|Year : 2002 | Volume
| Issue : 4 | Page : 7
Transseptal Cryoablation of a Left-Sided Accessory Pathway Guided by a Novel Three-Dimensional Navigation System
T Szili-Torok, DA Theuns, A Verblaauw, M Scholten, LJ Jordaens
Thoraxcentre, Department of Clinical Electrophysiology, Erasmus MC, Rotterdam, Netherlands
|Date of Web Publication||22-Jun-2010|
Thoraxcentre, Department of Clinical Electrophysiology, Erasmus MC, Rotterdam
Source of Support: None, Conflict of Interest: None
| Abstract|| |
A 39-year-old man presented with regular narrow complex tachycardia for electyrophysiology (EP) study and transcatheter ablation. EP study revealed the existence of a left lateral concealed accessory pathway. A transseptal cryothermal ablation was undertaken, after puncture of the interatrial septum.
The accessory pathway was mapped and successfully ablated using cryothermy and a novel 3D navigation system (LocaLisa, Medtronic), which provides a unique option of localizing electrophysiologically important reference structures as well as mapping and ablation sites. Using advanced imaging, technology efficacy of such ablations can significantly be improved.
Keywords: cryoablation, accessory pathway, transseptal
|How to cite this article:|
Szili-Torok T, Theuns D A, Verblaauw A, Scholten M, Jordaens L J. Transseptal Cryoablation of a Left-Sided Accessory Pathway Guided by a Novel Three-Dimensional Navigation System. Heart Views 2002;3:7
|How to cite this URL:|
Szili-Torok T, Theuns D A, Verblaauw A, Scholten M, Jordaens L J. Transseptal Cryoablation of a Left-Sided Accessory Pathway Guided by a Novel Three-Dimensional Navigation System. Heart Views [serial online] 2002 [cited 2023 Sep 24];3:7. Available from: https://www.heartviews.org/text.asp?2002/3/4/7/64522
| Introduction|| |
Conventionally, left-sided accessory pathways (AP) are ablated using radiofrequency energy either with retrograde or transseptal approaches , . In a considerable proportion of patients peripheral thromboembolic complications including transient ischemic attacks were reported , . Cryothermal energy has potential advantages including less thrombogenity.
Furthermore, unique options such as ice mapping allow significantly fewer applications. Cryothermy was reported feasible for various types of right-sided ablations ,, , however, until recently the value of cryothermy in ablations of left-sided accessory pathway was not evaluated.
The aim of the present report is to demonstrate how cryothermy can be effectively used for ablation of left-sided accessory pathways supported by advanced 3D-imaging/navigation techniques.
| Case report|| |
A 39-year-old man presented with regular narrow complex tachycardia for electrophysiology study and transvenous cryoablation. The 12-lead ECG of the tachycardia suggested the presence of orthodromic AV reentry tachycardia using a concealed accessory pathway. Resting 12-lead ECG of the patient was normal. Under local anesthesia a decapolar diagnostic catheter was inserted to the coronary sinus via a subclavian vein. A quadripolar catheter was positioned across the tricuspid valve to record stable His potential. A conventional bipolar pacing electrode was then inserted via a femoral vein to the right ventricular apex.
The antegrade activation sequence was normal during sinus rhythm and atrial pacing at CL 400, 500 and 600 ms. The retrograde activation sequence during ventricular pacing showed that the earliest retrograde activation was seen in the distal part (CS electrode pairs 3 and 4) of the decapolar catheter placed in the coronary sinus. Orthodromic atrio-ventricular re-entrant tachycardia was easily inducible with atrial stimulation and the activation sequence was identical to the observed sequence during ventricular pacing [Figure 1]. The AP had a retrograde refractory period of 250 ms, and the shortest retrograde 1:1 conduction was 270 ms. Induction atrial fibrillation occurred, which required DC shock for termination. Cryothermal catheter ablation was undertaken with transseptal left heart catheterization. Intracardiac echocardiography was used to guide the puncture of the interatrial septum using the technique described elsewhere ,.
Shortly, the left femoral vein was punctured and an intracardiac ultrasound transducer catheter (model 9900, EP Technologies, Boston Scientific) was introduced to the right atrium via a multipurpose introducing sheath (EP Technologies, Boston Scientific). The transseptal sheath (SL2, DAIG) was introduced to the SVC. The sheath was loaded with a Brockenbrough needle (DAIG), which was advanced to within 1 cm of the dilator tip. The position was checked in three fluoroscopy views (AP, LAO, RAO). The entire sheath was then withdrawn from the SVC to the right atrium. The intracardiac ultrasound was reactivated.
