Surgical ablation of atrial fibrillation (AF) received multi-society guideline recommendations in 2017 that have been updated in 2024 for concomitant (Class I) and stand-alone therapy (Class II). Despite increasing evidence supporting left atrial appendage (LAA) occlusion for patients with AF with or without the need of concomitant cardiac surgery, 3-year survival after surgical ablation plus LAA occlusion remains superior to LAA treatment alone. Moreover, catheter-based ablation success in patients with persistent AF remains limited, and recent epicardial subxiphoid ablation techniques remain arrhythmically and anatomically incomplete. Although recent years of robust contemporary evidence and guidelines in support of surgical ablation have resulted a modest increase adoption of concomitant surgical ablation, patients and referring cardiologists remain hesitant to undergo a stand-alone Cox CryoMaze-III procedure whether it is performed through a median sternotomy or minimally invasively via a mini-thoracotomy in the right anterior fourth intercostal space.
The Cox CryoMaze-III and Cox Maze-IV procedures have been shown to have similar results when they are performed minimally invasively compared with when they are performed through a median sternotomy. , These procedures are performed under direct vision by a tableside surgeon with or without videoscopic assistance. In addition to the need for potential rib spreading, occasional challenges may occur with the handling of cardiac tissues to avoid tissue gaps during the creation of a cryolesion. Chitwood and colleagues first introduced the robotic approach for AF ablation in 2003 using microwave technology and subsequently with cryothermia. , Chitwood’s robotic approach was performed through a single working right mini-thoracotomy similar to the minimally invasive cryosurgical Maze-III procedure first performed by Cox in 1996. Minimally invasive and robotic ablation procedures enjoyed short-term excellent outcomes, but historically, they have lacked consistency of the lesion set and often do not conform to the classic Cox CryoMaze-III procedure. Although the long-term results of the minimally invasive cryosurgical Cox CryoMaze-III procedure have been well-documented (see Chapter 38 ), there has been a paucity of reports documenting the long-term clinical and electrophysiological outcomes of the robotic Cox CryoMaze-III procedure. Since 2016, the West Virginia University robotic program has performed robotic Cox CryoMaze-III procedures using the identical cryosurgical lesion pattern of the minimally invasive Cox CryoMaze-III procedure. We perform the robotic approach through a non–rib-spreading 3-cm right lateral mini-thoracotomy placed at the anterior axillary line that has provided consistently excellent clinical and electrophysiological results on long-term follow-up. The objective of this chapter is to describe the current approach, technical details, and longitudinal results of the robotic Cox CryoMaze-III procedure.
Preoperative Preparation
After the presence of symptomatic AF has been confirmed and the patient has met guideline indications for surgical ablation, patients without prior cardiac surgery or a right thoracotomy are considered for a robotic approach, and preoperative anatomic imaging is performed. A history of prior catheter ablations is not a contraindication to robotic surgery. Coronary artery imaging for patients with significant risk factors is performed by radial cardiac catheterization or coronary computed tomography angiography (CTA). CTA of the chest, abdomen, and pelvis is obtained to detect occult stenoses that could potentially elevate the risk of peripheral cannulation for CPB. Preoperative transesophageal echocardiography (TEE) is performed if there is any concern for a thrombus in the LAA and if there is moderate or greater structural valve pathology on transthoracic echocardiography.
Operative Preparation and Surgical Technique
Patients receive a pre-induction intrathecal injection of 0.5 mg of morphine sulfate and an intercostal injection of 0.25% bupivacaine in the preoperative holding area to enhance rapid postoperative recovery and timely extubation. Patients also have double-lumen endotracheal intubation, a left brachial arterial line, left internal jugular large-bore intravenous (IV) access, and external defibrillator pads. The robotic-assisted Cox CryoMaze-III procedure is performed in the supine position via a 3-cm rib-sparing minimally invasive lateral thoracotomy at the level of the anterior axillary line and is facilitated by single lung ventilation. The superior vena cava (SVC) is cannulated percutaneously via the right internal jugular vein with an 18- to 20-Fr cannula (FemFlex II, Edwards Lifesciences) under TEE guidance that is flushed with heparinized saline. Folded towels are placed under the right side of the patient below the tip of the scapula to facilitate a slight drop of the right shoulder and opening of the rib spaces. The patient is then prepped and draped.
The cardiac structures are accessed via the fourth intercostal space, with the right superior pulmonary vein viewed under direct vision as the anatomic landmark to confirm the optimal level thoracic entry. A small soft tissue wound retractor is placed to facilitate exposure (Alexis, Applied Medical Resources). The pericardium is opened at least 3 cm anterior to the right phrenic nerve from the inferior vena cava (IVC) to the distal ascending aorta, and gentle retraction sutures are placed to facilitate exposure of the heart and aorta. Sharp dissection facilitates the mobilization of the SVC and IVC. The anterior surfaces of the right femoral vessels are exposed via a 1-cm skin incision, robotic port sites are prepared, and the patient is heparinized. The IVC is cannulated via the right common femoral vein with a 25-Fr multi’stage venous cannula that is positioned in the right atrium (RA) (Bio-Medicus, Medtronic). The right common femoral artery is cannulated with a 17- to 19-Fr arterial cannula (Bio-Medicus, Medtronic). A 5-Fr distal perfusion catheter is placed in the right superficial femoral artery (Micro-Introducer, Braun) and connected to the arterial line.
