Patients and Methods
From 24 November 2016 to 23 December 2019, 186 patients who had been
diagnosed with multivessel or left main coronary artery disease by
coronary angiography were referred for surgical revascularization. After
preoperative examination and exclusion of other cardiovascular
abnormalities, elective MICS CABG via small left thoracotomy was
performed by surgeons who had passed the steep learning curve of this
procedure. This study was approved by the ethics committee of Peking
University Third Hospital.
Contraindications for this procedure included an unstable preoperative
hemodynamic status, severe pulmonary dysfunction, severe obesity,
thoracic cavity deformity, and porcelain ascending aorta (A.o)
calcification as indicated by computed tomography (CT). The patients’
preoperative characteristics are listed in Table 1.
The preoperative antiplatelet regimen was administration of 100 mg of
oral aspirin per day from admission to the day before the operation. In
patients who had undergone percutaneous coronary intervention (PCI)
<1 year preoperatively while the stent remained patent, a dual
antiplatelet regimen of 100 mg of aspirin and 75 mg of clopidogrel per
day was adopted until the day before the operation.
An individualized surgical plan for revascularization was established
preoperatively according to each patient’s variables and coronary
anatomy. All 186 patients were intent to achieve complete myocardial
revascularization with the use of two grafts to bypass two or more of
three coronary systems: the left anterior descending artery (LAD), left
circumflex artery (LCX), and right coronary artery (RCA).
The patient was placed in the supine position with a soft pad under the
left scapula, which elevated the left chest by 10 cm. The patient was
then intubated with a double-lumen endotracheal tube. An external
defibrillator pad was placed for emergency defibrillation. A Swan-Ganz
catheter was placed via the right internal jugular vein into the
pulmonary artery for intraoperative hemodynamic monitoring. After
draping, a 7- to 8-cm-long incision, two-thirds lateral to the left
middle clavicle line, was made via the fifth intercostal space after
establishing single-lung ventilation. The chest wall was lifted with a
retraction system, and the LITA was carefully identified and harvested
in a pedicled manner under direct vision from the innominate vein
superiorly to its bifurcation or trifurcation inferiorly. The thymus and
pericardial fat tissue were dissected and removed with cautery for
exposure of the A.o before pericardiotomy. Heparin (1 mg/kg) was
administered to achieve an activated clotting time of >250
seconds. Heparin was supplemented at 30-minute intervals to keep the
activated clotting time at >250 seconds. After
pericardiotomy, the target vessel was identified and exposed. At the
same time, an endoscopic or open procedure to harvest the SV was
performed by the surgical staff. The SV was prepared in heparinized
solution after ligation of its branches.
An apical suction device was used to position the heart, and the target
vessel was then stabilized with a vacuum-assisted Octopus Nuvo
epicardial stabilizer (Medtronic, Minneapolis, MN, USA). After
arteriotomy, an intracoronary shunt was routinely inserted into the
vessel to minimize acute ischemia. Handsewn distal anastomosis was
accomplished with a running 7-0 or 8-0 Prolene suture (Ethicon, Inc.,
Somerville, NJ, USA). The routine revascularization strategy was the
LITA to LAD first, then proximal anastomosis to the A.o with the SV or
radial artery (RA), followed by sequential grafting with a single SV or
RA graft 14 to bypass the trunk or branch of the LAD,
LCX, or RCA.
Placement of traction sutures on the right pericardium lateral to the
A.o, together with insertion of a moist sponge between the right
pericardium and A.o, pushed the A.o leftward and facilitated exposure of
the proximal A.o. The proximal anastomosis was performed using 6-0
running propylene suture (Ethicon, Inc.) with the aid of a long-shaft
side clamp to connect the SV with the A.o. The presence of an eggshell
A.o that had not been visible in the preoperative CT scan excluded the
possibility of proximal A.o anastomosis. In such cases, the SV graft was
anastomosed to the left axillary artery via a horizontal incision placed
1 cm under the clavicle, then passed through the first intercostal space
as a sequential graft to bypass the target vessels. Epicardial coronary
arteries with a caliber of >1.5 mm and proximal stenosis of
>70% were grafted intraoperatively. In two patients, the
left RA was used because of shortage of the SV. The distribution of the
grafts and target vessels are listed in Table 2.
After neutralization of heparin with protamine, the pericardium was
closed. An indwelling catheter was inserted percutaneously and passed
underneath the pleura under direct visualization to block the
intercostal nerves and thus allow for continuous injection of analgesics
postoperatively. A #28 left chest drainage tube was inserted via the
sixth intercostal space lateral to the incision. The patients were
extubated in the intensive care unit and received an oral dual
antiplatelet regimen of daily aspirin (100 mg) and clopidogrel (75 mg).
The standard regimen after hospital discharge was lifelong continuation
of the aspirin and ≥1-year continuation of the clopidogrel.
The patients underwent invasive coronary artery and graft angiography
via the left RA or femoral artery before hospital discharge. The
postoperative angiograms were reviewed by three coronary surgeons. Each
graft was viewed in at least two orthogonal planes and scored on the
worst appearance of the graft. Graft assessment was standardized by the
FitzGibbon gradation as the presence of stenosis at either the
proximal/distal anastomosis or trunk of the graft: grade A, perfectly
patent; grade B, patent with stenosis reducing the caliber to
<50% of the target coronary artery; and grade O, occluded
graft. Grade A and B grafts were deemed patent. The CR rate was the
ratio of the number of grafts constructed intraoperatively to the number
of grafts intended to be constructed. Complementary PCI was performed
with a drug-eluting stent if indicated.
The patients were followed up via the WeChat app by a single physician
assistant after discharge. Major adverse cardiovascular and cerebral
events (MACCE) and all causes of death were recorded.