A New Vacuum-Assisted Probe for Minimally Invasive Radiofrequency Ablation

A New Vacuum-Assisted Probe for Minimally Invasive Radiofrequency Ablation
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  A New Vacuum-Assisted Probe for MinimallyInvasive Radiofrequency Ablation Stefano Bevilacqua,  MD,  Tommaso Gasbarri,  MD,  Alfredo Giuseppe Cerillo,  MD, Massimiliano Mariani,  MD,  Michele Murzi,  MD,  Tommaso Nannini,  MD,  andMattia Glauber,  MD Adult Cardiac Surgery Department and Adult Cardiology Department, Heart Hospital G. Pasquinucci, G. Monasterio Foundation,National Research Council, Massa, Italy Purpose.  The Cobra Adhere XL (Estech, San Ramon, CA) is a multiple-electrode,temperature-controlled, monopolar radiofrequency probe with a vacuum-assisted stabili-zation system. We evaluated this new technology for epicardial ablation of atrial fibrilla-tion in mitral valve patients through a right mini-thoracotomy. Description.  Between June and August 2008, 12 patients underwent minimal invasivesurgery for mitral disease and ablation for atrial fibrillation with the Cobra Adhere XL(Estech). Three patients had paroxysmal atrial fibrillation. Off-pump pulmonary veinisolation was performed with an epicardial oval lesion parallel to the mitral plane. In 10patients, an endocardial lesion to the mitral annulus was added. Evaluation.  There were no operative deaths or major postoperative complications. At amean follow-up of 8.76    1.0 months, 11 patients (91.67%) were in stable sinus rhythm.Echocardiography underscored a complete recovery of atrial transport function in most ofthese patients (90.91%). No major cardiac and cerebrovascular events occurred duringfollow-up. Conclusions.  Left-side ablation combined with minimally invasive surgery for mitraldisease can be easily, safely, and effectively performed with the Cobra Adhere XL probe.(Ann Thorac Surg 2009;88:1317–21)© 2009 by The Society of Thoracic Surgeons M inimally invasive surgery is becoming a broadlydiffused procedure to approach complex valvedisease. The development of new ablative technologies tosimplify the srcinal “cut and sew” Cox maze procedurehas lead to routine treatment of atrial fibrillation (AF) inpatients undergoing open heart surgery or as a stand-alone arrhythmia. The open competition with percutane-ous strategies has led surgeons to refine a valid mini-mally invasive surgical platform for AF treatment.We presently report the use of a novel monopolarradiofrequency vacuum-assisted system for epicardialoff-pump ablation using a right mini-thoracotomy access,called the Cobra Adhere XL (Estech, San Ramon, CA). Technology  Patients and Methods Between June and August 2008, 27 patients underwentminimally invasive surgery for isolated mitral or mitralplus tricuspid valve disease through a right mini-thoracotomy in the third intercostal space. Of these, 12received an ablation procedure for AF with the CobraAdhere XL probe (Estech). The study was approved bythe local Ethical Committee, and all patients signed aninformed consent to receive the ablation procedure.Table 1 shows preoperative and operative data. Technology The Cobra Adhere XL is a multiple-electrode, tempera-ture-controlled, monopolar radiofrequency probe with avacuum-assisted stabilization system that improves thecontact with atrial tissue and optimizes the power pene-tration in the myocardium (Fig 1). The probe has an internal cooling system with continuous saline irrigation(500 mL/h) to reduce temperature at tissue-electrodeinterface, allowing greater energy delivery and largerand deeper lesions. The probe is specifically designed foruse on the beating heart to neutralize the cooling