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Division of Cardiovascular Surgery, Peter Munk Cardiac Centre, Toronto General Hospital, Department of Surgery, University of Toronto, Toronto, Canada.
Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX.Cardiovascular Surgery Service, The Texas Heart Institute, Houston, TX.
Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX.Cardiovascular Surgery Service, The Texas Heart Institute, Houston, TX.
Open surgical repair remains the gold standard operation for thoracoabdominal aortic aneurysm (TAAA). Contemporary surgical approaches balance the need to maximize long-term benefit by replacing as much diseased aorta as possible with limiting ischemia-related risk to the spinal cord and other organs. Despite the formidable challenges that extensive aortic replacement entails, excellent outcomes and a durable repair can be achieved at experienced centers. Here, we describe in detail our current approach to open TAAA repair, which includes providing spinal cord and end-organ protection by the use of surgical adjuncts such as cerebrospinal fluid drainage, mild passive hypothermia (32-33°C nasopharyngeal), left heart bypass, sequential aortic cross-clamping, selective visceral artery perfusion and, whenever possible, reimplantation of segmental arteries and use of cold renal perfusion. We illustrate this approach in a case of Crawford extent II TAAA repair with a branched graft.
Open surgical repair remains the gold standard operation for thoracoabdominal aortic aneurysm (TAAA). These aneurysms can be caused by aortic dissection or by progressive medial degeneration without dissection. Contemporary surgical approaches balance the need to maximize long-term benefit by replacing as much diseased aorta as possible with limiting ischemia-related risk to the spinal cord and other organs. Despite the formidable challenges that extensive aortic replacement entails, excellent outcomes and a durable repair can be achieved at experienced centers. In the largest published series (n = 3309) of open TAAA repairs,
we observed an early mortality rate of 7.5% and low rates of permanent paraplegia (2.9%) and paraparesis (2.4%). Postoperative stroke and permanent renal failure occurred in 2.2% and 5.7% of patients, respectively.
Our technique for open TAAA repair has evolved from the simple unheparinized “clamp-and-sew” approach learned directly from E. Stanley Crawford to our current multimodal strategy, which uses an array of surgical adjuncts. Our strategies for organ protection during TAAA repair have been previously described in detail.
sequential aortic cross-clamping, and selective reimplantation of segmental arteries. The patient's mean arterial pressure is maintained at 70-90 mmHg throughout the case, and the cerebrospinal fluid pressure is maintained at less than 15 mmHg. To minimize ischemic damage to the kidneys, we administer a 4 °C perfusate consisting of lactated Ringer's solution, mannitol (12.5 g/L), and methylprednisolone (125 mg/L) to the renal arteries.
To protect the abdominal organs, we perfuse the celiac axis and superior mesenteric artery with isothermic blood from the left heart bypass circuit.
Operative technique
The Crawford classification (Fig. 1) describes the extent of TAAA repair, with Crawford extent II repairs being the most extensive and therefore incurring the greatest risk of postoperative adverse events. Here, we describe a case of Crawford extent II repair with a branched graft (Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11, Figure 12, Figure 13, Figure 14, Figure 15) to illustrate our current approach to open TAAA repair with the use of surgical adjuncts for spinal cord and end-organ protection. In addition, we provide some examples of alternative reconstructions of the visceral and renal arteries, as well as the distal aorta (Figs. 16 and 17).
Figure 1The Crawford extents of thoracoabdominal aortic aneurysm (TAAA) repair. Extent I repairs involve most or all of the descending thoracic aorta and the upper abdominal aorta. Extent II repairs involve the entire thoracic and abdominal aorta. Extent III repairs begin in the descending thoracic aorta, below the sixth rib, and involve varying portions of the abdominal aorta. Extent IV repairs involve the abdominal aorta below the diaphragm. Used with permission of Baylor College of Medicine.
