Background
In the past 25 years significant technological and conceptual advances have occurred in the field of robotic coronary artery bypass grafting (CABG), from the first experimental works in animals to the latest multivessel, off-pump, totally endoscopic procedures in humans .
The enthusiasm surrounding the first-in-man totally endoscopic coronary artery bypass (TECAB) procedure performed by Loulmet and colleagues was followed by a slow adoption rate on a larger scale. This has occurred for several underlying reasons, mainly related to the necessity of developing dedicated skills through a steep learning curve, the need for an experienced surgical team, the increasing scrutinization of outcomes in CABG, and the costs related to the robotic equipment. However, the benefits of minimizing surgical trauma together with the data published over the past two decades enhanced a growing interest in minimally invasive coronary surgery, leading several centers to foster the robotic approach and to publish their own, large case series .
Interestingly, the volume and pattern of procedures performed per year differ significantly between Europe and the United States , likely due to different reimbursement systems.
From a technical standpoint, the lack of tactile feedback was initially considered a serious limiting factor that can be a hinderance to surgeons sitting at the robotic console for the first time. However, the enhanced 3D visualization from the da Vinci system allows for excellent visual compensation, which for experienced users becomes a substitute for tactile sense through the observation of tissue displacement and deformation . The application of robotic technology to surgical myocardial revascularization also provides a full spectrum of enhanced skills, given that the robot allows increased operative dexterity and tremor-free movement with high-powered, magnified vision. Articulating instruments move with seven degrees of freedom and do not face the fulcrum effect, which is typical of long-shafted, endoscopic instruments. In addition, it has been proven that the graft patency of robotic-assisted CABG is equivalent to reported outcomes of the conventional approach , and that robotic-assisted CABG leads to excellent outcomes even in patients with a high Society of Thoracic Surgeons predicted risk of mortality .
In terms of patient selection, our criteria have evolved over time. Initially inclusion criteria should include nonredo patients with isolated single- or double-vessel disease and normal ventricular function. Having the ability to offer hybrid revascularization with staged percutaneous coronary intervention (PCI) is helpful in broadening the inclusion criteria. We currently have no absolute contraindications to perform robotic-assisted CABG procedures, even in patients requiring concomitant valve or atrial fibrillation surgery in some cases. Although we used to consider previous cardiac surgery as a contraindication in our initial experience, we have since expanded our indications to redo patients (i.e., patients with a history of either open or totally endoscopic procedures), provided at least one internal thoracic artery (ITA) is still available for grafting. In our current practice, relative contraindications to TECAB are severe left pleural scarring in patients with a history of lung surgery, or in patients with chronic lung disease. Patients with severely impaired lung function should be carefully evaluated and eventually excluded from receiving an off-pump approach; instead, there is still the option of using peripheral cardiopulmonary bypass (CPB) in order to improve gas exchange. Finally, emergent cases and cases with severe left ventricular dysfunction requiring the potential use of advanced myocardial support after surgery are currently excluded.
In terms of revascularization strategy a multidisciplinary heart team made up of robotic cardiac surgeons and interventional cardiologists should be evaluating each patient in order to plan for the best approach. Not uncommonly, the possibility of treating lesions of the right coronary artery (RCA) or distal circumflex artery branches with PCI often paves the way for proceeding with TECAB for the left anterior descending (LAD) and high marginal branches. Nevertheless, we have recently published a case series demonstrating the safety and feasibility of grafting the RCA using right-sided ports, provided the right internal mammary graft is of adequate length .
There are three strategies for robotic-assisted myocardial revascularization. The first one is minimally invasive direct coronary artery bypass (MIDCAB), consisting of robotic-assisted harvesting of the left internal thoracic artery (LITA), followed by a direct anastomosis performed through a minimally invasive thoracotomy. Techniques for MIDCAB are discussed elsewhere in this book. The second possible strategy is TECAB performed with the support of CPB, either on a beating-heart or on an arrested heart. And finally, TECAB performed without CPB, which in experienced hands achieves single or multivessel coronary grafting on a beating heart either with anastomotic connectors or using a hand-sewn technique.
