Procedure-specific and late complications of open aortic surgery in adults

INTRODUCTION — 

Repair of the aorta using open surgical techniques may be required for a variety of conditions, most commonly aortic aneurysm or aortic dissection, which can affect the thoracic aorta, the abdominal aorta, or both. The cause of death for most patients following open aortic surgery is multisystem organ failure. For patients who survive surgery, the main cause of death in the long term is cardiovascular disease. Contemporary studies show that survival is improved when surgery is undertaken in centers that care for more of these complex patients as a result of a multidisciplinary team of cardiac and vascular surgeons with established protocols for dealing with complications. Complications in such settings are likely to be recognized and treated earlier. There is a general consensus that the added time to transport a patient to an "aortic center" from a lower volume/experience center for complex aortic surgery is safe and worthwhile.

Complications of open aortic surgery include systemic complications, which are most often related to pre-existing medical conditions, procedure-specific complications related to the conduct of the procedure, and late complications. Systemic complications following open aortic repair are like other major surgical procedures and may include heart failure, acute kidney injury (related hypovolemia), pulmonary insufficiency, and pneumonia. A thorough preoperative evaluation and proper patient selection help to reduce the incidence of systemic complications. The management of these systemic issues is reviewed separately.

Complications of aortic surgery are often ischemic (eg, cardiac, cerebral, visceral, extremity, spinal cord), but may also be related to surgical site infection, venous thromboembolism, and peripheral nerve injury. Late complications include hernia, aortic graft infection, and anastomotic aneurysm/pseudoaneurysm; the latter two are often a delayed consequence of SSI.

Procedure-specific and late complications associated with open aortic surgery are reviewed. Clinical indications and technical aspects of these operations can be found in separate topic reviews.

●(See "Overview of open surgical repair of the thoracic aorta".)

●(See "Surgical and endovascular management of acute type B aortic dissection".)

●(See "Surgical and endovascular techniques for aortic arch branch and upper extremity revascularization".)

●(See "Open surgical repair of abdominal aortic aneurysm".)

OPEN AORTIC SURGERY — 

Open aortic surgery may be indicated for a variety of conditions, most commonly aortic aneurysm (figure 1) or aortic dissection (figure 2A-B), involving the ascending thoracic aorta, but also to manage descending thoracic or abdominal aortic disease that is not amenable to endovascular repair, or to remove an aortic graft or endograft because of infection. (See "Overview of open surgical repair of the thoracic aorta" and "Open surgical repair of abdominal aortic aneurysm".)

Complications of aortic surgery correlate with the extent of open surgical repair. (See 'Greater extent of aortic surgery' below.)

Aortic anatomy and collateral circulation — Knowledge of aortic anatomy is useful for understanding of the potential complications encountered during open surgical repair.

●The aorta begins at the aortic valve (figure 3). The initial segment of the aorta is defined by the aortic valve sinuses and the origins of the two main coronary arteries (figure 4). The sinotubular junction is defined by the transition from the slightly dilated sinus segment to the tubular portion of the ascending aorta. The initial segment of the aorta is contained within the pericardium (figure 5) such that aortic injury, dissection, or rupture may interfere with coronary blood flow, aortic valve functioning, or cause pericardial tamponade.

●In most patients, three aortic branches arise in the transverse segment of the aortic arch: the innominate artery, the left common carotid artery, and the left subclavian artery (figure 6). The most common variants include the so-called "bovine arch" in which there are only two branches and an aortic origin of the left vertebral artery (figure 7). The "bovine" aorta is characterized by a common origin of the innominate artery and the left common carotid artery, and ironically, is not present in cattle.

●The descending thoracic aorta begins at the left subclavian artery and extends to the diaphragm (figure 6), below which it is referred to as the abdominal aorta (figure 8 and picture 1). The abdominal aorta is commonly divided into the visceral segment (containing the origins of the celiac artery, superior mesenteric artery, and the bilateral renal arteries) and the infrarenal aorta, which continues to the aortic bifurcation.

