Robotic Totally Endoscopic CryoMaze Ablation Under Ventricular Fibrillatory Arrest

In this new CTSNet President’s Series, Dr. Husam Balkhy, president of ISMICS, showcases cutting-edge, totally endoscopic cardiac procedures from the University of Chicago. Watch for more videos in this series coming soon.  

Introduction 

CryoMaze ablation for the surgical treatment of atrial fibrillation has been performed either as an isolated procedure or concomitant with other intracardiac procedures to successfully treat patients with atrial fibrillation (1). Since 2014, University of Chicago Medicine surgeons have performed the CryoMaze procedure using a robotic totally endoscopic approach under moderate hypothermic ventricular fibrillatory arrest. 

Surgical Technique 

1.) Patient Selection 

Patients with paroxysmal or persistent atrial fibrillation who were refractory to medical and catheter ablation therapy were selected for this procedure. Patients with aortic regurgitation (more than moderate), low ejection fraction (less than 30 percent), significant coronary artery disease, and/or a history of right lung surgery were excluded. 

2.) Robotic Port Placement 

The patient was placed supine with a vertical roll under the right scapula. General anesthesia was induced with a single lumen endotracheal tube. External defibrillator pads were placed on the chest and back before draping. With the lungs deflated, an 8 mm camera port was placed in the fourth intercostal space. Humidified carbon dioxide was continuously insufflated through the port into the pleural space. An 8 mm robotic port for the third arm was placed in the anterior fifth intercostal space and a 14-gauge needle was inserted next to it. Two 8 mm robotic ports were placed in the second and sixth intercostal spaces. An 8 mm incision was made in the fourth intercostal space for a working port, and a soft tissue wound retractor was placed and closed off with wet gauze to maintain CO2 pressure inside. Two sump suction tubes were inserted in the fifth intercostal space posterior to the soft tissue retractor. Cardiopulmonary bypass was established with femoral arterial and venous cannulation. 

3.) Moderate Hypothermic Ventricular Fibrillatory Arrest 

Immediately after initiation of cardiopulmonary bypass, body core temperature was cooled to 31°C. The da Vinci Xi surgical robot was docked from the left side of the table. The pericardium was opened two centimeters above the phrenic nerve. The oblique sinus and transverse sinus were opened for future silastic snare placement for the superior vena cava (SVC) and inferior vena cava (IVC). A temporary epicardial pacing wire was placed on the right ventricle, brought out to the skin, and connected to the atrial side of a temporary external pacemaker. Rapid ventricular pacing was commenced using the rapid atrial pacing feature of the external pacemaker with a rate of 800 beats per minute and an amplitude of 20 milliamperes (mA) for several seconds to induce ventricular fibrillation. After confirming stable ventricular fibrillatory arrest, a left atriotomy was made. Using the dynamic atrial retractor, the left atrium was gently retracted to prevent significant aortic regurgitation, which could obscure the operative field. This technique has been described in detail in a previous publication (2). 

4.) Left-Sided CryoMaze Procedure 

The left-sided lesions of the CryoMaze procedure were performed using a Cryoablation probe for three minutes for each lesion. First, the superior box lesion was created on the dome of the left atrium from the left atriotomy incision to the base of the left atrial appendage. Next, the inferior box lesion was created on the floor of the left atrium and connected to the superior lesion to completely isolate the pulmonary veins. The left atrial appendage lesion was extended from the box lesion. The mitral isthmus lesion was created from the left atriotomy to the posterior mitral annulus, and the coronary sinus lesion was ablated externally through the oblique sinus at the same level of the mitral isthmus lesion. The left atrial appendage was closed with two layers of 4-0 running suture. The left atrium was closed with 4-0 Prolene running suture, leaving a transmitral drain in the left ventricle for deairing. The patient was rewarmed, and after left atriotomy closure and extensive deairing maneuvers, direct cardioversion was applied by using the external defibrillator pads. The left ventricular vent was left in for further deairing and was removed only after completion of the right-sided lesion set. 

5.) Right-Sided CryoMaze 

The SVC and IVC were encircled with silastic snares, and a small vertical right atriotomy was made. The SVC lesion and the IVC lesion were separately created from the incision. The probe was placed posteriorly to avoid injury of the sinoatrial node while performing the SVC lesion, taking care to avoid injury to the phrenic nerve. Lines to the right atrial appendage and to the tricuspid valve annulus were created from the incision as well. The right atriotomy was closed with 4-0 Prolene suture. 

