**7. Axillary artery cannulation**

If the axillary artery is selected as the cannulation site, the exposure should be completed prior to median sternotomy. The right side is preferred. To isolate the artery, an incision is made 2 fingerbreadths inferiorly at the middle 1/3 of the clavicle. The incision may be extended laterally. The subcutaneous tissue is dissected down to the level of the pectoralis major. The pectoralis major is then split in the direction of its fibers, and the pecoralis minor is retracted laterally. The axillary vein is the first vascular structure encountered. It is dissected out and retracted inferiorly. Care should be taken to ligate small venous branches. The brachial plexus is superior to the artery and should be avoided if possible. Once the axillary artery is dissected from the surrounding tissue and isolated, the decision must be made to cannulate the artery directly or use an extension graft, such as Dacron. If the artery is to be cannulated directly, open transverse arteriotomy may be made or Seldinger technique employed for cannula placement. A graft is most helpful for small arteries where there is concern that the size of the cannula will completely occlude distal flow or if there is concern that the artery will be significantly narrowed when the arteriotomy is closed. If a graft is to be used, proximal and distal clamps should be placed on the artery, followed by a longitudinal arteriotomy. Graft anastomosis is typically completed with a 6-0 polypropylene suture. After the anastomosis is complete, the graft can be cannulated and blood flow to the arm restored. At the completion of cardiopulmonary bypass, the graft may be ligated and oversewn. If a graft is not used, the arteriotomy can be closed in the standard fashion after decannulation. Standard cannulation strategies should be used, as discussed above. After

decannulation, the pectoralis major should be reapproximated so as to cover the arteriotomy, and the incision should be closed in layers [13, 14].

#### **8. Femoral artery cannulation**

The femoral artery has long been used for cardiopulmonary bypass since the advent of cardiac surgery. As mentioned above, the femoral artery is a good alternative to direct aortic cannulation in the setting of porcelain aorta, type A aortic dissection, and re-operative cardiac surgery, as well as minimally invasive cardiac procedures [15–17]. The femoral artery can be cannulated percutaneously or directly. An extension graft is almost never needed for femoral cannulation, as opposed to axillary artery cannulation.

Several commercial sets are available to assist in percutaneous cannulation. A percutaneous cannulation is unlikely to be successful in patients who do not have a palpable femoral pulse. To start, the femoral artery should be identified by palpation or ultrasound guidance. The common femoral artery should be punctured well above the superficial/profunda femoral artery bifurcation so as to decrease the incidence of limb malperfusion. Seldinger technique is then employed to completed cannulation. When using femoral artery cannulation for aortic dissection, it is vital to identify the guide wire in the true lumen by TEE prior to cannula placement. Closure preferences for the arteriotomy vary. Several commercial closure devices are available, such as Perclose Proglide Vascular Closure Device (Abbott Inc., Santa Clara, CA) [18]. The field of endovascular closure devices is rapidly growing due to the popularity of endovascular procedures such as abdominal aortic aneurysm repair and transcatheter valve replacement. If the arteriotomy is not hemostatic after attempted endovascular closure and prolonged pressure, a femoral cutdown may be necessary for direct surgical closure of the artery.

For open surgical femoral artery cannulation, an incision should be made parallel to the inguinal crease. The subcutaneous tissues should be dissected down until the femoral artery can be identified and isolated. Proximal and distal control is obtained, and the common femoral artery can be directly cannulated. At the termination of cardiopulmonary bypass, the artery is the repaired directly, typically with 4-0 or 5-0 polypropylene suture. Femoral approach, both percutaneous and via cutdown, can be significantly more difficult to successfully perform on obese patients and patients with severe peripheral vascular disease.

#### **9. Intraoperative techniques and imaging**

Patients undergoing cardiopulmonary bypass are at risk for developing neurological deficits due to the dislodgement of atheroma from the aorta and proximal arch during the procedure [19]. Therefore, it is imperative that these atheromas are identified accurately to avoid the development of such complications. The standard method for detecting atherosclerotic disease of the aorta intraoperatively is manual palpation performed by the surgeon [20]. However, it has been noted that this traditional technique is unable to detect approximately 50% of atheroma lesions due to the presence of soft calcifications that the surgeon cannot appropriately identify [21].

An imaging modality that is routinely utilized in cardiac procedures is intraoperative transesophageal echocardiogram (TEE). TEE has shown to be effective in identifying areas of the aorta that are affected by atherosclerotic disease [10].

