The 10 Commandments of Robotic Bilateral Internal Thoracic Artery Harvesting
Introduction
Coronary artery bypass grafting (CABG) has been evolving since its beginning. One recent development is the use of the surgical robot to perform closed-chest bilateral internal thoracic artery (BITA) graft harvesting, which greatly diminishes invasiveness and provides the 2 best-quality arterial conduits—all without sternotomy. After BITA harvest, the graft-coronary anastomoses can be performed robotically or via a small thoracotomy, the latter of which is the routine option at our center. Although not widely adopted due to economic considerations and a stiff learning curve—including harvesting the right ITA (RITA) impeccably over its full length—multivessel robot-assisted minimally invasive CABG (RA-MICS CABG) is becoming an established approach for treating surgical coronary artery disease.1–3 Indeed, increasing numbers of patients benefit either from multivessel RA-MICS CABG alone (e.g., using BITAs onto the left coronary circulation) or as part of a hybrid procedure, which combines RA-MICS CABG using BITAs with percutaneous coronary intervention, usually to the right coronary artery.3
Numerous studies have documented the potential clinical benefits of multiarterial grafting and BITA grafting, including prolonged graft patency, lower adverse cardiovascular event rates, and improved survival.4–7 The use of multivessel RA-MICS CABG with the da Vinci Surgical System (Intuitive Surgical Inc., Sunnyvale, CA, USA) allows for precise, full-length BITA harvesting through a minimally invasive approach while eliminating the surgical trauma of sternotomy. This combination offers the best of both worlds: high-quality grafts—because the BITAs are the grafts with the best patency in the literature—while minimizing wound complications and promoting faster recovery, through the avoidance of sternotomy.8
Novel, less invasive techniques are the future of our specialty and evolve constantly. In our view, mastering minimally invasive cardiac surgery starts with a mandatory patient-centered approach, a great deal of humility, a willingness to learn from errors, great attention to detail, and a constant regard for safety above everything else.9 To those active minds and supportive programs who seek to improve their competence in multivessel RA-MICS CABG, we offer the following 10 commandments for harvesting BITAs, highlighting key technical tricks and tips to succeed in this procedure. As a prerequisite, we strongly believe that surgeons and their team members should routinely master sternotomy off-pump CABG and single-vessel nonsternotomy CABG before starting a multiarterial or RA-MICS CABG program. Also, an engaged and consistent team with clearly stated institutional support is a must to succeed in this focused area of expertise.10
1. Position the Patient, Plan Your Trocar’s Position Right, and Dock the Robot
Just like in real estate, location is everything. The first step described in this article is the longest and most critical, as it can prevent many problems if performed correctly. The surgeon must personally lead the positioning of the patient and trocars, with support from the anesthesiologist and nursing team. Only after the patient is properly positioned will the surgeon accurately visualize the 3-dimensional perspective of each patient’s thorax and determine the best locations for trocar placement. Optimal trocar positioning ensures that the entire lengths of the BITAs are reachable without instrument collisions or, even worse, the need for repositioning or adding trocars in the middle of the procedure.
Patient Positioning
After general anesthesia with endotracheal intubation, using a double lumen tube or a left bronchial blocker, and with appropriate monitoring (which includes transesophageal echocardiography), the patient is placed in a slightly tilted right lateral decubitus position (15° to 25° is preferred). The left arm is gently extended downward at the shoulder joint and rests slightly posterior on the table at the patient’s side, thereby allowing full exposure to the left anterolateral thorax. In other words, the patient’s left shoulder should lie slightly posterior to the median axillary line to optimize the range of motion of the robotic right arm. To enable this, a towel roll or gel pad should be placed under the patient’s back no more cephalad than the low scapula, allowing the left shoulder to slightly fall by gravity and therefore extend posteriorly. If the left shoulder is not in a desirable position, it may interact with the robot’s right arm and make BITAs challenging to harvest. Figure 1 shows the patient positioning.
