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.
◆ 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.1 If there is extensive aortic disease or a hemiarch replacement is
considered, the innominate artery can also be cannulated.
· 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.
· 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).
· 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).
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,3 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).
Keywords : Cannulation Techniques for Cardiopulmonary Bypass, cannulation techniques, cardiopulmonary bypass, Surgical Anatomy, Operative Steps, Arterial Canulation, Venous Cannulation, Postoperative Care, Pearls and Pitfalls, Ascending Aorta, Femoral and Iliac Vessels, Axillary Artery