Figure 2Positioning, prepping, and draping. Immediately prior to positioning, a CSF drainage catheter is inserted. (A, B) The patient is placed on top of a beanbag in a modified right lateral decubitus position, with the shoulders rotated to 60° from horizontal and the hips rotated to 30° from horizontal, which ensures that both groins are accessible. An axillary roll is placed under the patient's right axilla, and the beanbag is suction-deflated and made firm to maintain the patient's position. The patient's left arm is placed on top of an elevated arm board and extended at an angle above the shoulders in a freestyle-swimming-stroke position. (C, D) The patient's left chest and back, abdomen, groins, and upper thighs are prepared and draped in a sterile fashion. An adhesive antimicrobial drape is placed over all exposed skin. ASIS = anterior superior iliac spine; CSF = cerebrospinal fluid.
Figure 3Incision and exposure. (A) A left thoracotomy is made, and the chest is entered through the fifth or sixth intercostal space. The incision is then curved inferiorly and extended across the costal margin and toward the umbilicus. Medial visceral rotation is performed through a transperitoneal approach; electrocautery is used to dissect along the line of Toldt. (B) The diaphragm is divided circumferentially, and a 3- to 4-cm rim of diaphragm is left attached to the lateral and posterior chest wall, with 2-0 silk retraction sutures along the edge of the divided diaphragm.
Figure 4Retraction. A table-mounted retractor is used for stable exposure throughout the procedure. The caudal aspect of the incision is exposed posteriorly and to the left with 2 bladder blades. The cranial aspect of the incision is exposed with a large Richardson retractor under the upper rib and an upper hand retractor under the scapula, both stabilized by the table-mounted ether screen.
Figure 5Aortic exposure and preparation of aortic clamp sites and left heart bypass (LHB). The entire thoracoabdominal aorta is exposed with electrocautery from the left subclavian artery to the aortic bifurcation. Care is taken to identify the origin of the left renal artery and to keep the incision posterior to the left ureter and gonadal vein. The initial proximal and distal clamp sites in the thorax are developed. For patients undergoing Crawford extent II repair, LHB is used to provide isothermic self-oxygenated blood to the distal aorta while the proximal anastomosis is being completed. The return line of the LHB circuit has a Y-connector attached that splits pump return between the line going to the distal aortic cannula and another line leading to two 9-Fr Pruitt balloon-tipped perfusion catheters for later delivery of selective visceral perfusion to the celiac axis and superior mesenteric artery. A separate system is set up with another two 9-Fr Pruitt balloon-tipped perfusion catheters attached to the end of its line for later administration of 4°C cold renal solution to the renal arteries.
Figure 6Venous drainage line of the left heart bypass circuit. Before cannulation, heparin is administered intravenously at a dose of 1.0 mg/kg; the patient's activated clotting time is confirmed to be ≥280 seconds. The pericardium is reflected or opened near the pulmonary veins, away from the phrenic nerve. A 3-0 pledgeted polypropylene suture is placed at the junction of the left atrium and the left inferior pulmonary vein in a mattress fashion. For outflow, the left atrium is cannulated with a 24-Fr angled-tip cannula connected to the venous drainage of the left heart bypass circuit and secured with a Rummel tourniquet.
Figure 7Arterial return line of the left heart bypass circuit. To establish an inflow or arterial return line, a 4-0 pledgeted polypropylene suture is used to secure a 22-Fr angled-tip cannula placed in either the distal descending thoracic aorta or the proximal abdominal aorta (ie, proximal to the left renal artery origin). Selection of the aortic cannulation site is aided by careful examination of the preoperative imaging results to identify and avoid areas with extensive intraluminal thrombus.
Figure 8Preparation and construction of the proximal anastomosis. (A) The proximal clamp site is prepared, and careful attention is paid to preserving the left recurrent laryngeal nerve. If possible, the proximal clamp is placed distal to the left subclavian artery (LSCA) to preserve its contribution to spinal cord blood flow. If there is a large distal arch aneurysm, however, the proximal clamp may have to be positioned between the left common carotid artery and the LSCA. (B) The distal clamp site is most commonly at the junction of the upper and middle thirds of the descending thoracic aorta and is developed anterior to the hemiazygos and intercostal veins. (C) After left heart bypass (LHB) is initiated at a flow of 500 mL/min, a straight, padded aortic cross-clamp is applied to the aorta at the previously prepared site. A Crafoord clamp is applied across the aorta at the distal clamp site. Once the aorta is clamped, the LHB flows are increased to a target of 1.5-2.5 L/min, with a goal mean arterial pressure of 80 mmHg. The proximal aorta is opened between the 2 clamps, and all of the intercostal arteries in this segment are oversewn. (D) The proximal anastomosis is constructed in an end-to-end fashion with 3-0 or 4-0 polypropylene suture. Note the small, stiff bulldog clamp occluding the LSCA.
