Robotic Coronary Artery Bypass Grafting
◆ The goal of any minimally
invasive procedure is to achieve the least surgical trauma possible and to
carry out the intervention in a port-only approach. After unsuccessful attempts
to perform endoscopic coronary bypass surgery using long-shafted thoracoscopic
instrumentation, the first totally endoscopic coronary bypass grafting (TECAB)
was carried out in 1998 using a surgical robot. Since then, TECAB has been
further developed from single-vessel to multivessel surgical
revascularization1,2 and is performed in beating heart and stopped heart
versions. TECAB can be combined with percutaneous coronary intervention in
so-called integrated or hybrid procedures. A second, third, and fourth
generation of surgical robots is available, and procedure-specific robotic
instrumentation has improved vision, exposure of target vessels, and overall
ergonomic features of the procedure.
1. Patient
Selection, Indications, and Contraindications
◆At the current stage, any patient
with a clear indication for surgical coronary revascularization can be
considered for TECAB. It is, however, highly important to respect the
contraindications listed in Box 7.1. In general, TECAB is elective surgery, and
redo procedures are difficult using open techniques and are long and tedious in
the endoscopic setting. Any factor that leads to distortion or reduction of the
pleural cavities, such as thoracic deformities, a severely enlarged heart, or
reduced lung volume, needs to be respected. Wise judgment needs to be applied
as to whether to expose patients to a potentially longer pump time, myocardial
ischemic time, and overall procedure time. This is especially true for patients
with multiple comorbidities. Because TECAB involves a significant technical
learning curve, we strongly recommend to start with simpler versions of the operation
in low-risk patients.
◆ All patients should receive the
same workup as for open coronary artery bypass grafting (CABG). The usual
battery of preoperative examinations consists of the clinical history and
physical examination, basic blood tests (complete blood count [CBC], basic
metabolic panel [BMP], international normalized ratio [INR], type, and screen),
carotid Doppler studies, ankle-brachial index (ABI), pulmonary function
studies, and echocardiography. To address TECAB-specific questions, computed
tomography (CT) angiography of the chest, abdomen, and pelvis is carried out.
The parameters that should be assessed for this procedure by the surgeon,
surgical team, and radiologist on this CT are listed in Box
7.2.
◆ Basic cardiac anesthesia
principles are applied but experienced anesthesiologists with specific skills
should lead the case. Box 7.3 lists specific
anesthesia aspects. Transesophageal echocardiography (TEE) is necessary for
monitoring heart function and regional wall motion, as well as for adequate
positioning of the endoballoon in arrested heart TECAB. Good communica- tion
with the anesthesia team is key, especially in regard to when to start single-lung
ventilation, level of CO2 inflation pressure, occurrence of leg ischemia if
femoral arterial heart-lung machine perfusion is chosen, migration of the
endoballoon in arrested heart TECAB, heart rate control and assessment of
regional wall motion in beating heart TECAB, and respiratory management after a
longer heart-lung machine run under single-lung ventilation.
· Currently, only one surgical robot is available
on the market that allows performance of TECAB (Intuitive Surgical, Sunnyvale,
CA). Surgeons who perform TECAB mostly use the third generation (Si version) of
the da Vinci system. Fig. 7.1 shows the surgeon sitting behind the robotic
console. Using so-called masters, the surgeon performs maneuvers with his or
her hands, which are translated into intrathoracic movements of a robotic
three-dimensional (3D) camera and the robotic instruments. Foot pedals are part
of the machine for switching between camera and instrument control, as well as
for electrocautery. The surgeon looks into a 3D binocular. At the time of this
writing, not all instruments used for TECAB are available for the fourth
generation (Xi version).
· TECAB can be performed with and without use of
the heart-lung machine. The former version is usually called AH (arrested
heart) TECAB; the latter is commonly referred to as BH (beating heart) TECAB.
We strongly recommend developing both methods because it gives a robotic
surgery team the best level of flexibility and allows for best tailoring of the
operation to the patient’s needs.
·
BH-TECAB can avoid side effects of the
heart-lung machine but target vessel exposure and anastomotic suturing are
technically more demanding than in AH-TECAB. Surgeons should master anastomotic
techniques in the arrested heart version before moving to the beating heart
technique. We also recommend cannulating the patient prophylactically for a
potential heart-lung machine run in BH-TECAB, which may be necessary if there
is limited intrathoracic space and if the patient develops myocardial ischemia,
hemodynamic instability, or ventricular arrhythmia. Installing the heart-lung
machine acutely in these situations is difficult with the robot docked, may
take too much time if there is significant hemodynamic compromise, and may be
associated with additional vascular complications. In our experience, having
the immediate safety net of a heart-lung machine available has proven to be
very valuable.
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The surgeon operates the
robotic instruments from a console. A third and fourth generation of operation
robots are currently available.
