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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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FIG. 9.36 Infusing cardioplegia down a graft before tying the suture.
Alternate Distal Anastomotic Techniques
Interrupted Suture Technique
The anastomosis can also be accomplished with interrupted sutures; this is considered a superior technique, at
least on theoretic grounds. Many surgeons combine both continuous and interrupted techniques, reserving the
latter for the toe of the anastomosis. The general principles are the same as described previously for the
continuous suture technique, but the incidence of anastomotic leaks is considerably higher, requiring additional
reinforcing sutures.
Sequential Anastomosis
When the availability of conduits is limited, the technique for sequential anastomosis may be helpful. However,
many surgeons prefer the routine use of sequential anastomoses for possible improved flow characteristics.
Although the technique can be applied to any combination of vessels, it is most applicable to the LAD and
diagonal coronary arteries or the posterior descending and distal right coronary arteries. Occasionally, multiple
sequential distal anastomoses with only one proximal anastomosis are used, but this is not generally considered
ideal. The technique of the anastomosis is the same as that already described in preceding text. However, the
alignment of the incisions is variable, resulting in side-to-side, T-, Y-, or diamond-shaped configurations.
Large Arteriotomy
The surgeon should always avoid large arteriotomies when performing sequential anastomosis to prevent
flattening of the anastomosis.
Distal Graft Occlusion
The patency of the most distal coronary artery anastomosis depends on the flow characteristics of the more
proximal coronary artery. The most distal target should be the largest coronary artery with the greatest flow. If the
flow in the most proximal coronary artery is significantly higher than the most distal coronary artery, the graft
segment to the more distal coronary artery may gradually occlude.
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Kinking of the Graft
The length of the intervening graft between the anastomoses must be correct. The conduit must lie comfortably
on the heart without kinking.
If all these technical details are accomplished and adhered to, excellent long-term results can be achieved with
the technique for sequential anastomosis.
Toe-First Anastomosis
Occasionally, the course of the coronary artery, particularly the branches of the right coronary artery are such
that this technique may facilitate the anastomosis. The first suture needle is passed from the outside into the
lumen of the artery at the toe of the anastomosis (Fig. 9.37). It is then passed from the inside to the outside of the
conduit. The same needle is now passed again from the outside into the arterial lumen adjacent to, but to the
surgeon's right of, the previous suture (Fig. 9.38) and through the conduit from the inside to the outside (Fig.
9.39). This arm of the suture is clamped. The graft is now lowered into position. At this point, an appropriately
sized probe is introduced into the lumen of the coronary artery to ensure a patent anastomosis at the toe.
The needle at the other end of the suture is passed through the graft wall and then through the arterial wall from
the inside to the outside (Fig. 9.40). The suturing is thus continued as an over-and-over stitch to a point well
around the heel of the anastomosis (Figs. 9.41, 9.42, 9.43, 9.44). The needle is then
clamped. The other needle is passed through the arterial wall from the outside to the inside and then from the
inside to the outside of the graft (Fig. 9.45). The anastomosis is then completed and the suture ends tied after
deairing by infusion of cardioplegic solution into the graft (Fig. 9.46).
FIG. 9.37 Stepwise technique for a toe-first distal anastomosis.
FIG. 9.38 Stepwise technique for a toe-first distal anastomosis.
FIG. 9.39 Stepwise technique for a toe-first distal anastomosis.
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FIG. 9.40 Stepwise technique for a toe-first distal anastomosis.
FIG. 9.41 Stepwise technique for a toe-first distal anastomosis.
FIG. 9.42
FIG. 9.43
FIG. 9.44
FIG. 9.45
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FIG. 9.46
FIG. 9.47 A needle picking up the back wall of a coronary artery at the toe.
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FIG. 9.48 Correct needle placement at the toe.
Inadvertent Suturing of the Posterior Wall
The needle may pick up the posterior wall of the coronary artery (Fig. 9.47). This complication can be prevented
if the lumen at the toe is fully visualized before passing the needle through the graft (Fig. 9.48). This part of the
anastomosis can also be accomplished with interrupted sutures.
Endarterectomy
The role of endarterectomy in coronary artery disease is controversial. Many surgeons have achieved excellent
results with the technique and use it when dealing with all the main branches of coronary arteries. Others are
less enthusiastic and reserve the technique for the distal right coronary artery, whereas still others refrain from
using endarterectomy at all. Nevertheless, in many cases, endarterectomy is the only way to provide a suitable
lumen that accepts a bypass graft. It may well be that endarterectomized coronary arteries have decreased late
patency and that the technique leads to increased perioperative myocardial infarction. It is nonetheless a useful
technique and, when used appropriately, does provide excellent results.