Important sources of collateral circulation that may help reduce the ischemic effects of aortic branch occlusion include the following:

●Circulation to the brain and collateral circulation between the internal carotid artery and external carotid artery (figure 9 and figure 10)

●Collateral circulation around the shoulder (figure 11)

●Collateral circulation of the infrarenal abdominal aorta (figure 12)

●Collateral circulation to the intestines (figure 13)

Extent of aortic surgery — Ascending aortic repair may involve the aortic root. Replacement of the aortic arch may be partial or complete (figure 14A-D).

The extent of open descending thoracic aortic repair is classified as follows:

●Crawford extent I repair – The repair extends from the just distal to the left subclavian artery to the renal arteries (figure 15).

●Crawford extent II repair – The repair extends from just distal to the left subclavian artery to the aortic bifurcation (figure 16). This repair has the highest rate of paraplegia given the number of segmental arteries feeding the spinal cord that may need to be covered.

●Crawford extent III repair – The repair extends from the mid-descending aorta to the aortic bifurcation (figure 17).

●Crawford extent IV repair – The repair extends from just below the diaphragm to the aortic bifurcation (figure 18).

For abdominal aortic repair, either a tube graft, typically extending just below the renal arteries to the bifurcation, or a bifurcated graft to the iliac or femoral arteries are most common.

GENERAL RISK FACTORS — 

Morbidity and mortality following open aortic repair of the thoracoabdominal aorta generally depends on the indication for surgery, patient comorbidities, urgency of repair, and the extent of repair which dictates whether cardiopulmonary bypass (partial, complete) is needed and the location and duration of any aortic clamping.

In one review of 1108 patients, the main predictors associated with an adverse perioperative (30-day) outcome included preoperative chronic kidney disease, older age, symptomatic disease, and Crawford type II aneurysms (proximal descending to infrarenal aorta) [1].

Emergency surgery — Emergency aortic surgery is associated with high mortality rates and is worse for thoracic aortic repair, and particularly ascending aortic repair compared with the descending thoracic aorta or abdominal aorta. In one series, perioperative mortality among 19 patients undergoing emergency thoracoabdominal repair was 42 percent [2]. The incidences of prolonged intubation with controlled ventilation >48 hours, kidney failure, and in-hospital mortality more than doubled after urgent or emergency aortic surgery [3-5].

For elective surgery, mortality rates are lower compared with emergency aortic repair but are generally higher for thoracic compared with abdominal aortic repair. However, morbidity and mortality for repair of the abdominal aorta involving the visceral segment is increased due to the potential for ischemic complications [6]. (See 'End-organ ischemia' below.)

Greater extent of aortic surgery — A greater extent of aortic coverage/replacement is a significant risk factor for increased morbidity and mortality. (See 'Extent of aortic surgery' above.)

The subsets of extensive aortic arch and Crawford type II aneurysms (proximal descending to infrarenal aorta) have the highest morbidity and mortality rates [7-15]. Even higher rates are associated with emergency surgery for thoracoabdominal aneurysm that has ruptured or dissected. (See 'Emergency surgery' above.)

Older patient age and comorbidities — Age is an independent risk factor for death, and older age is often a prohibitive risk for open aortic repair [1]. In a single-institution study, operative mortality for thoracic aortic repair was significantly higher for patients >80 years of age compared with ≤80 years of age (26 versus 7 percent) [16]. Chronic kidney disease (creatinine levels >1.8 mg/dL) is also an independent predictor of death (odds ratio [OR] 3.4, 95% CI 1.4-1.8) [1,10,17,18].

END-ORGAN ISCHEMIA — 

Ischemic complications are related to inadequate perfusion from prolonged reduction in flow or embolism of the brain (stroke), heart (myocardial infarction), spine (paraplegia, paraparesis), viscera (intestinal infarction, acute kidney injury), or extremity (acute limb ischemia).

Cardiac ischemia — The incidence of cardiac ischemia varies depending on the type and extent of the aortic procedure. Cardiac ischemia is most associated with false lumen compression or direct extension of an ascending aortic dissection that involves the coronary artery ostia or with the presence of aortic regurgitation. Cardiac ischemia related to the surgical procedure can be a consequence of hypoperfusion related to cardiopulmonary bypass or aortic clamping, or more directly related to surgical techniques in proximity to the coronary ostia, and rarely, as a direct result of surgical intraoperative myocardial protection.

●A systematic review of 7,629 patients undergoing aortic root and valve replacement (Bentall procedure) reported that 5.9 percent of early mortalities were secondary to myocardial infarction [19].

