facility with which vascular anastomoses can be created, and the avoidance of morbidity in harvesting

the vein. The adequacy and size of the vein can be assessed preoperatively using ultrasound techniques.

Generally, a conduit of 2 to 4 mm in diameter is considered suitable. Alternative veins, such as the

lesser saphenous vein and cephalic vein, are infrequently used for coronary bypass grafting because

patency rates have been reported to be low. The greater saphenous vein can be exposed with a single

long incision, beginning at the ankle, midway between the medial malleolus and the anterior tibial

tendon. It is important to handle the vein gently and avoid electrocautery directly on the vein to

minimize traumatic or thermal injury to the endothelial cells. The side branches are carefully ligated,

and the vein is preserved in a solution of cold heparinized blood, often with vasodilating agents such as

papaverine and nitroglycerine. If dissection is minimized and hemostasis is meticulously ensured, the

incidence of infection and wound healing complications is generally low. Patients will complain of pain

along the length of the incision, but this typically resolves after several weeks.

Figure 83-8. Instrumentation for cardiopulmonary bypass.

In more recent years, minimally invasive approaches using endoscopic techniques can harvest the

entire length of the greater saphenous vein with three small incisions. After exposure of the vessel at

the knee, a blunt dissector is used to create a tissue plane, which is then expanded with CO2

insufflation.

Direct visualization with magnifying endoscopic lenses allows identification and ligation of side

branches (Fig. 83-9). The dissection proceeds both proximally and distally, until the vein has been fully

mobilized. Small stab incisions allow ligation at the groin and the ankle, and extraction of the vein from

the initial incision. This technique has reduced pain, has improved patient satisfaction, and appears to

reduce hospital readmission from wound healing complications. However, the technique is more time

consuming, which can be aggravating for the impatient surgeon. In addition, the disposable equipment

is expensive, increasing the costs by approximately $500 to $1,000, depending on the manufacturer and

negotiated contract pricing. More importantly, a recent nonrandomized report described the use of

endoscopic vein harvesting as an independent predictor of vein graft occlusion, hospital readmission for

major cardiac adverse event, and mortality, as compared to open saphenous vein harvesting

techniques.42 This study was in contrast to the previous smaller randomized trials but raises concerns

about the use of this strategy. Proponents of endoscopic vein harvesting argue that the observational

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trial did not describe the operator’s previous experience using minimally invasive harvesting and

suggest that many centers remained on the early part of their learning curve. In addition, newer

technology now allows for safer delivery of bipolar electrocautery, minimizing the potential for heat

transmission and endothelial injury. In addition, many centers are now administering low doses of

heparin before initiating the dissection to reduce the likelihood of in situ thrombus during manipulation

of the vein. It is likely that the debate regarding minimally invasive saphenous vein harvesting will

continue in the near future.

8 Arterial conduits for coronary bypass grafting have been increasingly utilized because of early

neointimal hyperplasia and late accelerated atherosclerosis seen in saphenous vein grafts. The most

important of these arterial conduits is the left internal mammary artery, which originates from the left

subclavian artery and descends caudally behind the chest wall, just lateral to the sternal edge. It gives

off intercostal branches until it terminates distally as the bifurcation into the superior epigastric and

musculophrenic arteries. The artery is typically mobilized as a pedicle, left intact at its origin from the

subclavian artery. After completion of the median sternotomy, the left hemisternum is retracted

anteriorly using an elevating self-retaining retractor (Fig. 83-10). Under direct visualization, the

mammary artery, its accompanying paired veins, and a small swath of chest-wall soft tissue are gently

separated from the remaining chest wall. Intercostal branches are controlled with clips and divided

sharply or with cautery. The dissection proceeds proximally to the subclavian vein and distally to the

terminal bifurcation of the internal mammary. A helpful marker identifying the distal extent of the

dissection is the appearance of muscular transverse thoracic fibers. Caution must be taken during the

proximal extent of the dissection, as the phrenic nerve traverses close posteriorly to the origin of the

left internal mammary artery. Once fully mobilized, the internal mammary is divided at the distal

bifurcation after heparinization and soaked in a solution of vasodilating agents to overcome spasm from

manipulation.

Figure 83-9. Endoscopic vein harvesting. A: Endoscope is inserted through a small incision in the knee. B: Excellent visualization

of the saphenous vein with ample working space. (Images courtesy of Maquet.)

