Impact of Pulmonary Vein Cryoballoon Ablation on Bronchial Injury

Anatomical correlation between left atrium pulmonary vein ablation targets of atrial fibrillation and adjacent bronchi and pulmonary arteries by MSCT

BACKGROUND

The ablation targets of atrial fibrillation (AF) are adjacent to bronchi and pulmonary arteries (PAs). We used computed tomography (CT) to evaluate the anatomical correlation between left atrium (LA)-pulmonary vein (PV) and adjacent structures.

METHODS

Data were collected from 126 consecutive patients using coronary artery CT angiography. The LA roof was divided into three layers and nine points. The minimal spatial distances from the nine points and four PV orifices to the adjacent bronchi and PAs were measured. The distances from the PV orifices to the nearest contact points of the PVs, bronchi, and PAs were measured.

RESULTS

The anterior points of the LA roof were farther to the bronchi than the middle or posterior points. The distances from the nine points to the PAs were shorter than those to the bronchi (5.19 ± 3.33 mm vs 8.62 ± 3.07 mm; P < .001). The bilateral superior PV orifices, especially the right superior PV orifices were closer to the PAs than the inferior PV orifices (left superior PV: 7.59 ± 4.14 mm; right superior PV: 4.43 ± 2.51 mm; left inferior PV: 24.74 ± 5.26 mm; right inferior PV: 22.33 ± 4.75 mm) (P < .001).

CONCLUSIONS

The right superior PV orifices were closer to the bronchi and PAs than other PV orifices. The ablation at the mid-posterior LA roof had a higher possibility to damage bronchi. CT is a feasible method to assess the anatomical adjacency in vivo, which might provide guidance for AF ablation.

Cryoballoon ablation dosing: From the bench to the bedside and back

To date, multiple modes of research have been leveraged to study the optimal cryoballoon ablation parameters to safely, effectively, and efficiently isolate the pulmonary veins for the treatment of atrial fibrillation. Basic scientific investigation, preclinical studies, clinical observations, trials, and, more recently, computational modeling have helped to generate and test new hypotheses for the advancement of cryoballoon treatment in patients with atrial fibrillation. In this review, we examine the data and evidence that have contributed to the development of patient-tailored dosing strategies that are currently used for pulmonary vein isolation by using the Arctic Front series of cryoballoon ablation catheters.

Impact of cryoballoon applications on lesion gaps detected by magnetic resonance after pulmonary vein isolation

INTRODUCTION

Ablation with second-generation cryoballoon technology evolves as an effective and safe alternative to radiofrequency for atrial fibrillation ablation procedures. Nevertheless, the optimal freezing strategy remains unknown. Our objective was to identify the procedural cryoablation parameters predicting successful peri-pulmonary vein (PV) lesions by directly analyzing Postablation gaps in late-gadolinium-enhanced cardiac magnetic resonance (LGE-CMR).

METHODS AND RESULTS

Forty-nine consecutive patients (196 PVs) undergoing ablation with second-generation cryoballoon at our center were included. The number and duration of cryoballoon application to achieve PV isolation were left to operator discretion. Gap number and length were quantified in all patients with a LGE-CMR performed 3 months postablation. Application time (420 ± 217 seconds), number of applications (2.1 ± 1.2), application time after electrical isolation (311 ± 194 seconds) and minimum temperature (-45.8 ± 6.5°C) were similar in the 4 PVs. Gaps were observed in 148 PVs (76%), averaging 1.3 ± 1 gaps per vein. Gaps were longer and more frequent in the right PVs (91% vs 59% in left PVs, P < .001). Neither the number, total duration of applications, nor postisolation application time predicted relative length or number of gaps.

CONCLUSIONS

After successful PV isolation was achieved in patients undergoing cryoablation, increasing the number of applications, the total application time or application time postisolation did not result in a reduction in the number or the relative length of gaps.