●A study from the Dutch Surgical Aneurysm Audit reported that among 1657 patients who underwent open surgical repair for AAA, myocardial infarction occurred in 5.6 percent [20]. In the EVAR 1 trial, 40 patients of 626 (7 percent) had a fatal or nonfatal myocardial infarction [21].

Cerebral ischemia — Stroke is another complication that is predominantly associated with proximal aortic surgery. However, stroke can also occur with more distal aortic surgery related to hypoperfusion in those with atherosclerotic carotid artery stenosis. Staged carotid revascularization may be recommended for patients with symptoms and significant stenosis. (See "Management of symptomatic carotid atherosclerotic disease".)

In a systematic review of nearly 175,000 patients undergoing thoracic cardiovascular procedures, the incidence of stroke was 1.4 to 8.7 percent for descending thoracic and thoracoabdominal aortic repair, 3.5 to 5 percent for ascending aortic and aortic arch repair, and 1 percent for aortic valve repair [22].

In past studies documenting outcomes of ascending and arch aneurysm repair, overall 30-day stroke rates were 20 percent [23-25]. Stroke rates have decreased to approximately 3 to 6 percent for elective surgery, and 11 percent after urgent or emergency surgery [3-5,22]. This improvement is attributed, in part, to the contemporary use of cerebral protection strategies.

Spinal cord ischemia — The reported incidence of spinal cord ischemia and subsequent paraparesis/paraplegia complicating aortic surgery varies depending on the extent of the surgical procedure. Spinal cord injury is highest after open repair of extensive thoracoabdominal aortic disease (eg, Crawford type II thoracoabdominal aneurysm (figure 16)) [23-25]. In a series of 1509 patients who underwent open descending thoracic aneurysm repair, paraparesis or paraplegia developed in 16 percent [25]. Spinal cord injury is uncommon after surgical procedures confined to the infrarenal aorta. Spinal cord ischemia increases long-term morbidity and mortality. (See "Spinal cord infarction: Treatment and prognosis".)

Risk factors for spinal cord ischemia include the extent of aortic replacement, coverage/patency of the left subclavian artery, occlusion of the hypogastric arteries, and previous AAA repair. There is some thought that staged repair of extensive thoracoabdominal aortic aneurysm might be protective for spinal cord ischemia.

The management of perioperative spinal cord ischemia depends on whether it occurs intraoperative or postoperatively.

Intraoperative — Neuromonitoring intraoperatively can be challenging and is supplemented with motor- and sensory-evoked potentials to detect spinal cord ischemia. The approach to intraoperative treatment is reviewed separately (algorithm 1) (See "Anesthesia for open descending thoracic aortic surgery", section on 'Neuromonitoring for spinal cord ischemia'.)

Intraoperative measures to reduce spinal cord ischemia include optimizing spinal cord perfusion pressure, selective perfusion of intercostal and lumbar arteries, reimplantation of thoracic intercostal arteries, and distal aortic perfusion. Avoidance of hyperthermia (ie, fever) throughout the postoperative period is important, since even small increases in systemic temperature may exacerbate ischemic neurologic injury [26]. (See "Overview of open surgical repair of the thoracic aorta", section on 'Surgery'.)

Delayed spinal cord ischemia — Spinal cord ischemia is typically identified postoperatively and therefore an early examination and repeated assessments are necessary to diagnose and then rapidly apply protocols that can mitigate and reverse the injury. Signs and symptoms of spinal cord ischemia (ie, paraparesis/paraplegia) can present hours or even several days after surgery [27]. Thus, continued monitoring of neurologic function, mean arterial pressure (MAP), cerebrospinal fluid (CSF) pressure, and temperature is necessary to recognize and treat postoperative spinal cord ischemia [28-30]. If postoperative weakness or paralysis occurs in the immediate postoperative period in a patient with normal pulses, urgent management includes the following measures (algorithm 2) [29,30] (see "Spinal cord infarction: Treatment and prognosis", section on 'Following aortic surgery or endovascular repair'):

●CSF drainage is used to lower CSF pressure to 8 to 12 mmHg. There are several reports of reversal of postoperative paraplegia using this technique [31-36].