Other arterial conduits are also increasingly utilized, such as the right internal mammary artery, the

radial artery, the gastroepiploic artery, and the inferior epigastric artery. The internal mammary artery

tends to be spared of atherosclerotic disease, and its patency rates are excellent many years following

bypass surgery. As such, many surgeons routinely harvest both internal mammary arteries to take

advantage of this biologic privilege. However, utilization of both internal mammary arteries can

devascularize the sternum and increase the risk of postoperative sternal wound infections, particularly

in obese diabetics.43 The radial artery can be harvested safely in the majority of patients, as a complete

palmar arch allows collateral flow to the hand from the ulnar artery. Preoperative ultrasound in

addition to a bedside Allen test can reliably identify patients in which hand ischemia precludes radial

artery use. Although the radial artery is more resistant to late occlusions typical in saphenous vein

grafts, it tends to be prone to spasm from competitive flow originating from subcritically stenosed

native coronary vessels. Radial arteries should only be used on coronary targets with at least 70%

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proximal stenoses. The inferior epigastric artery has been used as an arterial conduit, but limitations in

length and the need for an abdominal incision have diminished enthusiasm. The right gastroepiploic

artery can be used, since it has more than adequate length after mobilization off of the greater curve of

the stomach. It is left on its pedicle from the gastroduodenal artery and tunneled through a hole in the

diaphragm. It is most frequently used to revascularize the posterior descending coronary branch, but

will easily reach posterolateral branches as well. Patency has generally been reported to be excellent,

but its widespread use is restricted by the additional morbidity of laparotomy and risks of intraabdominal complications.

Figure 83-10. Elevation of the left hemisternum for visualization of the left internal mammary artery.

Once conduits have been harvested, CPB has been instituted, and cardioplegia infusion has resulted in

adequate diastolic arrest, the heart is manipulated to expose the epicardial vessels of interest.

Occasionally, the coronary arteries are in fact not on the epicardial surface but run within the epicardial

fat or deep within the myocardium. This is common for intermediate branches and the LAD. Careful

dissection is often required. If the midportion of the LAD cannot be found, the vessel can be opened at

the apex and a small coronary probe can be inserted proximally and palpated to better localize the

vessel. Care must be taken to ensure the target has been properly identified. Even the most seasoned

cardiac surgeons have mistakenly anastomosed grafts to epicardial veins. Once the target vessel is

properly located, an appropriate site for anastomotic construction should be identified. It is important to

have a thorough understanding of the angiographic location of significant obstructions to ensure the

graft is bypassing all significant lesions. The anastomotic site should ideally be relatively spared of

atherosclerotic disease, although in patients with advanced diabetes this is not always possible. The

vessel is dissected using a no. 64 sharp scalpel and opened vertically in the midline. This maneuver is

among the most essential and challenging, and requires precision and experience. Eccentric incisions,

inadvertent incisions in the posterior wall, or incisions in friable plaques can result in stenotic or leaky

constructions. The arteriotomy is extended using fine Potts scissors 3 to 4 mm in length. The conduit is

beveled to the appropriate length and the anastomosis is created with a continuous running

polypropylene suture, usually size 7-0 or 8-0 (Fig. 83-11). Absolute technical precision is crucial, and

skills required for these distal coronary anastomoses take practice and experience. A motionless and dry

surgical field, 2.5 to 3.5 magnifying loupes, experienced assistance, and a steady hand are essential.

Some surgeons use gentle insufflation of CO2

to clear the field of obscuring blood and to distend the

coronary artery to improve visualization of the toe and heal. After completion of the anastomosis,

saphenous vein grafts or free arterial grafts can be hand injected with cold saline to visualize patency of

the vessel and competence of the construction. Pedicled arterial grafts can be opened, and flow down

the target will be easily visualized.

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Figure 83-11. Distal coronary anastomosis with saphenous vein conduit. Excellent visualization in a quiet bloodless field is

required to achieve a hemostatic and unobstructed graft.

