Surgical ablation of AF at the time of MV surgery is recommended by multiple different professional society guidelines. It is clear that there are several early and late clinical benefits associated with concomitant AF ablation such as a reduction in cerebrovascular events, preservation or improved left ventricular function, improvement in quality of life, and better long-term survival. Most patients undergoing MV surgery with or without TV surgery are good candidates for a concomitant Cox Maze procedure whether the valve surgery is to be performed through a median sternotomy or by a minimally invasive technique.

The addition of concomitant AF ablation to MV surgery is both safe and effective. ^, Because the left atrium (LA) has to be opened for the index MV surgery, performance of the LA lesions of the Maze procedure adds little time to the MV procedure. The right atrial lesions can be created through a small right atriotomy or through multiple right atrial purse-string sutures while the patient is being rewarmed and reperfused after cardioplegic arrest (see Chapter 14 ). Performing the right atrial lesions during this period avoids extra aortic cross-clamp time or prolongation of cardiopulmonary bypass time. The right atrial lesion pattern has been designed to minimize the need for new postoperative pacemakers by avoiding the atrial pacemaker complex as much as possible (see Chapter 13 ) and in addition, no properly performed Cox Maze procedure should ever cause heart block (see Chapter 21 ). However, because the biatrial surgical approach is more successful in ablating AF than a unilateral LA-only approach, more preexisting sick sinus syndrome is exposed with the biatrial approach and therefore may require a new pacemaker after surgery unless the sick sinus node recovers within a few days. When TV surgery is performed, the right atriotomy necessary for the index procedure makes the right atrial lesions even easier to perform.

Preoperative evaluation is especially important before any minimally invasive cardiac surgical procedure is performed. We recommend computed tomography angiography (CTA) of the chest, abdomen, and femoral vessels to determine if retrograde perfusion can be performed safely. The ascending aorta can also be assessed to ensure that it is of suitable caliber and to detect any aortic calcification that might preclude aortic cross-clamping for cardioplegic arrest. Prohibitive ascending aortic calcification can be overcome using fibrillatory arrest provided there is no significant aortic insufficiency.

In the case of significant CTA findings that are prohibitive of retrograde arterial perfusion, axillary cannulation can be performed, and in the presence of a normal-appearing ascending aorta, direct cannulation of the aorta is also possible. Axillary cannulation is also recommended in patients with significant iliofemoral disease. We accomplish this by direct femoral artery cannulation rather than with a side-arm technique. As mentioned, direct aortic cannulation is also possible. Finally, it is important to exclude significant aortoiliac calcification when performing femoral perfusion to minimize the incidence of stroke. This is a matter of individual judgment, but significant calcific burden, or the presence of soft plaque in the descending aorta and iliac arteries, should be approached with caution when considering femoral arterial perfusion.

We advise minimal dissection of the femoral vessels before cannulation to minimize the risk of postoperative lymphatic leaks. To further reduce the risk of postoperative lymphatic problems, we recommend placing the percutaneous arterial cannula on one side and the venous cannula on the opposite side. Ultrasound is used to guide the incision and the arterial cutdown such that it is very limited in size. Another option for femoral cannulation that is gaining popularity is percutaneous cannulation using either x-ray or ultrasound guidance and using specific closure devices to secure the vessels upon decannulation. Cannulation of the superior vena cava (SVC) is not necessary in the majority of patients, including those having tricuspid operations, so we use a single femoral venous cannula, being certain that it is advanced into the SVC. For operations in which bicaval venous cannulation is preferred, percutaneous low jugular vein cannulation at the base of the neck with a 6- to 8-Fr catheter can be performed by the anesthesiologist. This access can be upsized as needed, thus avoiding the need for insertion of a percutaneous large-bore jugular vein cannula.

