Fig. 7.1
Illustration of an open repair of an abdominal aortic aneurysm . This is accomplished through either a transabdominal or retroperitoneal approach. The aneurysm is exposed and the nonaneurysmal aorta above the aneurysm and iliac arteries below the aneurysm are occluded with vascular clamps. The aneurysm is opened longitudinally and an artificial graft is sutured in place. The aneurysmal segment is not typically resected, but the tissue can be wrapped around the graft material providing an additional layer of biologic material (not pictured)
Fig. 7.2
An illustration of an abdominal aortic aneurysm that was repaired with an endograft . The endograft is inserted, in pieces, either through small incisions over the femoral arteries or in a percutaneous fashion. The main body is deployed in the neck of the aorta, below the level of the renal arteries, above the level of the aneurysm. The metal framework of the stent graft provides a radial force that helps it achieve a durable seal and fixation in this location. Extension limbs are then placed that extend into the iliac arteries for a distal seal and fixation
Endovascular abdominal aortic aneurysm repair (EVAR ) has continued to evolve since it was first described in 1991 [1]. The operative technique and technology has undergone several major advancements, and EVAR is now felt to be a safe and feasible alternative to open repair. Three randomized prospective trials have evaluated EVAR compared to open surgery including EVAR1, the Dutch Randomized Endovascular Aneurysm Management (DREAM) trial , and the Open Versus Endovascular Repair (OVER) Veterans Affairs Cooperative Study Group [22–24]. All three were randomized, prospective trials that enrolled patients who were deemed fit to undergo open surgical repair of an AAA to either EVAR or open repair. All three studies demonstrated lower 30-day mortality rates that were lower in the EVAR group (0.5–1.7%) compared to the open surgical arm (3–5%). By 2 years, however, these differences resolved and survival after EVAR and open surgery were similar. Patients undergoing EVAR, however, had shorter hospital stays, had shorter operative durations, and required fewer blood transfusions. EVAR patients did have increased exposure to fluoroscopy and contrast. Given its promising initial results, it is not surprising that EVAR has become increasingly popular over the past decade.
One of the most controversial aspects of AAA repair, however, is when to perform EVAR and when to perform conventional open surgery. Open surgical repair of AAA has long been considered the gold standard, and there is evidence that this option provides good long-term durability [25, 26]. EVAR , however, relative to open surgery, does not have similar time-tested outcomes data. Recently, longer-term outcomes from both EVAR1 and DREAM have been reported [27, 28]. For EVAR1 [27], the median follow-up was 6 years (5–10 year range), and at follow-up the overall aneurysm-related mortality was 1.0 deaths per 100 person-years in the EVAR group and 1.2 deaths per 100 person-years in the open repair group (p = 0.73). All-cause mortality was 7.2 deaths per 100 person-years (EVAR) and 7.1 deaths per 100 person-years (open surgery). Graft-related complication rates were higher in the EVAR group (12.6 per 100-person-years) compared to the open surgical arm (2.5 per 100 person-years, p < 0.001), and significantly more patients in the EVAR group required re-intervention (5.1 per 100 person-years vs. 1.7 per 100 person-years, p < 0.001). In fact, new graft-related complications and re-interventions were reported for as long as 8 years following EVAR. For DREAM [8], at a median follow-up of 6.4 years (5.1–8.2 years), cumulative survival rates were 69.9% for open repair and 68.9% for EVAR. The cumulative rates of freedom from secondary interventions were 81.9% for the open repair group and 70.4% for EVAR (p = 0.03). Based on this data, it is clear that EVAR is not without its drawbacks. These factors may change as the technology improves and as we gain a better understanding of the long-term implications of placing an endovascular graft in the aorta. Given this, there is debate over whether repair with endovascular therapy is as durable as conventional repair, and it is not entirely clear when one approach should be used over another. This is especially true for the aged population in which there may be potentially higher risks associated with major surgery.
7.2.1 Open Repair Versus EVAR in Octogenarians
A recent retrospective study from France looked at patients 85–93 years of age undergoing both EVAR and open AAA repair [15]. This population comprised 6% of all AAA repairs at the authors’ institution during the study period. Fifty-six percent of patients underwent EVAR, 44% underwent an open repair. Thirty-day mortality was 6.7% (6% with EVAR, 7.6% open repair). Although the mortality was similar, perioperative morbidity in the open repair (OR) group was much higher (42% vs. 15%) than in the EVAR group. Complications in the OR group included MI, respiratory insufficiency, renal failure, stroke, and multiple organ failure. The EVAR group had a higher incidence of midterm complications, which was mostly related to appearance of type II endoleak. Overall survival was 53% at 5 years [15]. Perioperative mortality is higher but considered acceptable in octogenarians when looking at both open and endovascular AAA repair when compared to patients <80 years [29]. EVAR is safe in octogenarians, with a 30-day mortality of 1.5% in a large database. Not surprisingly, octogenarians do experience a significantly longer hospital stay [30]. EVAR can be performed with low perioperative mortality leading some to prefer an endovascular approach [31]. Another study showed no significant difference in operative mortality or long-term survival comparing open repair with EVAR, however, which suggests that either approach may be effective in appropriately selected patients [32].