Setup
Excellent communication among the team members is key to achieving perfect concentration and to prevent complications. This particularly applies in robotic procedures, where a decentralized dynamic exists (i.e., the surgeon is physically away from the operative field). We therefore recommend equipping the team members (console surgeon, tableside assistant, anesthesiologist, circulating nurse, perfusionist, and everyone else in the room) with Bluetooth headsets in order to effectively communicate throughout the case.
The patient is placed supine on the operating table, with an elevating roll (towel or silicon roll) placed in a cranial–caudal orientation under the left scapula. The left arm should be tucked loosely using a folded sheet and should be suspended slightly below the edge of the operating table to minimize conflict between the left shoulder and the right robotic arm. The left leg is prepared and draped as in standard CABG procedures, with liberal left groin exposure in order to enable femoral cannulation in case peripheral perfusion becomes necessary. Draping should also ensure that the sternum is easily accessible in case sternotomy becomes necessary.
Anesthetic management should include right radial and central venous catheters placed for intraoperative hemodynamic monitoring. Single-lung ventilation should be achieved using either a double-lumen endotracheal tube or a single-lumen tube with a left endobronchial balloon blocker, according to the anesthesia team preference. Transesophageal echocardiography should be maintained throughout the operation. External defibrillator pads should be placed across the cardiac axis, one on the left scapula and the other one on the right lateral chest.
Cardiopulmonary perfusion and myocardial protection
Robotic-assisted CABG can be performed in different ways, with or without stopping the heart and with or without the support of CPB ( Table 19.1 ).
| Nonbeating heart | Beating heart | |
|---|---|---|
| With CPB | AH-TECAB |
|
| Without CPB | n/a | BH-TECAB |
Peripheral CPB is used when an arrested heart approach is chosen or when hemodynamic or pulmonary support is needed during the course of off-pump TECAB. In our experience of over 800 beating-heart TECAB procedures, less than 2% required CPB and the majority of these were during our first 250 cases.
Cannulation techniques involve peripheral cannulation of the femoral or axillary arteries and of the femoral or jugular veins, according to the patient’s vascular status.
Aortic cross-clamping and cardioplegia delivery can be performed either with the IntraClude balloon occlusion catheter (Edwards Lifesciences, Irvine, California, United States) or with a long mechanical cross-clamp (e.g., Chitwood, Scanlon International, Minneapolis, Minnesota, United States) with antegrade cardioplegia (as described in the literature ). We recommend using the balloon occlusion catheter if an arrested heart approach is chosen, since cross-clamping the aorta from the left chest may be technically challenging because of the interposition of the pulmonary artery.
Perfusion through the femoral vessels is recommended. We expose the femoral artery and vein through a transverse left groin incision above the inguinal ligament. A 4-0 polypropylene purse-string suture is placed in each vessel, and tourniquets are applied. A perfusion cannula with a side arm (21-F or 23-F) is introduced into the femoral artery, and the femoral vein is usually cannulated with a 25-F venous cannula. The side arm of the arterial cannula is used to insert the IntraClude balloon occlusion catheter, which will be passed into the aortic root over a guide wire under careful transesophageal echo guidance. Care should be taken to place the balloon above the sino-tubular junction and well below the brachiocephalic trunk, with two arterial monitoring lines to detect accidental balloon migration. Antegrade, cold blood cardioplegia should be administered every 15 minutes or longer, based on the type of cardioplegia solution used.
Port placement
The camera port is first placed in the left fourth intercostal space, in the anterior axillary line. This is carefully performed after dropping both lungs, disconnecting the endotracheal tube from the ventilator and inserting a Veress needle to create a protective pneumothorax. Then, under endoscopic visualization, the right and left robotic instrument ports are placed in the second and sixth intercostal spaces, respectively, along the same anatomic line ( Fig. 19.1 ). After port placement the table is lowered and rotated 10 degrees toward the right, and the da Vinci Si system (Intuitive Surgical, Sunnyvale, California, United States) is docked with the robotic cart generally positioned at a about a 60-degree angle to the table from the right side ( Fig. 19.2 ). This angle decreases the likelihood of conflicts between the left arm and the stabilizer arms.
