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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. 2.8 A-E: Technique for repair of vena caval injury.
Small-Diameter Aorta
In patients with a relatively small-diameter aorta, the regular cannula may be space occupying, interfering with
satisfactory perfusion. Plastic right-angled cannulas have good flow characteristics and will not hit the back wall
of the aorta.
Systemic Hypertension
Whenever the systemic pressure is high, aortic decannulation may become hazardous and result in troublesome
bleeding. The systemic pressure can be lowered to a satisfactory level by temporarily removing some volume
through the venous line. The arterial cannula is then removed and its aortic entry site securely sutured. The
arterial line is then connected to the venous cannula, and blood is reinfused as needed.
A less effective but useful technique is transient lowering of the blood pressure by digital compression of the
main pulmonary artery for decannulation purposes. This technique can also be helpful when cannulating the
aorta.
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Repairing Aortic Injury
If the venous lines have already been removed, the cavae can be temporarily clamped, causing the systemic
pressure to drop significantly. The aortic cannula is removed, and the now soft, pliable aorta is repaired. The
caval clamps are then removed to allow drainage of the venous return into the right atrium. However, it is
preferable to recannulate the right atrium and manipulate the blood pressure by adding or removing volume,
thereby allowing for safe and controlled aortic repair.
FIG. 2.9 Aortic cannulation.
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FIG. 2.10 Aortic cannulation, completed.
Femoral Artery Cannulation
Technique
The common femoral artery (or occasionally the external iliac artery) is dissected free for a short distance above
the origin of the profunda femoris branch. Umbilical tapes are placed around the common femoral artery above
the prospective cannulation site as well as the superficial and profunda arteries distally. Vascular clamps are
applied to the femoral artery both above and below the intended arteriotomy site. The profunda artery may be
either clamped or snared. A small transverse arteriotomy is made where the arterial wall appears to be relatively
normal. A tapered cannula of appropriate size is then gently introduced through a transverse arteriotomy into the
arterial lumen and is secured in place (Fig. 2.12A). Alternatively and more commonly, cannulation is performed
through a purse-string using the modified Seldinger technique with serial dilations over a semi-stiff wire. The
guidewire must be visualized within the descending aorta on echo before any dilation is performed. For closure,
proximal and distal clamps are applied and the arteriotomy is closed with interrupted sutures.
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FIG. 2.11 Traumatic aortic wall dissection during introduction of a cannula.
Cannula Slippage
The perfusion pressure may cause the cannula to slip out. It should be secured by tying it to the umbilical tape
already placed around the artery (Fig. 2.12B).
Cannula Injury to the Arterial Wall
The cannula tip may injure the arterial wall and cause separation of intimal plaque, which can result in retrograde
aortic dissection (Fig. 2.13). The cannula must never be too large and should be introduced into the arterial
lumen in an area that is relatively disease-free.
Limb Ischemia Due to Arterial Occlusion
The arterial cannula may occasionally occlude the entire arterial lumen and cause distal malperfusion. This
problem is particularly common in younger patients with small arteries and little collateral flow. After cannulation,
flow in the distal vessel or the foot should be evaluated using a Doppler. In cases of inadequate flow, a 5 French
distal perfusion cannula is inserted distally using Seldinger technique and is attached to the side-arm of the
arterial cannula (Fig. 2.14).
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FIG. 2.12 Femoral artery cannulation. A: Transverse arteriotomy for introduction of the cannula. B: securing the
cannula to the umbilical tape.
Injury to the Femoral Artery
A tourniquet or clamp used to tighten the umbilical tape around the proximal femoral artery and cannula may
injure the wall of the artery. This can be avoided by placing a peanut sponge under the umbilical tape before
tightening it.
Femoral Artery Dissection
The surgeon should always look for a column of pulsating blood in the femoral cannula; in the absence of
obvious pulsation, it is very likely that the cannula tip is not in the lumen of the vessel.
FIG. 2.13 Cannula injury to the common femoral artery causing retrograde aortic dissection.
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FIG 2.14 Distal perfusion catheter with femoral arterial cannulation, to prevent ipsilateral leg ischemia.
Axillary Artery Cannulation
The axillary artery has emerged as a safe, usually disease-free, and accessible alternative site for arterial
cannulation. Right axillary artery cannulation is especially useful for antegrade cerebral perfusion in aortic
surgery when circulatory arrest may be necessary. When using right axillary artery perfusion for aortic surgery, a
right radial arterial line is necessary to monitor antegrade cerebral perfusion pressure during the circulatory
arrest time.