effect of circulating blood. The probe is connected to the CobraElectrosurgical Unit (Estech). Table 2 shows the relationbetween temperature, time, and depth of lesions inanimal models. The probe performs a single epicardiallesion encircling all four pulmonary veins in a planeparallel to the mitral valve annulus (Fig 2). Accepted for publication April 9, 2009.Address correspondence to Dr Bevilacqua, Adult Cardiac Surgery De-partment, Heart Hospital G. Pasquinucci, G. Monasterio Foundation, viaAurelia Sud, Massa, 54100, Italy; e-mail: © 2009 by The Society of Thoracic Surgeons 0003-4975/09/$36.00Published by Elsevier Inc doi:10.1016/j.athoracsur.2009.04.066     N    E    W    T    E    C    H    N    O    L    O    G    Y  Technique Surgical Technique The chest was entered through a 6-cm to 8-cm mini-thoracotomy in the third intercostal space. Percutane-ous cannulation of venae cavae through the rightcommon femoral vein with a dual stage RAP cannula(Estech, San Ramon, CA) and direct cannulation of theaorta with the EasyFlow cannula (Estech, San Ramon,CA) or Straight - shot cannula (Heartport Inc, RedwoodCity, CA) were routinely performed. The aorta wasdirectly cross clamped with a flexible clamp (Cygnet,Novare Surgical System Inc, Cupertino, CA), and theheart was arrested with antegrade cold crystalloidcardioplegia (Custodiol HTK Solution, Essential Phar-maceuticals, LLC, Newtown, PE). During aortic cross-clamp time, carbon dioxide was inflated into the thoraxat 2 L/min. A thoracoscopic 30° camera was insertedthrough a 5-mm port.  Ablation Technique The ablation procedure was completed after cannulationbefore starting cardiopulmonary bypass. Pericardial re-flections were bluntly dissected to access the transverseand oblique sinuses. A pre-curved “J-shaped” soft guideover a malleable mandrel was introduced in the trans-verse sinus underneath the superior vena cava. At the leftend of the sinus, the mandrel was retracted and the soft Table 1. Preoperative and Operative Data  VariableAge (yr) 61.17  14.84Male gender (%) 6 (50)NYHA functional class 2.25  .75Logistic Euroscore 4.8  2.63Predominant mitral disease (%)Regurgitation 10 (83,33)Stenosis 2 (16.67)Atrial fibrillation type (%)Paroxysmal 3 (25)Persistent 3 (25)Long-lasting persistent 6 (50)Atrial fibrillation duration (mo) 35.5  33.2Atrial fibrillation duration range (mo) 5–96LVEF (%) 57.25  7.78LVEDD (mm) 57.18  8.67LVESD (mm) 37.5  8.19LAD (mm) 50.08  7.4LAD, range (mm) 38–61Mitral replacement (%) 4 (33.33)Tricuspid repair (%) 2 (16.67)Mitral isthmus line (%) 10 (83.33)Left appendage exclusion (%) 11 (91.67)ECC time (min) 147.17  37.06Cross-clamp time (min) 99.58  36.04 ECC    extracorporeal circulation; LAD    left anterior descendingcoronary artery; LVEDD    left ventricular end-diastolic diameter;LVESD  left ventricular end-systolic diameter; LVEF  left ventric-ular ejection fraction; NYHA  New York Heart Association.  Fig 1. The Cobra Adhere XL system (Estech, San Ramon, CA) with probe, vacuum cuff and soft pre-curved guide. Table 2. Lesion Depth (mm) for Maximal Power (25W per  Five Active Channels) and Vacuum (600 mm Hg) a Time/Set Temperature 60°C 70°C 80°C 90°C15 seconds 2 2.75 2 3.530 seconds 2.75 4 4.75 4.2560 seconds 3.75 4.25 4.25 4.590 seconds 5.75 7.25 7.5 6.75120 seconds 7.75 7.25 6.5 6 a Based on extensive testing on animal tissue. (With permission of EstechCompany, San Ramon, CA).  Fig 2. Scheme of the posterior encircling lesion for en-block pulmo-nary vein isolation. 