What matters most is each patient’s particular anatomy. Looking at the positioned patient’s chest, the surgeon must 3-dimensionally imagine the trocars working inside the chest, reaching the entire lengths of the RITA and left ITA (LITA). It is helpful to mark on the skin where the LITA and RITA will be found, which is always ~1 cm (more precisely, 0.8 cm in small patients up to 1.1 cm in large patients) laterally to the lateral edge of the sternum. During this process, consideration is given to the camera being oriented 30° upward (except for the top of the RITA, where a 0° scope is preferred), while the 2 working ports and instruments are employed in a straight-shot fashion. It cannot be overemphasized how much can be learned and carefully planned from each patient’s chest, once the patient is positioned, to optimize the position of the trocars for BITA harvest. We find that such real-time, in-position immediate preoperative assessment is more valuable than just about anything else, including what a preoperative computed tomography (CT) scan might provide. That being said, if a CT scan could be performed in the operating room immediately after positioning, which our center does not currently have the capacity to perform, it certainly would be very useful!
Trocar Positioning
The trocar insertion process begins before the surgical field is prepped and draped for surgery. Once the patient is positioned, we draw on the patient’s thorax before skin preparation, following the principles described in the above paragraph. First, we draw a carefully centered sternotomy line, in case conversion were to be required. Next, we find the midpoint between the sternal angle (junction of the manubrium and sternal body) and the distal portion of the xiphoidal process. From this midpoint, we project an imaginary line toward the anterior axillary line in the left thorax. The intersection point between this projection and the anterior axillary line will usually determine the intercostal space (ICS) used for the 12 mm camera’s trocar. This is usually in the fifth ICS, but it can also be in the fourth ICS; this should be adjusted based on the angiogram according to how proximal versus midvessel the coronary targets for the distal anastomoses will be.
From the 12 mm trocar site of insertion—its laterality determined by using the above 3-dimensional imaginary reconstruction—we go about 4 fingers (6 cm) cephalad and about 4 fingers (6 cm) caudal, along the same line, which often is the anterior axillary line. These points will be the site of insertion of the 8 mm trocars for the right and left robotic arms. The 3 trocars are usually placed in a linear manner and only rarely placed in a slightly triangular configuration; again, this depends on the positioned patient’s chest 3-dimensional imaginary reconstruction. Supplemental Video 1 explains the steps used to make the trocar markings.
After skin preparation and placement of the surgical fields, we proceed with trocar insertion. Both lungs (rather than single lung) should be ventilated for at least 5 min prior to the first incision, with the systolic blood pressure kept at 120 mm Hg or higher, and then both lungs are deflated and disconnected immediately before the first incision. The reason for the latter is that single right-lung ventilation shifts the heart toward the left side and makes the heart more prone to traumatic injury during trocar insertion. We make a small incision at the marked camera site, followed by dissection of the ICS with a Kelly instrument, which we also use to gently enter and assess the left pleural cavity by feeling its tip moving freely, indicating avoidance of lung tissue or adhesions. We prefer the above method to the use of a Veress needle, which in our view can lead to blind entry and erroneous insufflation into lung tissue or adhesions. The first trocar is 12 mm in size and is placed once a free intrathoracic space is objectively felt; again, a secure and controlled insertion is imperative. We also monitor the electrocardiogram during this insertion, since the trocar’s tip touching the pericardium may trigger premature ventricular contractions (PVCs). If PVCs are seen during trocar placement, we check again whether the space is free with a Kelly, change the insertion angle to enter the cavity more anteriorly, and remove the introducer as soon as the trocar enters the chest cavity. Once the first trocar insertion is in, insufflation with CO2 is started, and ventilation is resumed on the right lung only. Blood pressure may drop because of insufflation, hence, the above systolic blood pressure threshold of 120 mm Hg or higher. Next, we insert the 30° upward camera through the 12 mm trocar and make a first inspection of the left pleural space. We look for adhesions and possible complications of the trocar insertion, and we scan the LITA bed. The trocars for the robot’s left and right arms are 8 mm in size and placed in the previously marked line, usually into the seventh and third ICS, respectively. That being said, we do not count ribs and rather position the trocars according to each patient’s chest anatomy, as described above. Each 8 mm trocar must be inserted under direct intrathoracic vision using the camera. Once they are securely inserted and with the chest still being insufflated, it is also advisable to leave each trocar tip a bit deeper into the pleural space, as they tend to come out during docking. Figure 2 shows the trocars being inserted into the left thorax.
