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Executive Summary

Endovascular repair of abdominal aortic aneurysm (AAA) allows the exclusion of the dilated aneurismal segment of the aorta from the systematic circulation. The procedure requires, however, that the endograft extends to the healthy parts of the aorta above and below the aneurysm, yet the neck of a juxtarenal aortic aneurysm (JRA) is too short for a standard endovascular repair. Fenestrated endovascular aortic repair (f—EVAR) provides a solution to overcome this problem by enabling the continuation of blood flow to the renal and visceral arteries through holes or ‘fenestrations’ in the graft. These fenestrations are designed to match the ostial diameter of the renal and visceral arteries.

There are three varieties fenestration, small, large, and scallop, and their location needs to be customized to fit the anatomy of the patient. If the device is not properly designed, if the alignment is inaccurate, or if the catheterization of the visceral arteries is not possible, the procedure may fail. In such cases, conversion to open surgery may become the only option as fenestrated endografts are not retrievable.

It is recommended that a stent be placed within each small fenestration to the target artery to prevent shuttering of the artery or occlusion. Many authors have noted an increased risk of vessel occlusion in unstented fenestrations and scallops.

Once placed in a patient, life-long follow-up at regular intervals is necessary to ensure the graft remains in its intended location, and that the components have adequate overlap. Should the need arise, routine follow-up allows the performance of timely and appropriate intervention through detection of events that could impact the long-term outcomes.

Alternative Technology

The technique of fenestrated endovascular grafting is still in evolution and few studies have been with published mid-term outcome data. As the technique become more common in vascular surgery practices, it will be important to determine if it can provide better outcomes than open surgical repair (OSR).

In an OSR approach, aortic clamping above one or both renal arteries, or above the visceral arteries, is required. The higher the level of aortic clamping, the greater the risk of cardiac stress and renal or visceral ischemia. During suprarenal or supraceliac aortic clamping, strain-induced myocardial ischemia may also occur due to concomitant rise in cardiac afterload and a decrease in cardiac output. Reports indicate that 6% of patients undergoing surgical repair develop myocardial infarction. The ideal level of clamp location remains controversial with conflicting views having been reported.

Method

A search of electronic databases (OVID MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, The Cochrane Library, and the International Agency for Health Technology Assessment [INAHTA] database was undertaken to identify evidence published from January 1, 2004 to December 19, 2008. The search was limited to English-language articles and human studies. The automatic search alerts were received and reviewed up to March 23, 2009.

The literature search and automatic search update identified 320 citations, of which 13 met inclusion/exclusion criteria. One comparative study presented at an international seminar, five single-arm studies on f—EVAR, and 7 studies on OSR (one prospective and six retrospective) were considered for this analysis.

To grade the strength of the body of evidence, the grading system formulated by the GRADE working group and adopted by MAS, was applied. The GRADE system classifies evidence quality as high (Grade A), moderate (Grade B), or low (Grade C) according to four key elements: study design, study quality, consistency across studies, and directness.

A summary of the characteristics of the f—EVAR and OSR studies found through the literature search is shown in Table ES-1.

Patient Characteristics: f–EVAR Studies versus OSR Studies

JRA, Juxtarenal aortic aneurysm; SRA, Suprarenal aortic aneurysm; TAA, Thoracic aortic aneurysm

Mortality Outcomes

The pooled estimate for 30-day mortality was 1.8% among the f—EVAR studies and 3.1% among the OSR studies that reported data for the repair of JRA separately. The pooled estimate for late mortality was 12.8% among the f—EVAR studies and 23.7% among the OSR studies that reported data for JRA separately.

Visceral Artery Events Reported in f—EVAR Studies

Renal Events during f-EVAR

A total of three main renal arteries and two accessory renal arteries became occluded during the procedure. These were all due to technical issues, except one accessory renal artery in which the artery was intentionally covered. One patient required open surgery following the procedure.

Renal Events During the follow-up

A total of 12 renal arteries (12 patients) were found to be occluded during follow-up. In two patients, the same side accessory renal artery was also occluded. Four (1.5%) patients lost one kidney and five (2.3%) patients underwent dialysis, three (1.4%) of which became permanent.

A total of 16 cases of renal artery stenosis (16 patients) occurred during follow-up. Eight of these were treated and eight were observed. Segmental renal infarcts were found in six patients but renal function was not impaired.

Mesenteric Events during f-EVAR

Three mesenteric events occurred during the f—EVAR procedures resulting in two deaths. One patient developed bowel ischemia due to embolization of the superior mesenteric artery (SMA); this patient died 13 days after the procedure from multiorgan failure. One patient died eights days after the procedure from mesenteric ischemia and bowel perforation. The third SMA event occurred during surgery with subsequent occlusion in early follow-up.

Mesenteric Events during Follow-up

During follow-up, five (1.8%) SMA occlusions/partial occlusions and one SMA stenosis were noted. Three of the five patients with SMA occlusion/partial occlusion remained asymptomatic and no further intervention was necessary. One patient underwent SMA bypass surgery and in two patients, the problem solved by SMA stenting. A summary of the outcomes reported in the f—EVAR and OSR studies is shown in Table ES-2.

Summary of Outcomes: Fenestrated Endovascular Graft Versus Open Surgical Repair for Treatment of Juxtarenal Aortic Aneurysm

Summary

Short- and medium-term results (up to 2 years) of f—EVAR for the repair of JRA showed that outcomes in f—EVAR series compare favourably with the figures for the OSR series; however, uncertainty remains regarding the long-term results. The following observations are based on low quality evidence.

