Performance of a novel bipolar/monopolar radiofrequency ablation device on the beating heart in an acute porcine model (original) (raw)
Related papers
Innovations (Philadelphia, Pa.), 2009
OBJECTIVE: To perform a minimally invasive procedure for atrial fibrillation without cardiopulmonary bypass, it is necessary to create transmural lesions on the beating heart. Although bipolar radiofrequency clamps can isolate the pulmonary veins, they have difficulty in performing any other left atrial lesions, particularly those of the traditional Cox-Maze procedure. This study examined the performance of an internally cooled, bipolar radiofrequency device designed for such an application. METHODS: Eleven domestic pigs underwent median sternotomy. Five animals had eight atrial lesions created with the radiofrequency device at times of 20, 30, 40, and 50 seconds. In six other pigs, the device was compared with another technology that has been used clinically for epicardial, beating heart ablation, the Guidant Flex 4 microwave device. The tissue was stained with 2,3,5-triphenyl-tetrazoluim chloride, and the lesions were sectioned at 5-mm intervals. Lesion width, depth, and transmura...
The Journal of Thoracic and Cardiovascular Surgery, 2010
Over recent years, a variety of energy sources have been used to replace the traditional incisions of the Cox maze procedure for the surgical treatment of atrial fibrillation. This study evaluated the safety and efficacy of a new bipolar radiofrequency ablation device for atrial ablation in a long-term porcine model. Methods: Six pigs underwent a Cox maze IV procedure on a beating heart off cardiopulmonary bypass using the AtriCure Isolator II bipolar ablation device (AtriCure, Inc, Cincinnati, Ohio). In addition, 6 pigs underwent median sternotomy and pericardiotomy alone to serve as a control group. All animals were allowed to survive for 30 days. Each pig underwent induction of atrial fibrillation and was then humanely killed to remove the heart en bloc for histologic assessment. Magnetic resonance imaging scans were also obtained preoperatively and postoperatively to assess atrial and ventricular function, pulmonary vein anatomy, valve function, and coronary artery patency. Results: All animals survived the operation. Electrical isolation of the left atrial appendage and the pulmonary veins was documented by pacing acutely and at 30 days in all animals. No animal that underwent the Cox maze IV procedure was able to be induced into atrial fibrillation at 30 days postoperatively, compared with all the sham animals. All 257 ablations examined were discrete, linear, and transmural, with a mean lesion width of 2.2 AE 1.1 mm and a mean lesion depth of 5.3 AE 3.0 mm.
Innovations (Philadelphia, Pa.), 2011
Over recent years, a variety of energy sources, including bipolar radiofrequency, have been used to replace the traditional incisions of the Cox-Maze procedure for the surgical treatment of atrial fibrillation (AF). The purpose of this study was to evaluate the safety and efficacy of a novel dual-electrode bipolar radiofrequency ablation device Synergy (Atricure, Inc., Cincinnati, OH USA) for AF in a chronic porcine model. Methods: Six domestic pigs underwent a modified Cox-Maze IV procedure without cardiopulmonary bypass using the Synergy device. Animals survived for 30 days. Each pig then underwent induction of AF and was killed to remove the heart en bloc for histologic assessment. Each ablation line was dissected perpendicularly at 5-mm intervals to assess the lesion width, depth, and transmurality. Results: All animals survived the operation. Electrical isolation of the left atrial appendage and the pulmonary veins were documented by pacing acutely and at 30 days after the operation in all six animals. All animals failed to be induced in AF at 30 days. There was no gross evidence of intra-atrial thrombus formation or stricture of the pulmonary veins. All ablations (n ϭ 209) examined were discrete, linear, and transmural, with a mean lesion width of 3.0 Ϯ 0.7 mm and a mean lesion depth of 5.4 Ϯ 3.3 mm. The mean ablation time was 16.3 Ϯ 4.4 seconds, with a mean total energy delivery of 238 Ϯ 170 J. Conclusions: The Atricure Synergy was able to create reliable chronic transmural lesions of the modified Cox-Maze IV procedure on a porcine beating heart without cardiopulmonary bypass. The ablation lines were significantly wider when compared with its predecessor, the Isolator II.
Animal studies of epicardial atrial ablation
Heart Rhythm, 2009
The Cox-Maze procedure is an effective treatment for atrial fibrillation with a long-term freedom from recurrence of >90%. The original procedure was highly invasive and required cardiopulmonary bypass (CPB). Modifications of the procedure have been proposed so that the procedure can be done without CPB. These approaches proposed to use alternative energy sources, to replace cut and sew lesions with lines of ablation, made from the epicardium on the beating heart. This has been challenging because the atrial wall muscle thickness is extremely variable and can be covered with an epicardial layer of fat. Moreover, the circulating intracavitary blood acts as a potential heat sink, making transmural lesions difficult to obtain. In this report, we summarize the use of nine different unidirectional devices to create continuous transmural lines of ablation from the atrial epicardium in a porcine model. We define a unidirectional device as one in which all the energy is applied by a single transducer on a single heart surface. These include four radiofrequency, two microwave, two lasers, and one cryothermic device. The maximum penetration of any device was 8.3 mm. All devices except one, the Atricure IsolatorT pen, failed to penetrate 2.0 mm in some non-transmural sections. Future development of unidirectional energy sources should be directed at increasing the maximum depth and the consistency of penetration.
