower Conduction in the TV-IVC Isthmus. Introduction: In human type I atrial flutter, the electrophysiologic substrate is unclear. In order to determine if slow conduction is mechanistically important, we evaluated conduction velocity in the tricuspid valve-inferior vena cava (TV-IVC) isthmus, right atriai free wall, and interatrial septum in patients with and without a history of atrial flutter undergoing electrophysiologic study. Methods and Results: Nine patients with (group 1) and nine without a history of type I atrial flutter (group 2) were studied. Conduction time (msec) in the right atrial free wall. TV-IVC isthmus (bidirectional), and interatrial septum was measured during pacing in sinus rhythm at cycle lengths of 600, 500, 400, and 300 msec from the low lateral right atrium and coronary sinus ostium. Conduction velocity (cm/sec) was calculated by dividing the distance between pacing electrodes and sensing electrodes (cm) by the conduction time (sec). Conduction velocity was slower in the TV-IVC isthmus in group 1 (range 37 ± 8 to 42 ± 8 cm/sec) versus group 2 (range 50 ± 8 to 55 ± 9 msec) at all pacing cycle lengths (P 〈 0.05). However, conduction velocity was not different in the right atrial free wall or interatrial septum between groups 1 and 2. Conduction velocity was also slower in the TV-IVC isthmus than in the right atrial free wall and interatrial septum in group 1 patients, at all pacing cycle lengths (P 〈 0.05). Atrial flutter cycle length correlated with total atrial conduction time (r ≥ 0.832, P 〈 0.05). Conclusion: Slow conduction in the TV-IVC isthmus may be mechanistically important for the development of human type I atrial flutter.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of interventional cardiac electrophysiology 4 (2000), S. 537-545 
    ISSN: 1572-8595
    Schlagwort(e): cryoablation ; ventricular tachycardia ; His bundle ablation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Introduction: Surgical cryoablation, a highly effective technique used during antiarrhythmic surgery, produces voluminous, histologically uniform and discreet myocardial lesions. In contrast, radiofrequency (RF) catheter ablation, which as a result of its less invasive nature has largely supplanted antiarrhythmic surgery, produces smaller, histologically heterogeneous myocardial lesions. Since small lesion size and heterogeneity may reduce antiarrhythmic efficacy, we sought to reproduce the large, histologically homogeneous lesions created by surgical cryoablation, using a catheter cryoablation system (Cryogen, Inc., San Diego, CA) in the canine ventricle. Methods and Results: In seven dogs, nineteen ventricular lesions (two right and seventeen left) were created with a 10F cryoablation catheter with either a 2 or 6[emsp4 ]mm tip. In one dog AV node ablation was also performed. For each 'freeze', catheter tip nadir temperature, lesion width, depth, and transmurality were recorded, and lesion volume calculated. Average tip nadir temperature was −79.6±4.9°C. Cooler nadir tip temperature was associated with deeper (p=.007) and more voluminous lesions (p=.042), and a greater likelihood of lesion transmurality (p=.034). Average lesion volume was 500±356[emsp4 ]mm3. No other variables predicted lesion volume or transmurality. Histologically, the catheter cryoablation lesions were sharply demarcated and homogeneous. The single freeze performed at the AV junction produced complete AV block. One complication, catheter rupture following its repetitive use, resulted in a coronary air embolus and death. Conclusion: Catheter cryoablation of canine ventricular myocardium produced voluminous, discrete, transmural lesions, which might be effective for ablation of ventricular tachycardia. Lesion volume and transmurality were dependent on catheter tip nadir temperature.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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