7.2.2 Open Repair Versus EVAR in Nonagenarians
A review of the Nationwide Inpatient Sample Database evaluated mortality in patients >90 years compared to patients 18–89 undergoing AAA repair. Mortality in patients >90 undergoing open AAA repair was 18.3% compared to 4.6% in patients <90. EVAR in nonagenarians carried a 3.1% mortality compared to 1.2% mortality in patients <90. The authors concluded that EVAR in nonagenarians is preferable to open repair. EVAR in nonagenarians was associated with a higher complication rate compared to younger patients in a recent systematic review [33]. Thirty-day mortality was 4%, considerably higher than the 1.8% mortality in the pivotal EVAR trial and 5-year mortality was 17% [27]. Although complications are higher in the >90 group compared to younger patients, EVAR carries substantially lower mortality compared to open repair and should be offered selectively to appropriate surgical candidates.
7.3 Thoracic Aortic and Thoracoabdominal Aortic Aneurysms
Thoracic aortic aneurysms and their relative the thoracoabdominal aortic aneurysms provide an even greater clinical challenge. Conventional open repair remains a major invasive surgical operation with significant inherent risk. This is frequently related to the requirement of a thoracotomy and the subsequent pulmonary morbidity associated with this in those undergoing TAA repair. TAAA repair has the added morbidity of requiring revascularization of the visceral vessels leading to increased rates of post-operative renal failure and spinal cord ischemia. Similar to AAA , endovascular approaches to these pathologies may significantly alter the short-term outcomes and allow for treatment of those patients at high risk for conventional surgery. Pivotal trials analyzing the outcomes of TEVAR for TAA have demonstrated that endovascular approaches demonstrate a marked reduction in 30-day mortality rates [34–36]. This may translate into reduced long-term aneurysm-related mortality, but not all-cause mortality. Whether these results translate to improved outcomes for the elderly will be discussed in more detail below.
7.3.1 Open Descending TAA and TAAA Repair
Conventional surgery for descending TAA (DTAA ) and TAAA has not been limited due to patients’ advanced age, but there are limited analyses of outcomes in the markedly aged population. Di Luozzo and colleagues have reported on the outcomes of septuagenarians and octogenarians undergoing repair of DTAA and TAAA [37]. In this series of 93 patients over a 6-year period of time, 22 (24%) had open repair of DTAA , while 71 (76%) underwent TAAA repair. Perioperative mortality was 13.6% for the DTAA group, while those undergoing more extensive repair had a higher rate of 15.5%. Interestingly, the in-hospital mortality was greater in the septuagenarians (16%) compared to the octogenarians (11%). Factors associated with mortality included pneumonia, tracheostomy, and acute respiratory distress syndrome. Long-term survival was equivalent to that of a normal age- and gender-matched population, and male gender provided a survival benefit. Similarly, Huynh and colleagues evaluated the outcomes of patients over the age of 79 years undergoing DTAR and TAAA repair [38]. A total of 56 patients between the ages of 79 and 88 years of age underwent open repair of the descending thoracic aorta (N = 16, 29%) or thoracoabdominal aortic aneurysms (N = 40, 71%). This represented only 6.6% of the patients undergoing these procedures during that time. Overall 30-day mortality was a striking 25% but was higher in those considered high risk (emergent presentation, diabetes, or congestive heart failure) at 50% compared to those lacking any of these risk factors at 17%. This mortality rate, however, is higher than previously reported for all consecutive patients from this institution (14%) [38]. The mean 5-year actuarial survival rate for this group was 48%. Similar results, however, with a 30-day mortality rate of 21% and a mean survival rate of 61% in patients over 70 years of age, have been reported [39].