Technique
The epicardium over the diseased segment of the coronary artery is incised. A 1-cm arteriotomy is made on the
anterior surface of the vessel in the usual manner. With a fine endarterectomy elevator, a plane is developed
between the calcified media and the elastic adventitial segment of the coronary artery wall. The calcific core is
dissected free from the arterial wall circumferentially as well as distally and proximally (Fig. 9.49). With peanut
dissectors providing traction and countertraction, the calcified plaque is gently withdrawn with a clamp or a pair
of forceps (Fig. 9.50).
The calcific core is withdrawn proximally and then divided with scissors. The distal segment is gently pulled and
withdrawn until it becomes detached.
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FIG. 9.49 Stepwise technique for a coronary endarterectomy.
FIG. 9.50 Stepwise technique for a coronary endarterectomy.
Tear of the Coronary Arterial Wall
Often the calcific core is adherent to the arterial wall to such an extent that its removal may create a tear in the
arterial wall. Dissection must therefore be carried out with great caution. If a tear occurs, it should be directly
sutured, provided that the lumen is adequate. Alternatively, the injured site is incorporated into the arteriotomy
and the vein graft anastomosis.
The lumen of the endarterectomized coronary artery is irrigated profusely to remove any debris, and the vein
graft is anastomosed to it in the usual manner.
Constriction of the Anastomotic Site
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Often the length of the anastomosis may be quite extensive. Care should be taken to prevent the purse-string
constrictive effect of the continuous suture technique.
Septal Branch Occlusion
Detachment of calcific plaque may occlude some of the arterial branches. This is particularly important whenever
the LAD coronary artery is endarterectomized because total occlusion of the septal branches may result in
perioperative myocardial infarction.
FIG. 9.51 Lengthening a vein graft with an extra vein segment.
The internal thoracic artery should preferably not be used as a conduit when endarterectomy is performed
because the internal thoracic artery is prone to distortion at the heel and compromised inflow when a long
arteriotomy is required.
Proximal Anastomoses
Increasingly, all proximal anastomoses are being performed with the aortic cross-clamp in place. This technique
appears to be associated with a reduced incidence of intraoperative stroke owing to detachment of calcific
plaques caused by clamp injury to the aorta. It is important for a surgeon to commit to memory the size of the
heart before the initiation of cardiopulmonary bypass and to envision how the vein grafts are to lie. With the heart
empty and flaccid, estimation of the correct length of the vein graft may be difficult. A good rule is to estimate the
length of the vein graft by the contour of the parietal pericardium. Alternatively, the heart can be filled and the
correct length of the conduit ascertained.
Another technique is to remove the aortic cross-clamp and allow the heart to beat normally. The vein grafts are
cut to the optimal length, and the proximal anastomoses are performed with a side-biting clamp applied to the
aorta.
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FIG. 9.52 A vein graft that is too long kinks or folds on itself behind the heart. Inset: Graft kinking when the
chest is closed.
Length of the Vein Graft
Saphenous vein grafts tend to shrink a little over time. If the length is a little short, shrinkage may cause tension
on the anastomosis and predispose the graft to premature failure. The vein graft must be divided at a point that
ensures a comfortable length of the graft when the heart is fully filled. This necessitates an extra length of 1 to 2
cm.
If the graft is noted to be too short, it should be repositioned on the aorta. Alternatively, the vein should be
divided obliquely and lengthened with an extra segment of vein (Fig. 9.51).
Leaving the vein graft too long may result in kinking or folding of the conduit on itself when the heart is placed
back in the pericardial well (Fig. 9.52). Sometimes the graft appears to be the appropriate length but kinks when
the chest is closed (Fig. 9.52, inset). This occurs most frequently with circumflex grafts. In this case, the graft
should be shortened by taking down the proximal anastomosis and excising the extra length before resuturing
the graft to the aorta. Alternatively, if the aorta is extensively diseased, the appropriate length of vein may be
excised and the two resulting vein ends reanastomosed, taking care not to twist the graft. Often a graft that is
slightly too long can be positioned well behind the left atrial appendage and kept in place with a piece of Surgicel
(Fig. 9.53).
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