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Transmembraneous irrigation of multipolar radiofrequency ablation catheters: induction of linear lesions encircling the pulmonary vein ostium without the risk of coagulum formation?
J Interv Card Electrophysiol. 2004 Jun; 10(3):199-209.JI

Abstract

INTRODUCTION

Pulmonary vein (PV) isolation for the curative treatment of atrial fibrillation using conventional radiofrequency ablation (RF) catheters with the point by point technique is time consuming and carries a remaining risk for thrombembolic complications.

AIMS OF THE STUDY

Aim of the present in vivo study was to evaluate feasibility and safety of a novel multipolar irrigated ablation catheter designed to create contiguous lesions encircling the PV ostium in a single ablation position.

METHODS

The entire ablation section (tripolar, length of each electrode 22 mm, interelectrode distance 2 mm, helix radius: 9 and 10 mm) of the 7F RF catheter (Encirclr, Medtronic, MN, USA) was covered by a porous membrane (pore size 30 micron) providing continuous irrigation. The helical formed catheter was used in two different experimental settings. Initially, a thigh muscle preparation has been performed in 7 anesthetized sheep in order to evaluate the development of lesions at different power level (40-80 W) and RF duration (30-90 sec). The ablation catheter was placed at the surface of the thigh muscle in a perpendicular position (0.1 N contact pressure) and perfused with heparinized blood (250 ml/min, 37C degrees). Irrigation was provided with a flow rate of 10 ml/min. The resulted lesion morphology was evaluated with regard to coagulum or crater formation and lesion depth and diameter. Subsequently in 9 anesthetized sheep intracardiac ablation has been achieved with 50 W and an irrigation flow of 10 ml/min. Transseptal puncture and RF ablations were guided using fluoroscopy and intracardiac echocardiography (ICE, Acuson, USA). Endpoint of the intracardiac RF applications was the reduction of local electrogram amplitude >50%. RF applications were achieved at both atrial appendages and in the orifices of the coronary sinus (CS), the vena cava inferior (VCI) and PV. Following RF ablation all animals were sacrificed and following in vivo staining (2% TTC) macroscopically and histologically investigations of the lesions were performed.

RESULTS

At the thigh muscle preparation 57 RF applications have been performed. The lesion depth was homogeneous without gaps between the ablation electrodes. There was a significant increase comparing 30 with 90 sec of RF duration for 40, 50 and 60 W applications respectively: 40 W: 1.1 +/- 0.4 vs. 3.6 +/- 0.5; 50 W: 1.2 +/- 0.3 vs. 4.6 +/- 0.4 mm and 60 W: 2.6 +/- 0.6 vs. 4.8 +/- 0.5 mm. All applications with 80 W (n = 3) had to be terminated due to immediate increase of impedance >150 omega. Late impedance rises (>60 sec) without occurrence of coagulum formation have been observed in 1 out of 4 RF applications with 60 W.A total of 85 RF applications could be achieved intracardiacally in the right atrium (right atrial appendage n = 18, ostium of the coronary sinus n = 12, ostium of the inferior caval vein: n = 12) and in the left atrium (left atrial appendage: n = 15, ostium of the PV: n = 28). ICE guided positioning of the catheter and showed during all applications no coagulum formation at the electrode or impedance rise (>150 Omega). Reduction of local electrograms (>50%) were observed following 48 out 85 (56%) RF applications. The lesions showed a homogeneous depth of 4 +/- 2 mm and a width 5 +/- 2 mm at the surface. No charring or crater formation could be observed in any of the lesions.

CONCLUSIONS

In the present in vivo studies it could be demonstrated that long irrigated ablation electrodes induce continuous lesions without the risk of thrombus formation at the electrode. Increase of RF duration from 30 to 90 seconds with power setting of 40-60 W, respectively, created deeper lesions without the risk of thrombus formation. Thus, the helical formed irrigated ablation catheter appears to be appropriate for simplified PV isolation.

Authors+Show Affiliations

Department of Cardiology, University Hospital Eppendorf, Minneapolis, Minnesota USA. Weiss@uke.uni-hamburg.deNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Evaluation Study
Journal Article