1318  NEW TECHNOLOGY BEVILACQUA ET AL Ann Thorac SurgABLATION THROUGH RIGHT MINI-THORACOTOMY 2009;88:1317–21  N E  W T  E  C H N O L  O G Y   guide, with the pre-curved tip oriented caudo-dorsally,advanced toward the oblique sinus. Under thoracoscopicview, the tip of the guide was retrieved underneath theinferior vena cava. After connection to the guide, with a“push and pull” technique, the probe was insertedaround the four pulmonary veins, on a plane parallel tothe mitral valve and posterior to the left atrial appendage.Probe position relative to the left appendage was endo-scopically visualized and controlled also with trans-esophageal echocardiography (Fig 3). The probe is formed by two series (proximal and distal) of five elec-trodes that were activated sequentially without movingthe probe. The generator was set to maintain the tissue at70°C for 90 seconds. The power of energy supplied wasautomatically determined by the machine. During theablation, the vacuum stabilizer was maintained at   600mm Hg. The circumferential lesion was completed bymoving the probe to overlap the two extremities of theprevious lesions.The completeness of the lesion and the presence of complete exit block was assessed with epicardial over-pacing of the left atrium dome only in patients in sinusrhythm (ie, 3 patients with paroxysmal AF and 1 patientwith persistent AF who was in sinus rhythm at admis-sion). No electrical cardioversion was intraoperativelyattempted. This test was conducted with a bipolar pacingprobe (AFfirm [Estech, San Ramon, CA]). In 3 patientsthe block was confirmed, and in 1 patient an additionalenergy application was required.In all patients with persistent and long-lasting persis-tent paroxysmal AF, and in 1 patient with paroxysmal AFwith a 56-mm left atrial diameter, a left isthmus line wasadded from the endocardial side. This lesion was per-formed with the same probe without vacuum suction,using a setting at 70°C temperature for only 60 seconds. Vacuum suction was stopped because it was not useful inthe arrested heart to avoid lesions that were too deepwith potential damage to coronary arteries. The exactlocation of isthmus lesion was tailored to angiographiccoronary anatomy, as described by Benussi and cowork-ers [1]. In most cases the left appendage was excluded with a polypropylene double mattress suture from theendocardial side.All procedures were performed on transesophagealechocardiography monitoring for excluding preoperativepresence of clots in the left appendage and documentingcomplete appendage exclusion after the operation. Thetransesophageal echocardiography probe was retractedduring radiofrequency application. Statistical Analysis Analysis of data was performed with the StatView 4Software (SAS Institute, Cary, NC). Data are reported asmean  standard deviation. Clinical Experience There was no operative death. No postoperative compli-cations occurred, except for a patient who presented withtransient neuropsychological damage with confusion andmotor hyperactivity. The mean length of hospital staywas 6.58  1.31 days. All patients were discharged home.Six patients (50%) had AF in the postoperative period. Allthese patients received intravenous amiodarone. Sinusrhythm was restored in 3 patients. At hospital discharge,3 patients (25%) had AF and 1 (8.33%) was in atrial flutter(Table 3). No electrical cardioversion was attempted in this early postoperative phase. All patients received war-farin for at least 6 months with a target internationalnormalized ratio of 2.5 to 3.The mean follow-up of 8.76  1.00 months (range, 6.89to 9.86) was 100% complete. The evaluation was per-formed on a regular basis at 1, 3, 6, and 9 months, andeach year with echocardiography, electrocardiogram,and 24 hour-Holter electrocardiogram. Follow-up wasended on March 31, 2009. One patient, discharged inatrial flutter