Figure 9Preparation of the distal aorta. After the proximal anastomosis is complete, left heart bypass is weaned and discontinued. (A, B) The distal aortic clamp is removed, and the thoracoabdominal aorta is opened longitudinally with electrocautery down to the aortic bifurcation, cutting posteriorly to the origin of the displaced left renal artery. Shed blood is collected by a cell-saver system and rapidly auto-transfused back into the patient. (C, D) The distal aortic segment is prepared, any large pieces of thrombus are removed, and the dissecting membrane is excised in patients with chronic dissection.
Figure 10Visceral and renal perfusion. Selective visceral perfusion with isothermic blood is given at a rate of 500 mL/min through 9-Fr Pruitt balloon catheters inserted into the celiac axis and the superior mesenteric artery (SMA). The catheters are connected to the left heart bypass circuit via a Y-branch. To provide cold (4°C) renal perfusion, a separate pump, set of lines, and 2 balloon catheters are connected to a cooling device; 9-Fr Pruitt catheters are placed in the renal arteries, and cold renal perfusion is delivered approximately every 6 minutes at a rate of 300 mL/min for 1-2 minutes. Nasopharyngeal temperature is carefully monitored to avoid hypothermia-induced arrhythmia. Our cooling perfusate consists of mannitol (12.5 g/L) and methylprednisolone (125 mg/L) with lactated Ringer solution.
Figure 11Intercostal artery reattachment. Patent segmental arteries, particularly those between T7 and L2, are carefully inspected; any that are large and have little back-bleeding are chosen for reimplantation, provided that the adjacent aortic tissue is suitable for anastomosis. (A) After specific intercostal arteries are selected for reimplantation, the graft is trimmed appropriately, and a side-to-side anastomosis is begun. (B) To limit back-bleeding, green (3-Fr) balloon occlusion catheters can be placed in the intercostal arteries. (C) The intercostal patch anastomosis is completed, incorporating as little native aortic tissue as possible to reduce the likelihood of a late patch aneurysm. (D) The proximal clamp is reapplied just distal to the intercostal patch anastomosis. To prevent a steal phenomenon of shunting blood away from the spinal cord, vigorously back-bleeding intercostal and lumbar arteries are suture ligated in a figure-of-eight fashion with 2-0 silk sutures.
Figure 12Visceral and renal artery configuration. Patients with extensive atheromatous disease (shown here) and those with chronic dissection may have widely displaced origins of the visceral and renal arteries. The origin of each of these vessels is carefully inspected for stenosis, calcification, or dissection. The dissecting membrane is often excised in cases of chronic dissection. Alternatively, the false channel may be obliterated during the end-to-end anastomosis or with circumferential interrupted fine polypropylene sutures. Stenotic visceral arteries may need endarterectomy, stenting, or both. If necessary, we typically use a 7- × 15-mm balloon-expandable stent (Boston Scientific Corporation, Marlborough, MA) and recommend a postoperative regimen of clopidogrel for 3-6 months. SMA = superior mesenteric artery.
Figure 13Visceral artery patch reimplantation. The configuration of visceral artery reimplantation depends on multiple factors, including the age of the patient, the presence of connective tissue disease, the quality of the aortic tissue, and the distance between the origins of the arteries. In older patients with degenerative aortic disease whose 4 vessels are close to one another, all 4 arteries can be reattached in 1 patch. (A) A common variation is to reimplant the right renal, superior mesenteric, and celiac arteries together and the left renal artery separately. (B) In this configuration, the left renal artery is separated from the aortic wall as a button and mobilized. It is reimplanted onto the aortic graft after the distal anastomosis is constructed, either directly or with an 8-mm graft. Care is taken to ensure that the artery or bypass graft will not kink once the abdominal organs are returned to their anatomical positions.