Acute Procedural Complications of Cryoballoon Ablation: A Comprehensive Review

Catheter ablation is increasingly performed for treatment of atrial fibrillation (AF). Balloon based procedures have been developed aiming at safer, easier and more effective treatment as compared to point to point ablation. In the present review article, we aimed to discuss acute procedural complications of cryoballoon ablation.

Thermodynamic properties of atrial fibrillation cryoablation: a model-based approach to improve knowledge on energy delivery

The objective of this study is to describe a suitable model of atrial fibrillation cryoablation thermodynamic properties. Three different thermal loads were applied to a cylindrical copper element simulating the cryoprobe, thermally coupled with a Peltier stack producing the freezing effect, and in contact with a bovine liver sample. Thermal events occurring inside the samples were measured using mirror image technique. Heat subtracted flux during ice formation and minimum temperature measured at probe-tissue interface were, respectively, 1.33 W cm^-2 and -27.8°C for Sample#0, 1.88 W cm^-2 and -35.6°C for Sample#1 and 1.82 W cm^-2 and 1.44 W cm^-2 before and after the ice trigger, respectively, and -29.3°C for Sample#2. Ice trigger temperature was around -8.5°C for Sample#0 and Sample#2, and -10.4°C for Sample#1. In all the investigated samples, ice front penetration was proportional to the square root of time and its velocity depended on the heat flux subtracted. The fraction of the useful energy spent for ice formation was less than 60% for Sample#0, and about 80% for Sample#1 and for Sample#2, before the reduction of the removed heat flux. Freezing time exceeding a cut-off, according to the heat subtracted flux, does not improve the procedure effectiveness and is detrimental to the surrounding tissues.

Predictors of hemoptysis in the setting of pulmonary vein isolation using the second-generation cryoballoon

INTRODUCTION

To assess the predictors of hemoptysis using second-generation cryoballoon (CB).

METHODS

Thirty patients with hemoptysis after second-generation CB ablation and 60 age-, gender-, and body mass index-matched controls were recruited. Anatomic parameters were obtained from preprocedural cardiac computed tomography (CT). Pulmonary vein isolation was performed with 28-mm balloon using single 3-minute freeze technique.

RESULTS

Clinical and procedural characteristics were similar between the groups. A shorter distance between left superior PV (LSPV) and left main bronchus (LMB) was associated with hemoptysis (7.8 ± 4.3 mm vs. 12.5 ± 3.5 mm, P < 0.001), whereas no significant difference in the distance between right superior PV (RSPV) and right main bronchus (RMB) was found between groups (11.9 ± 3.5 mm vs. 12.9 ± 4.6 mm, P = 0.089). Additionally, the mean thickness of the connective tissue interposed between RSPV and RMB was significantly thicker than that between LSPV and LMB in both groups (both P < 0.001). A stepwise logistic multivariate analysis identified only the LMB-LSPV distance as an independent predictor of hemoptysis (odd ratio [OR] 2.676; 95% CI 1.121-4.843, P < 0.001). A cutoff value ≤ 9.5 mm predicted hemoptysis after CB ablation with 93.8% sensitivity and 75.0% specificity.

CONCLUSION

Hemoptysis is a relatively rare event following second-generation CB ablation. The bronchi location obtained from CT aids in identifying high-risk population for the complication.

Cryoballoon Best Practices II: Practical guide to procedural monitoring and dosing during atrial fibrillation ablation from the perspective of experienced users

Since the evaluation of the cryoballoon in the Sustained Treatment Of Paroxysmal Atrial Fibrillation trial, more than 350,000 patients with atrial fibrillation have been treated. Several studies have reported improved outcomes using the second-generation cryoballoon, and recent publications have evaluated modifications, refinements, and improvements in procedural techniques. Here, peer-reviewed articles published since the first cryoballoon best practices review were summarized against the technical practices of physicians with a high level of experience with the cryoballoon (average ≥6 years of experience in ≥900 cases). This summary includes a comprehensive literature review along with practical usage guidance from physicians using the cryoballoon to facilitate safe, efficient, and effective outcomes for patients with atrial fibrillation.