on amiodarone and beta-blockers, was insinus rhythm at the 1-month visit. Approximately 3months after the operation, 2 patients underwent suc-cessful electrical cardioversion with sinus rhythm resto-ration. The last patients discharged in AF refused elec-trical cardioversion (Table 3). At the end of the follow-up, 11 patients (91.67%) were in sinus rhythm, with only 2patients receiving amiodarone. Freedom from AF was100% for paroxysmal patients (3 of 3) and 88.89% (8 of 9)for persistent and long-lasting persistent AF. Echocardi-ography assessment at follow-up underscored a com-plete recovery of atrial transport function in all patientsin sinus rhythm, except one showing atrial paralysis (10of 11 patients [90.91%]).During follow-up, no major cardiac and cerebrovascu-lar events occurred. Most of the patients were in New York Heart Association functional class I with only 1  Fig 3. Transesophageal view of the probe in the correct position be-tween the right superior pulmonary vein and the left appendage. 1319 Ann Thorac Surg NEW TECHNOLOGY BEVILACQUA ET AL2009;88:1317–21 ABLATION THROUGH RIGHT MINI-THORACOTOMY     N    E    W    T    E    C    H    N    O    L    O    G    Y  Table 3. Follow-Up Data: Rhythm and Drugs Patient AF Type Hospital Admission Isthmus Lesion Postoperative AF Hospital Discharge 1 Month 3 Months 6 Months 9 Months1 Persistent AFBeta-blocker Yes No SRAmiodaroneSRAmiodaroneSRAmiodaroneSR Not available2 LL Persistent AFDigitalis Yes No SRBeta-blockerSRBeta-blockerSRBeta-blockerSRBeta-blockerNot available3 a LL Persistent AFBeta-blocker Yes Yes AF AmiodaroneBeta-blockerAF AmiodaroneBeta-blockerAF AmiodaroneBeta-blockerSRAmiodaroneBeta-blockerSR AmiodaroneBeta-blocker4 LL Persistent AFBeta-blocker Yes Yes A-FlutterAmiodaroneSRAmiodaroneSRAmiodaroneSR SR5 Paroxysmal SRAmiodaroneNo No SR SR SR SR SR6 Paroxysmal SRPropafenoneNo No SR SR SR SR SR7 LL Persistent AFAmiodarone Yes No SR AmiodaroneBeta-blockerSR AmiodaroneBeta-blockerSR AmiodaroneBeta-blockerSRBeta-blockerSRBeta-blocker8 b LL Persistent AFBeta-blocker Yes Yes AFPropafenoneSRPropafenoneAFPropafenoneAF AF9 LL Persistent AFBeta-blocker Yes No SR AmiodaroneBeta-blockerSR AmiodaroneBeta-blockerSR AmiodaroneBeta-blockerSRBeta-blockerSRBeta-blocker10 Persistent SR Amiodarone Yes Yes SR AmiodaroneBeta-blockerSR AmiodaroneBeta-blockerSR AmiodaroneBeta-blockerSRBeta-blockerSR Beta-blocker11 a Persistent AFAmiodarone Yes Yes AFAmiodaroneAFAmiodaroneAFAmiodaroneSRAmiodaroneSR Amiodarone12 Paroxysmal SRAmiodarone Yes Yes SRAmiodaroneSRAmiodaroneSRAmiodaroneSR SR a Patients underwent successful electrical cardioversion.  b Patient refused electrical cardioversion.AF  atrial fibrillation; A-Flutter  atrial flutter; LL  long lasting; SR  sinus rhythm.  1  3  2  0   N E  W T  E  C H N O L  O G Y  B  E  V I   L  A C Q U A E  T  A L  A n n T  h  o r  a c  S  u r   g A B  L  A T  I   O N T  H R  O U G H R  I   G H T  M I   N I  - T  H O R  A C O T  O M Y  2  0  0  9  ;  8  8  :  1  3  1  7 – 2  1        N     E       W     T     E     C      H      N      O     L      O      G     Y  patient (8.33%) complaining of effort dyspnea (New York Heart Association functional class II). Comment Surgical ablation of paroxysmal or persistent AF has aclear indication in symptomatic and selected low-risk asymptomatic patients undergoing cardiac surgery forother reasons. Surgical treatment of stand-alone AF isadvocated only in symptomatic patients preferring sur-gery to percutaneous ablation or patients who have failedone or more catheter ablations or who showed clearcontraindication to percutaneous procedures (eg, thrombiin left atrial appendage) [2]. Different minimally