**21**

*Cannulation for Cardiopulmonary Bypass DOI: http://dx.doi.org/10.5772/intechopen.86033*

to its position between the aorta and esophagus [19].

**10. Arterial cannulation site complications**

the posterior wall of the ascending aorta.

**10.2 Malposition of cannula tip**

be maintained around 2.4 L/min/m<sup>2</sup>

**10.1 Bleeding**

erative TEE.

**10.3 Embolic events**

**10.4 Aortic dissection**

However, this method is not comprehensive as the bronchus creates a blind spot due

The best approach to identifying the presence of atheroma lesions in the aorta and proximal arch is epi-aortic scanning. This method involves directly imaging the aortic root and arch via ultrasound. An investigation conducted by Syliviris and colleagues [21] found that epi-aortic scanning was superior to both palpation and

Once the locations of atheroma lesions have been identified, modifications to the surgical approach can be made in order to ensure appropriate cannulation and clamping sites. Avoidance of these diseased locations will help to decrease the likelihood of neurologic complications due to disruption of the atherosclerotic regions.

Intraoperative bleeding can be a painful complication for both the surgeon and the patient. Bleeding from the aortic cannulation site is most commonly from too large of an aortotomy or inadequate snaring of the purse string sutures. To prevent this, careful attention should be paid to the diameter of the purse string "circle" that is created to ensure that it is 3–5 mm wider than the cannula diameter, typically 1.5–2 cm in total diameter. It can be challenging to place an additional circumferential suture after the aortotomy has been made. Additionally, care should be taken when making the aortotomy that the scalpel is not inserted too deeply so as to injure

Monitor circuit and peripheral arterial line mean arterial pressures to ensure adequate systemic circulation. Unequal mean arterial pressures suggests cannula malposition, which can typically be corrected by slightly withdrawing the cannula while taking care not to withdraw the cannula completely. Circuit flow rates should

are decreased, cannula position should be verified both visually and with intraop-

Visual inspection and palpation of the distal ascending aorta prior to cannulation is of utmost importance in preventing embolic events. A calcified aortic wall is more likely to cause not only difficulty in successfully inserting an aortic cannula but also showering of plaque to the systemic circulation. In addition, intraoperative TEE and epi-aortic ultrasound can be employed to help select an adequate cannulation site for complex aortic walls. If a heavy calcified porcelain aorta is present but not appreciated on preoperative imaging (which would be rare), alternate cannulation sites should be considered. A caveat to this is that atherosclerotic disease that

Aortic dissection is the most feared complication related to aortic cannulation. If not promptly recognized and addressed, the effects can be devastating. Placement

majorly affects the aorta is also likely to affect femoral or axillary vessels.

to ensure cerebral perfusion. If the flow rates

TEE in both identifying areas of atherosclerosis and grading the lesions.

#### *Cannulation for Cardiopulmonary Bypass DOI: http://dx.doi.org/10.5772/intechopen.86033*

However, this method is not comprehensive as the bronchus creates a blind spot due to its position between the aorta and esophagus [19].

The best approach to identifying the presence of atheroma lesions in the aorta and proximal arch is epi-aortic scanning. This method involves directly imaging the aortic root and arch via ultrasound. An investigation conducted by Syliviris and colleagues [21] found that epi-aortic scanning was superior to both palpation and TEE in both identifying areas of atherosclerosis and grading the lesions.

Once the locations of atheroma lesions have been identified, modifications to the surgical approach can be made in order to ensure appropriate cannulation and clamping sites. Avoidance of these diseased locations will help to decrease the likelihood of neurologic complications due to disruption of the atherosclerotic regions.

## **10. Arterial cannulation site complications**

#### **10.1 Bleeding**

*Cardiac Surgery Procedures*

**8. Femoral artery cannulation**

opposed to axillary artery cannulation.

closure of the artery.

decannulation, the pectoralis major should be reapproximated so as to cover the

The femoral artery has long been used for cardiopulmonary bypass since the advent of cardiac surgery. As mentioned above, the femoral artery is a good alternative to direct aortic cannulation in the setting of porcelain aorta, type A aortic dissection, and re-operative cardiac surgery, as well as minimally invasive cardiac procedures [15–17]. The femoral artery can be cannulated percutaneously or directly. An extension graft is almost never needed for femoral cannulation, as

