Introduction
Cardiac surgery was one of the first surgical specialties that was envisioned to be ideal for robotic surgery. While the breadth of cardiac applications has been not as broad as originally hoped, in some areas it has become a highly successful field of our specialty. As cardiac surgery originally evolved from thoracic surgery, the initial approach to the heart was via large thoracotomies. This was associated with significant issues, including limited access to the required anatomical structures, postoperative pain, and impaired respiratory function. The median sternotomy became the mainstay of cardiac surgical access. This approach gave good access to most areas of the heart. However, exposure of the left atrium (LA) through a median sternotomy remains challenging in a subset of patients. Recovery after median sternotomy can be protracted and there is a risk of significant wound complications. Patients generally experience a 2- to 3-month rehabilitation period, with limitations in daily activities such as driving and lifting no more than a few kilograms. The serious complication of deep sternal wound infection (DSWI) occurs in approximately 1% of patients. The incidence is higher in specific patient subgroups (e.g., patients with diabetes, obesity, or chronic airway disease). Mortality of DSWI may be up to 25%. While infection is less of an issue in the thoracotomy approach, incidence of chronic postthoracotomy pain syndrome may be as high as 30% to 40%.
Cardiothoracic surgeons have attempted many different minimally invasive approaches for procedures on the heart. The aim of these approaches has been to reduce wound complications and hospital length of stay, to allow early return to normal physical activity, and to improve cosmesis, without compromising the surgeon’s ability to perform complex surgical procedures. The safety concerns of performing cardiac surgery via smaller incisions have limited many of these approaches. In some cases, while the incisions have been smaller, there has been no advantage in recovery or cosmesis.
Early iterations of robotic systems were trialed in cardiac surgery but were found to have limited utility. There were concerns over performing cardiac surgery remotely using a bedside console. Further challenges of robotic cardiac surgery included the lack of tactile feedback, initial capital costs of the robot system, and training of the entire operating room (OR) team. The da Vinci Robotic system was used by Carpentier to perform the first robotic mitral valve repair in 1998. Subsequently, the robotic mitral valve repair was championed by Chitwood in North Carolina and was taken up by a limited number of surgeons around the world. While there is a paucity of randomized data, many centers have reported excellent results. Yanagawa et al. performed a nonrandomized study comparing outcomes of open cardiac surgery with almost 6000 robotic cardiac surgery cases. They found a significant reduction in length of hospital stay, morbidity, and mortality compared with nonrobotic surgery.
Robotic surgical techniques have evolved over the last 20 years and have been applied to complex cardiac procedures with efficacy and safety outcomes matching or even surpassing the conventional techniques. Procedures involving the mitral and tricuspid valves, repair of atrial septal defects, removal of intracardiac tumors, and adjunctive procedures such as ablation for atrial fibrillation have been shown to be most suited for the robotic approach. Robotic-assisted coronary revascularization for single-vessel disease involving the Left anterior descending artery (LAD) using the left internal mammary artery (LIMA) has also been successfully applied. Multi-arterial totally endoscopic robotic-assisted revascularization or procedures on the aortic valve have also been reported but remain niche procedures currently. This chapter will focus on robotic mitral valve surgery and robotic-assisted single-vessel coronary artery bypass grafting, which are the two most established procedures within the cardiac surgical specialty.
Robotic mitral valve surgery
The mitral valve is ideally suited for the robotic approach as it occupies a relatively small field at the back of the heart. Viewed from the left atrium, the valve faces the right shoulder. The robotic approach through the right chest allows an excellent visualization of the valve, which, in many cases, is superior to that afforded by the sternotomy approach. The lack of distortion improves the ability of the surgeon to assess the valve, aiding in complex valve repair. The opportunity for all in the operating theater to see the valve repair enables valve repair techniques to be taught more easily. It is common and straightforward to perform additional procedures at the time of robotic mitral valve repair, such as atrial fibrillation surgery, atrial septal defect repair, or closure of a patent foramen ovale (PFO).