The proximal ends of the grafts are usually connected to the ascending aorta. The grafts are cut to the

appropriate length. This maneuver also requires experience, as a short graft will create tension,

potentially impinging upon the distal anastomosis, and an excessively long graft may kink. The graft is

distended to prevent twisting, and the aortic root is filled by infusing antegrade cardioplegia to help

determine optimal graft length. One must take into account the change in geometry as the heart fills

after weaning from CPB. In general, the conduits should take a straight trajectory toward their target

(Fig. 83-12). An aortotomy is created using a specially designed punch of 4 or 5 mm diameter. The

grafts are beveled, and the proximal anastomosis is created with continuous running 5-0 or 6-0

polypropylene. Alternatively, the aortic cross-clamp can be removed after completion of all of the distal

coronary anastomoses, and a side-biting partial aortic clamp can be placed. This technique can reduce

total cardioplegia time but may increase risk of atheroembolic complications from additional aortic

manipulation.

After completion of all distal and proximal anastomoses and the aortic cross-clamp has been removed,

the temperature of extracorporeal circulation is warmed. Ventricular fibrillation often occurs but can

easily be defibrillated with a single internal shock. Ventilation of the lungs is resumed, and CPB flow is

gradually reduced. Careful inspection of myocardial contractility and volume is required during

weaning, as transient dysfunction often occurs. It is important to avoid distention of ventricular

chambers, which causes unnecessary increased myocardial strain. A period of empty beating reperfusion

is often helpful, particularly if the aortic cross-clamp period was prolonged or if the heart was severely

ischemic preoperatively. Temporary sinus node or atrioventricular node conduction abnormalities are

common, and it is standard to place temporary pacemaker leads on the ventricle, although permanent

conduction abnormalities are very rare. Suture lines should be inspected for hemostasis, and cannulas

for CPB are removed. Although not essential for routine CABG, pulmonary artery catheters and TEE are

helpful in weaning from CPB. Excessive pulmonary artery pressures or new regional wall motion

abnormalities can suggest perfusion abnormalities and should prompt careful inspection of the bypass

grafts. Once satisfactory hemodynamics are achieved, protamine is administered to reverse the

anticoagulation of heparin. A notch in the pericardium to the left of the pulmonary artery must be

created to allow unhindered passage of the pedicled left internal mammary artery to its distal target.

The pericardium is typically left open after coronary bypass grafting to avoid graft kinking or

compression; however, mediastinal and thymic fat can be carefully placed over the aorta and proximal

anastomoses to protect them from future sternal reentry. Drains are left within the mediastinum to

collect shed blood, and the sternum is closed with steel wires, cables, or plates.

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Figure 83-12. Bypass grafts take gentle curving but a direct approach to the coronary targets. The pericardium is typically left open

to avoid kinking.

Off-pump Technique

While the use of CPB was essential in allowing safe and reproducible coronary anastomoses, it is now

well understood that extracorporeal circulation incites a powerful inflammatory response, activating

neutrophils and monocytes to release cytokines and inhibiting the clotting cascade and platelet function.

Occasionally, these inflammatory changes can produce clinically relevant capillary leak, pulmonary

edema, renal dysfunction, hemodynamic instability, and coagulation dysfunction. In addition, iatrogenic

cardiac arrest induced by cardioplegia can infrequently result in myocardial injury and dysfunction. In

order to avoid some of these adversities, attempts to perform CABG without the use of CPB have

become increasingly popular in the last decade. Interestingly, CABG was originally performed without

CPB in the early 1960s; however, it was largely abandoned because technically sound anastomoses

could not be reliably constructed. Newer technologies are now available that have made creation of

surgical bypass grafts more feasible on the full and beating heart.

The heart is exposed via a median sternotomy, identical to the approach used for standard coronary

bypass grafting with CPB. Additional sutures are placed deep within the posterior pericardium, which

can be used to facilitate retraction of the heart anteriorly and rightward, exposing the anterior,

anterolateral, and obtuse marginal surfaces. Typically, the vessel with the most severe occlusion is

grafted first, since occlusion of the vessel will result in the least myocardial ischemia and

revascularization of this territory may collateralize other regions and improve tolerance to alternate

vessel occlusion. For saphenous vein and free arterial grafts, the proximal anastomoses are performed

first to allow immediate revascularization of ischemic territories following completion of the distal

anastomoses. A dose of heparin is administered, typically 150 IU/kg, and adequate anticoagulation is

confirmed with an ACT. A partial occlusion clamp is placed on the ascending aorta for control.

Alternatively, newer sealing systems allow clampless control of the ascending aorta during construction

of the proximal anastomoses, and sutureless connectors are available that can variably create

satisfactory graft–aorta constructs. Once the proximal connections are complete, the grafts are carefully

cut to the appropriate length after identification of the anticipated sites of the distal targets.

