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Indian
RACINGand ELECTROPHYSIOLOGY www.ipej.org 12
Journal
Review Article
Cryothermal Energy Ablation Of Cardiac Arrhythmias
2005: State Of The Art
Roberto De Ponti, MD
Department of Cardiovascular Sciences, Ospedale di Circolo e Fondazione Macchi, University
of Insubria, Varese, Italy
Address for correspondence: Roberto De Ponti, MD, Department of Cardiovascular Sciences,
Ospedale di Circolo e Fondazione Macchi, University of Insubria - Varese, Italy, Viale Borri,
57, I-21100 Varese, Italy. E-mail: [email protected]
Abstract
At the time of antiarrhythmic surgery, cryothermal energy application by a hand-held
probe was used to complement dissections and resections and permanently abolish the
arrhythmogenic substrate. Over the last decade, significant engineering advances allowed
percutaneous cryoablation based on catheters, apparently not very different from standard
radiofrequency ablation catheters. Cryothermal energy has peculiar characteristics. In fact, it
allows testing in a reversible way the effects of energy application at higher temperature, before
producing a permanent lesion at -75°C. Moreover, slow formation of the lesion allows timely
discontinuation of the application, as soon as inadvertent modifications of normal
atrioventricular conduction are observed during ablation in the proximity of atrioventricular node
and His bundle, avoiding its permanent damage. Over the last years, percutaneous cryothermal
ablation has been widely used for a variety of cardiac arrhythmias. From the data gathered, it is
unlikely that cryoablation will replace standard ablation in unselected cases. Nevertheless, for the
above mentioned peculiarities, cryothermal ablation has proved very effective and safe for
ablation of arrhythmogenic substrates close to the normal conduction pathways, becoming the
first choice method to ablate anteroseptal and midseptal accessory pathways. It can be also the
best treatment for ablation of the slow pathway to abolish atrioventricular node reentrant
tachycardia in pediatrics or when particular anatomy of the Koch’s triangle is observed.
Cryothermal ablation of the pulmonary veins for atrial fibrillation, although longer than
radiofrequency ablation, is not associated with pulmonary vein stenosis and is expected to be less
thrombogenic; new catheter designs for cryothermal ablation of this challenging arrhythmia are
to be tested to assess their efficacy and clinical usefulness.
Keywords: cryoablation; cardiac arrhythmia
From surgical to catheter-based cryoablation
In the 80’s, epicardial cryoablation was introduced in antiarrhythmic surgery for ablation
of accessory pathways by Klein et al1. A hand-held cryoprobe was applied at the site where
intraoperative mapping localized the arrhythmogenic substrate. The probe was refrigerated to
-60°C and its effectiveness was evaluated during continuous monitoring of the cardiac electrical
activity. This method, largely used in the past2,3,4 for antiarrhythmic surgery and still in use for
Indian Pacing and Electrophysiology Journal (ISSN 0972-6292), 5(1): 12-24 (2005)