F—EVAR has lower 30-day mortality than OSR (1.8% vs. 3.1%) and a lower late-mortality over the period of time that patients have been followed (12.8% vs. 23.7%).

There is a potential for the loss of target vessels during or after f—EVAR procedures. Loss of a target vessel may lead to loss of its respective end organ. The risk associated with this technique is mainly due to branch vessel ischemia or occlusion (primarily among the renal arteries and SMA). Ischemia or occlusion of these arteries can occur during surgery due to technical failure and/or embolization or it may occur during follow-up due to graft complications such as graft migration, component separation, or arterial thrombosis. The risk of kidney loss in this series of f—EVAR studies was 1.5% and the risk of mesenteric ischemia was 3.3%. In the OSR studies, the risk of developing renal insufficiency was 14.4% and the risk of mesenteric ischemia was 2.9%.

F—EVAR has a lower rate of postoperative cardiac and pulmonary complications.

Endoleak occurs in 22.5% of patients undergoing f—EVAR (all types) and about 8% of these require treatment. Most of the interventions performed to treat such endoleaks conducted using a minimally invasive approach.

Due to the complexity of the technique, patients must be appropriately selected for f—EVAR, the procedure performed by highly experienced operators, and in centers with advanced, high-resolution imaging systems to minimize the risk of complications.

Graft fenestrations have to be custom designed for each patient to fit and match the anatomy of their visceral arteries. Planning and sizing thus requires scrutiny of the target vessels with a high degree precision. This is important not only to prevent end organ ischemia and infarction, but to avoid prolonging procedures and subsequent adverse outcomes.

Assuming the average cost range of FEVAR procedure is $24,395-$30,070 as per hospital data and assuming the maximum number of annual cases in Ontario is 116, the average estimated cost impact range to the province for FEVAR procedures is $2.83M-$3.49M annually.

Open repair of thoracoabdominal aortic aneurysm is connected with high mortality and morbidity. On the other hand, endovascular treatment of thoraco-abdominal aneurysms, which started 10 years ago, reduced perioperative mortality and morbidity. However, it results in a high level of late complications. It seems that an interesting solution to the problem is a hybrid procedure, which allows late complications to be reduced with acceptable levels of operative mortality and morbidity. This case report presents the use of a hybrid procedure in treatment of symptomatic thoraco-abdominal aneurysm in a patient with prior abdominal aortic reconstruction. In the first stage the patient underwent open revascularization of visceral vessels of the aorta. One week later a thoraco-abdominal stent-graft was implanted. The perioperative and postoperative period was uncomplicated. Two months after the second intervention the patient returned to work. Control imaging conducted 30 and 90 days after the procedure confirmed patency of all revascularized vessels and did not reveal any graft-related complications. The hybrid procedure seems to be an interesting alternative for open and endovascular repair of thoraco-abdominal aneurysms because it combines the advantages of open and endovascular repair. It also gives an opportunity to perform the procedure within a reasonable period of time from diagnosis of symptomatic thoraco-abdominal aneurysm.

Suprarenal or supraceliac aortic clamping during repair of infrarenal abdominal aortic aneurysms can be complicated by renal, hepatic, and intestinal ischemia. To determine whether suprarenal or supraceliac clamping increases morbidity and mortality, we retrospectively reviewed our recent nonrandomized experience. Between January 1993 and December 1998, 716 patients underwent elective (n=682) or urgent (n=34) infrarenal abdominal aortic aneurysm repair. Infrarenal clamping was used in 516 (72.1%) and suprarenal or supraceliac clamping in 200 (27.9%). The suprarenal/supraceliac group had significantly more older patients (≥70 years of age) (65.5% vs 47.7%) and a higher incidence of preoperative renal insufficiency (7.5% vs 5.5%). Suprarenal or supraceliac clamping was used during repair of ruptured (n=25), juxtarenal (n=7), or inflammatory abdominal aortic aneurysms (n=4); during concomitant renal or visceral revascularization (n = 43); in other difficult settings (n=13); or at the surgeon's discretion (n=108). The decision for such clamping was always made during surgery. In treating ruptured aneurysms, suprarenal/supraceliac clamping (25/200) was used more often than infrarenal clamping (9/516) (12.5% vs 1.74%). Operative times were similar in both groups, but transfusion requirements and length of hospital stay were slightly greater in the suprarenal/supraceliac group. Perioperative mortality was 3.1% overall, but higher in the suprarenal/supraceliac group than in the infrarenal (7.5% vs 1.4%). Postoperative complications developed in 26 (13%) of patients who underwent suprarenal/supraceliac clamping. Abdominal re-exploration was required in 9 other patients. We conclude that, despite associated comorbidities, elective suprarenal/supraceliac clamping during infrarenal abdominal aortic aneurysm repair is safe, facilitates repair, and does not significantly increase mortality. (Tex Heart Inst J 2001;28:254–64)

Purpose

Despite significant improvements in surgery, anesthesia, and postoperative critical care, the postoperative mortality rate of ruptured abdominal aortic aneurysm (RAAA) has remained at 40% to 50% for several decades. Therefore, we evaluated factors associated with the postoperative mortality of RAAA.

