A Guide to Robotic Assisted Single Vessel Coronary Artery Bypass Graft Surgery

 

In the era of advancing structural heart procedures and increasing percutaneous interventions, minimally invasive coronary artery bypass graft (CABG) surgery is a must-learn for current and aspiring surgeons. It can be approached with left internal mammary artery (LIMA) takedown through a left anterior minithoracotomy using special retractors or with robotic assistance. The procedure may be used for a single or multivessel CABG. 

This article will only concentrate on robotic assisted takedown of LIMA with distal LIMA to left anterior descending artery (LAD) anastomosis through a 4 to 5 centimeter left anterior minithoracotomy. The steps outlined are for the purpose of starting a robotic assisted coronary artery bypass (R-CAB) program, or for current surgeons looking for a different perspective.

Patient Selection

This procedure can be applied in complex lesions, ostial stenosis, chronic total occlusion (CTO) of LAD, or in cases with comorbidities precluding a sternotomy, such as radiation therapy for single vessel disease CABG. In cases of multiple vessel disease, R-CAB may be utilized in a staged or simultaneous hybrid approach whereby R-CAB is used for LIMA to LAD, and non-LAD vessels are revascularized through percutaneous coronary intervention. Ideal patients will have a BMI less than 35, FEV1 more than 80 percent predicted value, EF greater than 50 percent, and CTO of LAD.

Anesthesia

General anesthesia with a double lumen endotracheal tube (ETT) is recommended for this procedure. Although single lumen ETT with an ipsilateral bronchial blocker works in normal lungs, double lumen ETT has an added advantage of positive-end expiratory pressure (PEEP) on contralateral lung in marginal pulmonary mechanics. Double lumen ETT is either removed at end of case for extubation or changed to a single lumen tube over a tube changer at end of case.

Vascular Access

A central venous access alone is sufficient in most cases. In patients with lower ejection fraction or pulmonary hypertension, a Swan Ganz catheter is beneficial. In addition, a radial or brachial arterial line is needed.

Patients should also have a 4 Fr sheath inserted in each common femoral artery and vein under US ultrasound guidance. This serves as access for any emergent or urgent need for peripheral cardiopulmonary bypass. The majority of patients either do not need it or have planned peripheral femoral arterial (Edwards OptiSite 16Fr or 18Fr) and venous (Liva Nova 22Fr or 25Fr) cannulation with US guided access and placement under fluoroscopic guidance. In this scenario, the femoral artery is perclosed with Perclose devices.

Positioning

The left side of the patient is raised at a 30 degree angle with a bean bag. Then, the patient is positioned to the left of table so that the left arm is supported and able to drop next to the table. These techniques help to drop the left shoulder so that it does not interfere with robotic arms. Next, the robot is positioned on the right side of patient. The sterile trays and scrub are on left side of patient, and the cardiopulmonary bypass machine is on right side of patient, toward the foot. In case of planned need for cardiopulmonary bypass, the machine will stay near the right lower extremity, and the robot can be docked at chest level. In case of urgent/emergent need (which is not common), the robot can undocked, cannulation will be facilitated by previously placed 4 Fr sheaths, cardiopulmonary bypass instituted, and robot redocked as the case proceeds as planned.

Robotic Trocar Positioning and Arm Docking

The middle, or camera port, trocar is first one to be inserted. This is followed by a trocar in the left subclavicular area, just anterior to the anterior axillary line. Again, its positioning is critical to prevent robotic arm conflict with left shoulder, which eventually affects its reach in takedown of distal LIMA. It is preferred to use a long trocar to prevent extrusion during the procedure. Lastly, the left lower trocar is inserted in left seventh interspace, in midclavicular line. Both trocars are inserted with direct robotic camera viewing.

The robot is then docked with camera arm only. The camera inserted and focused at the operative site for targeting of other arms (this step only applies to Da Vinci Xi). The other two arms are then docked.

