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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3683_Библиотеки_им_академика_М_И_Перельмана
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Although every attempt is made to identify a relatively normal site for the anastomosis, at times localized plaques
at the toe of the anastomosis may limit the flow and cause early occlusion of the graft. It is therefore important to
enlarge the arteriotomy by cutting across the obstructive plaque (Fig. 9.21). Similarly, the distal opening of the
conduit is enlarged and an anastomosis is then carried out. If the obstructing segment is too long and this
procedure is not feasible, a second bypass graft must be placed distal to the site of obstruction.
FIG. 9.21 Enlarging an arteriotomy across obstructive plaque.
Intimal Injury
Probing must be performed gently, taking every precaution not to force too large a probe into the arterial lumen
to prevent an intimal tear.
Intramyocardial Course of the Coronary Artery
The artery may follow an intramyocardial course. It must be followed into the muscle, and the myocardial bridge
over the artery must be divided with great caution. The intramyocardial segment of the artery is nearly always
disease free. The division of the myocardial bridge must be limited to the extent needed to perform a satisfactory
anastomosis. Low-current electrocoagulation is used to cauterize the edges of the muscular bridge.
Difficulty Identifying Coronary Arteries
In some patients, epicardial fat along the course of the coronary artery prevents the precise identification of the
vessel. Under such circumstances, the side branches of the artery are identified first and then followed toward
the parent trunk. The artery is then dissected clear of the fatty tissue. When the LAD coronary artery cannot be
identified, it may be useful to locate the posterior descending artery and follow it to the apex of the heart. The
distal anterior descending coronary artery should be near this site.
Positioning the Heart to Expose Coronary Arteries
Exposure of the Anterior Surface of the Heart
A laparotomy pad soaked in ice-cold saline solution is placed into the pericardium behind the empty and flaccid
heart. This maneuver usually exposes the anterior surface
of the heart quite well. The LAD, diagonal, and, with some minor adjustments, ramus intermedius coronary
arteries can be viewed with ease (Fig. 9.22).
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FIG. 9.22 Positioning the heart to expose anterior coronary artery branches.
Exposure of the Right Coronary Artery and Branches
The right coronary artery is usually a large vessel and is covered by epicardial fat in the right atrioventricular
groove. Its distal branches, the posterolateral and right posterior descending arteries, tend to be more superficial
as they course toward the apex of the heart.
The operating table is elevated, and the patient is placed in a slight Trendelenburg position. The acute margin of
the right ventricle is gently elevated and held in position by the assistant surgeon's hand. The distal right
coronary artery and the proximal segment of its branches are brought into view (Fig. 9.23). Distal right coronary
artery is usually palpable. The epicardium over the atrioventricular groove is incised. The distal right coronary is
identified and dissected for a short distance. To provide exposure for the posterior descending or posterolateral
arteries, the apex of the heart is elevated toward the patient's right shoulder (Fig. 9.24).
Exposure of the Circumflex Coronary Artery and Branches
The operating table is lowered slightly and its left side raised. Cold lap pads are placed behind the heart, near
left atrium. The empty, flaccid heart is gently elevated and held by the assistant surgeon's right hand. This
maneuver, with some minor adjustments, brings all the obtuse marginal and posterior lateral branches of both the
circumflex and right coronary arteries into view (Fig. 9.25).
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FIG. 9.23 Positioning the heart to expose the right coronary artery and branches.
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FIG. 9.24 Exposing posterior descending and posterolateral arteries.
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FIG. 9.25 Positioning the heart to expose the circumflex coronary artery and branches.
Anastomotic Techniques
The technique for anastomosis to all the coronary arteries is essentially the same. The arteriotomy is made at
the selected site. It is enlarged to a length of 5 to 7 mm with Potts scissors. The distal end of the conduit must be
tailored to have an oblique, hood-shaped lumen with a circumference at least 25% larger than that of the
arteriotomy (Fig. 9.13). The distal anastomosis is started with 30-in. long, 7-0 or 8-0 Prolene sutures, double
armed with tapered needles. The first needle is passed from the outside of the graft 2 mm to the surgeon's side
of the heel. It is then passed from the inside to the outside of the lumen of the coronary artery, 2 to 3 mm to the
right of its heel (Fig. 9.26). The same needle is now passed again from the outside to the inside of the graft,
adjacent to the previous suture in a clockwise direction. The needle is then passed from the inside to the outside
of the coronary artery, adjacent to the previous stitch and similarly in a clockwise direction (Fig. 9.27). This
sequence is repeated until four rounds of sutures have been placed in the internal thoracic artery graft or the
vein graft. By gently pulling on both ends of the suture in a seesaw manner, the graft is lowered into position
(Fig. 9.28).
Traditionally, the vein or the thoracic artery is held by the assistant surgeon with two atraumatic forceps (Fig.
9.26). The forceps ideally should hold the adventitial tissue of the conduit. This may be difficult, and the whole
wall thickness including the intima is often grasped by the forceps. This damages the wall of the conduit and may
lead to early graft closure.
The conduit can be held between the surgeon's left thumb and index finger; the anastomosis is carried out with
the right hand (Fig. 9.29). This technique eliminates any
possible forceps injury to the conduit and does not require the expertise of an assistant surgeon. Moreover,
although initially it may appear to be somewhat clumsy and difficult, with a little experience, this technique
becomes easy and actually expedites the anastomosis. Alternatively, the conduit is placed on the heart adjacent
and parallel to the anastomotic site on the coronary artery (Fig. 9.30). Some surgeons prefer to suspend the
conduit from the drape with a fine adventitial traction suture. The sequence of suturing remains the same for all
the techniques described.