Next, we dock the robot. The robot is placed on the patient’s right side, and the camera’s arm is connected to the 12 mm trocar. The robot’s right arm (number 1) is connected to the 8 mm trocar placed at or near the third ICS, and the left arm (number 2) is connected to the 8 mm trocar placed at or near the seventh ICS. The bipolar microtissue forceps are attached to the left robotic arm, and a cautery spatula is attached to the right arm, allowing graft harvest to begin. Vascular clip appliers and scissors can also be used throughout the BITA harvest. The surgeon leaves the bedside for the robotic console. Figure 3 shows the robot docked and ready for BITA harvesting.
2. Mobilize the Anterior Mediastinum and Start With the RITA
We do not open the pericardium until both ITAs are fully harvested; this helps prevent inadvertent injury to the heart. We always start by taking down the RITA first in the setting of BITA harvest. If we harvested the LITA first, we could damage it during RITA takedown as it would hang in the left pleural space and could be injured by the robotic instruments.
To reach the RITA bed, we first dissect the avascular plane between the posterior face of the sternum and the mediastinal adipose tissue. An anatomical plane is easily found between those. The key is to dissect this plane open as cephalad and as caudal as possible. Care must be taken to not injure the LITA or RITA cephalad, yet to “clear open” as much of the superior mediastinum as possible. Once we reach the right pleura, an effort is made to clean all the tissues to expose the RITA bed and visualize its full length. Obtaining good exposure is key to enabling full-length harvesting. The right pleural space is therefore usually opened over its entire length. Again, excellent and wide exposure is essential to facilitate full-length ITA harvesting, particularly the RITA, which, again, is more technically demanding than the LITA.
3. Work Under Insufflation With Both Lungs Ventilating to Give Yourself Time and Minimize Increases in pCO2
With insufflation, the lungs rarely compromise the surgical exposure, whereas adequate ventilation is essential to maintaining the patient’s physiological stability. We find that the RITA can be harvested mostly with both lungs ventilating with an insufflation pressure of 8 to 12 mm Hg. Single left-lung ventilation is necessary only for some portions of the RITA harvest, typically the high proximal segment. Sometimes, the heart gets in the way (which may mandate returning to single right-lung ventilation) and the instruments may be used to gently press it down, hence the importance of assessing the angle of approach for each individual patient prior to draping (see the first commandment) and keeping the pericardium closed at this stage. For the LITA harvest, both lungs can again be ventilated with small volumes throughout, and interaction with the heart is not a problem.
4. Find the Perfect Fascial Plane and Dissect It Away From the ITA, Keep the Fascia as Long as Feasible to Pull Down, and Never Touch the Artery but Rather Work and Grab Near the Artery
After exposure of the RITA bed, the dissection begins by opening the fascia and developing the plane between the medial internal thoracic vein and the artery itself. With the spatula cautery, this correct plane is identified. Ideally, it is easier if the surgeon preserves enough fascia to enable traction during harvest. After identifying the correct plane, the fascia can be dissected down throughout the RITA’s length. The thoracic transversus muscle will need to be sectioned in the distal portion of the RITA.
Skeletonization is performed by sweeping the robotic instruments away from the ITA rather than toward it. Remember that the fascia and loose fat or tissue on the adventitia, in this order, are your best friends for making traction during ITA dissection. Unintended arterial branch or venous wall tearing may occur while dissecting the ITA. If this happens, cautious observation is recommended. Light pressure may be applied, by gently bringing the dissected fascia and tissues on the bleeding area. In nearly all cases, bleeding resolves without any intervention being needed. Any further attempt to stop the bleeding, such as clipping or cauterizing in the setting of poor visualization, might lead to conduit injury or complications.
5. Deliberately Prepare and Low-Energy Cauterize Each Branch in the Same Manner
For cutting most branches, we use monopolar cautery, with the coagulation (using our hospital’s electrosurgical unit) set at 18W spray. Please note that specific hospital units and robotic instrument features may vary. Heat transmission through the artery wall can cause vasospasm or even damage. Therefore, the cauterization must be very precise and take place at least 4 to 5 mm away from the main ITA vessel to avoid hematomas, dissections, and bleeding. Regarding the latter, the systolic blood pressure while harvest is taking place should be no more than 110 to 115 mm Hg. For unusually large branches, we use vascular clips proximally and distally, followed by scissors to cut between the clips; however, we have found that we typically no longer use clips. When a clip is necessary, we swap the spatula monopolar cautery that is controlled by the robot’s right arm, followed by the scissors. Supplemental Video 2 exemplifies the fifth commandment.