Indications
Most patients with mitral valve disease are suitable for a robotic approach. Contraindications are mostly relative, and these are outlined in Table 63.1 . The surgical team’s experience and the degree of these conditions will have an impact on whether to proceed robotically. For example, a patient with single-vessel coronary disease would be suitable for a percutaneous intervention to that vessel and a subsequent robotic mitral procedure, while a patient with multi-vessel disease would be best served by a combined open mitral valve repair and coronary artery bypass surgery.
| Relative Contraindication | Reason |
|---|---|
| Annular calcification | Difficult to excise calcium and reconstruct |
| Aorto-iliac disease | Need for peripheral cannulation |
| Concomitant coronary artery disease | Unable to perform coronary artery bypass grafting |
| Previous pleurodesis | Access to heart via right chest |
| Severe ventricular dysfunction | Prolonged operation |
| Aortic regurgitation |
|
| Ascending aortic dilation >35 mm | Risk of injury with cross clamp |
Anesthesia and monitoring
The patient is intubated with a double lumen endotracheal tube (ETT) to facilitate left single lung ventilation. A right radial arterial line is placed and five lead ECG monitoring is required with electrode placement appropriate for surgical access. Pulse oximetry is via a finger or ear probe. Transesophageal echocardiography (TOE) is required for cannulation, guiding mitral valve surgery and cardiac monitoring.
A superior vena cava (SVC) cannula for upper body venous drainage for cardiopulmonary bypass (CPB) is placed via the right internal jugular (IJ) vein after induction of anesthesia. Ultrasound guidance is used to assess the site and size of the IJ vein and to guide the venous puncture. A 17 Fr cannula is placed percutaneously via the right IJ vein using the Seldinger technique and positioned at the junction of the right atrium (RA) and the SVC. The wire position and the position of the cannula are confirmed with TOE. The cannula is filled with heparinized saline and clamped to prevent thrombus formation.
A Swan Ganz catheter is placed approximately 1 cm superiorly in the same vein. Near-infrared spectrometry (NIRS) monitoring is used to assess calf bed perfusion and cerebral perfusion. External defibrillator pads are placed over the left lateral and the right posterior chest, to enable external defibrillation and emergency cardiac pacing.
Patient positioning
The patient is positioned supine with a 10- to 15-degree roll to the left. This is best achieved via a large gel wedge under the right chest and a smaller pad under the lower back and buttock. A roll is place under the knees to relieve stretch on the back and knees. The right arm is placed on an arm board to achieve access to the lower axilla and lateral chest. Care should be taken to avoid stress on the right shoulder, and the head is placed in a neutral position to avoid brachial plexus injury. The left arm is tucked by the patient’s side. The robotic cart is positioned on the left of the patient.
The most efficient way to perform robotic mitral valve repair is with two operators working contemporaneously. This allows one surgeon to work on the chest and one to set up peripheral CPB via the femoral vessels. This then flows on to the robotic component where there will be a console surgeon and a bedside surgeon. This does underline the importance of a dedicated team to enable this approach.
Cannulation and cardiopulmonary bypass
In order to facilitate small surgical incisions, peripheral cannulation is the mainstay of CPB for robotic surgery. The usual access for this is the right femoral arterial, the right femoral vein, and the right IJ vein. As mentioned above, the right IJ venous cannula is inserted after induction prior to surgical draping.
The femoral access can be either open or percutaneous ( Fig. 63.1 ). The open technique utilizes a 2- to 3-cm incision just above the lower border of the right inguinal ligament. The position can be marked by palpation, or with the aid of ultrasound guidance. This is particularly helpful in obese patients. The ligament is exposed and reflected superiorly with the aid of a self-retaining retractor. This gives excellent access to the common femoral artery and the lower part of the external iliac artery. It is important to cannulate the common femoral artery above the profound femoris artery to minimize the risk of limb ischemia.