Materials and Methods

From January 1999 to December 2008, a retrospective study was performed with 34 patients who underwent open repair of RAAA. The preoperative factors included age, sex, smoking, comorbidities, serum creatinine, hemoglobin, shock, pulse rate, and time from emergency room to operation room. The intraoperative factors included blood loss, transfusion, aortic clamping site and time, aneurysmal characteristics, rupture type, graft type, hourly urine output (HUO), and operative time. The postoperative factors included inotropic support, renal replacement therapy (RRT), reoperation, bowel ischemia, multiple organ failure (MOF), and intensive care unit stay. The 2-day and the 30-day mortality rates were analyzed separately.

Results

The 2-day and the 30-day mortality rates were 14.7% and 41.2%, respectively. On univariate analysis, shock, transfusion, HUO, inotropic support and MOF for the 2-day mortality and serum creatinine, transfusion, aortic clamping site, HUO, inotropic support, RRT and MOF for the 30-day mortality were statistically significant. On multivariate analysis, shock, inotropic support and MOF for the 2-day mortality and aortic clamping site, RRT and MOF for the 30-day mortality were statistically significant.

Conclusion

To decrease the postoperative mortality rate of RAAA, prevention of massive hemorrhage and acute renal failure with infrarenal aortic clamping, as well as prompt operative control of bleeding and maintenance of systemic perfusion are important.

Background

Aortic pathology progression and/or procedure related complications following endovascular repair should always be considered mostly in older patients. We herein describe a hybrid procedure for treatment of rapidly expanding thoracoabdominal aneurysm following endovascular treatment of a descending thoracic aortic aneurysm in an older patient.

Case presentation

A 82-year-old man at 18 months after endovascular surgery for a contained rupture of descending thoracic aortic aneurysm revealed a type IV thoracoabdominal aneurysm with significant increase of the aortic diameters at superior mesenteric and renal artery levels. A hybrid approach consisting of preventive visceral vessel revascularization and endovascular repair of entire abdominal aorta was performed. Under general anaesthesia and by xyphopubic laparotomy, the infrarenal aneurysmatic aorta and common iliac arteries were replaced by a bifurcated woven prosthetic graf. From each of the prosthetic branches two reverse 14x7 mm bifurcated PTFE prosthetic grafts were anastomized to both renal arteries and to the celiac axis and superior mesenteric artery, respectively. Vessel ischemia was restricted to the time required for anastomosis. Three 10 cm Gore endovascular stent-grafts for a total length of 15 cm, were used. The overlapping of the stent-grafts was carried out from the bottom upwards, starting from the aorto-iliac prosthetic body up to the healthy segment of thoracic aorta, 40 mm from the previous stent-grafts.

The patient was discharged on the 9th postoperative day.

Conclusion

This technique offers the advantage of a less invasive treatment, reducing the risk of paraplegia, visceral ischaemia and pulmonary complications, mostly in older patients.

INTRODUCTION:

A case of thoracic-abdominal dissection after open surgical exclusion of an infrarenal aortic aneurysm is presented.

CASE PRESENTATION:

A 62-year-old woman was diagnosed with an infrarenal abdominal aortic aneurysm with a rapid increase in maximal diameter. She underwent surgery for aneurysm exclusion by an end-to-end aortoaortic bypass with Dacron collagen (Intervascular; WL Gore & Associates Inc, USA). After 15 days, she was admitted to the emergency department with intense epigastric and lumbar pain. Computed tomography angiography with contrast revealed an aortic dissection with origin in the proximal bypass anastomosis and cranial extension to the thoracic aorta. The true lumen at the level of the eighth thoracic vertebra was practically collapsed by the false lumen. The celiac trunk, and the mesenteric and renal arteries were perfused by the true lumen. After the acute phase of the aortic dissection, surgical repair was planned. Two paths of false lumen were found – one at the thoracic aorta and the second in the proximal bypass anastomosis. Surgical repair comprised two approaches. First, a Valiant Thoracic stent graft (Medtronic Inc, UK) was implanted distal from the left subclavian artery, expanding the collapsed true lumen and covering the false and dissected lumen. Second, an infrarenal Endurant abdominal stent graft (Medtronic Inc) was implanted. This second device was complemented with an aortic infrarenal extension using a Talent abdominal stent graft (Medtronic Inc) in the infrarenal aortic neck to achieve a hermetic seal. The postoperative clinical course was uneventful, and her symptoms were completely resolved in six months.

CONCLUSION:

Arteritis must be taken into account in young patients with high inflammatory markers. Covered stents and endoprosthetic devices seem to be effective methods to seal the dissected lumen.

Purpose

Open infrarenal abdominal aortic aneurysm (AAA) repair is performed without event in most cases. However, some patients suffer major morbidities such as renal failure, myocardial infarction, paraplegia, acute respiratory distress syndrome, or hepatic dysfunction. Predicting what kinds of patient populations are more prone to develop such complications may keep the clinicians more attentive to the patients, possibly leading to better prognoses. In this retrospective study, we searched the incidence of and risk factors for postoperative complications and their predictive equations in 162 patients who underwent open infrarenal AAA repair.

Materials and Methods

Postoperative complications were observed within 30 days. Patient characteristics, types of aneurysm and surgery, and hemodynamic and metabolic variables during the periclamp period were analyzed in relation to postoperative complications using multiple logistic regression analysis.

