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”

Table 1. Review of cryoablation of anteroseptal or midseptal accessory pathways

Abbreviations: No.pts: number of patients; AntSept: number of patients with
anteroseptal accessory pathways; MidSept: number of patients with midseptal
accessory pathways; RBBB: right bundle branch block; n.r.: not reported

Focal atrial tachycardia and isthmus-dependent atrial flutter. Occasionally, successful
cryoablation of focal atrial tachycardia has been reported and its safety has been confirmed also
for ablation of atrial foci located close to the atrioventricular node³².

Several papers have reported cryoablation of the cavotricuspid isthmus for typical atrial
flutter with an acute and long-term success comparable to the one of radiofrequency
ablation^33,34,35,36. The use of larger catheter and longer electrode for ablation in this area is
associated with a lower number of applications and a shorter procedural time. As for
radiofrequency ablation, a case of transient ST segment elevation in the inferior leads was
observed during cryo application at the septal isthmus, with wall irregularities in the right
coronary artery without significant stenosis³⁵. The major advantage of using cryothermal energy
to produce bidirectional conduction block of the cavo-tricuspid isthmus is the absence of pain
perception related to energy application. In a prospective randomized trial in which a visual
analogue scale to evaluate pain was used, pain perception was by far lower if not existent in the
cryothermal as compared to radiofrequency energy group³⁴.

Pulmonary vein ablation for atrial fibrillation. When radiofrequency energy is applied at the os
of the pulmonary veins to prevent atrial fibrillation recurrences, a heat-induced contraction of the
pulmonary vein wall can be observed early or during the follow-up, which results in a variable
degree of lumen reduction and a wide spectrum of clinical presentations³⁷. This reaction is
typical of hyperthermic injury and results from a combination of edema, endothelial disruption
and collagen denaturation and shrinkage³⁸. The occurrence and the degree of stenosis correlate
with the amount of energy delivered³⁹ and lesion extension⁴⁰. As mentioned above, cryothermal
energy ablation causes less or minimal endothelial disruption, maintenance of extracellular
collagen matrix and no collagen contracture related to thermal effects. Moreover, lower
incidence of thrombus formation is reported with cryoenergy as compared to radiofrequency
energy ablation. For these characteristics, cryothermal energy ablation can be considered an ideal
and safer energy source also for pulmonary vein ablation and the incidence of both pulmonary

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

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