6. Use These Tricks for Cephalad Portion of RITA
For the cephalad aspect of the RITA, one can place a mitral fan retractor through a 6 mm trocar inserted subxiphoid. The camera is best switched to a 0° angle camera. Notably, simply rotating the camera from 30° up to 30° down while working on the cephalad RITA can lead to inadvertent rubbing against the LITA bed and injure the LITA, which we have experienced. The mitral fan retractor can be used by the assistant at the bedside to push down on the mediastinal fat, at the level of the innominate vein, and expose the proximal RITA segment. Proximal medial mammary vein dissection and ligation are essential for adequate RITA harvest to its fullest extension. After ligating the vein, the RITA can be dissected for another 2 to 3 cm cephalad, as described in the previous commandments. Care must be taken to avoid harming the phrenic nerve.
With experience, we have found that the extra trocar and mitral fan retractor are no longer necessary. To this end, the surgeon simply uses the left forceps to push down on the superior mediastinum/innominate vein while the cautery blade in the right trocar works in “one-handed” fashion to bring down the top portion of the RITA.
Following RITA harvest, we leave it attached and turn our attention to the LITA. We retract the instruments back to the left pleural space. Usually, the LITA harvest is easier and faster to harvest than the RITA, as it is an easier seen structure, closer to the instruments, and with the heart or mediastinum never in the way (notably in its proximal portion). For LITA harvest, we obey the aforementioned commandments and technical aspects described in this article. Of note, for the LITA proximal portion—in contrast to the RITA—no special instruments are necessary; however, it may be necessary to pull out the 8 mm right trocar slightly to gain cephalad mobility. In fact, adjusting the trocars in and out, especially the right trocar, helps to successfully carry out full-length harvesting of both the RITA (upper trocar carefully brought in) and LITA (upper trocar pulled out to near-minimal insertion). Supplemental Video 3 shows LITA being dissected in the setting of BITA harvesting.
7. Always Be Mindful of Your Instruments Potentially Causing Damage
The robot is strong and powerful. And even though robots enable excellent visualization, tactile sensation remains absent. Always be mindful of your instruments potentially causing damage, particularly when and where they are not seen, such as during instrument changes or when using 30° down on the camera, which if performed during RITA harvest (as indicated above), may rub against and damage the LITA. Your surgical gestures, constant situational awareness, and interaction with your fellow team members make all the difference in robotic surgery. Being fully aware and in control of the robot’s instruments is essential, because what causes major complications in robotic surgery is usually trocars or instruments that end up in unsuspected places. Syntony, clear communication among the surgical team members, and special awareness of the mediastinum and pleural spaces are mandatory. We call the initial dissection of the mediastinum fat, discussed in the second commandment above, a “warm-up.” Take your time to enter the robot’s world and get used to the instruments, their range of motion, cautery energy, and the notion of position inside your individual patient’s chest cavity. And remember to always have the instruments in your camera’s image field; if not, stop, pull them out, and reset.
Once BITA harvest is completed but prior to ligating the ITAs, switch again to the 0° scope, being always mindful of where the ITAs are situated. Go back to single-lung ventilation (i.e., right lung only). Open the posterior pericardium over 2 cm behind the left phrenic nerve, which allows to not insert a pericardial drain and may help decrease postoperative atrial fibrillation. Then, always being mindful of where the ITAs are, cauterize open the pericardium anterior to where you think the left anterior descending artery (LAD) is, usually just lateral to the anterior pericardial fat, as there much less fat to deal with if one opens a bit lateral. Open the pericardium to the pulmonary artery cephalad and as low as possible to near the diaphragm caudally, always being mindful not to injure the ITAs that are hanging down.
