Minimally Invasive Bi-Atrial CryoMaze Operation for Atrial Fibrillation

(A) The patient is positioned supine with a slight 30° left lateral decubitus position. The right arm is wrapped in a flexed position, beside the patient, to expose as much of the axilla as possible. Double-lumen endotracheal intubation is employed and transesophageal echocardiography (TEE) is used in each patient in addition to other standard monitoring devices. A 3- to 4-cm minithoracotomy incision is created in the right inframammary crease and the pleural space is entered through the fourth intercostal space (ICS). (B) A soft-tissue retractor (Edwards, Irvine, CA) is placed with minimum rib spreading to expose the mediastinum. The pericardium is opened 3 cm anterior to the phrenic nerve and pericardial and diaphragmatic retention sutures, 2-0 Ticron (US Surgical Corp, Norwalk, CT), are exteriorized as far posteriorly as possible to maximize intrathoracic working space. A 5-mm videoscope (Storz, Tuttlingen, Germany) is placed directly through the chest incision or through a 5-mm stab wound posterior to the incision in the fourth ICS to facilitate deep intracardiac visualization. PC = peripheral cannulation; MT = minithoracotomy.

Peripheral cannulation is achieved by exposing the femoral vessels through a 2-cm horizontal groin incision. Only the anterior surfaces of each vessel are exposed and 4-0 Prolene purse-string sutures (Johnson and Johnson Health Care Systems, Piscataway, NJ) are placed for cannulation. The patient is systemically heparinized. Using a Seldinger guide-wire technique with TEE guidance, we routinely perform right femoral arterial (17-19 Fr) and venous cannulation (21 Fr) using Bio-Medicus thin-wall cannulas (Medtronic-BioMedicus, Eden Prairie, MN). The venous cannula is guided to rest at the mid-right atrium level. In addition, a right internal jugular venous drainage line (15-17 Fr) is placed by the anesthesiologist in the distal superior vena cava well above the superior cavoatrial junction, before central line placement. Kinetic-assisted venous drainage is used in every case. Cardiopulmonary bypass (CPB) is initiated and the patient is cooled to 28°C.

Tapes are place around the superior and inferior vena cava in preparation for the right-sided lesions. a. = artery.

A long antegrade cardioplegia/aortic root vent needle (Medtronic) is placed in the ascending aorta. (A) A small stab wound is made as far superior and posterior as possible in the axilla to allow the Chitwood transthoracic aortic cross-clamp (Scanlan International, Minneapolis, MN) to be passed through the second ICS. (B) It is then applied through the transverse sinus with the concave aspect of the blades (C) facing cranially. Great care is taken to avoid injury to the pulmonary artery, left atrial appendage, and left main coronary artery. After the aorta has been cross-clamped, cold, intermittent, antegrade blood cardioplegia is used for myocardial protection. a. = artery; SVC = superior vena cava.

The surgical field is flooded with CO₂ via a 14-Fr angiocatheter, introduced through the right chest wall. The interatrial groove is developed with electrocautery and the left atrium is opened. The oblique sinus is developed with sharp or blunt dissection, and the left atriotomy incision is extended caudad posterior to the inferior vena cava, and anterior to the right inferior pulmonary vein. A weighted-tip DLP sump catheter (Medtronic) is placed via a separate stab incision on the chest wall near the aortic cross-clamp, through the atriotomy to rest in the left superior pulmonary vein. This allows the pulmonary vestibule to be free of pooled blood. Exposure of the left atrium can be facilitated with a handheld basket-type retractor or with a fixed blade retractor system (Estech, Danville, CA). A 5-mm videoscope (Storz) can be passed through the incision for assisted vision or through a separate port incision as shown in Figure 1A. In general, this minimally invasive approach provides superior visualization of all deeper cardiac structures, with minimal surgical exposure. SVC = superior vena cava.

All lesions are created by applying the CryoMaze Probe (ATS Medical) for 2 minutes directly to myocardial tissue with temperatures reaching −140°C to −160°C. Following lesion creation, the probe is thawed from the surrounding tissue by administering cold saline for the left-sided lesions and room temperature saline for the right-sided lesions. The left-sided lesions are created under cardiac standstill and the right-sided lesions are created on the beating heart, while rewarming.

The left-sided endocardial lesions are performed first. The pulmonary vestibule is isolated as a single island with a wide box lesion around it. The first cryo-lesion is performed on the inferior aspect of the pulmonary vestibule along the atrial ridge that separates the pulmonary vestibule from the mitral valve. PV = pulmonary vein.

