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Performance of a Novel Bipolar/Monopolar Radiofrequency Ablation Device on the Beating Heart in an Acute Porcine Model
Lindsey L. Saint, Christopher P. Lawrance, Richard B. Schuessler, Ralph J. Damiano, Jr..
Washington University, Saint Louis, MO, USA.
OBJECTIVE: Although the advent of ablation technology has simplified and shortened surgery for atrial fibrillation, only bipolar clamps have reliably been able to create transmural lesions on the beating heart. Currently there are no devices capable of reliably creating the long linear lesions in the right and left atria needed to perform a Cox-Maze procedure on the beating heart. This study evaluates the performance of a novel suction-assisted radiofrequency device that uses both bipolar and monopolar energy to create lesions from an epicardial approach.
METHODS: Six domestic pigs underwent median sternotomy. A dual bipolar/monopolar radiofrequency ablation device was used to create epicardial linear lesions on the superior and inferior vena cavae, right and left atrial free walls, and right and left atrial appendages. The heart was stained with 2,3,5-triphenyl-tetrazolium chloride and each lesion was cross-sectioned at 5mm intervals. Lesion depth and transmurality were determined.
RESULTS: Transmurality was documented in 94% of all cross-sections (see figure), and 68% of all ablation lines were transmural along their entire length. Tissue thickness was not different between transmural and non-transmural cross-sections (3.1 ± 1.3 and 3.4 ± 2.1, p=0.57, respectively), nor was anatomical location on the heart (p=0.45 for the distribution). Of the cross-sections located at the end of the ablation line, 11% (8/75) were found to be non-transmural, whereas only 4% (8/195) of cross-sections located within the line of ablation were found to be non-transmural (p=0.04). Logistic regression analysis demonstrated that failure of the device to create transmural lesions was associated with low body temperature (p=0.006), but not with cardiac output (p=0.54).
CONCLUSIONS: This novel device was able to consistently create transmural epicardial lesions on the beating heart, regardless of anatomical location, cardiac output or tissue thickness. The performance of this device was excellent, and the efficacy approached that of bipolar clamps. Transmurality was lower at the end of the lesions, highlighting the importance of overlapping lines of ablation in the clinical setting.
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