Volume 13, Issue 4 , Pages 232-243, Winter 2008
Aortic Arch Replacement Procedure—Extended Aortic Arch Replacement Through the L-Incision Approach
Article Outline
The operative results in surgery for aortic arch aneurysms are decided by several factors including preoperative patient condition, strategies for perfusion (how to cool patients), brain protection, myocardial protection, visceral organ protection, and adequate hemostasis at the anastomosis sites. Among various surgical approaches, a median sternotomy is most frequently used for total aortic arch replacement. However, in patients who have arch aneurysms extended to the descending aorta, the exposure afforded by the median sternotomy is less than ideal. Inadequate visualization of the proximal descending aorta may result in distal anastomotic bleeding and pseudoaneurysmal formation. The combination of a full median sternotomy and left thoracotomy has been used in such patients who need the extended total arch replacement. This extensive incision may provide excellent operative exposure; however, the postoperative morbidity is considered excessive. The “L-incision” approach (a combination of a left anterior thoracotomy and upper half median sternotomy) is thought to be less invasive and offer adequate operative field for extensive replacement of the aortic arch. We herein describe the L-incision approach1 in addition to our “proximal-first technique”2 for atherosclerotic extensive arch aneurysms.
Operative Technique
Figure 1.
Skin incisions for the L-incision approach and for arterial cannulation of the bilateral axillary arteries are shown. The skin incision is extended to the left anterior axillary line, and usually the 5th intercostal space (ICS) is used for the thoracotomy. A double-lumen endotracheal tube is routinely used to permit deflation of the left lung during the distal anastomosis. With a patient in either supine or left anterolateral position, a left anterior thoracotomy is made through the 4th to 6th ICS, and thereafter, an upper half median sternotomy is performed. Patient position depends on how the descending aortic aneurysm goes down. When the descending aorta goes down more medially than usual, the patient should be in the left anterolateral position with 30- to 45-degree rotation. The intercostal muscles are divided widely as much as possible to prevent rib fractures. The left internal thoracic artery is ligated and divided.
Figure 2.
In principle, the systemic arterial perfusion is delivered through the cannulae inserted into the axillary arteries.3 An 8-mm Hemashield graft (Hemashield Gold; Meadox Medicals, Inc., Oakland, NJ) is anastomosed in an end-to-side fashion to the axillary arteries for arterial perfusion. The graft anastomosis is performed instead of direct cannulation to obtain a large bore size for the arterial perfusion line and to prevent vascular injury including arterial dissection. When the intraoperative epiaortic echography reveals no significant atheromatous plaque on the ascending aortic wall, the ascending aorta can also be used as an alternative cannulation site. The right or left femoral artery is always exposed, and a 10-mm Hemashield graft is anastomosed on it only for lower systemic perfusion during arch vessel reconstruction. We avoid perfusing the arch vessels via the femoral artery because retrograde aortic perfusion carries the risk of cerebral embolism.4
Figure 3.
The operative view through the L-incision approach is shown. Two spring retractors (Kent-boomerang/spring retractor; Takasago, Tokyo, Japan) are placed to obtain an adequate operative field; one retracts the left half of the sternum in a left cranial direction and the other retracts the right half of the sternum in a right caudal direction. An adequate operative field for the ascending aorta, three arch vessels, innominate vein, and right atrial appendage can be obtained through this approach. The superior vena cava, which is used for retrograde cerebral perfusion, can also be accessible. When a surgical table is rotated to a surgeon and the lung is retracted to the medial side, the entire descending aorta can be observed in selected cases.
Figure 4.
A two-stage venous cannula is inserted through the right atrial appendage, and cardiopulmonary bypass is established. In L-incision approach, a left ventricular venting tube can be inserted from the left upper pulmonary vein, the roof of the left atrium, or the left atrial appendage. Of these, the left upper pulmonary vein is the most preferable site. Thereafter, systemic cooling is initiated; exposure of the ascending aorta, arch, arch vessels, and descending aorta is obtained, and vascular tapes are placed around them. The fat pad containing the vagal and phrenic nerve is identified and isolated by a piece of tape.
Figure 5.
A proximal anastomosis (graft to the ascending aorta) using a sealed graft with four branches (Hemashield Gold; Meadox Medicals, Inc.) is performed while cooling to 25°C rectal (or urinary bladder) temperature with cardiopulmonary bypass. After confirming with epiaortic echography that there are no plaques in the ascending aorta, aortic cross-clamping is performed, and antegrade cardioplegia is administered. The epiaortic echography is routinely used. We believe that the epiaortic echo is an essential tool for preventing catastrophic brain damage due to dislodging of the atherosclerotic plaque on the ascending aorta because preoperative computed tomographic scanning might pass away the small soft plaque occasionally.
Figure 6.
