Minimally Invasive Coronary Artery Bypass
Grafting
1.
This technique enables revascularization with a
similar configuration as that in a sternotomy technique, using left internal
thoracic artery (LITA) harvesting and hand-sewn proximal and distal anastomoses
under direct visualization.1,2 Complete revascularization is achieved in 95% of
cases,1 allowing access to the anterior, lateral, and inferior walls of the
heart, with or without the use of pump assistance.
s
Anatomic considerations are the same as those
for a standard median sternotomy, except that the view is now from the apical
position through a small left thoracotomy window.
Step 2. Preoperative Considerations
◆ These
follow the current guidelines for coronary revascularization.
·
Hemodynamic instability or acute ischemia
·
Chest wall deformities and significant pleural
adhesions
·
Obesity
·
Intolerance to single-lung ventilation
·
Significant ascending aorta calcification, if
aortic proximal anastomoses are planned
· Poor status of the femoral vessels for
peripheral cardiopulmonary bypass (CPB) cannulation, whether planned or not
·
Inadequate distal target size and quality. The
right coronary artery and proximal posterior interventricular (PIV),
posterolateral (PL), and proximal obtuse marginal (OM) targets are not easily
accessible.
Step 3. Operative Technique
1. Anesthesia
· Paravertebral block is optional but may be
preferred, especially for patients who are being planned for immediate
extubation postoperatively.
· Single-lung ventilation is instituted either
through a double-lumen endotracheal tube or through a bronchial blocker.
· Transesophageal echocardiography (TEE) may
provide additional guidance if the patient develops instability. It can
identify wall motion abnormalities and recovery. In the case of peripheral CPB
cannulation, TEE must guide wire and cannula placement.
· Ensure that the endotracheal tube is still in
the correct position after repositioning the patient.
2. Positioning
◆ The
patient is placed in a semi–right lateral decubitus position (Fig. 5.1). The
right arm may be tucked at the patient’s side or extended to enable harvest of
the right radial artery. The left arm is placed in a sling held above the
patient’s head.
◆ The
hips are placed in a nearly supine position to enable access to the groin in
case of CPB, as well as to harvest the saphenous vein.
◆ External
defibrillator pads are placed on the right anterior chest and the left back.
Internal defibrillators will not fit through the small surgical access.
◆ The
chest may be marked to identify the area of the LITA bed easily.
◆ Prepare
the skin and place the sterile drapes in such a way that the sternum is easily
accessible in case sternotomy conversion is needed.
 |
Figure 5.1 (A) Patient positioning in MICS
CABG. (B) Sterile draping in MICS CABG.
3. Incision
·
A 5-cm incision is made in the fifth intercostal
space (ICS) at the left midclavicular line, usually located just below the
nipple in this positioning.
·
The fascia and muscles are transected layer by
layer. The left lung should begin deflating at this stage.
· Palpation as to the location of the cardiac apex
is done to check adequacy of the position. The apex should be around 2 cm
caudal to the intercostal opening. This decision should be tailored based on
the planned procedure; an incision that is placed too caudally will enable a
relatively easy distal anastomosis, but will restrict access to the aorta for
the proximal anastomoses and a more difficult mobilization of the proximal
portion of the LITA. The ICS opening may be revised as needed.
· A retractor is placed and is spread gently. The
pericardial fat is removed and the pericardium is opened. If a multivessel
bypass and an aortic anastomosis are planned, the pericardium is opened from
the diaphragmatic surface to the pericardial reflection on the aorta. The
distal targets are inspected as a last feasibility check when using the MICS
CABG approach.
· The LITA is harvested throughout its full
length, from the bifurcation to the level of the subclavian vein. This is
facilitated using ThoraTrak (Medtronic, Minneapolis) and Rultract (Rultract,
Independence, OH) retractors (Fig. 5.2). Other necessary accessories are
headlights, long fine instruments, and long cautery blades. The LITA may be
harvested in a skeletonized or nonskeletonized fashion. Adequate hemostasis is
ensured at all times.
· Systemic heparin is given. We target for an
activated clotting time (ACT) of 250 to 300 seconds for an off-pump CABG case
(OPCAB) and 480 seconds for a CPB case.
◆ An
option for beating heart CPB-assisted MICS CABG is available to decompress the
heart or to maintain hemodynamic stability.
◆ Peripheral
cannulation is through the femoral vessels.
◆ We
prefer the sequence of placing all the proximal anastomoses first, followed by
the distal grafting.
 |
| LITA harvest setup. (A, B) Cephalad traction on the retractor to harvest the midproximal LITA. (C) Caudal retraction on the retractor to harvest the distal LITA (patient’s head is toward the right). |
·
The aorta is exposed and brought toward the
surgical window (Fig. 5.3A and B):
1.
Pull up the pericardium using stitches.
2.
Place a small sponge to the right of the aorta,
pushing it toward the left.
3.
Place continuous positive airway pressure (CPAP)
on the right lung.
4.
Place an Octopus on top of the pulmonary artery
(PA) to retract and depress it.
5.
Place the patient on CPB.
·
For blood pressure (BP) control, aim for a
systolic pressure of 80 to 90 mm Hg.
·
Mobilize the aorta-PA junction and place a
side-biting clamp (see Fig. 5.3C).
· A hand-sewn anastomosis of a conduit to the
aorta is similar to the sternotomy approach. Challenges include a deep surgical
field and often the inability of the assistant to help because of the
restricted field.
