Hybrid Minimal Invasive Epicardial and Transvenous Catheter Ablation for Atrial Fibrillation

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Hybrid Minimal Invasive Epicardial and Transvenous Catheter Ablation for Atrial Fibrillation


Mark La Meir, MD, PhD; Laurent Pison, MD, PhD


Introduction


The concept of hybrid atrial fibrillation (AF) ablation consists of a surgical minimally invasive epicardial approach and a catheter-based endocardial approach performed by the electrophysiologist. According to the 2012 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation, a hybrid AF surgical ablation procedure is defined as an AF ablation procedure performed by electrophysiologists and cardiac surgeons, either as part of a single “joint” procedure or performed as two separate, pre-planned ablation procedures that take place no more than six months apart.1 This chapter will discuss the current techniques for this procedure, aimed at combining the advantages of a predominantly epicardial ablation strategy with an endocardial mapping and touch-up strategy. These procedures are always performed on the beating heart with minimally invasive surgical techniques (Figure 29.1).



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Figure 29.1 Hybrid setup.


There are currently four different surgical strategies depending on the surgical access to the heart:


1. A right thoracoscopic approach with three ports using a suction catheter delivering both bipolar and monopolar radiofrequency (RF) energy (Fusion, AtriCure Inc., Mason, OH). The left atrial appendage (LAA) typically is not excluded with this approach.


2. A bilateral thoracoscopic approach utilizing three ports on each side, to deliver bipolar bidirectional RF clamping devices, and bipolar or unipolar unidirectional energy linear ablation devices (Synergy, AtriCure Inc., and Cardioblate, Medtronic Inc., Minneapolis, MN). The LAA typically is excluded during this procedure.


3. A transabdominal, transdiaphragmatic approach via abdominal working ports, using a unipolar suction assisted RF device, the Epicardial Pericardioscopic Posterior LA ablation procedure (“Convergent Procedure”, Epi-Sense, AtriCure Inc.). The LAA typically is not excluded in this procedure.


4. A left thoracoscopic approach utilizing three ports to deliver bipolar RF clamping devices (Synergy, AtriCure, Inc.) and a bipolar unidirectional RF device (Coolrail, AtriCure, Inc.). The LAA typically is excluded during this procedure.


Regarding the timing of the endocardial electrophysiology procedure, there are typically two options. One option is a single-step procedure where epicardial and endocardial procedures are performed on the same day. This is typically done in a hybrid room, but in some centers, the patient is transferred after the surgical step from the operating room to the electrophysiology lab, for reasons of infrastructure and mapping capabilities. The second option is a staged procedure in which the preplanned electrophysiologic study may be performed during the same hospitalization or up to six months after the surgical procedure.


Anatomy


The anatomical structures relevant to the epicardial treatment of AF include the pulmonary veins, (PVs), the LA and right atrium (RA), the ganglionated plexi (GPs), the ligament of Marshall (LOM), the caval veins, the left atrial appendage (LAA), the pericardial space, the pericardial sinuses, the phrenic nerve, and the esophagus. The differences in anatomy between an epicardial approach and the endocardial procedure will be briefly highlighted.


The pericardial space is continuous with the epicardium and reflects around the roots of the great vessels. Posteriorly, it is related to the bronchi, esophagus, descending thoracic aorta, and mediastinal surface of the lungs.


The right phrenic nerve passes lateral to the superior vena cava (SVC), superior to the antrum of the right superior PV (RSPV), the RA, and the inferior vena cava (IVC). The left phrenic nerve runs laterally down the pericardium over the left ventricle towards the apex of the heart.


The transverse sinus is a passage from right to left, located superiorly to the heart. To access the transverse sinus, the pericardial reflections between the right pulmonary artery, the SVC, and the RSPV are dissected to visualize the retrocaval recess. From the left side, the transverse sinus can be entered without dissection.


The oblique sinus is a recess located behind the LA formed by the reflection of the pericardium around the large PVs and caval veins. From the right side, the oblique sinus is entered by dissection of the pericardial reflections adjacent to the right inferior PV (RIPV) and the IVC. From the left side, the oblique sinus can be accessed without dissection.


The LOM, a remnant of the embryonic left SVC, is located on the epicardium between the LAA and the left PVs. It is easily accessible and ablated by the epicardial approach.


