Keywords
cannulation techniques, cardiopulmonary bypass
Step 1
Surgical Anatomy
1
Ascending Aorta
- ◆
Cannulation sites on the ascending aorta should be as high as safely possible. Surgeons today more frequently perform complete arterial revascularization, which in some cases may require delicate proximal anastomoses of arterial conduits (e.g., free internal thoracic arteries, radial arteries) directly to the aorta. These anastomoses are more difficult to construct if the aorta is under tension and distorted, such as may occur with a partial occluding clamp. A landmark for cannulation that is consistently successful for this approach is the pericardial reflection on the left anterolateral surface of the aorta, just below the innominate vein ( Fig. 2.1 ). This reflection can be divided to expose an area approximately 1 cm in diameter.
Figure 2.1
- ◆
Higher sites of cannulation (arch) may be desirable in cases of demonstrated aortic disease, and this form of cannulation may be associated with fewer neurologic problems. If there is extensive aortic disease or a hemiarch replacement is considered, the innominate artery can also be cannulated.
2
Femoral and Iliac Vessels
- ◆
It is essential that all trainees be familiar with the anatomy of the common femoral artery, with emphasis on its branches and its relationship to the inguinal ligament and common femoral vein ( Fig. 2.2 ). We believe that it is critical to identify the superficial femoral and profunda femoris arteries to ensure cannulation of the common femoral artery proper.
Figure 2.2
- ◆
In some cases, part of the inguinal ligament may need to be divided to provide safe control of the proximal aspect of the vessel. However, this is not commonly required because of the availability of easier sites for cannulation (e.g., axillary artery).
3
Axillary Artery
- ◆
Cardiac surgeons should also be familiar with the pertinent anatomy of the axillary artery. In particular, the axillary vein is anterosuperior to the artery, and the brachial plexus is posterolateral ( Fig. 2.3 ).
Figure 2.3
Step 2
Preoperative Considerations
- ◆
It is essential to identify prospective cannulation sites, even when off-pump surgery is contemplated, and to communicate this plan with the anesthetist to allow for appropriate monitoring (e.g., arterial monitoring of both upper extremities).
- ◆
The surgeon must anticipate vascular access problems in patients with vascular pathology and in those with cerebrovascular disease. Bilateral blood pressure recording to detect subclavian stenosis is essential for every patient. The lower extremity vascular assessment should also be thorough to prepare for a potential femoral artery cannulation. Patients with absent femoral pulses should undergo vascular imaging to evaluate the size and quality of the lower vessels and patency of the abdominal aorta. A previous history of lower or upper extremity deep vein thrombosis must be elicited.
- ◆
The surgeon should assess the ascending aorta on the chest radiograph and angiogram. If there is any concern, echocardiography or computed tomography of the ascending aorta should be used liberally. Intraoperative epiaortic scanning, which is used by some teams routinely to guide cannulation, should also be considered. Although an aortic plaque may be palpated—often at the base of the innominate artery—it is the presence of mobile plaque that is most concerning, and an off-pump so-called no-touch aorta approach should be considered in this situation, if possible.
- ◆
High-risk patients should be appropriately draped to access alternative sites, such as the axillary artery, and the surgeon should discuss all potential approaches and strategies with the anesthetist and perfusionist before starting to ensure readiness of cannulation and appropriate monitoring lines.
- ◆
Finally, with regard to venous cannulation, our practice has been to use two single-stage cannulae for all cases except simple coronary artery bypass. This provides the greatest flexibility if the operative strategy has to be modified midway through surgery (e.g., open insertion of a retrograde cannula, retrograde cerebral perfusion, control of an inadvertent opening of the right atrium with a left atriotomy).
Step 3
Operative Steps
1
Arterial Cannulation
Ascending Aortic Cannulation
- ◆
The target area should be digitally palpated. The cannula should be inserted so that its flow direction and jet are away from the arch vessels ( Fig. 2.4 ).
Figure 2.4
- ◆
Two sets of purse-string sutures (braided nonabsorbable 2-0) are placed around the target (8 to 10 mm diameter), with the free ends controlled with tourniquets on each side.
- ◆
There are several options for the actual cannulation, using a no. 15 or no. 11 blade. Some surgeons prefer to incise transmurally and control the opening with their finger, passing the tip of the cannula under the digit into the aortic opening ( Fig. 2.5 ). Some cut in an oblique manner but control the resulting flap with the forceps, directing the cannula under control into the opening. Another elegant method involves incising only the adventitia and media, leaving the paper-thin intima to be punctured by the cannula ( Fig. 2.6 ).
Figure 2.5
Figure 2.6
Femoral Artery Cannulation
- ◆
The safest skin incision for femoral cannulation is a vertical incision overlying and just slightly medial to the femoral pulse ( Fig. 2.7 ). An alternative incision is a slightly oblique incision aligned with the inguinal ligament to facilitate healing.
Figure 2.7
- ◆
Lymphatic vessels should be carefully cauterized or ligated to prevent the formation of a lymphocele and persistent drainage.
- ◆
Proximal and distal control of the femoral artery should be obtained. A target site for the arteriotomy should be chosen after considering where the proximal clamp may be safely placed and how the repair will be accomplished when the cannula is removed ( Fig. 2.8, A ). The distal vessels may be occluded with separate clamps or tapes (see Fig. 2.8, B ).
Figure 2.8
- ◆
The arteriotomy should be made in a transverse fashion and the femoral cannula gently introduced while an assistant releases the proximal clamp. The cannula is then secured by tying it to the proximal snare, with a second suture securing the tubing to the surface of the thigh.
Axillary Artery Cannulation
- ◆
A 5- to 8-cm transverse incision is made about 2 cm below the clavicle, overlying the deltopectoral groove ( Fig. 2.9 ). The dissection is continued between the fibers of the pectoralis major. There is often soft fat in this space, and the area should be dissected gently to avoid tearing of vessels and blood staining. The exposure is further aided by two self-retaining retractors. In an emergency, it is often necessary to sacrifice small nerves to the pectoralis major.