●MAP is simultaneously increased to augment spinal cord perfusion; typically, the recommended postoperative range is 80 to 100 mmHg [32,33].

●Optimal oxygen (O₂) delivery to the spinal cord is achieved by maintaining cardiac output and optimal O₂ content in the blood, including normal to high hemoglobin (Hgb) saturation (measured with pulse oximetry) and arterial PaO₂ (measured with arterial blood gases), as well as adequate Hgb levels ≥8 g/dL.

Visceral ischemia — Visceral ischemia is a consequence of aortic clamping. The site and duration of clamping correlate with the location and severity of ischemia.

Acute kidney injury — Kidney dysfunction can result from embolism of debris into the renal arteries or from decreased renal blood flow while mobilizing and clamping the aorta. (See "Clinical presentation, evaluation, and treatment of renal atheroemboli" and "Renal infarction".)

The incidence of kidney dysfunction is greater with suprarenal compared with infrarenal aneurysm aortic cross clamping [37,38]; however, even infrarenal clamping can reduce renal blood flow up to 60 percent of normal. In a retrospective review of 2347 patients, kidney failure occurred in 140 patients (6 percent) [39]. In another review, the incidence of postoperative acute kidney failure severe enough to require dialysis was 7 percent [40].

Risk factors for postoperative kidney failure included age >75, symptomatic AAA, supra/juxtarenal AAA, elevated preoperative serum creatinine, treated hypertension, and respiratory disease. Recognition and prompt management of abdominal compartment syndrome may also reduce the incidence of significant postoperative kidney dysfunction. Patients with postoperative kidney failure had significantly higher 30-day mortality (35.0 versus 4.3 percent).

Intestinal ischemia — Bowel ischemia can affect the small or large intestine.

●Mesenteric ischemia – The incidence of acute mesenteric ischemia involving the small bowel is generally low and is related to the level and duration of aortic clamping and the adequacy of visceral revascularization. For extensive aortic repairs that directly involve the visceral aorta, supplemental perfusion catheters may be used to reduce the incidence of ischemia.

For infrarenal abdominal aortic surgery, the incidence of ischemia involving the small bowel is much lower than ischemia involving the sigmoid colon. Determining the precise incidence of small bowel versus colonic ischemia is complicated by the fact that some datasets do not differentiate the location of the ischemia. The incidence of small bowel ischemia after infrarenal aortic surgery is probably less than 1 percent [41-43]. (See "Acute mesenteric arterial occlusion".)

●Colonic ischemia – The sigmoid colon is the most common site of ischemia following infrarenal aortic surgery. There are conflicting reports regarding the relative risk of colonic ischemia following open or endovascular aortic repair (EVAR). In a large retrospective report from the Society for Vascular Surgery/ Vascular Quality Initiative (SVS/VQI), colonic ischemia was observed in 1.9 percent overall, and the rate was significantly higher for open surgery compared with EVAR (6.2 versus 0.8 percent) [43]. In another report from Europe, the overall prevalence was slightly greater after elective open aortic repair (2.1 to 3.6 percent) than after EVAR (0.5 to 1 percent) [44]. Others have reported the incidence of colonic ischemia is the same for open and endovascular aneurysm repair [45]. The incidence varies greatly depending upon the diagnostic algorithm to detect it [46]. Routine flexible sigmoidoscopy detects more colonic ischemia than selective examination because many patients do not have symptoms, and only 30 percent have bloody diarrhea [46]. (See "Colonic ischemia", section on 'Risk factors'.)

Early postoperative bowel movement (eg, on the day of surgery or the first postoperation day) may be the only sign of possible colon ischemia. A high index of suspicion should lead to immediate flexible sigmoidoscopy to assess the viability of the colonic mucosa. Patients with full-thickness ischemia are treated with colon resection. For partial-thickness ischemia, most surgeons recommend bowel rest, antibiotics to cover typical colon flora, and repeat sigmoidoscopy in one to two days to assess resolution or identify progression. It may be appropriate to consider reimplantation of the inferior mesenteric artery for partial-thickness bowel ischemia that does not require resection. The diagnosis and management of colon ischemia are discussed elsewhere. (See "Colonic ischemia", section on 'Diagnosis' and "Colonic ischemia", section on 'Treatment'.)