"Crosstalk" technique: A comparison between two generations of cryoballoon catheter

INTRODUCTION

The "Crosstalk" technique: if pulmonary vein isolation (PVI) of the superior one is not achieved due to a gap in the inferior part, it could be done during inferior vein cryoablation. This maneuver minimizes the total energy delivery time and number of lesions. We aimed to correlate the likelihood of crosstalk phenomenon with certain anatomic characteristics.

METHODS

A total of 676 patients undergoing a first ablation procedure for paroxysmal or persistent atrial fibrillation (470 first-generation cryoballoon [CB] and 206 second-generation CB) between June 2014 and December 2016 were included.

RESULTS

"Crosstalk" phenomenon occurred in 32 patients (18 first-generation CB, 14 second-generation CB). Compared to 54 control patients without crosstalk, the angle between left superior pulmonary vein (LSPV) and left atrial (LA) roof-plane, left pulmonary common ostia were significant parameters associated with crosstalk (odds ratio [OR] = 1.20, ±95% confidence interval [CI]: 1.11-1.31, P < 0.001; OR = 5.67, ±95% CI: 1.08-28.69, P = 0.04). As for angle between LSPV and LA roof-plane, the cut-off value was 28.68° with a sensitivity of 72.22%, a specificity of 81.25%, and an area under the receiver operating characteristic curve of 0.87 to predict the possibility of crosstalk technique application to get isolated in LSPV. Among the crosstalk group, there was no statistical difference between first-generation CB and second-generation CB in pulmonary anatomic characteristics.

CONCLUSION

Crosstalk technique can be effective in patients with AF undergoing CB ablation using with both first and second-generation CBs. Anatomic characteristics predictive of crosstalk include a left common ostia and smaller angle between the LSPV and LA roof-plane.

Bronchial effects of cryoballoon ablation for atrial fibrillation

BACKGROUND

Damage to extracardiac structures, including the esophagus and phrenic nerve, is a known complication of cryoballoon ablation (CBA) during pulmonary vein (PV) isolation for atrial fibrillation (AF). Other adjacent structures, including the pulmonary bronchi and lung parenchyma, may be affected during CBA at the PV ostia.

OBJECTIVE

The purpose of this study was to prospectively study the bronchial effects of CBA in humans undergoing CBA for PV isolation.

METHODS

Ten patients undergoing CBA for AF under general anesthesia were enrolled in an institutional review board-approved prospective observational study. Real-time bronchoscopy was performed during cryoablation of PVs adjacent to pulmonary bronchi to monitor for thermal injury. Patients were followed for the development of respiratory complaints postprocedure.

RESULTS

In 7 of 10 patients (70%) and in 13 of 22 freezes (59%), ice formation was visualized in the left mainstem bronchus during CBA in the left upper PV. Ice formation was not seen in the right mainstem bronchus during right upper PV CBA. The average time to ice formation was 89 seconds. There was no significant difference (P = -.45) in average minimum balloon temperature during freezes with ice formation (-48.5°C) and freezes without ice formation (-46.3°C). No patients went on to develop respiratory complications.

CONCLUSION

Unrecognized ice formation occurs frequently in the left mainstem bronchus during CBA for AF. This information helps explain the source of cough and hemoptysis in some patients who undergo CBA. The long-term consequences of this novel finding and the implications for procedural safety are unknown.

How to Prevent, Detect and Manage Complications Caused by Cryoballoon Ablation of Atrial Fibrillation

Atrial fibrillation is the most common cardiac arrhythmia and the prevalence is increasing every year. Patients who fail to maintain sinus rhythm with use of anti-arrhythmic drug therapy are referred for catheter ablation. Cryoballoon (CB) ablation has emerged as an effective and alternative treatment option to traditional point-by-point radiofrequency ablation, but there can be complications. This article reviews the incidence, presentation, risk factors, management and preventative strategies of three major complications associated with CB ablation: phrenic nerve injury, atrial oesophageal fistula and bronchial injury. Although these complications are rare, electrophysiologists should institute measures to identify high-risk patients, implement best-practice techniques to minimise risks and maintain a high index of suspicion to recognise the complications quickly and implement correct treatment strategies.

