Elsevier

Heart Rhythm

Volume 8, Issue 6, June 2011, Pages 821-825
Heart Rhythm

Clinical
Ablation
Cryoballoon temperature predicts acute pulmonary vein isolation

https://doi.org/10.1016/j.hrthm.2011.01.044Get rights and content

Background

Cryoballoon pulmonary vein isolation (PVI) currently requires a long cryoballoon application (CBA) time of 240 to 300 seconds, thus repeated ineffective CBA prolongs procedure duration. We hypothesized that cryoballoon temperature (CBT) may be used to discriminate between effective and ineffective CBA during freezing.

Objective

This study sought to evaluate CBT as a predictor of CBA efficiency.

Methods

Sixty-six patients with atrial fibrillation underwent PVI using the single big (28 mm) cryoballoon technique. CBT was continuously recorded. After each CBA (300 seconds), a Lasso catheter (Biosense Webster, Inc., Diamond Bar, California) was placed into the target pulmonary vein (PV) to determine whether electrical PV disconnection was present. Only the first CBA at each PV was analyzed to avoid cumulative effects.

Results

The CBT was lower during CBA at superior compared with inferior PVs. When individual CBAs were grouped according to successful/failed PVI, CBT was lower for those CBAs that resulted in successful PVI at all time points analyzed. To test the performance of CBT to predict failed CBA, receiver-operator curves were constructed. A minimal CBT of ≥ −42°C/ −39°C (superior/inferior PVs) predicted failed PVI with 73%/92% specificity (area under the curve 0.82/0.81); positive predictive value (PPV) 74%/74%. A minimal CBT of < −51°C was invariably associated with PVI. After 120 seconds of freezing, a CBT of ≥ −36°C/ −33°C (superior/inferior PVs) predicted failed PVI with 97%/95% specificity (area under the curve 0.82/0.76); PPV 82%/80%.

Conclusion

Balloon temperature predicts successful target PVI during cryoablation and may serve in the early identification of noneffective balloon applications.

Introduction

Cryoballoon technology is increasingly used to perform pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF).1, 2, 3, 4 The device is designed to create circumferential lesions around the target PV, ideally with a single cryoballoon application (CBA). However, cryoablation vitally depends on balloon-tissue contact or pulmonary vein (PV) occlusion, because residual blood flow interferes with lesion formation. In addition, complete PV occlusion reduces surrounding blood flow, resulting in lower cryoballoon temperatures.5 Failure to achieve complete balloon-tissue contact results in ineffective CBA. Because CBA is performed for 4 to 5 minutes, repeated ineffective CBA prolongs procedure duration. Different techniques to evaluate PV occlusion have been proposed, some of which require additional diagnostic tools such as intracardiac ultrasound.5, 6, 7, 8 The simplest and most widely used technique is angiography via the balloon tip.1, 2, 3, 4 Angiography, however, cannot be used to evaluate contact during freezing, and it has been shown that balloon dislocation may occur after initiation of CBA.5

Cryoballoon temperature (CBT) is measured continuously during CBA by a thermocouple in the proximal inner balloon (Figure 1). We hypothesized that CBT, a readily available parameter during cryoballoon PVI, may be used to discriminate between effective and ineffective CBA during freezing.

Section snippets

Patients

Between April 2006 and March 2010, a total of 134 patients underwent cryoballoon PVI using the single big cryoballoon technique.1 In 66 of these patients, complete recordings of CBT over time during each CBA was available. These patients constitute the study population. Baseline clinical characteristics are shown in Table 1.

Cryoballoon ablation

The concept of the single big cryoballoon technique for PVI (Arctic Front, 28-mm diameter, Medtronic CryoCath LP, Pointe-Claire, Quebec, Canada) has been described in detail

Cryoballoon ablation

PV anatomy consisted of 4 individual PVs in 60 patients. In the remaining 6 patients, a left common PV was found (Table 2). In 5 of these patients with a short common trunk, superior and inferior branches were isolated individually and included in the temperature analysis as left superior PV and left inferior PV, respectively. In 1 patient, the left common PV was isolated by sequentially performing CBA at the superior and inferior circumference and omitted from temperature analysis. Of a total

Discussion

The main findings of this study are as follows. (1) Cryoballoon temperature may be used to discriminate between successful and failed CBA at various time points during freezing. (2) A high CBT predicted a failed freeze with high specificity. (3) Very low CBT was invariably associated with successful PVI.

Although the ideal freezing duration of a CBA remains to be determined, cryoballoon ablation is generally performed for 4 to 5 minutes.1, 2, 3, 4, 9 During this period, the operator is usually

Conclusion

CBT, a simple parameter provided by the cryoballoon system, may be used to discriminate between successful and failed PVI at various time points during freezing. Cutoff temperatures were defined that predicted failed ablation during freezing with high specificity. CBT may be used to guide cryoablation and avoid prolonged inefficient freezing.

References (16)

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    Citation Excerpt :

    Using the first-generation cryoballoon, the temperature at 120 seconds after ablation initiation was used to predict lesion durability. In these series, temperatures warmer than –36°C for superior PVs and warmer than –33°C for inferior PVs predicted ineffective PVI with >95% specificity (positive predictive value 80% for superior PVs and 82% for inferior PVs).22,23 As such, we consider lesions that fail to achieve a temperature colder than –35°C after 60 seconds ineffectual.24,25

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K. H. Kuck is a consultant for Cryocath and received research grant and honoraria for Medtronic educational lectures. A. Fürnkranz and J. Chun received honoraria payments for Medtronic educational lectures.

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