Figure 14Visceral branch anastomoses with 4-vessel branch graft. In a younger patient with connective tissue disease or a patient whose arterial origins are significantly displaced as in Fig. 12, we use a graft with 4 presewn branches to reimplant each vessel separately.
When using a multibranched graft, we generally perform the distal aortic anastomosis before reattaching the visceral branches; this enables restoration of blood flow to the iliac arteries that provide collateral perfusion to the spinal cord. Then, each of the branches of the graft is trimmed to appropriate length and anastomosed to its corresponding artery. (A) The right renal artery is generally reattached first via the right-sided 8-mm branch in an end-to-end fashion with 5-0 polypropylene. (B) The left renal artery is reattached via the left-sided 8-mm branch. (C) The superior mesenteric artery (SMA) is reattached via the more inferior 10-mm branch. (D) Finally, the celiac artery is reattached via the more superior 10-mm branch. The graft to the SMA remains clamped to avoid celiac back-bleeding during the anastomosis.
Figure 15Distal aortic and limb anastomoses. The location of the distal anastomosis depends on the degree of aneurysmal dilatation of the distal aorta, iliac, and femoral vessels. (A) If the aorta is of adequate quality and caliber proximal to the bifurcation, an end-to-end anastomosis is made at this level. (B) Alternatively, if the vessels beyond the bifurcation are involved, we sew an end-to-end anastomosis to a bifurcated abdominal aortic graft. The limbs of this graft are anastomosed to the common iliac, external iliac, or common femoral arteries, targeting on each side the most proximal level where distal arteries of sufficient quality and caliber are encountered. Flow into the internal iliac arteries is preserved whenever possible.
Figure 16Completed thoracoabdominal aortic repairs. Several examples of completed aortic repairs are depicted. (A) Tube graft sewn to previous elephant trunk graft. (B) Tube graft with direct reimplantation of left renal artery. (C) Bifurcated abdominal graft. (D) Multibranched thoracoabdominal graft. After the aortic replacement is completed, intravenous protamine and indigo carmine are administered to reverse the effect of heparin and assess the adequacy of renal perfusion, respectively. Each anastomosis is inspected for bleeding and repaired as necessary by using reinforcing sutures with felt strips or pledgets. The left atrial cannula is removed, and the venotomy is repaired. The field is irrigated with warm water, and blood products are administered as necessary. Satisfactory perfusion to the abdominal organs and the iliac and femoral arteries is confirmed. The spleen is assessed to ensure that there are no capsular tears or subcapsular hematomas. SMA = superior mesenteric artery.
Figure 17Closure. (A) A 19-Fr closed-suction abdominal drain is placed over the psoas muscle in the upper left retroperitoneum. (B and C) The diaphragm is reapproximated with a continuous #1 polypropylene suture. (D) The thorax is closed with braided #2 pericostal sutures and 2 #7 surgical-steel wires. Two pericostal analgesia catheters are placed along the thoracotomy incision. The abdominal fascia, serratus anterior, and latissimus dorsi are each closed with separate continuous #1 polypropylene suture.
Our approach to open TAAA repair has evolved over several decades and now includes a multimodal strategy of surgical adjuncts based on the extent of aortic repair required and the overall risk of ischemic complications to the spinal cord and abdominal organs. Although extent II TAAA repairs remain challenging, contemporary techniques afford a good outcome and a durable repair in experienced centers.
Disclosures
Dr. Coselli serves as a consultant for Terumo Aortic and receives royalties related to Vascutek Gelweave Coselli thoracoabdominal grafts. Dr. LeMaire has served as a consultant to Vascutek Terumo and has received research support as principal investigator and co-investigator for clinical studies. None of the remaining authors has any potential conflict of interest with regard to the work described in this manuscript.
Acknowledgments
We thank Stephen N. Palmer, PhD, ELS, and Susan Y. Green, MPH, for contributing to the editing of the manuscript. Figures used with permission of Baylor College of Medicine.
References
Coselli JS
LeMaire SA
Preventza O
et al.
Outcomes of 3309 thoracoabdominal aortic aneurysm repairs.
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