Cryothermal Energy Ablation Of Cardiac Arrhythmias 2005: State Of The Art

Roberto De Ponti, “Cryothermal Energy Ablation Of Cardiac Arrhythmias 2005:
State Of The Art”

veins stenosis and thromboembolic events is expected to be dramatically reduced by using
cryoablation. On the other hand, the presence of high blood flow in the pulmonary vein may
represent a considerable heat load, which may limit the size and depth of the lesion produced by
cryothermal energy at the os of the pulmonary vein. Moreover, the longer time required to
produce a permanent lesion may relevantly reflect on procedure duration, limiting the clinical
use of this theoretically optimal energy source. Initial experiences of electrophysiologically-
guided segmental ostial ablation of the pulmonary vein by using cryothermal energy application
with 10 or 7 F catheters^20,41 have been reported. These experiences show that pulmonary vein
isolation is feasible with a comparable number of applications and clinical outcome with regard
to radiofrequency ablation; longer procedural times, observed for both the 10 F and the 7 F
catheter, correlate with longer application times required when cryothermal energy is used.

Figure 3. Example of disappearance of ventricular preexcitation in a case of
parahissian accessory pathway. Surface ECG and bipolar recordings from the distal
(ABLd) and proximal (ABLp) electrode pairs of the cryoablation catheter are
displayed. The relative position of His bundle and the accessory pathway has been
identified during accurate mapping, also during orthodromic atrioventricular
reentrant tachycardia. Accessory pathway turned out to be located at the same site
where a high amplitude His bundle potential was recorded. In this figure, the tip
electrode temperature is -23°C and minor artefacts in ABLd suggest that ice is
forming on the tip electrode. In the first sinus beat, ventricular preexcitation is still
present with optimal A-V and V-delta interval recorded at this site. In the second
beat, conduction over the accessory pathway is interrupted with disappearance of
ventricular preexcitation; now a high amplitude His bundle potential is well evident
in the distal electrode pair of the ablation catheter. Permanent ablation of this
parahissian pathway could be accomplished by limited cryothermal energy delivery
in this site with no modification of conduction over the normal atrioventricular
conduction pathway.

Indian Pacing and Electrophysiology Journal (ISSN 0972-6292), 5(1): 12-24 (2005)

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