Purse strings are placed on the anterior surface of the artery and the vein using 5/0 proline sutures. These are approximately 8 mm × 4 mm in size. Appropriate size cannulae are selected based on the size of the patient and their vessels. Commonly, a 20 Fr arterial and a 24 Fr multi-stage venous cannulae are used. Systemic heparin is given and an activated clotting time (ACT) is taken.
The femoral vein is cannulated first. A long guide wire is placed into the right atrium and the position confirmed with TOE guidance. The bicaval view on the TOE is the most helpful, with additional imaging of the inferior vena cava (IVC) at the diaphragm sometimes needed. The cannula is carefully advanced into the right atrium approximately 2 cm from the RA-IVC junction. If an SVC cannula via the right IJ is not used, the IVC cannula can be advanced into the SVC to provide complete drainage, which is often possible in patients with small body surface area. The femoral arterial line is inserted next, with the guidewire visualized in the proximal descending aorta on the TOE. The arterial cannula is inserted to a depth of 5 to 10 cm. Consideration should be given to lower limb perfusion, in particular for very long cases. NIRS monitoring is very helpful to monitor the change in perfusion. Optimal lower limb perfusion can be achieved with arterial cannulation in the common femoral artery, which allows collateral circulation via the side branches to provide perfusion for the leg. On occasion, a downstream arterial cannula is required in patients with very small femoral arteries. The authors have also had good experience with the use of a proprietary bidirectional arterial cannula (Bi-Flow, LivaNova) in such settings. Careful imaging to ensure wire visualization and meticulous wire technique is paramount to avoid major and potential life-threatening vascular injury.
Once the ACT has reached 450 seconds, CPB is initiated and the patient cooled to 32°C. It is important to pay close attention to arterial line pressure at all times during the case. This should be less than 300 mm Hg. TOE is used to ensure adequate collapse of the right atrium and absence of aortic injury. A negative pressure of between 10 and 40 mm Hg is applied to the venous reservoir to create vacuum-assisted venous drainage. Kinetic venous drainage is used as an alternative in some centers.
Chest incisions and port positions
The first step of the thoracic component of the operation is to create the thoracotomy working port. There are then a number of stab incisions placed in reference to this primary incision ( Fig. 63.2 ). A 3- to 4-cm incision for the right thoracotomy is made in the fifth intercostal space posterior to the nipple line in men and in the breast crease in women. The working port can be used in a variety of ways. It allows sutures and devices to be passed to the surgeon. A number of steps can be performed via this incision by the bedside surgeon depending upon the team’s preference and the patient’s anatomy. It is the authors’ standard approach to use the working incision to open the pericardium, place the antegrade cardioplegia purse string and cannula in the ascending aorta, and to open and close the left atrium. Alternately, any or all of these steps can be performed with the robotic instruments by the console surgeon.
The choice of rib space to enter the thoracic cavity is determined by the position of the right lung hilum on the preoperative chest x-ray. This may range from the fourth to the sixth space. The fifth space is the most common. The chest is entered at the superior border of the lower rib. There is no need to widen the intrathoracic component of the wound. A plastic soft tissue retractor is placed. Any pleural adhesions are divided and the lung swept away. The bedside surgeon can place a couple of fingers through the port to help guide the other port placements. A diaphragm retraction suture may be necessary to improve the access to the lower pericardium and left atrium. This is a 2/0 braided suture with a polytetrafluoroethylene (PTFE) pledget. It is placed in the fibrous dome of the diaphragm as a U stitch. Care is taken not to go deeply in order to avoid the liver. The ends are brought out to the exterior with a hook placed through the ninth intercostal space along the anterior axillary line. Traction is placed under vision and the suture tied over a plastic bumper (see Fig. 63.2 g ).
