Nondissecting thoracoabdominal aortic aneurysms: Part I

Promising Novel Therapies in the Treatment of Aortic and Visceral Aneurysms

Aortic and visceral aneurysms affect large arterial vessels, including the thoracic and abdominal aorta, as well as visceral arterial branches, such as the splenic, hepatic, and mesenteric arteries, respectively. Although these clinical entities have not been equally researched, it seems that they might share certain common pathophysiological changes and molecular mechanisms. The yet limited published data, with regard to newly designed, novel therapies, could serve as a nidus for the evaluation and potential implementation of such treatments in large artery aneurysms. In both animal models and clinical trials, various novel treatments have been employed in an attempt to not only reduce the complications of the already implemented modalities, through manufacturing of more durable materials, but also to regenerate or replace affected tissues themselves. Cellular populations like stem and differentiated vascular cell types, large diameter tissue-engineered vascular grafts (TEVGs), and various molecules and biological factors that might target aspects of the pathophysiological process, including cell-adhesion stabilizers, metalloproteinase inhibitors, and miRNAs, could potentially contribute significantly to the treatment of these types of aneurysms. In this narrative review, we sought to collect and present relevant evidence in the literature, in an effort to unveil promising biological therapies, possibly applicable to the treatment of aortic aneurysms, both thoracic and abdominal, as well as visceral aneurysms.

A 52-year-old man with asymptomatic giant thoracic-abdominal aortic aneurysm

A 52-year-old man was admitted to our hospital for a "CT-diagnosed thoracic-abdominal aortic aneurysm." One week ago, the patient had repeated dry coughs and went to the local hospital for treatment. A chest radiograph revealed a huge mass in the left thoracic cavity. A further chest computerized tomography examination revealed a thoracic-abdominal aortic aneurysm and was transferred to our hospital for surgical treatment. The patient is almost healthy, with no fever, no severe chest and abdomen pain, no dyspnea, no dysphagia, or other clinical symptoms. Ten years ago, the patient underwent "ascending aorta and total aortic arch replacement surgery" in another cardiovascular hospital due to aortic dissection involving the ascending aorta and aortic arch (Debakey I). The patient's thoracic-abdominal aortic aneurysm is huge and has a high risk of rupture. Recently, the patient has undergone thoracic-abdominal aortic replacement surgery and is recovering well.

State-of the-art review on the renal and visceral protection during open thoracoabdominal aortic aneurysm repair

During open thoracoabdominal aortic aneurysm repair (OTAAAR), there is an inevitable organ ischemic period that occurs when the abdominal arteries are being reattached to the aortic graft. Despite various protective techniques, the incidence of renal and visceral complications remains substantial. This state-of-the-art review gives an overview of the current and most evidence-based organ protection methods during OTAAAR, based on the most recent publications and personal experience. An electronic search was performed in four medical databases, using the following MeSH terms: thoracoabdominal aneurysm, TAAAR, visceral protection, renal protection, kidney, perfusion, and intestines. Every publication type was considered. The literature search was ended on August 31st, 2017. The left heart bypass (LHB) is currently the most frequent adjunct to provide distal aortic perfusion (DAP) during aortic clamping. Together with systemic hypothermia, it forms the cornerstone in organ protection during aortic clamping. Further renal protection can be obtained by selective renal perfusion (SRP) with cold blood or cold crystalloid solution, the latter enriched with mannitol. The perfusion should be administered in a volume- and pressure-controlled way and, if possible, by use of a pulsatile pump. Selective visceral perfusion (SVP) is not routinely used, as it does not provide adequate blood flow for visceral protection. The best way to protect the intestines is by minimizing the ischemic time. The preservation of renal and visceral function after OTAAAR can only be obtained with specific strategies before, during, and after the operation. This involves a series of measures, including selective digestive decontamination (SDD), avoidance of nephrotoxic drugs, minimizing the renal and intestinal ischemic time, systemic cooling, avoidance of hemodynamic instability, and regional protective perfusion of the kidneys. Future innovations in catheters, cardiac bypass flow types, mechanical components, hybrid vascular grafts, and pharmaceutical protection measures will hopefully further reduce organ complications.