Results

Postoperative complications involved the cardiac (20%), pulmonary (14%), renal (13%), gastrointestinal (6%), hepatic (3.1%), and neurologic (2.5%) systems, and bleeding occurred in 1.2% of cases. The mortality rate was 5.6%. The risk factors were age [> 67 yrs, odds ratio (OR) 2.6], clamp duration (> 110 min, OR 4.7), volume of blood transfusion (> 1,280 mL, OR 4.4), emergency operation (OR 1.4), and vasopressor infusion during clamp (OR 1.4). The prediction model was: P(x) = exp(α)/[1 + exp(α)] α;-2.2 + 0.9 × age + 1.5 × clamp duration + 1.5 × transfusion + 0.3 × emergency + 0.4 × vasopressor infusion [insert 1 if risk factors exist, otherwise, insert 0 to each variable].

Conclusion

A significant number of complications occurred after infrarenal AAA repair. Therefore, creating a protocol to identify and monitor high risk patients would improve postoperative care.

Fenestrated endovascular repair of an abdominal aortic aneurysm has been developed to treat patients with a short or complicated aneurysm neck. Fenestration involves creating an opening in the graft fabric to accommodate the orifice of the vessel that is targeted for preservation. Fixation of the fenestration to the renal arteries and the other visceral arteries can be done by implanting bare or covered stents across the graft-artery ostia interfaces so that a portion of the stent protrudes into the aortic lumen. Accurate alignment of the targeted vessels in a longitudinal aspect is hard to achieve during stent deployment because rotation of the stent graft may take place during delivery from the sheath. Understanding the 3D relationship of the aortic branches and the fenestrated vessel stents following fenestration will aid endovascular specialists to evaluate how the stent graft is situated within the aorta after placement of fenestrations. The aim of this article is to provide the 2D and 3D imaging appearances of the fenestrated endovascular grafts that were implanted in a group of patients with abdominal aortic aneurysms, based on the multislice CT angiography. The potential applications of each visualization technique were explored and compared with the 2D axial images.

Renal transplant recipients requiring aortic reconstruction due to abdominal aortic aneurysm (AAA) pose a unique clinical problem. The concern during surgery is causing ischemic injury to the renal allograft. A variety of strategies for protection of the renal allograft during AAA intervention have been described including a temporary shunt, cold renal perfusion, extracorporeal bypass, general hypothermia, and endovascular stent-grafting. In addition, some investigators have reported no remarkable complications of the renal allograft without any specific measures. We treated a case of AAA in a patient with a renal allograft using a temporary aortofemoral shunt with good result. Since this technique is safe and effective, it should be considered in similar patients with AAA and previously placed renal allografts.

Retroperitoneal fibrosis is associated with fibroblast proliferation due to inflammatory changes in adipose/fibrous tissue. Given that aortic dilation in abdominal aortic aneurysm can cause compression of the ureter, abdominal aortic aneurysm complicated by retroperitoneal fibrosis is likely to result in urinary tract obstruction. Accordingly, close attention to changes in perioperative urine volume is warranted when operating on patients with abdominal aortic aneurysm complicated by retroperitoneal fibrosis. We have recently performed laparotomies on two cases of abdominal aortic aneurysm complicated by retroperitoneal fibrosis. In the first case, surgery was performed without the placement of a ureteral stent. The patient developed postrenal acute renal failure caused by postoperative urinary retention. In the second case, ureteral stent placement in advance enabled perioperative management without complications. The clinical course of these cases suggests that, in laparotomy with concomitant retroperitoneal fibrosis, preoperative ureteral stent placement can prevent postoperative complications in the renal and urinary systems.

ABSTRACT

The emergence of endovascular repair of the thoracic aorta (TEVAR) quickly followed the development of technology for the exclusion of infrarenal abdominal aortic aneurysms. Stent grafts comprised of metal struts covered with fabric made of Dacron/polyester or polytetrafluoroethylene were developed for the purpose of achieving an adequate seal at the proximal and distal aspects of thoracic aneurysms, thus excluding sac flow. The recognition of the decreased morbidity of this approach compared with open repair was readily apparent, as it avoided left thoracotomy, aortic cross-clamping, and left heart bypass. Since then, TEVAR is increasingly being used for other aortic pathologies such as complicated type B dissection, traumatic aortic transection, and aneurysmal disease extending into the arch or visceral segment, requiring debranching procedures.

The Leicester experience of treatment of aortic aneurysms indicates that workload is increasing. Despite an increase in elective repairs, the number of ruptured abdominal aortic aneurysms is also increasing. The mortality of ruptured abdominal aortic aneurysm remains static despite advances in critical care medicine. Multi-organ failure is the commonest cause of death following ruptured abdominal aortic aneurysm and the systemic inflammatory response syndrome, ischaemia-reperfusion injury and activation of inflammatory pathways are important precursors. Organ failure, reperfusion injury and inflammatory pathway activation can be studied at a cellular and biochemical level in animal models of aortic cross-clamping. The nitric oxide response is an important component of the inflammatory response and augmentation of the NO response may protect against renal injury caused by aortic cross-clamping during aortic aneurysm repair.

The present study aimed to evaluate the diagnostic reliability of computed tomography in determining the proximal extent of abdominal aortic aneurysms and the possibility of infrarenal clamping.

Preoperative computed tomographic findings, together with the operative data for 95 patients, were retrospectively analyzed in light of the operative findings. Eighty-nine (93.68%) of the patients were men and 6 (6.32%) were women, with a mean age of 66.27 ± 18.14 years.