◆ In AH-TECAB, anastomotic suturing
is easier, but AH-TECAB requires specific skill sets in remote access perfusion
and the use of endoballoon or transthoracic clamping. These skills should be
developed in procedures other than TECAB (e.g., atrial septal defect [ASD] II
repair or minithoracotomy mitral valve repair) before application in totally
endoscopic CABG. In our hands, placement of bypass grafts to the right coronary
artery (RCA) and circumflex coronary artery territories only works reasonably
using the arrested heart technique because the heart is completely flaccid and
can be adequately rotated.
◆ The patient is placed on the
operating table in the supine position. The arms are tucked to the body, and
the left chest is slightly elevated using a towel roll. Because the team needs
to be prepared for conversion to an open procedure, the patient is prepped and
draped as for open CABG, and the equipment for conducting open CABG should always
be available.
◆ The ports are usually placed on
the patient’s left chest and should be inserted by the most experienced team
member, because correct port placement plays a key role in the operation.
Insertion requires complete left lung collapse and must be confirmed by the
anesthesia team before placement. The camera port is placed in the fifth
intercostal space on the anterior axillary line, and CO2 is
insufflated at a pressure of 8 mm Hg. Should hemodynamic compromise (e.g.,
hypotension) occur during this phase, the CO2 pressure should be
lowered. The thoracic cavity is then inspected and, under scope vision, the
left and right instrument ports are inserted cranially and caudally four
fingerbreadths away from the camera port, midway between the anterior axillary
line and midclavicular line. The surgical robot is then docked and a robotic
cautery spatula (right arm) and DeBakey forceps (left arm) are inserted. Fig.
7.2 depicts the port arrangement and instruments inserted, and Fig. 7.3 shows
the robotic arms docked to the patient.
◆ Using the camera-up view with the
30-degree angled robotic camera, the internal mammary artery (IMA) is
identified by its visible pulsations. The electrocautery is set at 15 to 20 W,
and the endothoracic fascia and muscle covering the IMA are removed (Fig. 7.3).
The IMA is then harvested in a skeletonized fashion using mechanical takedown
and cauterization of the side branches close to the chest wall (Fig. 7.4).
Clipping is necessary only for large branches and in case of side branch
bleeding. If both IMAs are harvested, the right pleura is entered via generous
robotic endoscopic retrosternal dissection and opening of the right pleura. In
double-IMA harvesting, the right IMA should be taken down before the left IMA.
After heparinization, the IMA can be clipped distally, divided using robotic
Pott’s scissors, and dropped into the left chest for autodilation.
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Figure 7.2 Port arrangement in TECAB.
Figure
7.3 The robotic arms are docked to the
patient’s left chest, with the camera port inserted into the fifth intercostal
space on the anterior axillary line and the right instrument port
inserted into the third intercostal space midway between anterior axillary line
and midclavicular line. The left instrument port is placed in the
seventh intercostal space midway between anterior axillary line and
midclavicular line.
Figure
7.4 The internal mammary artery is
harvested in a skeletonized technique using a robotic electrocautery spatula at
a power of 15 to 20 Watts and a robotic deBakey forceps.
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◆ After IMA harvesting under scope
visualization, a 5-mm assistance port is placed in the left parasternal region,
opposite to the camera port. Since introduction of this step, significant time
gains in TECAB have been noted. This port allows the insertion and removal of
material needed throughout the procedure (e.g., bulldogs, suture material,
Silastic tapes, suction tubing).
◆ To gain access to the pericardial
fat pad and the pericardium, the scope view is switched to the camera-down
mode. Using an electrocautery spatula on the right and a long tip forceps on
the left, the fat pad is resected, starting with its cranial sternal portion
and then moving caudally. If the fat pad is large, starting the heart-lung
machine can significantly improve intrathoracic space and facilitate removal.
The pericardium is opened above the right ventricular outflow tract, incised
(heading toward the substernal part of the pericardial reflection), and then
taken out laterally. Cranially, the pericardium is opened, moving toward the
phrenic nerve, which needs to be clearly identified. The phrenic nerve and left
atrial appendage, which is close, need to be respected.
·
If the preoperative CT angiogram shows no or
only mild grades of aortoiliac atherosclerosis, we feel comfortable using
femorofemoral cannulation for the cardiopulmonary bypass. Usually, the left
groin is exposed. We keep dissection of the femoral artery and vein limited to
prevent lymphatic leaks. A distal leg perfusion line is inserted in all cases,
and leg perfusion is monitored by near-infrared spectroscopy (NIRS) throughout
the whole procedure. A 25 F venous drainage cannula is then advanced into the
superior vena cava under TEE guidance and connected to the heart-lung machine
tubing. A 21 F or 23 F arterial perfusion cannula with a side arm is inserted
into the femoral artery and connected to the arterial line of the
cardiopulmonary bypass circuit.