The LAA is easily accessible via the left-sided epicardial approach. LAA excision or ligation may be challenging during thoracoscopic surgery. This has led to the development of non-stapling devices, like the AtriClip device (AtriCure Inc.).


The esophagus is in contact with the posterior pericardium at the area of the posterior LA. The esophagus typically traverses a length of around 45 mm and a width of around 13 mm along the posterior LA. The anatomic relation with regard to the oblique sinus is variable because of displacement of the esophagus by the aorta. It can potentially be located in any area between the right and left PV posterior orifices. (image Video 29.1).


Hybrid Procedure


As mentioned above, there are four different surgical strategies. All procedures have a common trunk of four important steps. Patient positioning and port placement, dissection of the pericardial reflections, correct positioning of the device(s) and ablation.


All procedures, except for the “Convergent Procedure,” need a selective pulmonary ventilation. Before incision, a transesophageal echocardiography (TEE) examination is performed to rule out the presence of a thrombus in the LA or LAA. The patient is positioned in the supine position with elevation of one side of the chest if needed.


A Right Thoracoscopic Approach


The right chest is entered with 3 5- to 10-mm working ports. A camera port in the fifth intercostal space at the mid-axillary line, a port for instruments in the third intercostal space at the anterior axillary line, and a port for instruments in the seventh intercostal space at the anterior axillary line. After placement of the camera port, CO2 insufflation is started at a pressure of 8 mmHg. This will increase the working space by pushing the diaphragm down and the heart towards the left chest. Based on the patient’s morphology and the cardiac anatomy, the locations of these ports may vary. The pericardium is opened with an endoscopic coagulation hook and/or scissors longitudinally, 2 cm anterior to the phrenic nerve towards the SVC and IVC. To improve visibility and facilitate the dissection of the pericardial reflections (to gain access to the transverse and oblique sinuses), the posterior part of the pericardium is retracted with 2 sutures that are pulled outside the chest posteriorly to the camera port. The pericardial reflections of the SVC and IVC are bluntly dissected until the access to the transverse sinus and oblique sinus is achieved. The epicardial fat, at the level of Waterston’s groove and the roof of the LA, is partially dissected to improve energy delivery and penetration. Two magnetic tip guidance catheters (Fusion Magnetic Tip Introducer Set, AtriCure Inc.) are introduced into the transverse and oblique sinus; once connected, they are retrieved. The position of the guidance catheters in relation to the LAA is confirmed visually, and, if necessary, by TEE. A temperature-controlled RF ablation catheter (Fusion, AtriCure Inc.) is advanced over the posterior LA, and after suction to the atrial tissue is achieved, sequential bipolar and/or monopolar energy is applied. The ablation catheter is repositioned during the procedure to create a complete left atrial box lesion. Intraoperatively, epicardial entrance and exit blocks across the box lesions are measured. If needed, it is possible to make a triangular lesion on the free wall of the RA by making an ablation line between the 2 caval veins and a connection towards the superior border of the free wall of the RA.2


A Bilateral Thoracoscopic Approach


The right thoracoscopic approach is similar to the procedure described above, except bipolar clamping devices are used to perform the pulmonary vein isolation (PVI). To facilitate the passage of the bipolar clamp, a lighted tip dissector is carefully placed under the RIPV and positioned towards the area between the right pulmonary artery (RPA) and the RSPV posteriorly. A guidance catheter is passed around the posterior veins and connected to the bipolar clamp, (Synergy, AtriCure, Inc.) which is then safely positioned around the antral area of the right PVs. Ablation of the right PV antrum is performed utilizing bi-polar radio frequency (RF). At this point, the inferior 5mm trocar is removed. A roof line (connecting both superior PVs) and an inferior line (connecting both inferior PVs) can be made using a bipolar unidirectional RF pen or linear pen device. If the RA is dilated, 2 additional ablation lines can be placed, one encircling the SVC using the clamp, the other connecting both caval veins (intercaval lesions) using a bipolar unidirectional RF pen or linear pen device.