Several commercial sets are available to assist in percutaneous cannulation. A percutaneous cannulation is unlikely to be successful in patients who do not have a palpable femoral pulse. To start, the femoral artery should be identified by palpation or ultrasound guidance. The common femoral artery should be punctured well above the superficial/profunda femoral artery bifurcation so as to decrease the incidence of limb malperfusion. Seldinger technique is then employed to completed cannulation. When using femoral artery cannulation for aortic dissection, it is vital to identify the guide wire in the true lumen by TEE prior to cannula placement. Closure preferences for the arteriotomy vary. Several commercial closure devices are available, such as Perclose Proglide Vascular Closure Device (Abbott Inc., Santa Clara, CA) [18]. The field of endovascular closure devices is rapidly growing due to the popularity of endovascular procedures such as abdominal aortic aneurysm repair and transcatheter valve replacement. If the arteriotomy is not hemostatic after attempted endovascular closure and prolonged pressure, a femoral cutdown may be necessary for direct surgical

For open surgical femoral artery cannulation, an incision should be made parallel to the inguinal crease. The subcutaneous tissues should be dissected down until the femoral artery can be identified and isolated. Proximal and distal control is obtained, and the common femoral artery can be directly cannulated. At the termination of cardiopulmonary bypass, the artery is the repaired directly, typically with 4-0 or 5-0 polypropylene suture. Femoral approach, both percutaneous and via cutdown, can be significantly more difficult to successfully perform on obese

Patients undergoing cardiopulmonary bypass are at risk for developing neurological deficits due to the dislodgement of atheroma from the aorta and proximal arch during the procedure [19]. Therefore, it is imperative that these atheromas are identified accurately to avoid the development of such complications. The standard method for detecting atherosclerotic disease of the aorta intraoperatively is manual palpation performed by the surgeon [20]. However, it has been noted that this traditional technique is unable to detect approximately 50% of atheroma lesions due to the presence of soft calcifications that the surgeon cannot appropri-

An imaging modality that is routinely utilized in cardiac procedures is intraoperative transesophageal echocardiogram (TEE). TEE has shown to be effective in identifying areas of the aorta that are affected by atherosclerotic disease [10].

patients and patients with severe peripheral vascular disease.

**9. Intraoperative techniques and imaging**

arteriotomy, and the incision should be closed in layers [13, 14].

**20**

ately identify [21].

Intraoperative bleeding can be a painful complication for both the surgeon and the patient. Bleeding from the aortic cannulation site is most commonly from too large of an aortotomy or inadequate snaring of the purse string sutures. To prevent this, careful attention should be paid to the diameter of the purse string "circle" that is created to ensure that it is 3–5 mm wider than the cannula diameter, typically 1.5–2 cm in total diameter. It can be challenging to place an additional circumferential suture after the aortotomy has been made. Additionally, care should be taken when making the aortotomy that the scalpel is not inserted too deeply so as to injure the posterior wall of the ascending aorta.

#### **10.2 Malposition of cannula tip**

Monitor circuit and peripheral arterial line mean arterial pressures to ensure adequate systemic circulation. Unequal mean arterial pressures suggests cannula malposition, which can typically be corrected by slightly withdrawing the cannula while taking care not to withdraw the cannula completely. Circuit flow rates should be maintained around 2.4 L/min/m<sup>2</sup> to ensure cerebral perfusion. If the flow rates are decreased, cannula position should be verified both visually and with intraoperative TEE.

#### **10.3 Embolic events**

Visual inspection and palpation of the distal ascending aorta prior to cannulation is of utmost importance in preventing embolic events. A calcified aortic wall is more likely to cause not only difficulty in successfully inserting an aortic cannula but also showering of plaque to the systemic circulation. In addition, intraoperative TEE and epi-aortic ultrasound can be employed to help select an adequate cannulation site for complex aortic walls. If a heavy calcified porcelain aorta is present but not appreciated on preoperative imaging (which would be rare), alternate cannulation sites should be considered. A caveat to this is that atherosclerotic disease that majorly affects the aorta is also likely to affect femoral or axillary vessels.

#### **10.4 Aortic dissection**

Aortic dissection is the most feared complication related to aortic cannulation. If not promptly recognized and addressed, the effects can be devastating. Placement

of the cannula into the true aortic lumen, as detailed above using adequate pressure gradient monitoring in the bypass circuit, sufficient blood return in the cannula after placement, and verification of placement with TEE significantly decrease the risk of dissection. Atherosclerotic plaques can tear between the medial and intimal layers causing dissection if a cannula is attempted to be forced though a calcified area on the aortic wall. In addition, severe hypertension after decannulation when the aortic purse string sutures are being tied down can lead to tears in the aortic wall layers [3, 22, 23].