·
For safe use of the ascending aortic endoballoon
for cardioplegia, we specifically look into a lack of ascending, arch, and
descending thoracic aortic atherosclerosis. The maximum ascending aortic
diameter we accept is 38 mm. The aortic valve should be competent and free of
thickening or stenosis. The balloon is completely de-aired and inserted through
the side arm of the arterial perfusion cannula. The guidewire is advanced into
the aortic root under TEE guidance, and the endoballoon is then placed above
the aortic valve. The catheter is connected to the heart-lung machine tubing,
and the pressure lines for measurement of aortic root pressure and balloon
pressure are de-aired and connected to corresponding manometers. Aspiration or
injection of air through the catheter into the aortic root has to be avoided by
all means.
· The heart-lung machine is started slowly in all
procedures. With adequate venous drainage, low blood pressure, and lack of
ventricular ejections, the endoballoon is inflated, and its correct position in
the aortic root is confirmed by TEE. After endoballoon inflation, cardioplegia
is induced. For initial rapid induction, adenosine (6 mg diluted in 20 mL of
saline solution) may be injected. We start cooling only after a stable balloon
position has been achieved. Cardioplegia is repeated every 20 minutes. If a
percutaneous retrograde cardioplegia catheter has been inserted, both antegrade
and retrograde cardioplegia can be given following customary protocols.
· In cases of moderate to severe aortoiliac
atherosclerosis, we strictly avoid femoral arterial retroperfusion. Instead,
the left axillary artery is exposed in the left infraclavicular region and an
8-mm prosthetic side arm is anastomosed to the artery and connected to the
arterial line of the cardiopulmonary bypass circuit. Axillary cannulation
ensures antegrade perfusion from the descending thoracic aortic level
downstream and may reduce the risk of retrograde aortoiliac dissection. The
endoballoon catheter can in most cases still be inserted through a separate 19
F cannula placed into the common femoral artery.
·
If severe-grade aortoiliac atherosclerosis is
present, or if protruding and mobile atheroma is seen on TEE, the endoballoon
is contraindicated. In these cases, we use a BH-TECAB approach. BH-TECAB
patients are still cannulated, and the cannulae are placed at an activated
clotting time (ACT) level of 300 seconds. Should a pump run become necessary,
we raise the ACT to 480 seconds. Supportive cardiopulmonary bypass is extremely
helpful—for example, in BH multivessel TECAB, in cases of ischemia during
target vessel occlusion, if space inside the chest is limited, or if bleeding
problems are encountered. During supportive pump runs, significant diffuse
bleeding from portholes, the IMA bed, and other structures may be observed and
may require intermittent evacuation of pleural blood using transthoracic
suction.
◆ The
robotic endostabilizer can be used as an exposure device in BH-TECAB and
AH-TECAB. For positioning of this device, a 12-mm port is placed subcostally
into the left chest using a port incision two fingerbreadths lateral to the
xiphoid angle. Insertion of the port can be guided by the robotic camera using
the up view. The subcostal port is docked to the fourth arm of the da Vinci
system.
◆ For
all work on the coronary target vessels, the scope view is camera down. With
the subcostally placed endostabilizer, the left anterior descending artery
(LAD) and circumflex coronary artery systems can be well reached. The
endostabilizer is activated using a dedicated foot pedal, and the suction pods
are placed alongside the target area of the target vessel. In this way, local
immobilization can be achieved in BH-TECAB, and the target vessel can be moved
into a comfortable position in both BH-TECAB and AH-TECAB.
◆ The
right coronary artery system can be accessed by inserting the endostabilizer
through a 12-mm left-sided instrument port. With this port arrangement, the
subcostal port can be used as the left robotic instrument arm. The acute margin
of the right ventricle is lifted up using the endostabilizer, and excellent
access to the posterior descending artery and posterolateral artery can be
gained. To date, we have applied this method only in AH-TECAB.
◆ After
appropriate exposure of the target vessel, the epicardium is incised with
robotic Pott’s scissors.
·
Before starting the anastomosis, final
preparations are carried out on the bypass graft. After occlusion with a
bulldog, the graft is trimmed in an oblique manner distally and opened further,
to a total length of 4 mm. Free flow must be checked.
·
For incision of the target vessel, we use a
DeBakey forceps and robotic lancet beaver knife. The incision is enlarged to
approximately 4 mm using robotic Pott’s scissors. A 7-cm double- armed
polypropylene suture is then brought in through the assistance port. For
suturing the anastomosis, two robotic black diamond microforceps are used.
·
The suture is started at the toe of the
anastomosis on the back wall with an inside-out stitch. The needle is parked
away in the epicardium. With the other needle, the suture is continued on the
back wall, stitching the graft inside out and the coronary artery outside in.