8. Understand and Mitigate the Rotational Propensity of Robotically Skeletonized Arteries
After giving heparin, placing clips at the ITA bifurcation level, distally and proximally, and cutting in between (LITA first and then RITA), you will notice that both ITAs twist 180° to 360° clockwise (coronal CT scan plane). If you leave the ITA loose inside the mediastinum, it may twist even more. This is an important detail to remember with robotically harvested BITA, being cognizant of it at the time of anastomosis and considering gently unrolling each ITA counterclockwise. One way to avoid ITA twisting is to fix the tip of each ITA with a vascular clip on the pericardium fat right after cutting its distal portion. Following this step is not foolproof but helps enable less twist of the ITA prior to their recovery through the minithoracotomy.
9. Use These Adjuncts to Hemodynamically and Pharmacologically Dilate Both Arteries
Working with a robust and bigger artery makes the anastomoses easier. During BITA dissection, we use a systolic arterial pressure of 100 to 115 mm Hg, but after the artery is clipped, we ask to raise it well above 120 mm Hg to produce mechanical dilation. If possible, mechanical dilatation can also be enhanced by dissecting each ITA from proximal to distal (cephalad to caudal) rather than in the reverse order. Once the BITAs are recovered via the small thoracotomy, one can use papaverine topically or intragraft to produce a chemical vasodilation. Keep in mind that papaverine can produce systemic vasodilation. Also, if you introduce a catheter in the ITA lumen, ensure first that a probe can go freely, be gentle, and inject while pulling back, as injection may inadvertently cause a vascular dissection.
10. Graft Your Beautiful, Perfectly Robotically Harvested BITAs in Several Creative Ways and Do Not Hesitate to Convert to a Sternotomy If Necessary
Harvest your ITAs as long as possible. This will give you more assurance regarding the grafts reaching their coronary targets. Proximally, your landmark will be the subclavian vein on both sides and distally down to the bifurcation level. There is always a very high medial mediastinal branch to the ITA, which is quite cephalad and more easily seen on the left side than on the right. Overall, more length will give you more flexibility to choose the best coronary target sites, reach the posterior circumflex territory, perform in situ sequential grafts, avoid y-grafts, and provide more options regarding grafting configurations.
The bypass configuration might be achieved in several creative ways, including but not limited to LITA to the LAD at any site; RITA to the diagonal, ramus, or an obtuse marginal (1 or 2); RITA to the proximal or mid-LAD; and LITA to the diagonal, ramus, or almost any marginal including posterolateral. Sequential anastomoses with the LITA to the diagonal and LAD and/or “Y” or “T” configurations using the RITA as a composite graft from the LIMA can also be used. In sum, many graft configurations are possible, and one must individualize the best configuration to each patient’s needs. Of course, such flexibility with different configurations implies considerable prior experience with multivessel minimally invasive CABG via a small thoracotomy.1,9,10
Always remember that the top priority of any surgical procedure is safety, with efficacy being next, and invasiveness last. The minimally invasive nature of the RA-MICS CABG must never jeopardize the patient’s security and the procedure’s efficacy. If indicated, convert to sternotomy. Because complications should be avoided at all costs, sternotomy is not a failure or complication, unless delaying conversion has already led to a complication. Conversion should be indicated in scenarios such as injury of mediastinum structures, uncontrolled bleeding, the impossibility of achieving good surgical visualization or exposure or, even, mere failure to reasonably progress with the operation. MICS CABG is definitely a difficult operation. As such, in our view, a program that never converts probably exposes some patients to risky or unduly difficult situations or reflects an overly conservative or selective program that does not offer MICS CABG to a sufficient percentage of patients.
Conclusions
Robot-assisted BITA harvesting represents a paradigm shift in CABG surgery, combining the durability of arterial revascularization with the benefits of minimally invasive surgery. The 10 commandments outlined in this article serve as essential guidelines for surgeons seeking to master this technique and enhance patient outcomes. With meticulous attention to detail, teamwork, and execution, RA-MICS CABG procedures using BITAs can achieve reproducible, safe, and durable results.10 As cardiac surgery evolves, mastering robotic techniques will be essential for the next generation of coronary surgeons.
Declaration of Conflicting Interests
The authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr. Ruel discloses support for the Minimally Invasive versus STernotomy (MIST) randomized controlled trial and as a MICS CABG proctor (both from Medtronic, Inc.).
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The University of Ottawa Heart Institute Program is supported by a generous gift from the Crabtree Foundation. Dr. Ruel is supported by an Endowed Research Chair in Minimally Invasive Cardiac Surgery.
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