In order to properly distend the surgical field and maintain an adequate intrathoracic workspace, continuous warm humidified carbon dioxide (CO 2 ) insufflation is required to compress the lung after deflation. We utilize two CO 2 insufflation devices in order to avoid sudden loss of intrathoracic workspace leading to potential injury of the heart by the instruments. Attention has to be paid to maintaining the intrathoracic pressure within values that do not compromise hemodynamic stability—usually between 8 and 12 mmHg. When the right pleural space is opened for bilateral ITA harvesting, the CO 2 flow does not need to be modified.
Internal thoracic artery harvesting and preparation
After insertion of the endoscopic camera (30-degree up), the right arm is equipped with monopolar curved scissors, and the left is equipped with a Maryland bipolar forceps.
The pericardial fat pad is dissected free and reflected laterally ( Fig. 19.3A ). The pericardium is then opened in specific sites, according to the grafting strategy: for grafting the LAD the pericardiotomy should be performed anterior to the phrenic nerve, and for circumflex marginal coronary targets the pericardium is entered posterior to the phrenic nerve. We routinely make a small pericardial incision posterior to the phrenic nerve in order to help drain the pericardial space postoperatively ( Fig. 19.3B ). We feel that this helps to prevent postoperative pericarditis. The phrenic nerve should be identified throughout its whole course and care should be taken to avoid injuring it during pericardial manipulation.
After the epicardial surface is exposed, review of the angiography is helpful to identify the correct coronary target vessels. Once the targets are found and considered suitable for endoscopic grafting, attention is directed toward the ITA(s).
When viewed endoscopically and with an intact sternum, the two ITAs are much closer to each other (and to the heart) than is generally appreciated (given that the vast majority of surgeons encounter them only when the sternum is widely separated). Therefore either ITA can be used to graft the LAD and high marginal branches as an in situ conduit. Also, it is safe and feasible to perform bilateral harvesting even in patients considered at high risk for deep sternal wound infections, if they were to undergo a sternotomy approach (i.e., obesity, diabetes with elevated preoperative hemoglobin A1c, chronic obstructive pulmonary disease, advanced age, and peripheral arterial occlusive disease ).
If the right ITA (RITA) is to be used, it should be harvested first. Otherwise, attention should be directed toward the LITA, without opening the right pleura. The dissection technique is the same for both conduits.
A 0-degree robotic endoscope provides the best view during dissection of the substernal anterior mediastinal fibro-fatty tissue and during entering the right pleural space. After this is achieved, a 30-degree (focused-up) scope should be used to harvest the RITA. It is extremely important to avoid mechanical contact with the heart when the instruments are directed inside the right pleural space. Therefore every time the instruments need to be exchanged, they should first be brought back into the left pleural space under direct vision and then extracted.
For skeletonized RITA harvesting, both the endothoracic fascia and transverse thoracic muscle are divided to expose the vessel ( Fig. 19.4A ). A low electrocautery setting is used for the monopolar spatula and microbipolar forceps (20 W), which is used to cauterize small branches, while larger branches should be divided sharply with a Potts scissors between robotically applied metal clips. In order to optimize the harvesting of the most proximal and distal parts of the RITA, the Endo-Wrist stabilizer is needed to compress the anterior mediastinal fat and the heart, respectively. This instrument is of extreme value in TECAB surgery whether performed on a beating or arrested heart to stabilize the target (as will be described later) but is also important during the conduit harvesting phase as it allows routine bilateral internal thoracic artery harvesting regardless of the patient’s anatomy. It is inserted through a 12-mm subcostal fourth robotic port, placed between the xyphoid process and the midclavicular line. We have previously described this in some detail . Of note, docking the fourth robotic arm at this subcostal port requires a “setup joint” adjustment cephalad of both the left robotic and camera arms, in order to avoid external conflicts.