invasive surgical techniques with different ablative devices havebeen proposed [3, 4].Wolf and colleagues [5] reported a series of patientstreated with a bipolar radiofrequency clamp using abilateral approach and a video-assisted technique, with91% freedom from AF at 3 months. Similar results with a97.6% long-term freedom from AF are reported by Adand Cox [6] with cryoablation.Epicardial radiofrequency ablation with irrigatedprobe has demonstrated up to 86% of transmural lesionsin the animal model [7]. Clinical use of conventional epicardial radiofrequency ablation on the beating hearthas shown a 3-year freedom from AF of 77% [8].The Cobra Adhere XL probe can represent an easy andreproducible tool to perform left-sided ablation in con-comitant and stand-alone cases of AF. Internal coolingand vacuum-assisted stabilization provides an efficacioususe on the beating heart reducing ischemic time withrespect to the endocardial approach as with cryotherapyand monopolar radiofrequency. The limited anatomicdissection to introduce the probe and the monolateralapproach can offer significant advantages respect to bi-polar clamps in terms of time and technical complexity.The present report aims to describe this new tool thatcan enrich the surgical armamentarium for AF treatment.Despite the encouraging clinical results, however, fur-ther, larger, and prospective studies are needed to eval-uate the real efficacy of this new technology. Disclosures and Freedom of Investigation All tested materials were regularly purchased with institu-tional funds of the Heart Hospital—Fondazione G. Monas-terio. The authors have performed an independent pro-spective evaluation of the technology. The authors have nofinancial relationship with the Estech Company. References 1. Benussi S, Nascimbene S, Calvi S, Alfieri O. A tailoredanatomical approach to prevent complications during leftatrial ablation. Ann Thorac Surg 2003;75:1979–81.2. Calkins H, Brugada J, Packer DL, et al. HRS/EHRA/ECASexpert consensus statement on catheter and surgical ablationof atrial fibrillation: recommendations for personnel, policy,procedures and follow-up. Europace 2007;9:335–79.3. Loulmet DF, Patel NC, Patel NU, et al. First robotic endo-scopic epicardial isolation of the pulmonary veins with mi-crowave energy in a patient in chronic atrial fibrillation. AnnThorac Surg 2004;78:e24–5.4. Pruitt JC, Lazzara RR, Dworkin GH, et al. Totally endoscopicablation of lone atrial fibrillation: initial clinical experience.Ann Thorac Surg 2006;81:1325–30.5. Wolf RK, Schneeberger EW, Osterday R, et al. Video-assistedbilateral pulmonary vein isolation and left atrial appendageexclusion for atrial fibrillation. J Thorac Cardiovasc Surg2005;797-802:130.6. Ad N, Cox JL. The maze procedure for the treatment of atrialfibrillation: a minimally invasive approach. J Card Surg 2004;19:196–200.7. Ishikawa S, Oki S, Muraoka M, Oshima K, Kashiwabara K,Morishita Y. Epicardial radiofrequency ablation on a beatingheart: an experimental study. Ann Thorac Cardiovasc Surg2005;11:21–4.8. Benussi S, Nascimbene S, Agricola E, et al. Surgical ablationof atrial fibrillation using the epicardial radiofrequency ap-proach: mid-term results and risk analysis. Ann Thorac Surg2002;74:1050–6. Disclaimer The Society of Thoracic Surgeons, the Southern ThoracicSurgical Association, and  The Annals of Thoracic Surgery neither endorse nor discourage use of the new technol-ogy described in this article.1321 Ann Thorac Surg NEW TECHNOLOGY BEVILACQUA ET AL2009;88:1317–21 ABLATION THROUGH RIGHT MINI-THORACOTOMY     N    E    W    T    E    C    H    N    O    L    O    G    Y
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