Diagnosis of infrarenal aneurysm by computed tomography was confirmed at the time of surgery in 91 (95.79%) of 95 patients. The negative-predictive value of computed tomography in detecting supra-aneurysmal renal arteries was found to be 95.79%. The specificity was 98.91%. Infrarenal cross-clamping was performed in 59 (62.11%) of 95 patients, whose aortic segments between the renal artery orifices and the proximal borders of the aneurysms had a mean length of 26.4 ± 7.11 mm by computed tomography. Suprarenal clamping was required in 36 (37.89%) of the 95 patients, whose aortic segments had a mean length of 12.7 ± 3.48 mm.

We conclude that conventional computed tomography is reasonably accurate in determining the proximal extent of abdominal aortic aneurysms. Although there is a high rate of error in determining the possibility of infrarenal clamping when no specific measurements are taken, infrarenal clamping can be planned when measurement by computed tomography shows a length of ≥26 mm between the renal arteries and the proximal extent of the aneurysm. In patients with shorter aortic segments, suprarenal aortic clamping should be considered. (Tex Heart Inst J 2002;29:172–5)

To determine the effects of beating heart surgery on patients undergoing simultaneous coronary artery bypass grafting and abdominal aortic surgery, we performed such surgery on 20 patients (mean age, 64.55 ± 7.96 SD years). Abdominal aortic disease was defined as an abdominal aortic aneurysm larger than 5 cm in diameter or as end-stage aortic occlusive disease. Hemodynamic measurements, inotropic requirements, and incidence of perioperative myocardial infarction and arrhythmias were recorded, as were subsystem clinical outcomes, length of intensive care unit and hospital stays, blood loss, and transfusion requirements.

There was no incidence of death, perioperative myocardial infarction, stroke, or acute renal failure. The mean number of grafts per patient was 1.95 ± 0.69. Only 4 minor postoperative complications were observed: three patients (15%) had evidence of supraventricular tachyarrhythmias, and 1 patient (5%) had chest infection that required a longer-than-average intubation period. Six patients (30%) required minimal-to-moderate inotropic support. The mean blood loss was 673 ± 246.8 mL and transfusion requirements were low. The mean intensive care unit and hospital lengths of stay were 2.12 ± 0.33 days and 7.08 ± 1.44 days, respectively. Clinical follow-up (mean, 10 months) showed all patients to be in New York Heart Association functional class I or II with no late cardiac or abdominal events.

We conclude that simultaneous coronary artery bypass grafting and abdominal aortic surgery on the beating heart is safe and effective, and has a low perioperative clinical morbidity rate. To our knowledge, ours is the 1st report on this procedure. Larger studies with longer follow-up are needed.

Introduction

An aortoenteric fistula is a communication between the aorta and an adjacent loop of the bowel. Here we report a case with this rare complication with typical herald bleeding.

Case report

A 66-year-old man underwent elective repair of a large supra-renal abdominal aortic aneurysm and returned 6 months later to our clinic after experiencing a melena with hematochezia. The source of bleeding could not be identified by gastroscopy but the following day he vomited a large volume of blood, rapidly became haemodynamically unstable and died of hypotensive shock. A CT scan on the same day showed an increasing area of low-density soft tissue around the graft wall compared with the previous CT scan images obtained initially after the aortic repair. An aortoenteric fistula was confirmed by autopsy.

Conclusion

In patients that underwent abdominal aortic surgery, both the occurrence of herald bleeding and CT findings of increasing para graft soft tissue might play a crucial role in early detection of aortoenteric fistula.

The repair of abdominal aortic aneurysm (AAA) in patients with functioning renal transplant is critical because it is important to avoid ischemic and reperfusion injury to the transplanted kidney. Endovascular aneurysm repair (EVAR) avoids aortic cross clamping and can prevent renal graft ischemia. Here we report the endovascular management and outcome of AAA in two renal transplant patients using a bifurcated aortic stent graft. One patient underwent EVAR using a small amount of contrast (30 mL) due to decreased renal function resulting from chronic rejection. Another patient had EVAR performed with iliac conduit because of the heavily calcified, stenotic lesion of external iliac artery. EVAR in patients with a renal transplant is a feasible option without impairing renal arterial flow.

Paraplegia secondary to spinal cord ischemia is a devastating complication in operations on the descending and thoracoabdominal aorta. We hypothesized that the tolerance of the spinal cord to an ischemic insult could be improved by means of regional administration of lidocaine. Thirty-one New Zealand white rabbits were anesthetized and spinal cord ischemia was induced by the placement of clamps both below the left renal vein and above the aortic bifurcation. The animals were divided into 5 groups. Aortic occlusion time was 20 minutes in Group 1 and 30 minutes in all other groups. Groups 1 and 2 functioned as controls. Lidocaine (Group 5) or normal saline solution (Group 3) was infused into the isolated aortic segment after cross-clamping. Group 4 animals received 20% mannitol regionally, before and after reperfusion. Postoperatively, rabbits were classified as either neurologically normal or injured (paralyzed or paretic). Among controls, 20 minutes of aortic occlusion did not produce any neurologic deficit (Group 1: 0/4 injured), while 30 minutes of occlusion resulted in more consistent injury (Group 2: 6/8 injured). Animals that received normal saline (Group 3) or mannitol (Group 4) regionally showed 80% neurologic injury (4/5). Animals treated with the regional lidocaine infusion (Group 5) showed much better neurologic outcomes (7/9 normal: 78%). This superiority of Group 5 over Groups 2, 3, and 4 was significant (P < 0.02). We conclude that regional administration of lidocaine reduced neurologic injury secondary to spinal cord ischemia and reperfusion after aortic occlusion in the rabbit model.