Language

eng

PubMed ID

15133356

Citation

Weiss, Christian, et al. "Transmembraneous Irrigation of Multipolar Radiofrequency Ablation Catheters: Induction of Linear Lesions Encircling the Pulmonary Vein Ostium Without the Risk of Coagulum Formation?" Journal of Interventional Cardiac Electrophysiology : an International Journal of Arrhythmias and Pacing, vol. 10, no. 3, 2004, pp. 199-209.
Weiss C, Stewart M, Franzen O, et al. Transmembraneous irrigation of multipolar radiofrequency ablation catheters: induction of linear lesions encircling the pulmonary vein ostium without the risk of coagulum formation? J Interv Card Electrophysiol. 2004;10(3):199-209.
Weiss, C., Stewart, M., Franzen, O., Rostock, T., Becker, J., Skarda, J. R., Meinertz, T., & Willems, S. (2004). Transmembraneous irrigation of multipolar radiofrequency ablation catheters: induction of linear lesions encircling the pulmonary vein ostium without the risk of coagulum formation? Journal of Interventional Cardiac Electrophysiology : an International Journal of Arrhythmias and Pacing, 10(3), 199-209.
Weiss C, et al. Transmembraneous Irrigation of Multipolar Radiofrequency Ablation Catheters: Induction of Linear Lesions Encircling the Pulmonary Vein Ostium Without the Risk of Coagulum Formation. J Interv Card Electrophysiol. 2004;10(3):199-209. PubMed PMID: 15133356.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Transmembraneous irrigation of multipolar radiofrequency ablation catheters: induction of linear lesions encircling the pulmonary vein ostium without the risk of coagulum formation? AU - Weiss,Christian, AU - Stewart,Mark, AU - Franzen,Olaf, AU - Rostock,Thomas, AU - Becker,Jan, AU - Skarda,Jim R, AU - Meinertz,Thomas, AU - Willems,Stephan, PY - 2004/5/11/pubmed PY - 2004/11/9/medline PY - 2004/5/11/entrez SP - 199 EP - 209 JF - Journal of interventional cardiac electrophysiology : an international journal of arrhythmias and pacing JO - J Interv Card Electrophysiol VL - 10 IS - 3 N2 - INTRODUCTION: Pulmonary vein (PV) isolation for the curative treatment of atrial fibrillation using conventional radiofrequency ablation (RF) catheters with the point by point technique is time consuming and carries a remaining risk for thrombembolic complications. AIMS OF THE STUDY: Aim of the present in vivo study was to evaluate feasibility and safety of a novel multipolar irrigated ablation catheter designed to create contiguous lesions encircling the PV ostium in a single ablation position. METHODS: The entire ablation section (tripolar, length of each electrode 22 mm, interelectrode distance 2 mm, helix radius: 9 and 10 mm) of the 7F RF catheter (Encirclr, Medtronic, MN, USA) was covered by a porous membrane (pore size 30 micron) providing continuous irrigation. The helical formed catheter was used in two different experimental settings. Initially, a thigh muscle preparation has been performed in 7 anesthetized sheep in order to evaluate the development of lesions at different power level (40-80 W) and RF duration (30-90 sec). The ablation catheter was placed at the surface of the thigh muscle in a perpendicular position (0.1 N contact pressure) and perfused with heparinized blood (250 ml/min, 37C degrees). Irrigation was provided with a flow rate of 10 ml/min. The resulted lesion morphology was evaluated with regard to coagulum or crater formation and lesion depth and diameter. Subsequently in 9 anesthetized sheep intracardiac ablation has been achieved with 50 W and an irrigation flow of 10 ml/min. Transseptal puncture and RF ablations were guided using fluoroscopy and intracardiac echocardiography (ICE, Acuson, USA). Endpoint of the intracardiac RF applications was the reduction of local electrogram amplitude >50%. RF applications were achieved at both atrial appendages and in the orifices of the coronary sinus (CS), the vena cava inferior (VCI) and PV. Following RF ablation all animals were sacrificed and following in vivo staining (2% TTC) macroscopically and histologically investigations of the lesions were performed. RESULTS: At the thigh muscle preparation 57 RF applications have been performed. The lesion depth was homogeneous without gaps between the ablation electrodes. There was a significant increase comparing 30 with 90 sec of RF duration for 40, 50 and 60 W applications respectively: 40 W: 1.1 +/- 0.4 vs. 3.6 +/- 0.5; 50 W: 1.2 +/- 0.3 vs. 4.6 +/- 0.4 mm and 60 W: 2.6 +/- 0.6 vs. 4.8 +/- 0.5 mm. All applications with 80 W (n = 3) had to be terminated due to immediate increase of impedance >150 omega. Late impedance rises (>60 sec) without occurrence of coagulum formation have been observed in 1 out of 4 RF applications with 60 W.A total of 85 RF applications could be achieved intracardiacally in the right atrium (right atrial appendage n = 18, ostium of the coronary sinus n = 12, ostium of the inferior caval vein: n = 12) and in the left atrium (left atrial appendage: n = 15, ostium of the PV: n = 28). ICE guided positioning of the catheter and showed during all applications no coagulum formation at the electrode or impedance rise (>150 Omega). Reduction of local electrograms (>50%) were observed following 48 out 85 (56%) RF applications. The lesions showed a homogeneous depth of 4 +/- 2 mm and a width 5 +/- 2 mm at the surface. No charring or crater formation could be observed in any of the lesions. CONCLUSIONS: In the present in vivo studies it could be demonstrated that long irrigated ablation electrodes induce continuous lesions without the risk of thrombus formation at the electrode. Increase of RF duration from 30 to 90 seconds with power setting of 40-60 W, respectively, created deeper lesions without the risk of thrombus formation. Thus, the helical formed irrigated ablation catheter appears to be appropriate for simplified PV isolation. SN - 1383-875X UR - https://www.unboundmedicine.com/medline/citation/15133356/Transmembraneous_irrigation_of_multipolar_radiofrequency_ablation_catheters:_induction_of_linear_lesions_encircling_the_pulmonary_vein_ostium_without_the_risk_of_coagulum_formation DB - PRIME DP - Unbound Medicine ER -