After peripheral cannulation, a 6-cm or smaller right mini-thoracotomy or a totally endoscopic approach (robotic or a single endoscope) is used. This can be done laterally or anterolaterally depending on surgeon preference. The more lateral the approach, the narrower the intercostal space. Thus, retraction pain may be worse with more lateral mini-thoracotomies. Therefore, we prefer a more medial (anterolateral) access around the nipple area. In addition, when TV operations are involved, a more anterolateral incision is often advantageous for exposure.

To facilitate visibility of the atria, we recommend placing an endoscope in the same interspace as the mini-thoracotomy (usually the fourth interspace) just posterior to the incision. Alternate sites include a second interspace camera port or a port placed one interspace below the mini-thoracotomy incision. We secure the cardioplegia site in the ascending aorta with a pledgeted suture and use antegrade del Nido cardioplegia. This can then be secured with a titanium fastener after weaning off bypass and de-airing of the heart. For antegrade cardioplegia, IntraClude can be used as well. The retrograde cardioplegia cannula can be placed directly into the right atrium (RA) and coronary sinus or by the anesthesiologist, but it may interfere with the application of the epicardial coronary sinus lesion as part of the ablation. The most common technique that we use currently is fibrillatory arrest via a single bipolar pacing wire placed on the surface of the right ventricle (RV) that is connected to a fibrillatory or a standard external pacemaker using the rapid pacing mode. During fibrillatory arrest, the perfusion pressure is kept slightly higher than normal, preferably around 70 mm Hg, and the systemic perfusion temperature is kept between 28° and 32°C.

After initiation of cardiopulmonary bypass, the oblique sinus is exposed to facilitate access to the posterior pericardium. The LA is then opened in Waterston’s groove, and the first lesion performed is the epicardial coronary sinus lesion that creates an iceball that can be seen inside the LA. While the iceball is still visible on the LA endocardium, we mark it with methylene blue to be certain exactly where the coronary sinus lesion has been created after the iceball has thawed and disappeared ( Fig. 28.1 ). We then place the endocardial “mitral line” from the lower end of the left atriotomy, across the site of the previous iceball (methylene blue mark), down to the MV isthmus ( Fig. 28.2 ). If no iceball forms on the endocardium of the LA during the application of the epicardial coronary sinus lesion, it should serve a warning sign, and reapplication of the coronary sinus cryolesion is warranted to achieve visual confirmation that the coronary sinus cryolesion is circumferential. It is crucial that the mitral line and coronary sinus lesions overlap in exactly the same plane because a residual gap between them can result in postoperative peri-mitral flutter (see Chapter 48 , Fig. 48.6 ). Experimental and clinical models have shown that neither the endocardial mitral line alone nor the epicardial coronary sinus cryolesion alone will ensure conduction block across the left atrial isthmus, a critical arm of the peri-mitral flutter wave. In patients with a right-dominant coronary circulation (90% of patients), these lesions are usually placed between at the level of the P2 or P3 leaflets of the MV. In patients with a left-dominant coronary circulation (10% of patients), these lesions are placed closer to the posteromedial commissure in the direction of the P3 leaflet. Visual verification of the location of the circumflex coronary artery is always preferred before ablation regardless of coronary artery dominance. Following these two lesions, one can place a suture near P3 and exteriorize it through the back wall of the LA to expose the LA for the MV operation. This suture is placed after the mitral line and coronary sinus lesions have been completed across the left atrial isthmus to avoid obstructing placement of these lesions.

(A) Diagram of a cryoprobe passed behind the heart with its tip pressing upward (toward the viewer) against the coronary sinus that collapses the coronary sinus and results in an iceball (white spot) forming on the inside (endocardium) of the left atrium during epicardial freezing of the coronary sinus. The site of the endocardial left atrial iceball is marked with methylene blue dye (blue mark) so that when the coronary sinus freezing is discontinued and the iceball disappears, the exact site where the coronary sinus lesion was created will be marked. (B) Operative photo of left atrial endocardial iceball being marked with methylene blue during freezing of the coronary sinus from the epicardium to serve as guidance for the proper placement of the left atrial mitral line.

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