Historically, open surgical repair of thoracoabdominal aortic aneurysms has been associated with high morbidity and mortality rates. Furthermore, endovascular exclusion alone can restrict blood flow to visceral arteries. We report a case of thoracoabdominal aortic aneurysm that was repaired using a hybrid approach: surgery followed by an endovascular procedure. A 53-year-old woman was admitted to our hospital for endovascular exclusion of a thoracoabdominal aortic aneurysm that included the superior mesenteric artery and the celiac artery. Aorto–mesenteric and aorto–celiac artery bypass grafting was performed to create a landing zone for subsequent endovascular exclusion of the aneurysm, which was completed successfully 6 weeks after the bypass procedure.

For thoracoabdominal aortic aneurysms that extend beyond the superior mesenteric artery and the celiac or renal arteries, a hybrid approach, consisting of limited surgical treatment followed by endovascular exclusion of the aneurysm, may yield optimal results in selected patients with serious preoperative comorbidities.

In the surgical treatment of abdominal aortic aneurysm, the single proximal cross-clamp can be placed at 3 alternative aortic levels: infrarenal, hiatal, and thoracic. We performed this retrospective study to evaluate the advantages and disadvantages of the 3 main aortic clamping locations. Eighty patients presented at our institution with abdominal aortic aneurysms from March 1993 through May 1998. Fifty of these patients had intact aneurysms and underwent elective surgery, and 30 had ruptured aneurysms that necessitated emergency surgery. Proximal aortic clamping was applied at the infrarenal level in 24 patients (22 from the intact aneurysm group, 2 from the ruptured group), at the hiatal level in 34 patients (22 intact, 12 ruptured), and at the thoracic level (descending aorta) via a limited left lateral thoracotomy in 22 patients (6 intact, 16 ruptured). Early mortality rates (within 30 days) were 4% (2 of 50 patients) among patients with intact aneurysms and 40% (12 of 30 patients) among those with ruptured aneurysms. In the 2 patients from the intact aneurysm group, proximal aortic clamps were applied at the hiatal level. In the ruptured aneurysm group, proximal aortic clamps were placed at the thoracic level in 10 patients, the infrarenal level in 1, and the hiatal level in 1. According to our study, the clinical status of the patient and the degree of operative urgency--as determined by the extent of the aneurysm--generally dictate the proximal clamp location. Patients who present with aneurysmal rupture or hypovolemic shock benefit from thoracic clamping, because it restores the blood pressure and allows time to replace the volume deficit. Infrarenal placement is advantageous in patients with intact aneurysms if there is sufficient space for the clamp between the renal arteries and the aortic aneurysm. In patients with juxtarenal aneurysms, hiatal clamping enables safe and easy anastomosis to the healthy aorta. Clamping at this level also helps prevent late anastomotic aneurysm formation, which is frequently encountered after inadvertent anastomosis of the graft to a diseased portion of the aorta. Further studies are needed in order to confirm these results.

Introduction

Surgical repair of an aortic aneurysm might be complicated by spinal cord injury and paraplegia. Since β-adrenoreceptor agonists showed neuroprotective effects, the study was designed to investigate the effect of clenbuterol on post-aortic clamping paraplegia and to identify if there is hyperemia associated with paraplegia.

Material and methods

Material and methods: Thirty rabbits were divided into two groups: 15 control and 15 experimental (given clenbuterol 9 mg in drinking water 24 h prior to surgery). All the animals were subjected to laparotomy whereas the abdominal aorta was identified. Using a vascular clamp, the abdominal aorta was clamped just distal to the renal arteries. Abdominal aortic blood flow was recorded with a transonic flow meter. The neurological assessment was made according to Tarlov’s Neurological Scale upon recovering from anesthesia. Anal sphincter tonus and bladder sphincter function were also checked.

Results

Four rabbits (2 control and 2 experimental) developed complete paraplegia within 30 min of cross-clamping of the aorta. Of the 13 controls, 77% developed paraplegia, and of the 13 experimental rabbits administered clenbuterol 24 h prior to surgery with 22 min of aortic cross-clamping, 38% developed paraplegia The rabbits which did not develop paraplegia had a minimal increase in aortic blood flow, whereas the rabbits which developed paraplegia had a significant increase in aortic blood flow measurements after aortic decamping.

Conclusions

Post-aortic clamping paraplegia is associated with hyperemia and clenbuterol has a significant neuroprotective effect, obviously by preventing an increase in aortic blood flow following unclamping.

OBJECTIVE

Thoracic, arch, and proximal descending thoracic aorta diseases are still considered an enormous challenge. The hybrid approach developed in recent years (supra-aortic trunks debranching and thoracic endovascular repair aortic repair; TEVAR) may improve the morbidity and mortality of the population at risk. The aim of this study was to analyze retrospectively our experience in the hybrid treatment of aortic-arch aneurysms and dissections.