The pericardium is opened approximately 2 cm anterior to the right phrenic nerve. This extends from the diaphragm to the pericardial reflection anterior to the aorta. It may be necessary to excise excess pericardial fat anteriorly and inferiorly. It is important to follow the course of the right phrenic nerve which lies more anteriorly in its superior portion. The shape of the pericardial incision is similar to a “J.” Two pericardial stay sutures are placed on the lower pericardial edge and taken through the chest wall in the fifth space using the same site as the left atrial vent (see Fig. 63.2 c ). To reduce the chance of atrial fibrillation, the pericardium can be opened after CPB is initiated.
As shown in Fig. 63.2 , the Chitwood aortic cross clamp (see Fig. 63.2 b ) is the most superior incision and is placed in the third intercostal space in the mid axillary line. The exact position of this will depend on the position of the patient’s aorta and transverse sinus. Left atrial vent is the most posterior incision. It is usually in the fourth of fifth intercostal space, posterior to the working port.
Four arms of the da Vinci system are required for mitral valve surgery. They are deployed as follows: Arm 1 (left instrument arm) is placed via the third intercostal space a couple of centimeters anterior to the anterior axillary line. This coincides with the lower end of the working port incision. This is generally fitted with a Debakey type grasper as the console surgeon’s left hand for the majority of the procedure. Arm 2 is the camera arm and is placed in the fourth or fifth intercostal space posterior to the nipple. The authors place the camera at the superior end of the working port, while others will use a separate port site. Arm 3 is deployed as the left atrial retractor arm and is positioned one to two intercostal spaces below the camera port and anteriorly toward the sternum. Care should be taken with this port position to avoid injuring the right internal thoracic artery and with sufficient space to avoid clashes with the camera. Arm 4 (right instrument arm) is placed two intercostal spaces below the camera at the level of the anterior axillary line. This usually is at the lower level of the working port. This is used as the surgeon’s right hand and is usually fitted with a suture-cut needle holder. This arm may also be fitted with a scissor or a cryoablation probe holder for robotic CryoMaze procedures.
Myocardial protection
Myocardial protection can be performed in a number of ways. The most common technique is aortic cross clamping with a Chitwood clamp and antegrade cardioplegia. A variety of other approaches have been successfully employed, including endoaortic balloon occlusion, fibrillation, and beating heart. Retrograde cardioplegia may be used via a direct right atrium approach or via steerable catheter from the right IJ vein.
The authors place an antegrade cardioplegia line in the lower ascending aorta as anterior as possible. The aortic wall here is more robust than the sinus of Valsalva. As the aortic cross clamp will sit in the traverse sinus the purse string should be placed just below the superior margin of this sinus. It is helpful to sit the cross clamp in the sinus to help guide the suture position. A 4/0 proline suture with two moderate-sized pledgets is generally advised. The majority of patients are managed with a single dose of antegrade intracellular cardioplegia. A number of cardioplegia solutions have been found satisfactory. It is incumbent upon the surgeon to be familiar with the specifics of the utilization of their chosen agent.
Mitral valve repair
The cross clamp is applied, and cardioplegia is delivered. The inter-atrial groove is developed, and the left atrium is opened by the bedside surgeon. It is helpful to open the oblique sinus, but it is usually not necessary to mobilize the IVC or SVC. The robot bedside cart is docked close to the left side of the operating table, centered on the thoracotomy/working port. The ports are connected and the instruments installed.
The left atrial retractor gives excellent exposure to the mitral valve. The camera used is 30-degree scope placed in the “up” position and the display usually set at 2× magnification. The mitral valve is inspected, and the valve repair planned ( Fig. 63.3 ). The full suite of mitral valve repair techniques can be employed robotically. The view of the mitral valve enface from the lateral approach is generally superior to that from the front. In addition, the lack of the distortion of the mitral valve makes assessing the length of cords easier and enables greater confidence in the saline test. Being able to drive the camera into the ventricle is a great advantage for placing artificial chords as is the facility for moving the left atrial retractor.