The next cryo-lesion extends around the lateral aspect of the left pulmonary veins, between the orifice of the LAA and the left superior pulmonary vein. Great care is taken to avoid skip lesions by ensuring complete contact between the probe and atrial tissue along the entire lesion and crossing well over the last lesion to form a connection. PV = pulmonary vein.

The box lesion is completed by a cryo-lesion across the superior aspect of the pulmonary veins that connects with the left atriotomy incision, which is the only non-cryo-lesion of the pulmonary vein isolation. In general, the box lesion can be constructed with 2 or 3 cryo-lesions; however, if the left atrium is particularly large and redundant, more lesions may be required.

We create an additional lesion from the pulmonary vein isolation box to the LAA if this area was not completely ablated during the creation of the pulmonary vein isolation box. PV = pulmonary vein.

An endocardial lesion is then created to join the box lesion around the pulmonary veins to the mitral valve annulus at the level of P3. By extending this lesion medially toward P3, the lesion can be created while avoiding circumflex coronary artery injury. Most of our recurrent AF after the CryoMaze operation, as identified in the electrophysiology laboratory, has originated from this lesion line incompletely crossing the annulus. As a result, we routinely place the Cryo probe across the entire mitral annulus on to the posterior leaflet. We have not experienced any injury to the leaflet with appropriate thawing of the leaflet tissue. PV = pulmonary vein.

The final left atrial lesion is an epicardial lesion across the coronary sinus, via the oblique sinus. As demonstrated in the drawing, this lesion ensures complete transmurality at the mitral valve annulus. The videoscope can be helpful to allow accurate placement of the CryoMaze probe across the coronary sinus. We place a suction catheter posterior and lateral to the CryoMaze probe to prevent the probe from freezing the oblique sinus closed, making it difficult to extricate the probe, and to protect the left phrenic nerve, which may lie just adjacent to probe. It is crucial that this lesion incorporates the coronary sinus and that it is parallel and right on top of the endocardial lesion toward P3. Alternatively this lesion can be created first and a mark in the left atrial endocardium with methylene blue could be made to delineate the location for the endocardial lesion extending toward P3 to have both lesions on top of each other.

The LAA is routinely closed as part of the CryoMaze operation, unless there are significant pericardial adhesions keeping the appendage patent, for example, during reoperative cardiac surgery. The LAA is closed in a 2-layer fashion using a 3-0 Gore-Tex (W.L. Gore & Associates, Flagstaff, AZ) suture. The suture bites should be within the thicker tubular portion, away from the trabeculated portion, of the LAA to allow complete appendage obliteration without tearing.

The left atrium is then de-aired and closed with a running 3-0 Prolene suture. The transthoracic aortic cross-clamp can now be removed; rewarming can begin and the right-sided lesions can be performed with the heart beating.

The intercaval lesion is created between the superior vena cava and the inferior vena cava, avoiding both the sinoatrial node as well as the left atriotomy incision. Alternatively, the intercaval lesion could be created at the beginning of the procedure, before cardiac arrest and opening of the left atrium, and thus obviating the potential for freezing over your left atriotomy suture line. This lesion can usually be created with 1 freeze but may require 2 freezes. Care is taken at this point to avoid contact between the CryoMaze probe and the phrenic nerve. A small surgical sponge could be placed at the peri-cardio-caval reflections to protect the phrenic nerve.

We recommend performing a small vertical atriotomy as an inverted T connecting to the intercaval lesion after securing the caval tapes. Two endocardial lesions are created, 1 toward the tricuspid annulus at the 2 o'clock position and another between the right atrial appendage and the tricuspid annulus at the 10 o'clock position.

Alternatively, a puncture site is made in the midbody of the right atrium and an endocardial lesion is created along the endocardial surface of the right atrium out to the tricuspid valve annulus anteriorly. This lesion is performed on full cardiopulmonary bypass with the atrium emptied, ensuring contact between the endocardium and the CryoMaze probe. The right atrium is then filled to thaw the probe and separate it from the tissue. Caval tapes are usually not required.

The atriotomy incision shown in Figure 12 is replaced by an epicardial cryolesion, shown in Figure 13 as the second lesion connecting between the tricuspid lesion and the intercaval lesion, with the tip of the catheter aiming toward the oblique sinus. After completion of this lesion, a 4-0 Prolene purse-string is placed to close the small right atrial stab wound.

Temporary ventricular and atrial pacing wires are placed, and then the patient is weaned from CPB. After de-airing is confirmed by TEE, the vented cardioplegia cannula is removed and the purse-string is secured. Once hemostasis of the suture lines has been achieved, the protamine is administered, and the femoral artery and vein are decannulated.