After three throws in parachute technique, the graft is brought down to the
anastomotic level, and suturing becomes easier. It is very important to apply
adequate suture tension to avoid leaks on the back wall, which are harder to
correct than if they occur on the front wall. Fig. 7.5 shows the suturing of
the anastomotic back wall. Figs. 7.6 and 7.7 depict the further suturing
sequence. After going around the heel, the needle is parked away again, and the
contralateral needle is taken to suture around the toe of the anastomosis and
complete the suture line. Gentle probing of lumen patency with the tips of the
microforceps is possible. The whole suture line needs to be carefully inspected
for slings, which can be corrected using one of the suture needles. A video of
the suturing technique is also available at.
· At the current stage, grafts can be placed to
all coronary territories. The most common TECAB versions are left internal
mammary artery to left anterior descending artery (LIMA to LAD), right internal
mammary artery (RIMA) to LAD combined with LIMA to the diagonal, ramus, or
circumflex artery branches, and LIMA to LAD combined with RIMA to the RCA
territory. The latter is a Y graft construct.
· There are some specifics to consider when
suturing on the arrested heart or beating heart. In AH-TECAB, the target vessel
can be incised as cardioplegia is initiated, which may reduce the risk of
injury to the back wall. Backbleeding from the target vessel may be present,
caused by inadequate venous drainage or low endoaortic balloon pressure leading
to retrograde aortic root flow. Correction of the venous drainage cannula
position, additional inflation of the endoballoon, or placement of a Silastic
tape is an appropriate measure to take to reduce backbleeding. Suturing should
only be started if a clear view of the target vessel is ensured.
· In BH-TECAB, Silastic tapes are placed
proximally and distally to the graft landing zone. Only the proximal one is
occluded. The target vessel is then opened and an intraluminal shunt is
inserted first, completely into the distal vessel. It is then pulled into the proximal
vessel and the Silastic tape is loosened. In BH-TECAB, the stitching maneuvers
must be very gentle to avoid lacerations of the coronary artery wall. An
esmolol drip may improve the comfort of suturing. The surgeon has to deal with
magnified bouncing movements of the operative field; intense simulation
training in dry and wet laboratory models is strongly recommended before moving
into the clinical setting.
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Figure
7.5 Suturing of the back wall of the
anastomosis in videoscopic view. Two robotic microforceps are used. Suture
material is a 7 cm-long double-armed 7/0 polypropylene suture.
Figure
7.6 After completing the back wall and
hell of the anastomosis, the toe and anterior wall suture are complete.
Figure
7.7 The multiwristed robotic
instruments allow for comfortable robotic knot tying.
·
Transit time ultrasound flow measurements of the
bypass are carried out in all cases using a specifically designed endoscopic
flow probe. The probe is brought in through the subcostal port. Blood
collections in the left pleural space are evacuated using a flexible suction
tube brought in through the assistance port.
· After pump runs, the patient is weaned from
cardiopulmonary bypass, leaving the robot docked and leaving instruments parked
in the IMA bed. This is done because the heart will be filled after
decannulation, and re-insertion of instruments may be difficult. The
combination of single-lung ventilation and the use of cardiopulmonary bypass
may lead to transient, significant respiratory compromise, which is usually
self-limited.
·
Once the patient is oxygenating stably and pump
function is adequate, protamine is given. A final robotic inspection of the
thoracic cavity follows. This phase requires ongoing thorough attention of the
console surgeon and tableside team. Once adequate hemostasis has been achieved,
the robotic system is undocked but the ports are left in place. This is
important to avoid CO2 losses during final manual inspections with
the robotic camera. The ports are removed in a stepwise manner under scope
inspection. They are cauterized and packed with Surgicel. A chest tube is
inserted through the camera porthole. This should be done with the left lung
inflated to avoid graft injuries during this last phase of the operation.
◆ Postoperative care basically
follows the principles of care after coronary bypass surgery through a sternotomy.
After single-lung ventilation, atelectasis may be present, which usually can be
managed with respiratory therapy. Attention should be paid to peripheral
arterial and venous circulation after remote access cannulation. Pain may be
quite intense, specifically around the camera port side area, but usually goes
away within the first few postoperative days. Sternal precautions do not need
to be prescribed.
Keywords: coronary artery disease, coronary artery bypass grafting, minimally
invasive surgery, endoscopic surgery, robotic surgery
1. Bonatti J, Schachner T, Bonaros N, et al. Robotic assisted
endoscopic coronary bypass surgery. Circulation. 2011;124:236–244.
2. Bonatti J, Lee JD, Bonaros N, et al. Robotic totally endoscopic
multivessel coronary artery bypass grafting: procedure development, challenges,
results. Innovations. 2012;7:3–8.