METHOD

We carried out a retrospective review of 27 patients who required a surgical debranching of the supra-aortic trunks and a TEVAR in the management of the aortic arch and proximal descending thoracic aortic disease. The aortic lesions included 18 degenerative arch-aortic aneurysms, four complicated aortic dissections, two subclavian artery aneurysms, and three penetrating atherosclerotic ulcers. Technical success was achieved in all patients.

RESULTS

The 30-day mortality rate was 11.1% (3/27). Mean follow-up was 16.7 months (range, 1–56), and the survival rate was 77.8%. The endoleaks’ rate was 3.7% (1/27), due to a stent-graft migration.

CONCLUSION

Hybrid approaches may represent an alternative option in the treatment of complex aortic lesions involving the arch and the proximal descending thoracic aorta in high-risk patients and emergency cases. However, the promising early results need to be confirmed by longer follow-up and larger comparative series.

EXECUTIVE SUMMARY

The Medical Advisory Secretariat conducted a systematic review of the evidence on the effectiveness and cost-effectiveness of endovascular repair of abdominal aortic aneurysm in comparison to open surgical repair. An abdominal aortic aneurysm [AAA] is the enlargement and weakening of the aorta (major blood artery) that may rupture and result in stroke and death. Endovascular abdominal aortic aneurysm repair [EVAR] is a procedure for repairing abdominal aortic aneurysms from within the blood vessel without open surgery. In this procedure, an aneurysm is excluded from blood circulation by an endograft (a device) delivered to the site of the aneurysm via a catheter inserted into an artery in the groin. The Medical Advisory Secretariat conducted a review of the evidence on the effectiveness and cost-effectiveness of this technology. The review included 44 eligible articles out of 489 citations identified through a systematic literature search. Most of the research evidence is based on non-randomized comparative studies and case series. In the short-term, EVAR appears to be safe and comparable to open surgical repair in terms of survival. It is associated with less severe hemodynamic changes, less blood transfusion and shorter stay in the intensive care and hospital. However, there is concern about a high incidence of endoleak, requiring secondary interventions, and in some cases, conversion to open surgical repair. Current evidence does not support the use of EVAR in all patients. EVAR might benefit individuals who are not fit for surgical repair of abdominal aortic aneurysm and whose risk of rupture of the aneurysm outweighs the risk of death from EVAR. The long-term effectiveness and cost-effectiveness of EVAR cannot be determined at this time. Further evaluation of this technology is required.

OBJECTIVE

The objective of this health technology policy assessment was to determine the effectiveness and cost-effectiveness of endovascular repair of abdominal aortic aneurysms (EVAR) in comparison to open surgical repair (OSR).

BACKGROUND

Clinical Need

An abdominal aortic aneurysm (AAA) is a localized, abnormal dilatation of the aorta greater than 3 cm or 50% of the aortic diameter at the diaphragm. (1) A true AAA involves all 3 layers of the vessel wall. If left untreated, the continuing extension and thinning of the vessel wall may eventually result in rupture of the AAA. The risk of death from ruptured AAA is 80% to 90%. (61) Heller et al. (44) analyzed information from a national hospital database in the United States. They found no significant change in the incidence rate of elective AAA repair or ruptured AAA presented to the nation’s hospitals. The investigators concluded that technologic and treatment advances over the past 19 years have not affected the outcomes of patients with AAAs, and the ability to identify and to treat patients with AAAs has not improved.

Classification of Abdominal Aortic Aneurysms

At least 90% of the AAAs are affected by atherosclerosis, and most of these aneurysms are below the level of the renal arteries.(1)

An abdominal aortic aneurysm may be symptomatic or asymptomatic. An AAA may be classified according to their sizes:(7)

Small aneurysms: less than 5 cm in diameter.

Medium aneurysms: 5-7cm.

Large aneurysms: more than 7 cm in diameter.

Small aneurysms account for approximately 50% of all clinically recognized aneurysms.(7)

Aortic aneurysms may be classified according to their gross appearance as follows (1):

Fusiform aneurysms affect the entire circumference of a vessel, resulting in a diffusely dilated lesion

Saccular aneurysms involve only a portion of the circumference, resulting in an outpouching (protrusion) in the vessel wall.

Prevalence of Abdominal Aortic Aneurysms

In community surveys, the prevalence of AAA is reported to be between 1% and 5.4%. (61) The prevalence is related to age and vascular risk factors. It is more common in men and in those with a positive family history.

In Canada, Abdominal aortic aneurysms are the 10th leading cause of death in men 65 years of age or older. (60) Naylor (60) reported that the rate of AAA repair in Ontario has increased from 38 per 100,000 population in 1981/1982 to 54 per 100,000 population in 1991/1992. For the period of 1989/90 to 1991/92, the rate of AAA repair in Ontarians age 45 years and over was 53 per 100,000. (60) In the United States, about 200,000 new cases are diagnosed each year, and 50,000 to 60,000 surgical AAA repairs are performed. (2) Ruptured AAAs are responsible for about 15,000 deaths in the United States annually. One in 10 men older than 80 years has some aneurysmal change in his aorta. (2)

Symptoms of Abdominal Aortic Aneurysms

AAAs usually do not produce symptoms. However, as they expand, they may become painful. Compression or erosion of adjacent tissue by aneurysms also may cause symptoms. The formation of mural thrombi, a type of blood clots, within the aneurysm may predispose people to peripheral embolization, where blood vessels become blocked. Occasionally, an aneurysm may leak into the vessel wall and the periadventitial area, causing pain and local tenderness. More often, acute rupture occurs without any prior warning, causing acute pain and hypotension. This complication is always life-threatening and requires an emergency operation.

