Cryoballoon Technology Research Articles

Novel approach for atrial fibrillation ablation during open-heart surgery using cryoballoon technology

The role of cryoballoon pulmonary vein isolation for the treatment of atrial fibrillation (AF) is unclear. In a 61-year-old man with persistent AF and severe mitral valve regurgitation, surgical cryoballoon pulmonary vein isolation was performed during open-heart surgery, without complication. Surgical cryoballoon ablation is feasible and can effectively isolate PV.

The Biophysics and Biomechanics of Cryoballoon Ablation

Recent clinical and preclinical studies have demonstrated that cryothermal ablation using a balloon catheter (Artic Front®, Medtronic CryoCath LP, Pointe-Claire, Canada) provides an effective means of achieving pulmonary vein isolation. This review explores the biophysics and biomechanics of cryoballoon ablation. Components of the cryoballoon catheter system are examined, mechanisms of cryothermal injury are summarized, and potential advantages of cryoballoon technology over standard radiofrequency ablation in isolating pulmonary veins are discussed. Practical aspects of biophysics and biomechanics relevant to the clinical electrophysiologist are emphasized, particularly with regards to the selection of the most appropriate cryoballoon catheter and minimizing peri-procedural complications.

Treating Atrial Fibrillation With Cryoballoon Technology.

Cryoballoon ablation has emerged as a novel tool to perform pulmonary vein isolation. The aim of this paper is to review the advantages, drawbacks as well as possible complications and clinical outcomes of this technology and to discuss some important technical issues.

A novel double cryoballoon strategy in persistent atrial fibrillation: a pilot study

Cryoballoon technology is a promising technique in paroxysmal atrial fibrillation (AF) ablation. However, success rates in patients with persistent AF have not been convincing. There is a trend toward performing more extensive procedures that are referred to as 'pulmonary vein isolation plus.' To combine pulmonary vein isolation (PVI) and antral substrate modification, we used both the 23-mm and 28-mm cryoballoon in a single approach in patients with persistent AF. 33 consecutive patients (26 men, age 60±10years, LA size 44±5mm) with persistent AF were prospectively included. All patients underwent the "double balloon strategy:" at least two applications at each pulmonary vein (PV) using the smaller 23-mm balloon to isolate the PV at the ostial level plus at least one additional freeze by the 28-mm balloon at the wide PV antral level. 7-day Holter monitors were performed during follow-up at 1, 3, 6, 9, 12, 18 and 24months post-ablation. 131 of 133 PVs were targeted and isolated (98.4%). A mean of 14±2 cryoballoon applications per patient or 3.5±1.5 applications per vein were performed. After a single procedure and mean follow-up of 15±3months, 69.7% of patients remained in sinus rhythm (3-month blanking period). There were no major complications. In persistent AF, the "double balloon strategy;" combining the small and large cryoballoon allowed ostial PV isolation followed by antral cryoablation is feasible, safe and associated with a favorable outcome.

Cryoballoon in atrial fibrillation ablation

Encouraging results of ablation therapy in patients with paroxysmal atrial fibrillation (AF) have prompted changes in professional practice guidelines. The most recent European guidelines have suggested that ablation might be offered as first-line therapy in selected patients. Cryoballoon ablation is a promising technology in interventional AF therapy. Two different sizes of the cryoballoon are currently available: a smaller (23mm) and a larger (28mm) balloon relative to the ostial diameter of the pulmonary veins. New tools, the circular mapping catheter and the use of intracardiac echocardiography, provide important periprocedural information. A meta-analysis of previous studies revealed outcome data with an AF-free survival rate of 72.83% at the 1-year follow-up in paroxysmal AF patients undergoing cryoballoon ablation. The most frequent, but reversible complication is phrenic nerve palsy with reported incidences up to 10%. All efforts must be taken to overcome this limitation, since the overall major complication rate tends to be lower in cryoballoon compared to radiofrequency ablation. In persistent AF, reported results in cryoballoon ablation had a limited success rate below 50% after a single procedure. A double balloon approach using both cryoballoon sizes might overcome some of the limitations in persistent AF. Prospective data and randomized studies are required. This article outlines the current status of cryoballoon technology in AF ablation therapy.

POSTER PRESENTATIONS

POSTER PRESENTATIONS

Cryoballoon Ablation of Atrial Fibrillation

Pulmonary vein isolation using a cryoballoon has evolved into a relatively simple alternative for point-by-point radiofrequency ablation because this technology theoretically allows for PV isolation with a single application. Recent clinical studies indicate a high efficacy rate of the procedure; however, the incidence of the most common complication-phrenic nerve palsy (PNP)-has been reported in up to 11.2% of cases. Based on the present data, PNP is mainly associated with the use of the smaller 23 mm balloon. Very recently, it became evident that cryoballoon ablation may be associated with PV stenosis. Thus, the use of cryoballoon technology needs to be combined with a strategy aiming for maximal patient safety. The "single big (28 mm) cryoballoon technique" is a straightforward single-device strategy to deploy cryothermal lesions proximal to the PV ostium at the antrum level, thereby reducing the risk of collateral damage. Using this technique the endpoint of complete PV isolation was achieved in 97% of patients in our laboratory. PNP was observed in 4.4% of patients and resolved within 12 months in the majority of cases. In the future, development of an even bigger (32 mm) cryoballoon may further increase procedural safety by reducing the risk of PNP or PV stenosis.