Extremity ischemia — Acute limb ischemia (ALI) after aortic surgery is associated with high rates of morbidity and mortality.

In a retrospective review of 11,343 patients undergoing cardiac or thoracic aortic surgery between 2002 and 2012, the incidence of ALI was 1.4 percent [47]. In multivariate analysis, significant risk factors were body surface area (odds ratio [OR] 0.41, 95% CI 0.18-0.92), current smoking status (OR 2.2, 95% CI 1.3-3.7), peripheral artery disease (OR 2.5, 95% CI 1.6-3.7), nonelective operative status (OR 1.9-5, 95% CI 1.2-19.7), use of extracorporeal membrane oxygenation (OR 5.6, 95% CI 2.5-11.6) or intra-aortic balloon pump (OR 4.7, 95% CI 2.9-7.5), and valve operation (OR 2.1, 95% CI 1.1-4).

●Upper extremity ischemia – Symptomatic upper extremity ischemia is rare following open aortic surgery but can be a complication of cannulation, retrograde dissection from a Type B aortic dissection, or alterations of a false lumen, and rarely, coverage by thoracic endograft (eg, hybrid procedure). Many teams monitor radial artery pressures in both arms during these procedures. In the above review, among 16 patients requiring amputation, two were related to upper extremity ischemia [47]. (See "Overview of upper extremity ischemia".)

●Lower extremity ischemia – Lower extremity ischemia may occur due to arterial occlusion due to clamp injury, arterial wall dissection, or thrombosis or thromboembolism distally. Measures to reduce the risk of lower extremity ischemia during open AAA repair include minimizing aortic and iliac artery dissection to the regions that will be clamped, avoiding clamping through thrombus or heavily calcified regions, routinely flushing and irrigating the vessel lumen prior to closure, and assessing femoral and distal extremity pulses prior to leaving the operating room. (See "Clinical features and diagnosis of acute arterial occlusion of the lower extremities".)

OTHER POSTOPERATIVE COMPLICATIONS

Surgical site infection — Surgical site infection (SSI) occurs in about 3 percent of patients following open aortic surgery [48-51]. Measures to prevent infection are important as SSI can lead to aortic graft infection, which requires repeat surgery to manage and is associated with a high mortality rate. (See "Overview of the evaluation and management of surgical site infection" and 'Aortic graft infection' below.)

●Median sternotomy – The incidence of postoperative mediastinitis after sternotomy is 1 to 2 percent. In a review of 18 patients who had a deep sternal wound infection following aortic grafting through a median sternotomy, the mean duration from primary aortic surgery to resternotomy was 24 days and chest wall reconstruction was 31 days [48]. Mortality associated with the infection was 16.7 percent, although no patient died of wound-related causes. (See "Postoperative mediastinitis after cardiac surgery" and "Surgical management of sternal wound complications".)

●Thoracoabdominal incision – In a review from a single institution from 2012 to 2014, the cumulative incidence of SSI following thoracic aortic surgery was 4.1 percent [50]. Staphylococci were the most frequent pathogens isolated. Risk for SSI include longer duration of operation, emergency surgery, and male sex.

●Midline abdominal incision – In a review of patients undergoing open surgery for aortoiliac aneurysm, SSI occurred in 3.8 percent of open repairs [49]. (See "Management of ventral hernias".)

Venous thromboembolism — Most patients undergoing aortic surgery are at moderate-to-high risk for venous thromboembolism based upon age, comorbidities, and procedure duration (table 1). (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)

The reported incidence of venous thromboembolism varies by site and extent of aortic surgery, which correlate with procedure duration and complexity [52-56]. The incidence of venous thromboembolism is higher for cardiac surgery (eg, ascending aorta, aortic valve) compared with the descending or abdominal aorta. In a review of the American College of Surgeons National Surgical Quality Improvement Program database, the overall incidence of deep vein thrombosis was 0.69 percent among nearly 3 million surgical operations from 2005 to 2010 [57]. The incidence of deep vein thrombosis was 2 percent for cardiac surgery, 0.99 percent for vascular surgery, and 0.66 percent for general surgery.