The characteristic downward "jump" of the sheath was detected simultaneously by fluoroscopy and intracardiac echocardiography. When the septum was approached by the sheath, the ultrasound demonstrated the characteristic tenting of the fossa. Sudden collapse of the tented fossa indicated a successful puncture. Finally, echo contrast material was injected into the left atrium and detected by the echocardiography.
| Cryoablation system|| |
The cryocatheter is a 7F steerable catheter with four electrodes at its distal end, a distal cooling 4-mm-tip electrode, and three proximal ring electrodes. The catheter has a hollow shaft with a closed tip into which the refrigerant fluid, nitrous oxide, is delivered under pressure from a control console. Within the tip, a phase change occurs (liquid to gas), and the resultant gas is removed under vacuum. This transformation causes cooling of the tip to temperatures as low as -70 degree Celsius. The gas is conducted away from the tip through the vacuum return lumen and is collected in the console.
A Cryothermy ablation catheter (type I) was then used to map the mitral annulus and to deliver cryothermy through the transseptal sheath. Initially ice mapping was performed by cooling to -30 degree Celsius for a maximum of 80 seconds. Because of catheter adherence at this level of cooling, ventricular extrastimulus testing could be sed, to show loss of VA conduction, respectively. If mapping was performed during orthodromic tachycardia, the termination of the tachycardia or a progressive increase of VA time was considered to be a promising site [Figure 2]. When these signs were observed, cryoablation was performed by cooling to -75° C for a 4-minute period, to create a permanent lesion [Figure 3] and [Figure 4].
In order to visualize anatomically and electrophysiologically important structures, a novel 3D navigation system (LocaLisa, Medtronic) was used. The LocaLisa system is based on the principle that when electrical current is externally applied through the thorax, a voltage drop occurs across internal organs like the heart, which can be recorded via standard catheter electrodes and potentially can be used to determine electrode position.'
Using a combination of the above mentioned systems, a total of three applications were applied to the atrial side of the mitral annulus with continuous VA signals during orthodromic tachycardia [Figure 2]. The first ablation resulted in a termination of the tachycardia and consequent VA block during ventricular pacing 47 seconds after the onset of cryothermy energy.
The conduction of the accessory pathway returned 20 minutes after this application. Using the LocaLisa system, an adjacent but more ventricular site was searched for, and confirmed by the local electrograms [Figure 5]. The second application was unsuccessful. The last pulse - delivered to an adjacent site to the distal CS catheter - which was temporary, was displayed on the screen of the LocaLisa system and resulted in an abrupt (2,7-sec) termination of the tachycardia [Figure 4]. The retrograde activation sequence showed a loss of accessory pathway conduction. Thirty minutes after ablation, ventricular pacing showed VA block. Post ablation, there were no signs of recurrence of accessory pathway conduction. Intravenous administration of adenosine (12 mg) resulted in a short lasting VA block during ventricular pacing confirming successful ablation of the left-sided accessory pathway.
| Comments|| |
Radiofrequency catheter ablation of accessory pathways, including the ones located in the left side of the heart, is first-line therapy with high acute success rate. Although ablations of accessory pathways guided by fluoroscopic landmarks and electrograms have a success rate of around 94%, thromboembolic complications are reported in a considerable proportion of the patients ,.
Alternative energy sources are on trial to increase efficacy and to decrease procedure-related complications. Cryothermy has some potential advantages. The lesion created by cryothermy seems more homogenous and the underlying tissue structure remains intact  . Theoretically it is less thrombogenic and less proarrhythmic. Furthermore, the unique option of ice mapping, which is tissue cooling to less negative values to demonstrate reversible loss of function, enables us to predict the effect of permanent lesion formation ,,,.
This approach may result in a significant reduction of the number of permanent lesions. The cryoadherence is an additional benefit, which prevents the catheter tip from dislodgment during cryoenergy application , . This can reduce fluoroscopy time, since continuous monitoring of the catheter position is not necessary. These advantages stimulate the further development of cryothermy.
The feasibility of cryothermal ablation in right sided procedures were demonstrated recently ,,,,,, . The His bundle and the slow pathway can be reliably and effectively ablated using this method , . Right-sided accessory pathways, including right anteroseptal accessory pathways, are also successfully and safely ablated by cryothermy .
However, the role of cryothermy in the treatment of left-sided accessory pathways has not been clarified. It was demonstrated that cryothermy is very sensitive to blood pool warming while delivering cryoablation lesions  .This warming effect can be disadvantageous in high-flow areas, especially in the left side of the heart. This potential pitfall can be counteracted by more accurate mapping during the ablation procedure. Mapping that is purely based on electrogram analysis has certain limitations. Filter setting, noise, and artifacts can influence the objective judgment of the signals, and previous energy applications can modify the arrhythmia substrate which can influence the results. Accurate three-dimensional localization of the mapping catheters can facilitate the ablation procedure as it was demonstrated in the present case. Using the LocaLisa system, the position of important anatomical landmarks could be easily identified.
Furthermore, all of the previous mapping and ablation sites can be indicated, stored, and consequently retrieved by using the system.
| Conclusion|| |
The growing experience with this novel 3D-navigation system and cryothermy technique, these methods are becoming valuable tools for increasing the efficacy of transcatheter ablation, including the treatment of left-sided accessory pathways.
Theoretically, the risk for thromboembolic complications can be minimized during ablation procedures by using this setup. Furthermore, with more experience the radiation exposure of the procedure could be decreased significantly .®
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]