TY - JOUR
T1 - Wide variations in energy delivery using an impedance-controlled algorithm in bipolar radiofrequency ablation
T2 - Evidence against fixed time ablation
AU - Melby, Spencer J.
AU - Zierer, Andreas
AU - Voeller, Rochus K.
AU - Lall, Shelly C.
AU - Bailey, Marci S.
AU - Moon, Marc R.
AU - Schuessler, Richard B.
AU - Damiano, Ralph J.
PY - 2007/3
Y1 - 2007/3
N2 - OBJECTIVE: Bipolar radiofrequency ablation recently has been used to replace many of the incisions of the Cox-Maze procedure in the surgical treatment of atrial fibrillation. The unique aspect of this technology is that it uses an algorithm based on changes in tissue conductance to determine the energy required to achieve a transmural lesion instead of relying on predetermined time and/or temperature criteria to determine ablation duration, as with most other ablation technologies. The purpose of this study was to determine variations in the different parameters of ablation needed to create transmural lesions in human atria. METHODS: Initial impedance, total energy, temperature, and ablation time were measured in 38 patients undergoing surgery, using an impedance-controlled bipolar radiofrequency device (AtriCure Isolator, Cincinnati, OH). Lesions were categorized into the following groups: right atrial free wall, left atrial free wall, atrium up to mitral valve annulus, atrium up to tricuspid valve annulus, and right or left pulmonary veins. RESULTS: There was a wide range of initial impedance (32.3 to 760.7 Ohms), and this correlated with total energy delivered (r = -0.31, P = 0.002). Ablation times varied widely (2.0 to 29.9 seconds) and were longer on left atrial structures than right (P < 0.005) and shortest near the tricuspid annulus (P < 0.001). Mean tissue temperature 1 mm from the electrode was only 45.7 ± 7.8°C (range, 23.7°C to 69.3°C). CONCLUSIONS: Bipolar ablation of different atrial structures required widely different amounts of energy and ablation times, probably as the result of the inhomogeneity of atrial geometry and tissue impedance. These data cast doubt on the efficacy of any fixed-time or temperature ablations in the clinical setting.
AB - OBJECTIVE: Bipolar radiofrequency ablation recently has been used to replace many of the incisions of the Cox-Maze procedure in the surgical treatment of atrial fibrillation. The unique aspect of this technology is that it uses an algorithm based on changes in tissue conductance to determine the energy required to achieve a transmural lesion instead of relying on predetermined time and/or temperature criteria to determine ablation duration, as with most other ablation technologies. The purpose of this study was to determine variations in the different parameters of ablation needed to create transmural lesions in human atria. METHODS: Initial impedance, total energy, temperature, and ablation time were measured in 38 patients undergoing surgery, using an impedance-controlled bipolar radiofrequency device (AtriCure Isolator, Cincinnati, OH). Lesions were categorized into the following groups: right atrial free wall, left atrial free wall, atrium up to mitral valve annulus, atrium up to tricuspid valve annulus, and right or left pulmonary veins. RESULTS: There was a wide range of initial impedance (32.3 to 760.7 Ohms), and this correlated with total energy delivered (r = -0.31, P = 0.002). Ablation times varied widely (2.0 to 29.9 seconds) and were longer on left atrial structures than right (P < 0.005) and shortest near the tricuspid annulus (P < 0.001). Mean tissue temperature 1 mm from the electrode was only 45.7 ± 7.8°C (range, 23.7°C to 69.3°C). CONCLUSIONS: Bipolar ablation of different atrial structures required widely different amounts of energy and ablation times, probably as the result of the inhomogeneity of atrial geometry and tissue impedance. These data cast doubt on the efficacy of any fixed-time or temperature ablations in the clinical setting.
KW - Ablation
KW - Arrhythmia surgery
KW - Atrial fibrillation
KW - Transmural
UR - http://www.scopus.com/inward/record.url?scp=34547479871&partnerID=8YFLogxK
U2 - 10.1097/IMI.0b013e31803c9b11
DO - 10.1097/IMI.0b013e31803c9b11
M3 - Article
C2 - 22436925
AN - SCOPUS:34547479871
SN - 1556-9845
VL - 2
SP - 67
EP - 72
JO - Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery
JF - Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery
IS - 2
ER -