Another database review looked at over 45,000 vascular procedures [58]. Among 361 patients who underwent thoracoabdominal aortic aneurysm repair, the incidence of venous thromboembolism was 4.2 percent, and among 6195 who underwent open abdominal aortic aneurysm (AAA) repair, the incidence was 1.7 percent. Approximately 40 percent of patients were diagnosed following discharge with the diagnosis made at a median of 10 days following surgery. Risk factors for venous thromboembolism included type of surgical procedure, totally dependent functional status, presence of disseminated cancer, postoperative organ/space infection, postoperative cerebrovascular accident, failure to wean from ventilator ≤48 hours and return to the operating room.

Postoperative bleeding — Significant postoperative bleeding requiring urgent or emergency surgical re-exploration occurs in approximately 3 percent of patients after elective thoracic aortic surgery and approximately 10 percent after urgent or emergency surgery (table 2) [4]. Postoperative bleeding can lead to cardiac tamponade and hemothorax, as well as shock, dilutional coagulopathy, and transfusion-related complications. Prevention of postoperative bleeding involves the correction of coagulation defects and obtaining hemostasis in the postbypass period [3]. The use of antifibrinolytic agents and surgical technical advances have reduced the risk [4,59].

Peripheral nerve injury — Peripheral nerve injuries can be related to patient positioning but may also be related to surgical traction. (See "Patient positioning for surgery and anesthesia in adults", section on 'Nerve injury' and "Nerve injury associated with pelvic surgery".)

Several nerves are at risk for injury related to aortic dissection or inadvertent compression by clamps or loops used for vascular control. These types of peripheral nerve injuries (ie, neurapraxia) typically improve with conservative management. (See "Traumatic peripheral neuropathies".)

These include:

●Recurrent laryngeal nerve – The recurrent laryngeal nerve passes around the aorta near the takeoff of the subclavian artery on the left and around the innominate artery on the right (figure 19). Operations involving the distal aortic arch are associated with a risk of injury that may cause hoarseness or vocal cord paralysis, and which can lead to aspiration [3].

●Phrenic nerve – The phrenic nerves descend from the neck into the chest. The left phrenic nerve passes over the thoracic aorta distal to the takeoff of the left subclavian artery (figure 20). The right phrenic artery passes between the subclavian artery and vein (figure 20 and figure 21), descending posterolateral to the superior vena cava (figure 21). The right phrenic nerve can be injured with subclavian artery cannulation for bypass. The phrenic nerve inserts into the diaphragm medially fanning out laterally (figure 22). Injury to the left nerve can occur with division of the diaphragm for exposure during thoracoabdominal aortic repair. Injuries to the phrenic nerve may contribute to postoperative respiratory failure caused by diaphragmatic paralysis. Immediate repair of phrenic nerve injury is recommended if it is identified intraoperatively. (See "Surgical treatment of phrenic nerve injury", section on 'Iatrogenic'.)

●Pelvic autonomic nerve injury – Sexual dysfunction following open AAA repair may be due to pelvic nerve dysfunction as a result of injury to the autonomic nerves with exposure of the aorta at the distal bifurcation (figure 23). In a large retrospective review, 40 percent of patients complained of impotence prior to AAA repair; fewer than 10 percent developed new impotence in the first year following AAA repair.

LATE COMPLICATIONS — 

Some patients may require late reoperation following open aortic surgery.

Following repair of an ascending aorta or aortic root aneurysm, reoperation may be needed because of insufficiency or stenosis of an aortic valve substitute, true or false aneurysm formation, acute dissection, or prosthetic valve endocarditis. In a study of 134 patients who required reoperation, hospital mortality was 6.6 percent [60]. Predictors of death were an interval of less than six months between the first and second operations, elevated preoperative creatinine level and need for postoperative dialysis, and acute aortic dissection as the indication for repeat surgery.

Late complications may also necessitate reoperation following open abdominal aortic surgery. In a retrospective review, 9.5 percent of patients required reoperation after abdominal aortic aneurysm (AAA) repair [61]. The mean time between aortic repairs was 11 years.

Hernia

Ventral hernia — The risk for incisional hernia depends on the indication for open aortic surgery (highest for aneurysm repair), length of incision, and other patient-specific factors.