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FIG. 9.26 Stepwise technique for a distal anastomosis.
FIG. 9.27 Stepwise technique for a distal anastomosis.
FIG. 9.28 Stepwise technique for a distal anastomosis.
FIG. 9.29 Holding a vein graft between the left thumb and index finger.
FIG. 9.30 Placing conduit on the heart next to the anastomotic site on a coronary artery.
Anastomotic Leak at the Heel
The sutures at the heel must be extremely close to each other to minimize the possibility of leaks. Subsequent
placement of reinforcing sutures in this area is difficult and may compromise the lumen of the anastomosis.
Patency of the Lumen at the Heel of the Anastomosis
An appropriately sized ballpoint probe is now introduced into the lumen of the coronary artery, the internal
thoracic artery, or the vein conduit for a short distance to ensure a satisfactory anastomosis at the heel (Fig.
9.28).
This probe can be left in the lumen of the coronary artery to stop the flow of blood and allow accurate
placement of stitches.
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The left arm of the suture is tagged with a rubber-shod clamp to provide gentle traction. The needle at the other
end of the suture is now continued as an over-and-over stitch, outside in on the conduit and inside out on the
coronary artery (Fig. 9.31). This is continued forward, passing well around the toe of the anastomosis (Fig. 9.32).
The needle should take small and superficial bites very close to each other on the coronary artery at the toe.
FIG. 9.31 Completing a distal anastomosis.
FIG. 9.32 Completing distal anastomosis.
The needle may include a very thin segment of the surrounding epicardium to minimize anastomotic leaks.
At this time, an appropriately sized probe is passed through the toe of the anastomosis to ensure its patency.
The suturing is continued until the other suture end is reached.
Calcified Arterial Wall
When the wall of the coronary artery is heavily calcified, a diamond-tipped needle swaged on a 7-0 Prolene
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suture is used to perform the anastomosis. These needles are much stronger and can pierce the calcified
plaques with minimal difficulty. Alternatively, when the edge of the coronary arterial wall is calcified, the vein graft
can be sewn in place within the arterial lumen, excluding the calcified segment. Because the diameter of the vein
is larger than that of the artery, the lumen of the anastomosis will be adequate (Fig. 9.33).
FIG. 9.33 Sewing a vein graft within an arterial lumen excluding a calcified segment.
FIG. 9.34 A needle inadvertently picking up the back wall at the toe of an anastomosis.
Inadvertent Suturing of the Posterior Wall
The toe of the anastomosis is its most critical part because it determines the outflow capacity of the graft. When
the lumen of the artery is small or the visibility and exposure are suboptimal, the needle may pick up the posterior
wall of the artery (Fig. 9.34). An appropriately sized ballpoint probe or a disposable plastic probe passed for a
short distance into the distal artery may allow the precise placement of sutures and prevent the occurrence of
this complication.
Constriction at the Toe of the Anastomosis
Although passing the needle from inside the coronary artery at the toe of the anastomosis certainly minimizes the
possibility of incorporating the posterior wall of the artery in the stitch, nevertheless, it is difficult to predict exactly
where the needle will exit the artery, and a longer and larger segment of arterial wall may become included in the
stitch. When tightened, the stitch produces some dimpling and stenosis of the anastomosis at the toe. Every
precaution must be taken to avoid this complication (Fig. 9.35).
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FIG. 9.35 A: Dimpling and narrowing at the toe of the anastomosis. B: Small, close-together suturing at the toe
prevents narrowing of the anastomosis.
Appearance of the Anastomosis at the Toe
Sutures should be placed further apart on the graft than the coronary artery at the toe of the anastomosis. When
blood flow is established, the graft will bulge and provide a “hood” over the anastomosis.
Blood cardioplegic solution is gently infused through the graft before tightening the suture line to allow air to
escape and prevent any air embolization to the coronary arteries. The sutures are tightened with care and
securely tied (Fig. 9.36). Similarly, in the case of the internal thoracic artery, the bulldog clamp is removed. It is
reapplied after the sutures have been tied if other coronary anastomoses are still to be done.
Often this step of the procedure is preceded by retrograde infusion of blood cardioplegia to wash out any
debris and air from within the distal coronary artery.
Incorporation of the Epicardium into the Anastomosis
The epicardial tissue on each side of the coronary arteriotomy is very often incorporated into the suturing
process to ensure a more secure anastomosis.
The pedicle of the internal thoracic artery is tacked to the epicardium on each side of the anastomotic site with
simple 6-0 Prolene sutures. This prevents the pedicle from twisting on itself and therefore obstructing flow
through the vessel.
Flattening of the Thoracic Pedicle
If the tacking sutures are placed too far from the coronary artery, the pedicle may be stretched when the heart
fills. This lateral traction may compress the internal thoracic artery and compromise the graft flow.
Anastomotic Leak
Infusion of blood cardioplegic solution through the vein graft reveals any anastomotic leaks. These are best
controlled at this time with a separate suture, taking care not to impinge on the lumen of the anastomosis. The
surrounding epicardial tissue can be incorporated in the suture over the leak site.
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