Robotic ports are inserted at the following locations: (1) the third intercostal space anterior axillary line for the first or left robotic arm, (2) the working incision is used for the robotic camera connected to the second robotic arm, (3) the fourth intercostal space mid-clavicular line for the dual blade left atrial retractor connected to the third robotic arm, and (4) the fifth intercostal space mid-axillary line for the fourth or right robotic arm. A stab incision in the second intercostal space at the posterior axillary line is made for passage of a transthoracic aortic cross-clamp and one at the same level in the fifth intercostal space for later passage of a left ventricular vent. After commencement of CPB, a cardioplegia cannula is inserted into the ascending aorta for the administration of antegrade cold cardioplegia, and a left ventricular vent is inserted via the right superior pulmonary vein. The Da Vinci Xi robotic system (Intuitive Surgical, Inc.) is then docked. The high-definition camera is positioned at the superior aspect of the working incision. The robotic instruments used are the DeBakey forceps via the first or left arm, the EndoWrist dual-blade atrial retractor in third arm, and the needle driver and curved scissors in the right or fourth arm ( Fig. 16.1 ). Carbon dioxide is continuously infused via the third arm port at 2 L/min. A previously positioned transthoracic aortic cross-clamp is gently applied to the distal ascending aorta under full camera visualization. Intermittent antegrade cold blood cardioplegia is delivered at 20-minute intervals to maintain optimal myocardial protection throughout the operative procedure. Cardioplegia management may be tailored to institutional protocols, but it is important to avoid retrograde catheters in the coronary sinus that may impair lesion creation.
Surgeon’s view of the operative preparation for a robotic Maze procedure through a 3-cm right mini-thoracotomy.
After robotically performed atriotomies, a nitrous oxide cryoprobe (AtriCure, Inc.) is used to create cryolesions in a prespecified manner consistent with the pattern of the minimally invasive Cox CryoMaze-III procedure while complete tissue contact is visually confirmed to avoid gaps in the lesions ( Fig. 16.2 ). Left atrial lesions are each performed for 3 minutes, and right atrial lesions are performed for 2 minutes to assure complete transmurality. If at any time non-transmurality is suspected (e.g., thick or scarred atrial tissue), cryoablation time is extended until transmurality can be assured. In this situation, it is also helpful to apply the cryoprobe on the opposite side of the first cryolesion if possible so that the tissue is frozen from both sides of the atrial wall. After completion of the cryolesions, the LAA is surgically closed.
Robotic Cox Maze-IIII lesions. The cryosurgical Cox Maze-III lesion setup performed robotically. While an AtriClip LAAO device is shown in this diagram, it is not always applied in the robotic procedures. IVC, Inferior vena cava; LAA , left atrial appendage; RAA , right atrial appendage; SVC , superior vena cava.
Left Atrial Lesions
After a robotically performed curvilinear standard left atriotomy is placed just beyond the left inferior pulmonary vein via the oblique sinus, the dual-blade atrial retractor is inserted to provide full exposure of the inside of the left atrium. A left ventricular vent is positioned into the left inferior pulmonary vein to create a relatively bloodless operative field. We begin by creating the coronary sinus cryolesion that is performed epicardially via the oblique sinus. An endocardial iceball occurs inside the left atrium during this coronay sinus freeze and its location is marked inside the LA with methylene blue so that we will know exactly where to place the mitral line later ( Fig. 16.3 ). Next, the floor lesion of the left atrial box is created around the inferior half of the pulmonary veins with the tip of the probe extending into the LAA orifice, which simultaneously creates the line across the coumadin ridge ( Fig. 16.4 ). The roof lesion is then placed above the right and left superior pulmonary veins extending from the superior end of the left atriotomy to the end of the floor lesion where it overlaps with the floor lesion ( Fig. 16.5 ). Importantly, the distal portion of this roof lesion is placed low and parallel to the right superior and left superior pulmonary veins to avoid inadvertent electrical interruption of Bachman’s bundle. Finally, the endocardial mitral line is placed from the floor lesion to the posterior mitral annulus, and we usually end it toward the P3 mitral valve scallop. To avoid postoperative peri-mitral atrial flutter, this mitral line is placed in the same plane as the epicardial ablation of the coronary sinus, covering the previously placed methylene blue mark in the LA ( Fig. 16.6 ). ,
Coronary sinus cryolesion. (A) The coronary sinus cryolesion is created epicardially just below the inferior end of the left atriotomy in Waterston’s groove. (B) During creation of the epicardial coronary sinus lesion, an iceball appears on the endocardial surface of the left atrium (LA). The site of this endocardial iceball is marked with methylene blue to identify exactly where the endocardial mitral line will have to be placed. It is critical to position the endocardial mitral line and the epicardial coronary sinus cryolesion in exactly the same plane to prevent the possibility of postoperative peri-mitral flutter (see Chapter 48, Figs. 48.6 and 48.7).
Inferior (floor) lesion of the left atrial box and left atrial appendage (LAA) lesion across the coumadin ridge. (A) Creation of the endocardial floor lesion that extends from the inferior end of the left atriotomy across the posteroinferior left atrium (LA) to the orifice of the LAA. By extending this lesion to the LAA orifice, macro-reentrant circuits (drivers) that use the coumadin ridge are prevented. (B) Appearance of the floor lesion after removal of the cryoprobe documenting that the lesion is homogenous and free of tissue gaps. LIPV, Left inferior pulmonary vein; LSPV, left superior pulmonary vein; MV, mitral valve; RIPV, right inferior pulmonary vein.