Incisional hernia is common following open AAA repair [62]. The frequency of incisional hernia following AAA repair is the same for vertical and transverse incisions [63,64]. Using appropriate abdominal wall closure techniques (eg, interrupted suture) helps reduce but may not eliminate the occurrence of incisional hernia [63], owing to a likely global problem with connective tissue integrity that is responsible for aneurysm formation in these patients. Using prophylactic mesh has been suggested for reducing the incidence [65,66].

The incidence of incisional hernia after open AAA repair ranges from 14 to 46 percent, with a typical time for development of two years [62,64]. This rate is much higher compared with overall incidence following midline laparotomy for a variety of reasons, which was 13 percent in a systematic review [67].

Increasing body mass index, length of the incision, chronic obstructive pulmonary disease, and smoking are risk factors for the development of incisional hernia [63,64,68].

In one review, among patients who developed a ventral hernia following open AAA repair, 10 percent required surgery in the first five years [64]. The diagnosis and management of incisional hernia are discussed in detail elsewhere. (See "Overview of abdominal wall hernias in adults", section on 'Ventral incisional hernia'.)

Diaphragmatic hernia — Postoperative iatrogenic diaphragmatic hernia has been reported following various thoracic and upper abdominal surgeries but is overall rare [69-72]. The incidence following thoracoabdominal aortic surgery is unknown. From available case reports, the diagnosis is often delayed [71]. (See "Recognition and management of diaphragmatic injury in adults".)

Aortic graft infection — Aortic graft infection may occur in the early postoperative period following aortic surgery or be delayed by as many as 20 years. Risk factors for aortic graft infection include increasing age, increased duration of surgery, higher American Society of Anesthesiologists (ASA) classification, emergency operation, and surgical site infection (SSI) [73]. Mortality associated with aortic graft infection remains high between 25 and 75 percent and is largely unchanged despite technologic advances in surgical techniques and perioperative care.

●In the thoracic aorta, aortic graft infection occurs in approximately 3 percent [73-77]. Most proximal thoracic aortic graft infections are thought to be a consequence of SSI (ie, sternal wound infection). (See 'Surgical site infection' above.)

●Abdominal aortic graft infection occurs in approximately 0.3 percent of patients undergoing open AAA repair. In a review of 845 patients who underwent aortoiliac reconstruction (open, endovascular), aortic graft infection was highly associated with SSI (odds ratio [OR] 7.10, 95% CI 2.1-24.0) and mycotic aneurysm (OR 9.38, 95% CI 1.8-54.2) [49]. Extension of the aortic graft into the femoral region increases the incidence to as much as 3 percent. Aortic graft infection may also be the cause or consequence of aortoenteric fistula, which is related to erosion of the proximal aortic graft into the small bowel, usually the third portion of the duodenum. (See "Clinical features and diagnosis of abdominal aortic graft or endograft infection" and "Aortoenteric fistula: Recognition and management".)

Management of aortic graft infection depends on the location of the infection. (See "Clinical features and diagnosis of abdominal aortic graft or endograft infection".)

●For ascending or arch thoracic aortic graft infection, the sternotomy is reopened and infected and necrotic tissue are debrided. Subsequently, the mediastinum is packed open and irrigated and antimicrobial dressings are changed every 8 hours until sternal closure can be completed, usually with omental flap overlying the graft [73]. (See "Postoperative mediastinitis after cardiac surgery" and "Surgical management of sternal wound complications".)

●For descending thoracic aortic infection, surgical treatment typically involves removal of the infected graft and in situ replacement with an alternative conduit such as cryopreserved aorta or a rifampin-impregnated polyester graft. In some cases, the thoracic aortic graft is removed and the involved segment ligated and the distal circulation restored via extra-anatomic bypass (eg, axillofemoral graft or ascending aorta to abdominal aorta).

●For infected abdominal aortic grafts, treatment generally requires removal of infected graft material [77]. Blood flow to the lower extremities is provided by extra-anatomic reconstruction (axillofemoral bypass) or in situ reconstruction with autogenous vein (femoral vein), but antibiotic-impregnated grafts, cryopreserved arterial conduits, and endovascular grafting have also been used. The use of prosthetic material is associated with a reinfection rate of 25 percent.

Anastomotic aneurysm/pseudoaneurysm — Anastomotic aneurysms can be true aneurysms due to ongoing degeneration of the aortic wall or false aneurysms (ie, pseudoaneurysms) from disruption of the suture repair between the native aorta and prosthetic material. Anastomotic aneurysm can occur proximally or distally.