The first testing of double balloon cryo ablation of PVs LA tissues for the creation of circumferential LA lesions

The application of Cryo balloon technology for the ablation of atrial fibrillation (AF) would require large size balloon (30–35 mm diameter) to effectively create the desired circumferential LA lesions at the base of the PVs. The construction of such balloon introduces significant difficulties such as sheath size to allow the large balloon to be introduced into the LA, increasing probability of balloon damage during insertion and withdrawal leading to gas leakage. With these safety and technical issues in mind we have tested the efficacy of the application of two 15–22 mm cryo balloons side by side into the same PV antrum in four dogs, (30–35 Kg).

Ablation of Atrial-Ventricular Junction Tissues via the Coronary Sinus Using Cryo Balloon Technology

The coronary sinus (CS) can provide access to targets across and within the atrioventricular (AV) junction. In 12 dogs (32 +/- 3 Kg), cryo balloons (10-19 mm) were applied to regions of the AV junction for 3 minutes at a temperature of -75.9( composite function) +/- 9(composite function)C (ranging -57 to -83). Electrical activity and pacing within the CS were assessed pre and post ablation and at least 3 months later in 9 dogs. In the 3 other dogs, hearts were examined immediately after cryo ablation. CS and circumflex angiography was performed pre and post ablation. The hearts, CS, and Cx were then examined for structural injury. The AV junction was sectioned and the hearts were immersed in Tetrazolium, and the lesions were inspected for transmurality across the AV groove. In 3/12 dogs the distal CS cryo lesions resulted in inferior ST segment depression that resolved within 5 minutes. There was no arrhythmia or hemodynamic changes. No CS electrical activity was noted post ablation. The pacing threshold increased from 2 +/- 2.3 mA to 7.4 +/- 3.6 mA (p < 0.001). Pathological examination of 3 acute hearts revealed hematomas. There was no pericardial effusion. No evidence of stenosis or thrombosis was seen within the CS and the circumflex artery. After 3 months of recovery, transmural lesions across the AV groove were present in all of the targeted AV regions. Intra-CS cryo balloon ablation is safe and can potentially replace endocardial RF ablation targeting the AV junction and the CS muscular sleeve.

The safety and efficacy of multiple consecutive cryo lesions in canine pulmonary veins-left atrial junction

Objective The purpose of the study is to evaluate the safety and efficacy of multiple cryo lesions in canine pulmonary veins-left atrial junction. Background The use of radiofrequency to achieve electrical isolation of the pulmonary veins (PVs) has been associated with PV stenosis. No information is currently available concerning the safety and the electrophysiological effects of multiple and consecutive cryo applications at the PV-left atrial junction. Methods Liquid N 2O was delivered into semi-compliant 15 to 22-mm-diameter balloons. In 13 dogs weighing 34 ± 2 kg, one to four consecutive cryo lesions were randomly applied to each PV for 3 minutes in 6-minute intervals. The pre- and post-PV sizes were recorded by angiography. Electrogram activity and pacing thresholds were recorded before and after cryo. PV patency and the PV-atrial tissue characteristics were evaluated grossly and histologically. Results Pacing capture was not possible with 10 mA postablation in 26/46 (57%) electrodes, and in 20 (43%) electrodes pacing threshold increased from 1.6 ± 1.7 mA to 7.8 ± 3.2 mA. The total elimination of recorded electrograms was noted in 22%, 29%, and 18% following 1, 2, and 3 cryo lesions respectively. After 4 lesions this value increased to 53%. No significant changes in PV diameter were recorded in any of the veins pre vs the terminal study. The PVs and PV-atrial interface tissue were soft, compliant, and without collagen or cartilaginous tissue. There was no hemoptysis in any of the dogs. Conclusion In this study, cryo balloon technology is effective and safe regardless of the number of lesions applied and the freezing temperatures achieved. Four consecutive cryo applications result in a significant increase in pacing threshold and a decrease in activity of local atrial electrograms.

New cryotechnology for electrical isolation of the pulmonary veins.

Creation of radiofrequency lesions to isolate the pulmonary veins (PV) and ablate atrial fibrillation (AF) has been complicated by stenosis of the PVs. We tested a cryoballoon technology that can create electrical isolation of the PVs, with the hypothesis that cryoenergy will not result in PV stenosis. Lesions were created in 9 dogs (weight 31-37 kg). Cryoenergy was applied to the PV-left atrial (LA) interface. Data collected before and after ablation included PV orifice size, arrhythmia inducibility, electrogram activity, and pacing threshold in the PVs. Tissue examination was performed immediately after ablation in 3 dogs and after 3 months (4.8 +/- 1.0) in 6 dogs. After ablation there was no localized P wave activity in the ablation zone and no LA-PV conduction. Before ablation, the pacing threshold was 1.9 +/- 1.1 mA in each PV. After ablation, the pacing threshold increased significantly to 7.2 +/- 1.8 mA, or capture was not possible. Burst pacing did not induce any sustained arrhythmias. Most dogs had hemoptysis during the first 24 to 48 hours. Acute tissue examination revealed hemorrhagic injury of the atrial-PV junction that extended into the lung parenchyma. After recovery, the lesions were circumferential and soft with no PV stenosis. Histologic examination revealed fibrous tissue with no PV-LA interface thickening. This new cryoballoon technology effectively isolates the PVs from LA tissue. No PV stenosis was noted. Acute tissue hemorrhage and hemoptysis are short-term complications of this procedure. After 3 months of recovery, cryoablated tissue exhibits no collagen or cartilage formation.