Of the potential epicardial vessels, the LAD is the easiest to expose, since it lies anteriorly. Gentle

retraction on the pericardial sutures, occasionally along with a pad placed behind the heart, will usually

expose the vessel adequately. The diagonal branches are exposed with slightly further rightward

retraction. The obtuse marginal vessels can be exposed with the help of a suction device placed on the

apex of the heart and slowly and gently retracting the apex anteriorly and rightward. This maneuver

must be performed carefully, as cardiac chamber and/or outflow tracts can become compressed. The

anesthesiologist must be alerted to and familiar with these maneuvers, as temporary vasoactive

infusions may be required. Exposure of the right coronary artery and its branches is often the most

challenging. The right ventricle can become compressed with retraction superiorly. The suction

apparatus placed on the acute margin can facilitate exposure, as can stiff retraction of the right-sided

pericardial edges.

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Once the epicardial vessel of interest is identified, a U-shaped epicardial suction stabilizing device is

applied around the vessel (Fig. 83-13). This device can reduce myocardial motion in a small region of

interest, maintaining reasonable contractility. Silastic tapes loaded on blunt needles are carefully

encircled around the proximal and distal portions of the coronary artery and gently retracted for blood

flow control. A variable degree of ischemia may be seen on the ECG and TEE. The vessel is dissected

and opened in the same way as is done for on-pump techniques. If ischemia is pronounced, small shunts

can be inserted in the arteriotomy and the silastic snares released to reestablish some distal flow.

Continuous insufflation of CO2 can reduce obscuring blood from the field. The anastomosis is

constructed, and competency is assessed. Electrocardiographic normalization should be seen

immediately, confirming graft patency. Once all the grafts are complete, protamine is given to reverse

the anticoagulation effect of heparin. Hemostasis is confirmed and closure proceeds routinely.

Figure 83-13. Suction-stabilizing devices allow isolation and immo-bilization of epicardial coronary targets.

Despite early enthusiasm for off-pump coronary bypass surgery, concerns regarding long-term

patency of bypass grafts have prompted investigation into its true benefits and general application. A

large multicenter randomized trial recently published investigated short- and midterm outcomes of

patients undergoing either standard coronary bypass surgery with CPB or off-pump bypass.44 Over

2,000 patients referred for coronary bypass grafting were randomly assigned to undergo standard

versus off-pump CABG. All patients were felt to be suitable candidates for both approaches, and all

surgeons had previously completed a median of 50 off-pump procedures to ensure competency. The

primary endpoints were morbidity and mortality at 30 days and 1 year, and secondary endpoints were

graft patency and neuropsychologic testing. Thirty-day mortality was similar in both groups (1.6% vs.

1.2% in off-pump vs. on-pump, respectively; p = 0.47), as was the rate of perioperative stroke (1.3%

vs. 0.7%; p = 0.28). However, at 1 year, there was a higher rate of cardiac death in the off-pump group

(2.7% vs. 1.3%; p = 0.03). At 1 year, 65% of patients underwent routine cardiac catheterization,

revealing a significantly reduced rate of graft patency in the off-pump group (82.6% vs. 87.8%; p <

0.01), particularly for saphenous vein grafts (76.6% vs. 83.8%; p < 0.01). Neuropsychologic testing

was performed to attempt to quantify benefits from eliminating proposed neurocognitive dysfunction

attributed to CPB. Fifty-four percent of randomized patients completed neuropsychologic testing at

baseline and at 1 year, and interestingly, there were no significant differences observed from baseline to

1 year between off-pump and on-pump strategies. In summary, this important and well-conducted study

showed no advantages and potential disadvantages of off-pump surgical revascularization in this

selected cohort of patients. While there are valid criticisms of this study, these data certainly suggest

that routine use of off-pump CABG is not superior, and perhaps should be reserved to selected

populations. This author uses off-pump techniques for patients with a heavily calcified or atheromatous

ascending aorta or those with severe renal or hepatic dysfunction.

In addition to off-pump CABG, a variety of “minimally invasive” approaches have been

conceptualized. The minimally invasive direct coronary bypass (MIDCAB) involves creating a small left

anterior thoracotomy. After entering the chest in the fourth intercostal space and resecting a portion of

the fourth costal cartilage, a portion of the left internal mammary artery is mobilized under direct

vision. Using off-pump techniques and stabilizing equipment, the internal mammary artery is

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