When the epiaortic echography reveals atheromatous plaques on the ascending aorta, core cooling to 25°C is performed, and the tourniquets around both the brachiocephalic and the left subclavian arteries are tightened. Thereafter, the ascending aorta is transected after lower body circulatory arrest. We start selective cerebral perfusion using a 12-Fr perfusion catheter placed into the left carotid artery. Care must be taken not to dislodge the soft plaque that is frequently seen at the orifice of the left carotid artery. Crystalloid cardioplegia is directly infused into the left and right coronary arteries. Next, the descending aorta is clamped, and lower body perfusion is instituted through the femoral artery. One pump circuit is used for bilateral axillary arteries and femoral artery. The perfusion pressure is maintained at around 60 mm Hg as measuring in the opposite site of the femoral artery. As the perfusion rate for each vessel is not monitored, care must be taken not to kink the arterial line.
Figure 7.
Immediately after proximal anastomosis, the heart is reperfused from one branch of the graft. Next, three arch vessels are reconstructed, one by one, from the left subclavian artery, left carotid artery, and brachiocephalic artery.
Figure 8.
After completion of arch vessel reconstruction, the antegrade cerebral flow is restored from the graft.
Figure 9.
Then the left lung is deflated for adequate exposure of the descending aorta, and we perform the distal anastomosis. The surgical table is rotated 30° from supine toward the patient's right side, and the operator moves from the patient's right side to left side. The open distal anastomosis using elephant trunk technique can be done safely under direct vision. Care must be taken to check bleeding from the intercostal arteries and branch vessels to the esophagus and bronchus. Deep bite of suturing for hemostasis from the inside of the aorta should be performed carefully, not penetrating the esophagus, which is located closely to the aorta. The left lung should be manipulated gently to prevent postoperative pulmonary dysfunction.
Figure 10.
Regarding the distal anastomosis, we use two techniques. One of them is shown in this figure: that is, a modified elephant trunk technique.5 After ceasing lower systemic perfusion, the folded graft is inserted into the descending aorta. Then, over-and-over sutures are made and the graft is pulled out. To reinforce the anastomosis, we routinely perform double running sutures. As this anastomosis is being completed, perfusion through the femoral arterial line is reestablished to remove air and debris.
Figure 11.
If the descending aorta is too small to put the folded graft in, a straight unfolded graft is inserted into the descending aorta.6 After double running suture technique is performed, the graft is reversed and pulled out. Occasionally, a modified elephant technique for a small descending aorta causes stenosis at the anastomosis.
Figure 12.
After completion of the distal anastomosis, we initiate systemic rewarming. During the open distal anastomosis, the rectal temperature is maintained at 25°C to protect the spinal cord. The previously anastomosed graft to the ascending aorta and arch vessels is passed down through the opening under the pedicle containing the vagal and phrenic nerves. Then, the graft-to-graft anastomosis (between the four-branched graft and the graft to the descending thoracic aorta) completes the operation. Total arch replacement with extended replacement of the descending aorta can be easily performed through the L-incision approach.
Comments
The L-incision approach has several advantages in extended total aortic arch replacement. First, the entire descending aorta can be seen directly through the anterior left thoracotomy. We can reduce occurrence of postoperative hemorrhage from the site of distal anastomosis. Second, both of the phrenic and vagal nerves can be isolated easily and safely preserved. These nerves play important roles for maintaining lung function. Especially in aged patients, postoperative recurrent laryngeal nerve palsy frequently causes lethal aspiration pneumonia. Third, the lower part of the sternum is not split, and the structure of the thorax can be maintained, which is favorable for keeping the postoperative pulmonary function or physical capability. Fourth, three arch vessels, especially the left subclavian artery, can be easily observed for anastomosis, which leads to reducing the duration of retrograde cerebral perfusion time or selective cerebral perfusion time. Finally, the L-incision approach is always accessible to the ascending aorta and allows replacement of the aortic root. It also secures the ascending aorta as an arterial cannulation site.
Several disadvantages of this procedure include the sacrifice of the left internal thoracic artery and wound pain. Through the L-incision approach, it would be feasible to perform coronary revascularization to either the left anterior descending coronary artery or the region of the left circumflex coronary artery. Inadequate exposure may make right coronary artery bypass difficult. Regarding wound pain, it is important to prevent rib fractures by using spring retractors.
In conclusion, the L-incision approach facilitates extensive replacement of the thoracic aorta, while reducing bleeding and neurological and respiratory complications. This approach is considered one useful option for performing total arch replacement.
References
- Total aortic arch replacement through the L-incision approach. Ann Thorac Surg. 2003;75:121–125
- Early proximal aortic perfusion in total arch replacement. Jpn J Vasc Surg. 2002;11:511–516
- Bilateral axillary arterial perfusion in surgery on thoracic aorta. Asian Cardiovasc Thorac Ann. 2006;14:145–149
- . Proximal aortic perfusion for complex arch and descending aortic disease. J Thorac Cardiovasc Surg. 1998;115:162–167
- . Extensive aortic replacement using “elephant trunk” prosthesis. Thorac Cardiovasc Surg. 1983;31:40
- Prosthetic replacement of the aortic arch. J Thorac Cardiovasc Surg. 1975;70:1051–1063
PII: S1522-2942(08)00064-0
doi:10.1053/j.optechstcvs.2008.06.005
© 2008 Elsevier Inc. All rights reserved.
Volume 13, Issue 4 , Pages 232-243, Winter 2008