Acute Hemodynamic and Tissue Effects of Cryoballoon Ablation on Pulmonary Vessels: The IVUS-Cryo Study

Background

Cryoballoon‐based pulmonary vein isolation (CB‐PVI) has been widely used for the treatment of atrial fibrillation. Although generally safe and effective, the procedure may be associated with pulmonary vein (PV) stenosis and bronchial or esophageal injury. The mechanisms leading to these complications have not been studied in detail. Our aim was to examine acute effects of cryoballoon on the pulmonary vessel and right heart pressures as well as PV wall morphology.

Methods and Results

In 8 patients (5 men, mean age 55±14 years) undergoing CB‐PVI, pressure in each PV was measured by catheter located inside the PV directly before and after CB‐PVI. The right atrial, right ventricular, and pulmonary artery pressures as well as pulmonary arterial wedge capillary pressure in the pulmonary artery branch corresponding to target PV were also measured. Morphological changes in PVs were assessed using intravascular ultrasonography.

There were no significant differences in PV pressures before and after ablation. The pulmonary arterial wedge capillary pressure significantly increased during cryoapplication (left superior: 20±10 versus 29±8.5 mm Hg, P=0.004; left inferior: 24±10 versus 32±6 mm Hg, P=0.012; right superior: 25±9 versus 35±10 mm Hg, P=0.002; right inferior: 24±10 versus 37±12 mm Hg, P=0.0036). The right atrial and pulmonary artery pressures increased significantly after CB‐PVI (9±6 versus 13±8 mm Hg, P=0.004, and 20±9 versus 24±10 mm Hg, P=0.048, respectively). Intravascular ultrasonography showed acute edema and dissection‐like changes causing relative lumen narrowing in 90% of PVs.

Conclusions

CB‐PVI causes significant rise in pulmonary artery and right atrial pressures as well as PV wall damage. The clinical significance of these findings warrants further investigations.

Relationship of the lungs to the left atrium of particular relevance for ablation of atrial fibrillation

BACKGROUND

Symptoms of possible lung and pleural injury such as chest pain and hemoptysis occur during and after radiofrequency ablation (RFA) and cryoablation (CA) of the left atrium (LA) for treatment of atrial fibrillation (AF). We determined the anatomical relationship of the lungs to the LA with particular reference to areas commonly targeted during AF ablation.

METHODS

Distances from the LA endocardium to the lungs were measured from pre-procedure CT angiograms of 100 consecutive patients (71 males, age 60 ± 8 years) who underwent AF ablation.

RESULTS

In 97% of the patients, the posterior right pulmonary vein antrum was <5 mm from the lower lobe of the right lung (RLL) over a supero-inferior distance of 3.6 ± 1.5 cm (minimum distance 1.2 ± 0.7 mm). The right inferior pulmonary vein (RIPV) ostium was <5 mm from the RLL in 94% (mean 2.7 ± 1.9 mm). The right superior pulmonary vein ostium was <5 mm from the RLL in 29% (mean 7.1 ± 3.8 mm). The medial segment of the right middle lobe was <5 mm from the carina between right pulmonary veins in 83% (mean 3.6 ± 1.9 mm). The mitral isthmus was <5 mm from the lingula in 5% (mean 9.4 ± 3.6 mm). The inferior lobe of the left lung was <5 mm from the posterior aspect of the ostia of the left inferior and superior pulmonary veins in 9 and 0%, respectively. The bronchi were <5 mm from the LA in 5%.

CONCLUSIONS

The lungs are intimately related to sites of the LA commonly targeted during AF RFA. Whether this anatomical proximity translates into clinically significant potential for collateral lung damage during RFA merits further study.