Para-anastomotic pseudoaneurysm is one potential late complication following open thoracic aortic repair and usually occurs in the setting of graft infection [78-80]. In the abdominal aorta, proximal anastomotic aneurysms have a propensity to develop when the proximal aortic anastomosis is placed too far inferior to the renal arteries. When anastomotic aneurysms occur at the site of a femoral anastomosis, they are frequently associated with infection.

Conventional treatment requires redo open surgical repair, which is associated with significant morbidity and mortality. Endovascular repair with stent-graft placement is a reasonable option for patients with suitable anatomy to avoid reoperative complications but may be only a temporizing measure, as graft reinfection commonly occurs [81,82]. Similarly, anastomotic aneurysms occurring in the abdominal aorta traditionally required redo surgery for repair; however, relining the original surgical repair with an endograft is an alternative, provided it is anatomically feasible and graft infection has been ruled out.

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Aortic and other peripheral aneurysms".)

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (See "Patient education: Abdominal aortic aneurysm (The Basics)" and "Patient education: Thoracic aortic aneurysm (The Basics)".)

●Beyond the Basics topics (see "Patient education: Abdominal aortic aneurysm (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Open thoracic aortic surgery – Open aortic surgery may be indicated for a variety of conditions, most commonly aortic aneurysm or aortic dissection, involving the ascending thoracic aorta, but also to manage descending thoracic or abdominal aortic disease that is not amenable to endovascular repair, or to remove an aortic graft or endograft because of infection. Open surgery is classified using the Crawford system. (See 'Open aortic surgery' above and 'Extent of aortic surgery' above.)

●Overall incidence of complications and risk factors – Aortic arch and Crawford type II (proximal descending to infrarenal aorta (figure 16)) aneurysms have the highest morbidity rates. Emergency surgery for thoracoabdominal aneurysm that has ruptured or dissected is associated with postoperative complications occurring in approximately 30 percent of patients. Complication rates have overall decreased, possibly attributable to earlier diagnosis, improving technology, and increased use of end-organ protection. (See "Overview of open surgical repair of the thoracic aorta", section on 'Morbidity and mortality'.)

●Ischemic complications – Ischemic complications are related to inadequate perfusion from prolonged reduction in flow or due to embolism and may involve the brain (stroke), heart (myocardial infarction), spine (paraplegia, paraparesis), viscera (intestinal infarction, acute kidney injury), or extremity (acute upper or lower limb ischemia). (See 'End-organ ischemia' above.)

●Surgical site infection/aortic graft infection – Surgical site infection (SSI) occurs in approximately 3 percent of patients following open aortic surgery. Measures to prevent infection are important as SSI can lead to aortic graft infection, which requires repeat surgery to manage and is associated with a high mortality rate. (See 'Surgical site infection' above.)

●Venous thromboembolism – Most patients undergoing aortic surgery are at moderate-to-high risk for venous thromboembolism based on age, comorbidities, and procedure duration (table 1). The reported incidence of venous thromboembolism varies by site and extent of aortic surgery, which correlates with procedure duration and complexity. The incidence of venous thromboembolism is higher for proximal aortic surgery (eg, ascending aorta, aortic valve) at 2 to 4 percent compared with the descending or abdominal aorta at 1 to 2 percent. (See 'Venous thromboembolism' above.)

●Peripheral nerve injury – Peripheral nerve injuries can be related to patient positioning or manipulations during surgery. Several nerves are at risk for injury related to aortic dissection or inadvertent compression by clamps or loops used for vascular control. These include the recurrent laryngeal nerve, the phrenic nerve, and the pelvic autonomic nerves. These types of peripheral nerve injuries (ie, neurapraxia) typically improve with conservative management. (See 'Peripheral nerve injury' above.)

●Late complications – Late complications of aortic surgery, which may necessitate aortic reoperation or other surgery, include the development of hernia, anastomotic aneurysm or pseudoaneurysm, and aortic graft infection. Aortic pseudoaneurysm and aortic graft infection are often a consequence of postoperative SSI, underscoring the importance of appropriate antimicrobial prophylaxis at the time of surgery. (See 'Late complications' above.)