[IMAGE: Port position]

[IMAGE: Robot docked]

LIMA Takedown

As a first step, it is good practice to check the robot arms’ range of motion and review any conflicts. It is recommended to use a Bovie spatula in the right hand and Micro Diamond fine forceps in the left hand. Clips and scissors are used as needed. Later, the surgeons will switch to DeBakey forceps for taking down pericardial fat and opening up the pericardium. LIMA takedown is performed with robotic scope in 30 degrees up.

The whole length of visible LIMA and areas that are intramuscular are then looked at, and the takedown follows the same steps as for an open case. The whole length is not skeletonized, except the distal end, to facilitate flow measurements at the end. The rest of LIMA has a vein on each side, but fascia is completely off.

The whole length is visualized, and fascia taken down. Next, the spatula is used to perform sharp dissection, along with blunt dissection on inferior aspect of inferior vein. The superior vein is pulled down and dissection carried superior to it, exposing arterial and venous branches. Generally, a few branches are exposed, their LIMA end clipped, and anterior chest wall end of vessels electrocauterized. This process begins in the middle and moves proximally, beyond first cartilage, and just above the phrenic nerve, so that LIMA can drop down well with no proximal kink. It also ensures adequate length each time. Once proximal LIMA is dissected circumferentially, the mid- to distal end is approached. Once in the right plane, a lot may be dissected bluntly. The last 4 to 5 cm is completely skeletonized to facilitate clipping the distal end for flow measurements, until the vessel bifurcates or dives medially. Three clips are placed distally, one proximal, and then the distal LIMA is divided with scissors. The divided end is then clipped to anterior chest wall.

[IMAGE: Dissecting fascia]

[IMAGE: Dissecting inferiorly below mammary vein from end to end]

[IMAGE: Dissecting superiorly above mammary artery, end to end]

Dissection of Subxiphoid Space

Next, the subxiphoid dissection with electrocautery is performed to facilitate the insertion of Medtronic Nuovo stabilizer rod.

Pericardial Fat and Pericardial Dissection

The Micro Diamond forceps are then switched to DeBakey forceps in the left hand, and pericardial resection is performed from medial to lateral to just above the phrenic nerve. Camera orientation is changed to 30 degrees down at this time, and a small lateral rent is made in the pericardium above the phrenic nerve. This facilitates insertion of a drop sucker during distal anastomosis and later for egress of blood or pericardial fluid into left pleural space postoperatively. Next, the anterior pericardium is opened from distal medial reflection to ascending aorta. On inferior aspect, the incision is not extended over the apex of heart, lest there be potential cardiac herniation. The ability to open the pericardium robotically is a critical advantage, since it gives the surgeon a bird’s-eye view of the anterior epicardial surface of the heart. Thus, one could ascertain, the course of LAD—whether it is on the surface, intramyocardial, only visible distally, or has large diagonal branches¬—is to plan a minithoracotomy incision, identify LAD correctly, perform distal anastomosis accordingly, and avoid any potential complications. Since the heart is being pushed medially, and because of CO2 insufflation, the exact location of structures may not be possible.

Insertion of Stabilizer Rod

Next, all instruments are removed and the camera is pointed toward the subxiphoid space. In thin patients, one can clearly see the site for external incision in the subxiphoid area externally, by illumination from the camera. The incision is generally a centimeter or two from the subxiphoid area and, initially, a Kelley forceps is inserted under robotic vision. This is followed by insertion of a stabilizer rod.

CO2 insufflation is then stopped, all ports are removed, and the right port site is closed in layers.

Minithoracotomy

A 4-5 cm minithoracotomy is made in left fourth intercostal space, generally by extension of camera port. However, if the patient is obese or has larger breast tissue, the camera port incision is closed and a separate 4-5 cm is made medially. The pericardial space exposed. A soft tissue retractor is inserted, followed by insertion of minimally invasive rib spreader. In the case of thinner patients and a shallow chest, one may not even need a rib spreader and exposure is good enough with a tissue spreader alone.

Preparation of LIMA

Next, LIMA is pulled into the incision. Orientation of LIMA is confirmed by looking at the entire length of the vessel. A 6-0 Prolene suture is inserted on each vein to keep the orientation of LIMA. Next, the distal end is prepared. LIMA is confirmed for good blood flow, and a proximal bulldog clamp is applied.

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