7.3.2 Thoracic Endovascular Aneurysm Repair
There are few analyses comparing open repair of DTAA and TEVAR in the markedly aged population. The University of Michigan evaluated outcomes in 93 patients aged 75 years and older undergoing either open (N = 41) or endovascular (N = 52) descending aortic repair between 1993 and 2008 [40]. Selection criteria for entry into this study were indications for operations were identical in both groups, the extent of pathology was confined to the left chest distal to the left carotid artery, and all patients were initially evaluated for open repair by a thoracic surgeon. The option for TEVAR was offered to patients who were deemed high risk for conventional surgery, who had localized pathology, or who specifically requested endovascular repair. Final suitability for TEVAR was determined by a collaborative multidisciplinary team. While the mean age of the whole group was nearly 79 years, the group undergoing TEVAR were older, had smaller thoracic aortic aneurysms, and had a higher incidence of COPD and prior infrarenal AAA repair. The procedure was observed to be elective in only 63% of patients, and contained rupture was more frequently seen in the TEVAR group (26.9% vs. 4.9%, p = 0.005), but a larger proportion of patients undergoing open repaired had an aneurysm involving the distal aortic arch. Technical success was observed in 96% of patients undergoing TEVAR . There was a trend to reduced perioperative mortality in those undergoing TEVAR (5.8% vs. 17.1%, p = 0.1), and the incidence of stroke was the same for both groups (14.6% vs. 9.6%, p = 0.53). Spinal cord ischemia and renal failure were rare events overall. Crude mortality at last follow-up was 45%, and Kaplan-Meier estimates demonstrate no difference between the open and endovascular cohorts. Endoleaks were observed in 23% of the TEVAR group, and five patients had indications for conversion to open surgery but were considered non-operative candidates. The authors concluded that TEVAR may be a more suitable therapeutic option in this complex elderly group.
7.3.3 F/B-EVAR for Juxtarenal and TAAA
Fenestrated and branched endograft repair began in 1999 in patients with infrarenal aortic necks that were too short for traditional EVAR . The technology has evolved to allow for the treatment of juxtarenal AAA to more complex thoracoabdominal aortic aneurysms. These endovascular surgeries allow for a less-invasive approach to complex AAA and TAAA treatment, but add a complexity of requiring preservation of flow to the renal and/or visceral vessels depending upon the extent of the aneurysm undergoing repair. The preservation of flow is accomplished by incorporating fenestrations or branches on a conventional stent graft (Fig. 7.3). These are connected to their target vessels using a self-expanding or balloon-expandable bridging stent graft. While still fairly early in its development, these procedures have been used to treat patients considered high risk for conventional surgery [3].
Fig. 7.3
For more complex, extensive abdominal aortic aneurysms, or for thoracoabdominal aortic aneurysms , in which the disease involves the renal or visceral vessels, fenestrated/branched endograft are used. (a) Typically these are custom-made grafts that incorporate fenestrations (arrow) or directional branches (triangles) to allow for preservation of flow to the renal and visceral arteries. (b) An illustration of a device with two directional branches and two fenestrations used to treat a thoracoabdominal aortic aneurysm. The branches and fenestrations are mated with their corresponding renal or visceral vessels using balloon-expandable or self-expanding bridging stent grafts
A U.S. multicenter trial evaluated fenestrated endograft repair of juxtarenal AAA . Mean age at the time of repair was 74 years and mean aneurysm diameter was 6 cm. Thirty-day mortality was 1.5%. Freedom from all-cause mortality at 5 years was 91%. This multicenter prospective trial showed that fenestrated endograft repair for short-necked AAA can be done with low mortality in experienced hands [41]. Other analyses have analyzed extensive aneurysm repair involving juxtarenal aneurysms as well as TAAA . The French multicenter experience represented a medium-term outcome assessment of prospectively collected data on 134 patients deemed high risk for conventional repair from 16 French academic centers treated between 2004 and 2009 who underwent fenestrated aortic endografting [42]. Unlike the U.S. trial, while the majority of patients were treated for juxtarenal AAA (74%), inclusion of more extensive aneurysms including suprarenal (20%) and type IV TAAA (6%) were included. Median age for this cohort was 73 years (range 48–91 years). Completion angiography confirmed 99% of the target vessels were patent with occlusion of four renal arteries and one celiac artery. Two patients required permanent hemodialysis post-operatively, one related to thrombosis of a renal artery. There was one conversion to open surgery secondary to aortic bifurcation occlusion. The 30-day mortality rate was 2%. Two patients died secondary to multisystem organ failure as a consequence of ruptured iliac artery (N = 1) and conversion to open surgery (N = 1), while one patient suffered a suspected myocardial infarction after discharge. Twelve- and 24-month survival was 93% and 86%, respectively, with no aneurysm-related mortalities.
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