Part 2 of the procedure is completed via left thoracoscopic port access utilizing a similar 3-port technique at the right side, but more posteriorly for better visualization and access. The pericardium is opened with an endoscopic coagulation hook and/or scissors longitudinally, 2 cm inferior to the phrenic nerve. No dissection has to be performed to gain access to the transverse and oblique sinuses. To facilitate the passage of the bipolar clamp around the left PVs a lighted tip dissector is carefully placed under the left inferior pulmonary vein (LIPV) and preferably positioned medial to the LOM towards the area between the pulmonary artery and the roof of the LA. The dissector can also be placed at the region of the LOM (after cutting the ligament) in a more lateral position. The disadvantage of this technique is the necessity to create a longer roof line with a unidirectional catheter. The ablation procedure is similar to the right thoracoscopic approach. The LAA can then be excluded.3,4


A Transabdominal, Transdiaphragmatic Approach


A 3-cm incision is made 3 cm below the xyphoid process and extended into the peritoneum under direct visualization. Two 5-mm ports are placed in the left and right subcostal areas, a 10-mm port is placed in the midline incision and the abdomen is insufflated with CO2 to 12 mmHg. The central diaphragmatic tendon is opened longitudinally 2 cm, the pericardium is visualized and also opened longitudinally providing access to the posterior region of the heart. The 10-mm port is removed and the paracardioscopic cannula (AtriCure Inc.) is positioned through the midline incision. The epicardial portion of the procedure is performed by a unipolar, vacuum-assisted RF linear ablation catheter (Epi-Sense). The epicardial lesion set includes partial PV ablation and extensive posterior LA wall ablation. Endocardial ablation, immediately following the epicardial procedure, includes completion of antral PVI. Complex fractionated atrial electrogram- (CFAE-) guided ablation, SVC ablation and cavotricuspid isthmus ablation can be completed as needed.5


A Left Thoracoscopic Approach


The left thoracoscopic approach is similar to the left-sided procedure described in the bilateral thoracoscopic approach. However, dissection to gain access to the transverse and oblique sinuses is not required for this procedure. In order to position the bipolar clamp coming from the left side around the right PVs, the pericardial reflections of the SVC and IVC are bluntly dissected starting from the transverse sinus and oblique sinus, respectively. Ablation of the left PVs, the roof and inferior lines are performed as described above. To ablate the right PVs, a dissector is carefully placed anterior to the RIPV and positioned over the Waterstone’s groove towards the area between the RPA and the RSPV anteriorly. A guidance catheter is passed anterior to the veins and connected to the bipolar clamp, which is then safely positioned around the antral area of the right PVs. The roof and floor lines will connect with the PVI ablations. After the epicardial ablation the LAA is typically excluded (image Videos 29.229.13).


There are several endocardial electrophysiological approaches, based upon the timing of the endocardial procedure, the specific patient presentation and the devices employed. We describe a possible ablation strategy, but other alternatives may be utilized.


Via the femoral venous approach, a His bundle (CRD-2, St. Jude Medical, St. Paul, MN) and coronary sinus catheter (Medtronic) are placed under fluoroscopy, and transseptal puncture is performed with a long 8-Fr sheath (SL0, St. Jude Medical) into the LA. The patient is then heparinized (1000 U heparin per 10 kg body weight and a heparin infusion), with activated clotting time > 300 seconds. During rapid ventricular pacing, contrast is injected through the long sheath to visualize LA anatomy. The PVs are mapped with a circular mapping catheter (Lasso, Biosense Webster, Diamond Bar, CA). If the patient is in sinus rhythm at this stage, endocardial entrance and exit block in all the PVs and the box lesion should be checked. Not completely transmural lesions (defined as absence of entrance and/or exit block) can be touched up endocardially using cooled-tip RF energy catheters with contact force feedback (Figure 29.2, A and B). Gaps in linear lesions mostly present as low amplitude and fragmented or narrowly split double atrial potentials. The endpoint of the procedure is 1) bidirectional block in all PVs and the box lesion, and 2) non-inducibility for AF using burstpacing in the CS for 10 seconds at the shortest cycle length, resulting in 1:1 atrial capture.



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Figure 29.2 Panels A and B: After epicardial ablation the roofline is not transmural. Using an endocardial cooled-tip RF catheter with contact-force feedback, the roofline is completed (red dots) until isolation of the box lesion.

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Aug 27, 2018 | Posted by in CARDIOLOGY | Comments Off on Hybrid Minimal Invasive Epicardial and Transvenous Catheter Ablation for Atrial Fibrillation
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