Diagnosis of Abdominal Aortic Aneurysms

An AAA is usually detected on routine examination as a palpable, pulsatile, and non-tender mass. (1)

Abdominal radiography may show the calcified outline of the aneurysms; however, about 25% of aneurysms are not calcified and cannot be visualized by plain x-ray. (1) An abdominal ultrasound provides more accurate detection, can delineate the traverse and longitudinal dimensions of the aneurysm, and is useful for serial documentation of aneurysm size. Computed tomography and magnetic resonance have also been used for follow-up of aortic aneurysms. These technologies, particularly contrast-enhanced computer tomography, provide higher resolution than ultrasound.

Abdominal aortography remains the gold standard to evaluate patients with aneurysms for surgery. This technique helps document the extent of the aneurysms, especially their upper and lower limits. It also helps show the extent of associated athereosclerotic vascular disease. However, the procedure carries a small risk of complications, such as bleeding, allergic reactions, and atheroembolism. (1)

Prognosis of Abdominal Aortic Aneurysms

The risk of rupture of an untreated AAA is a continuous function of aneurysm size as represented by the maximal diameter of the AAA. The annual rupture rate is near zero for aneurysms less than 4 cm in diameter. The risk is about 1% per year for aneurysms 4 to 4.9 cm, 11% per year for aneurysms 5 to 5.9 cm, and 25% per year or more for aneurysms greater than 6 cm. (7)

The 1-year mortality rate of patients with AAAs who do not undergo surgical treatment is about 25% if the aneurysms are 4 to 6 cm in diameter. This increases to 50% for aneurysms exceeding 6 cm. Other major causes of mortality for people with AAAs include coronary heart disease and stroke.

Treatment of Abdominal Aortic Aneurysms

Treatment of an aneurysm is indicated under any one of the following conditions:

The AAA is greater than 6 cm in diameter.

The patient is symptomatic.

The AAA is rapidly expanding irrespective of the absolute diameter.

Open surgical repair of AAA is still the gold standard. It is a major operation involving the excision of dilated area and placement of a sutured woven graft. The surgery may be performed under emergent situation following the rupture of an AAA, or it may be performed electively.

Elective OSR is generally considered appropriate for healthy patients with aneurysms 5 to 6 cm in diameter. (7) Coronary artery disease is the major underlying illness contributing to morbidity and mortality in OSR. Other medical comorbidities, such as chronic renal failure, chronic lung disease, and liver cirrhosis with portal hypertension, may double or triple the usual risk of OSR.

Serial noninvasive follow-up of small aneurysms (less than 5 cm) is an alternative to immediate surgery.

Endovascular repair of AAA is the third treatment option and is the topic of this review.

Aortic aneurysm is one several well-known cardiovascular complications in patients with autosomal dominant polycystic kidney disease (ADPCKD). Commonly affected site of aortic aneurysm and its related dissection in ADPCKD is abdominal aorta. Long standing hypertension, haemodialysis, old age are closely related with discovering of aortic aneurysm and dissection in ADPCKD. However, thoracic aortic aneurysms and its related severe aortic regurgitations (ARs) are rare in younger patients suffering from ADPCKD, especially ones who have normal renal function. Here, we report a case involving a 27-year-old Asian male patient with severe AR due to an ascending aneurysm of the thoracic aorta associated with ADPCKD. The patient had normal renal function without Marfan's habitus. The AR and thoracic aortic aneurysm were corrected surgically.

Surgical treatment of an abdominal aortic aneurysm in patients with a heart disease is risky. Aortic cross-clamping is featured by important consequences on cardiac, renal and gastrointestinal functions. Endovascular aortic repair is considered to be the gold standard in patients with severe comorbidities. However, in the case of unsuccessful endovascular treatment, surgery can be reconsidered with the use of extracorporeal membrane oxygenation, which seems to be a new tool for the management of cardiac and gastrointestinal events ensuring better post-operative outcomes.

We propose a new cannulation and perfusion technique for aortic arch surgery, in order to achieve continuous antegrade total-body perfusion under moderate hypothermia.

The heart and the aortic arch are exposed through a median sternotomy. Cardiopulmonary bypass is established from the right atrium to the right axillary artery. At 26 °C of body temperature, the supra-aortic vessels are clamped, the ascending aorta and the aortic arch are incised, and a cuffed endotracheal cannula, connected to an arterial line geared by a separate roller pump, is inserted into the descending thoracic aorta. Perfusion is started in the distal body, while the brain is perfused through the right axillary artery. Once the aortic arch has been replaced with a Dacron graft and the supra-aortic vessels have been reimplanted on the graft, the arterial line in the descending thoracic aorta is clamped and removed. The supra-aortic vessel clamps are removed, the proximal part of the Dacron graft is clamped, and systemic cardiopulmonary bypass is resumed via the right axillary artery.

From January 2002 through December 2005, this technique was used in 12 consecutive patients on an emergency basis, due to acute aortic dissection that required total arch replacement. Within the first 30 postoperative days, 1 patient (8.3%) died, and no patient had permanent neurologic deficits.

This simple technique ensures a full-flow antegrade total-body perfusion during all phases of the surgical procedure, thereby eliminating ischemia–reperfusion syndrome and yielding excellent clinical results.