·
In patients for whom an aortic anastomosis is
not feasible, other options include T-grafting to the LITA or the left
subclavian artery.
· Ensure adequate hemostasis because these will be
difficult to re-access further on in the procedure.
 |
Figure 5.3 (A, B) Proximal anastomosis setup
(patient’s head is toward the bottom). (C) Aortotomy as seen through the
small thoracotomy.
|
·
The sequence of the distal anastomosis will
depend on the surgeon’s judgment. We generally prefer doing the posterior
vessels first, followed by the lateral and then the anterior wall vessels. It
is important to individualize this based on the patient’s anatomy and clinical
status.
· A Starfish nonsternotomy heart positioner
(Medtronic) is prepared. We prefer to use it in a flexible way (armless)
whereby we place a tape and suspend the suction tip by clipping it to the
outside structures, instead of using the rod. We suspend the heart toward the
left shoulder when accessing the posterior vessels and toward the right hip
when accessing the lateral vessels (Fig. 5.4). See Video 5.1.
· An Octopus nonsternotomy tissue stabilizer is
placed through a small incision on the left anterior axillary line of the sixth
or seventh ICS. Care is taken to push this into the cavity safely using a
Seldinger technique, with a red rubber catheter to avoid penetrating injuries
to the heart. The Octopus is placed parallel to the target vessel, just as with
routine CABG cases, and the rod is anchored solidly to the operating room (OR)
table.
·
It is important that the systolic BP be raised
to 140 mm Hg prior to manipulating the heart. Once the heart is positioned, its
status is observed for a few seconds to ensure that the hemodynamics are stable.
· To provide bleeding control, we prefer to place
a Silastic proximal to the planned anastomosis site prior to opening the
vessel. In case of ischemia, a coronary shunt is placed, and the Silastic is
removed.
·
Distal anastomoses are performed similar to what
is done in routine sternotomy cases (Fig. 5.5). Exposure is facilitated by
using a blow mister device and occasionally by the coronary shunt.
·
Immediate graft patency is routinely checked
using a transit time flow probe.
 |
Distal anastomosis setup (with video). (A)
Exposure of anterior wall vessels. (B) Left anterior descending (LAD)
artery arteriotomy, with proximal Silastic control (patient’s head is toward
the right).
|
 |
(C) Exposure of lateral wall vessels. (D) Exposure of
posterior wall vessels.
|
◆ Heparin
reversal is carried out with protamine.
◆ A
thoracic drain is placed in the small incision where the Octopus was passed.
This is hooked to low suction.
◆ There
is the option of placing intercostal bupivacaine and muscle blockade prior to
closing the intercostal space (ICS).
◆ The
thoracotomy is closed using one heavy suture, with routine closure of the
fascia and skin.
◆ Perioperative
mortality is low, at 1.3%.1
◆ Other
advantages include decreased need for blood transfusion, lower surgical site
infection rates, and earlier return to full physical function.1,3,4
◆ Postoperative
pain can be an issue initially after the procedure but it is transient and
control-lable. It rapidly abates by the third postoperative day and is
associated with an overall improved postoperative pain picture, with improved
pulmonary function.5,6
◆ The
anastomotic patency results have been validated to be very good up to short and
intermediate-term follow-up.7,8
◆ The
rate of sternotomy conversion is 3%.
◆ A
left-sided pleural effusion can be an issue, and we maintain the thoracic drain
for 3 days.
◆ Communication
between the surgeon and anesthesiologist is key.
◆ The
surgeon and team should first be facile with sternotomy OPCAB before proceeding
to doing MICS CABG.
◆ CPB
assistance helps mitigate the learning curve.
 |
Figure 5.5 LITA-LAD and saphenous vein–diagonal artery grafts
(patient’s head is toward the right).
|
Keywords : coronary artery, bypass grafting, minimally invasive, MICS CABG, Operations for Coronary Artery Disease
References
1. McGinn J, Usman S, Lapierre H, et al. Minimally
invasive coronary artery bypass grafting. Circulation. 2009;120(suppl
1):S78–S84.
2. Chan V, Lapierre H, Sohmer B, et al. Handsewn proximal
anastomoses onto the ascending aorta through a small left thoracotomy during
minimally invasive multivessel coronary artery bypass grafting: a stepwise
approach to safety and reproducibility. Semin Thorac Cardiovasc Surg.
2012;24:79–83.
3. Lapierre H, Chan V, Sohmer B, et al. Minimally invasive
coronary artery bypass grafting via a small thoracotomy versus off-pump: a
case-matched study. Eur J Cardiothorac Surg. 2011;40:804–810.
4. Une D, Lapierre H, Sohmer B, et al. Can minimally
invasive coronary artery bypass grafting be initiated and practiced safely? A
learning curve analysis. Innovations (Phila). 2013;8(6):403–409.
5. Lichtenberg A, Hagl C, Harringer W, et al. Effects of
minimally invasive coronary artery bypass on pulmonary function and
postoperative pain. Ann Thorac Surg. 2000;70(2):461–465.
6. Walther T, Falk V, Metz S, et al. Pain and quality of
life after minimally invasive versus conventional cardiac surgery. Ann
Thorac Surg. 1999;67(6):1643–1647.
7. Ruel M, Shariff M, Lapierre H, et al. Results of the
minimally invasive coronary artery bypass grafting angiographic patency study. J
Thorac Cardiovasc Surg. 2014;147:203–209.
8. Hoff S, Ball S, Leacche M, et al. Results of completion
arteriography after minimally invasive off-pump coronary artery bypass. Ann
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