Strategies to Improve the Efficacy of Epicardial Linear Ablation on the Beating Heart
Innovations (Philadelphia, Pa.)
Creating transmural linear lesions on the beating heart is an important component of minimally invasive surgical ablation for atrial fibrillation. Animal studies have shown poor efficacy for surface bipolar radiofrequency ablation (RFA). Clinicians have developed strategies including multiple device applications and vena caval occlusion (VCO) to improve ablation efficacy. These techniques were evaluated in an acute porcine model. In the first experiment, an RFA device was used to perform two 40-second epicardial ablations on the right atrium of six pigs. Ablations were performed with and without VCO. Ultrasonic flow probes were used to verify VCO. In the second experiment, an RFA device was used to perform two 40-second epicardial ablations at six locations on the left and right atria of six pigs. All animals were sacrificed. The hearts were removed and stained with 2,3,5-triphenyltetrazolium chloride. Sections were examined using digital photography. With VCO, 42 (81%) of 52 sectio...
Experimental observation of vitro pigs' hearts with bipolar radiofrequency ablation
International journal of clinical and experimental medicine, 2013
Bipolar ablation is an innovative direction of catheter ablation technology. The aim of this study was to investigate the damaged area of bipolar radiofrequency ablation in vitro pigs' hearts under different conditions and to evaluate the effectiveness and safety. The bipolar radiofrequency ablation was performed in vitro pigs' hearts with a 4 mm bipolar electrode under different conditions at various combinations of the parameters (Distance: from 12 mm to 17 mm; Power: 30 w or 40 w; Time: from 20 s to 90 s; Temperature: 45°C or 60°C; Saline Perfusion: 0 ml/h, 1000 ml/h or 1500 ml/h). We measured the length, width, depth, connection rate and blasting rate of the connective ablation lesion and then evaluated the effectiveness and safety of connective ablation lesion. Numerical analysis showed that there was a positive correlation between the time, temperature and the length, depth, connection rate, blasting rate. There was a negative correlation between the power, perfusion a...
Transcatheter Radiofrequency Ablation of Atrial Tissue Using a Suction Catheter
Pacing and Clinical Electrophysiology, 1989
Catheter. Closed chest ablative technique that avoid barotrauma would be attractive for ablation at thin walled cardiac structures, such as the atria] free wall or coronary sinus. Transcatheter radio/requency (RF) currents produce tissue necrosis the size of which is dependent on the contact between the tissue and the electrode. Jn order to assess the effects of transvenous RF ablation of atrial free wall using a suction electrode catheter, we delivered in ten dogs, one single unmodulated RF pulse 1.2 MHz, in a unipolar mode, through the distal electrode of a lumen catheter {VSCI 8F) (USCI, Billerica, MA, USA) located in the right appendage. During the pulse an 80 KPa vacuum depression was applied to the iumen ofthe catheter. Each pulse had a 10 seconds duration and the mean delivered power was 4.3 ± 1.4 W. Aortic pressure and electrocardiogram were monitored during the procedure. A right airial eiectrophysioiogicai study was performed at the ablated site, at control, after suction application and after RF pulse delivery. The animals were sacrificed after 14 or 21 days. Atrial pacing threshoid values decreased after suction application in comparison to control values after the pulse (0.42 ± 0.06 vs 0.60 ± 0.23 mA, P < O.05) but increased after the pulse delivery (2.60 ± 1.85 mA, P < 0.01). In contrast, the atrial effective refractory period did not significantly change after suction, nor after RF pulse delivery. Aortic pressure remained unchanged throughout the procedure. Complex arrhythmias were not observed during or after RF pulse delivery. One dog died suddenly at the jirst day after ablation, but this death was most probably unrelated to RF abiation. Anatomiclesionshadalengthof8.8±3.3mm, a width o/4.6± 2.5 mm and a depth of 3.6 ± 1.1 mm. They were transmurai in nine of the ten dogs but without atrial wall perforation in any case. Lesions suggesting tissue volatilization were present in four dogs. These results demonstrate that low energy RF currents delivered with a suction electrode catheter can produce transmural necrosis of free wall, without risk of perforation. Such ablative technique would be of interest for ablation of right sided accessory pathways or atrial ectopic foci. Further experimental data are required in order to dejine the optimal energy level required to avoid tissue volatilization. (PACE, Vol. 12, January Part II 1989) catheter ablation, radiofrequency energy, atrial arrhythmia