Technique
An approximately 5 to 6 cm incision is made 1 cm inferior and parallel to the midportion of the right clavicle. The
dissection is carried through the subcutaneous tissue toward the insertion of the pectoralis minor muscle and the
deltopectoral groove. The pectoralis major muscle is dissected and divided along its fibers and the deltopectoral
fascia is incised. The axillary vein and then the artery are encountered. The brachial plexus is located cephalad
to the vascular bundle and must be identified and protected when the axillary artery is to be encircled (Fig. 2.15).
Injury to Brachial Plexus
Traction and manipulation of brachial plexus should be avoided. Electrocautery should not be used close to the
brachial plexus to prevent nerve injury.
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Although the axillary artery can be directly cannulated in many individuals, the risk of dissection has led many
surgeons to suture a 7- or 8-mm Dacron tube graft (end to side) to the axillary artery with a 5-0 or 6-0 Prolene
suture, followed by cannulation of the tube graft (Fig. 2.15). At the completion of cardiopulmonary bypass, the
base of the tube graft is ligated with two large metal clips flush with the axillary artery wall. The graft is trimmed to
1 cm and the end is oversewn with 5-0 Prolene.
FIG. 2.15 Axillary artery cannulation.
Axillary Artery Dissection
In patients with aortic dissection, it is important to ensure that the axillary artery is free of dissection before
cannulation.
Transapical Aortic Cannulation
In patients with type A aortic dissection, aortic cannulation through the left ventricular apex is another technique
that can be utilized.
Technique
A stab incision of 1 cm is made on the anterior wall of left ventricle close to the apex but offset from the LAD. A
22-French aortic cannula with stylet (such as the Edwards Fem-Flex Aortic Cannula) is gently introduced into the
left ventricle (Fig. 2.16). It is advanced across the aortic valve into the ascending aorta guided by
transesophageal echocardiography. When the cannula is removed, the opening is closed with two or three
pledgeted horizontal mattress sutures of 4-0 Prolene.
The tip of the cannula must be in the true lumen of the aorta before starting cardiopulmonary bypass. This
can be confirmed by transesophageal echocardiography.
The cannula is removed from the left ventricle at the beginning of circulatory arrest. Following the anastomosis of
the tube graft to the distal aorta, the graft itself is cannulated and cardiopulmonary bypass is resumed.
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P.30
Severe Aortic Stenosis
The technique is contraindicated in patients with critical aortic stenosis. The cannula may not pass through the
aortic valve.
FIG. 2.16 Transapical aortic cannulation; cannula passed across the aortic valve.
FIG. 2.17 Right atrial cannulation with a single, dual-staged cannula.
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Left Ventricular Wall Bleeding
Purse-string sutures are not required to hold the cannula in place, and may cause troublesome bleeding.
Injury to Left Anterior Descending Artery
The cannulation site should be well away from the left anterior descending coronary artery on the anterior wall of
the left ventricle.
VENOUS CANNULATION
Right Atrial Cannulation
Technique
A single, large, dual-stage atriocaval cannula provides satisfactory venous return for most cardiac surgical
procedures. This cannula is introduced through a purse-string suture in the right atrial appendage so that the tip
lies in the inferior vena cava and the basket lies in the right atrium (Fig. 2.17).
Injury to the Sinoatrial Node
The sinoatrial node is located at the superior end of the sulcus terminalis near the cavoatrial junction (Fig. 2.18).
Injury to the sinoatrial node (Fig. 2.19) may cause temporary conduction disturbances, which can generally be
managed with a temporary atrial pacemaker wire and the infusion of isoproterenol or dopamine in the immediate
postoperative period. Rarely, it may be necessary to pace the atrium permanently.
Injury to the Right Coronary Artery
The right coronary artery follows a course in the right atrioventricular groove. Whenever the right atrial
appendage is clamped, usually during cannulation, the sinoatrial node and the right coronary artery are at risk of
injury (Fig. 2.20). This is more likely to occur during reoperations. Right coronary artery injury can be treated by
bypassing the injured segment with a saphenous vein graft from the aorta to the middle of the right coronary
artery (Fig. 2.21).
Cannulation Site
When the right atrial appendage is too friable, another site on the atrial wall is selected for cannulation. Bleeding
from a tear of the auricle can be controlled with fine Prolene sutures, sometimes reinforced with a small pledget.
Atrial Cannulation in Reoperation
In reoperation, the atrial wall is sometimes thin and friable, and its dissection can be tedious and hazardous. It is
advantageous to leave a segment of pericardium intact on the atrial wall through which cannulation can be
performed safely and securely (Fig. 2.22).
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FIG. 2.18 Surgical anatomy of the sinoatrial node and surrounding structures.
FIG. 2.19 Clamp injury to the sinoatrial node.
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