Comments 

The excellent long-term outcomes of surgical stand-alone or concomitant CryoMaze ablation for atrial fibrillation were reported recently (3). Based on the satisfying results, performing concomitant CryoMaze ablation procedure during intracardiac surgery has been increasing during the past decade (1). However, there is still some hesitancy to perform isolated CryoMaze ablation for stand-alone atrial fibrillation due to its invasive nature, especially with a large sternotomy incision. Multiple minimally invasive approaches for surgical ablation have been introduced to avoid sternotomy, including mini-thoracotomy CryoMaze ablation (4), epicardial radiofrequency ablation (5), and hybrid surgical epicardial and catheter-based ablation procedures (6). A systematic review paper demonstrated that the minimally invasive CryoMaze procedure could be the most effective treatment with more than 90 percent sinus restoration rate at one year, which was 10 percent higher than those of epicardial ablation or hybrid ablation (7). Therefore, minimally invasive CryoMaze ablation, despite its requirement for cardiopulmonary bypass, has gained acceptance as a safe and feasible procedure for stand-alone atrial fibrillation. Performing this procedure via thoracotomy with robotic assistance has the potential to make it even less invasive, as reported by Badhwar and colleagues using cardioplegic arrested (8).  

The authors have been performing robotic totally endoscopic CryoMaze ablation under ventricular fibrillatory arrest at their institution since 2014. Of a total of 152 patients undergoing robotic totally endoscopic CryoMaze surgery in their center, 39 patients with stand-alone atrial fibrillation were treated with this approach. The mean age was 63 years old. Two patients had previous cardiac surgery. Bi-atrial cryoablation was performed in 27 patients (68 percent) and left atrial cryoablation in 12 patients (32 percent). The mean ventricular fibrillation time was 74 minutes. The mean length of the hospital stay was 2.8 days. There were no mortality, perioperative strokes, or myocardial infarctions, and 90 percent of patients were free from atrial fibrillation at 12 months. Based on the author’s experience and outcomes, they believe that robotic totally endoscopic CryoMaze ablation with ventricular fibrillatory arrest is a safe, simple, reproducible, and the least invasive approach for stand-alone atrial fibrillation with a low risk of cerebrovascular and cardiac complications. 

References

1. Badhwar V, Rankin JS, Ad N, Grau-Sepulveda M, Damiano RJ, Gillinov AM, et al. Surgical ablation of atrial fibrillation in the United States: trends and propensity matched outcomes. Ann Thorac Surg. 2017 Aug;104(2):493-500.
2. Kitahara H, Nisivaco S, Piech R, Grady K, Balkhy HH. Ventricular Fibrillatory Arrest: A Safe Option in Robotic Totally Endoscopic Intracardiac Surgery. Ann Thorac Surg. 2023;115(6):1438-1444.
3. Khiabani AJ, MacGregor RM, Bakir NH, Manghelli JL, Sinn LA, Maniar HS, et al. The long-term outcomes and durability of the Cox-Maze IV procedure for atrial fibrillation. J Thorac Cardiovasc Surg. 2022 Feb;163(2):629-641.e7.
4. Ad N, Holmes SD, Friehling T. Minimally invasive stand-alone Cox Maze procedure for persistent and long-standing persistent atrial fibrillation – perioperative safety and 5-year outcomes. Circ Arrhythm Electrophysiol. 2017 Nov;10(11):e005352.
5. Haldar S, Khan HR, Boyalla V, Kralj-Hans I, Jones S, Lord J, et al. Catheter ablation vs. thoracoscopic surgical ablation in long-standing persistent atrial fibrillation: CASA-AF randomized controlled trial. Eur Heart J. 2020 Dec 14;41(47):4471-4480.
6. DeLurgio DB, Crossen KJ, Gill J, Blauth C, Oza SR, Magnano AR, et al. Hybrid Convergent Procedure for the Treatment of Persistent and Long-Standing Persistent Atrial Fibrillation: Results of CONVERGE Clinical Trial. Circ Arrhythm Electrophysiol. 2020 Dec;13(12):e009288.
7. Je HG, Shuman DJ, Ad N. A systematic review of minimally invasive surgical treatment for atrialfibrillation: a comparison of the Cox-Maze procedure, beating-heartepicardial ablation, and the hybrid procedure on safety and efficacy. Eur J Cardiothorac Surg. 2015 Oct;48(4):531-40; discussion 540-1
8. Badhwar V. Robotic-assisted biatrial Cox-maze ablation for atrial fibrillation. J Thorac Cardiovasc Surg. 2021 Oct 5:S0022-5223(21)01408-2.

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