Bypass Techniques for Descending Thoracic Aortic Surgery

The conduct of partial left heart bypass or partial car diopulmonary bypass (CPB) during surgery involving the descending thoracic aorta or thoracoabdominal aorta is one of the most unappreciated and misunder stood extracorporeal circulation procedures in cardio vascular surgery. It is different from conventional CPB, and although some uninitiated practitioners consider it simpler, it is in fact more complicated than conven tional CPB and involves different concepts. It requires expertise and skill in regulating the flow, pressure, and oxygenation of blood going to both the proximal and distal parts of the body and management of the special bypass or shunt procedures used, specialized monitor ing, and knowledge about the protection and preserva tion of organs both proximal and distal to the aortic clamping. It demands exquisite communication and un derstanding of the unique problems faced by the sur geon, anesthesiologist, and perfusionist.

Neurologic complications of aortic diseases and aortic surgery

Aortic disease processes have a wide range of clinical manifestations. The inflammatory disease process of Takayasu's arteritis differs dramatically from the visceral ischemia of aortic dissection. The catastrophic event of aortic rupture tends to overshadow life-altering events such as stroke and paraplegia. However, these neurologic manifestations of aortic diseases have dramatic effects that extend beyond the individual patient to include both social and financial ramifications. This chapter focuses on the major aortic disease processes and how they can initiate, both directly and indirectly, adverse neurologic events. The chapter concludes with a brief discussion of aortic surgery, how interventions on the aorta can cause neurologic complications, and techniques to avoid these feared adverse neurologic outcomes.

Subacute anterior spinal cord ischemia with lower limb monoplegia: a clinical dilemma and challenging scenario

A 70-year-old woman presented with crescendo right lower limb monoplegia. Magnetic resonance imaging depicted anterior spinal artery syndrome with an 8.5 cm Crawford type II thoracoabdominal aortic aneurysm (TAAA). A staged hybrid procedure was performed, following which she had total exclusion of her TAAA and full resolution of her monoplegia. Clinical presentations of TAAAs can be diverse and require detailed clinical knowledge and lateral thinking to unearth unorthodox presentations. This erratic presentation of a TAAA with anterior spinal artery syndrome outlines particular challenges with management and portrays the need for tailored utilization of contemporary techniques to deal with the growing complexity of TAAAs.

Safety of elective management of synchronous aortic disease with simultaneous thoracic and aortic stent graft placement

BACKGROUND

Simultaneous treatment of multilevel aortic disease is controversial due to the theoretic increase in morbidity. This study was conducted to define the outcomes in patients treated electively with simultaneous thoracic endovascular aortic aneurysm repair (TEVAR) and abdominal aortic endovascular endografting for synchronous aortic pathology.

METHODS

Patients treated with simultaneous TEVAR and endovascular aneurysm repair (T&E) at the University of Florida were identified from a prospectively maintained endovascular aortic registry and compared with those treated with TEVAR alone (TA). The study excluded patients with urgent or emergency indications, thoracoabdominal or mycotic aneurysm, and those requiring chimney stents, fenestrations, or visceral debranching procedures. Demographics, anatomic characteristics, operative details, and periprocedural morbidity were recorded. Mortality and reintervention were estimated using life-table analysis.

RESULTS

From 2001 to 2011, 595 patients underwent TEVAR, of whom 457 had elective repair. Twenty-two (18 men, 82%) were identified who were treated electively with simultaneous T&E. Mean ± standard deviation age was 66 ± 9 years, and median follow-up was 8.8 months (range, 1-34 months). Operative indications for the procedure included dissection-related pathology in 10 (45%) and various combinations of degenerative etiologies in 12 (55%). Compared with TA, T&E patients had significantly higher blood loss (P < .0001), contrast exposure (P < .0001), fluoroscopy time (P < .0001), and operative time (P < .0001). The temporary spinal cord ischemia rate was 13.6% (n = 3) for the T&E group and 6.0% for TA (P = .15); however, the permanent spinal cord ischemia rate was 4% for both groups (P = .96). The 30-day mortality for T&E was 4.5% (n = 1) compared with 2.1% (n = 10) for TA. Temporary renal injury (defined by a 25% increase over baseline creatinine) occurred in two T&E patients (9.1%), with none requiring permanent hemodialysis; no significant difference was noted between the two groups (P = .14). One-year mortality and freedom from reintervention in the T&E patients were 81% and 91%, respectively.

CONCLUSIONS

Acceptable short-term morbidity and mortality can be achieved with T&E compared with TA, despite longer operative times, greater blood loss, and higher contrast exposure. There was a trend toward higher rates of renal and spinal cord injury, so implementation of strategies to reduce the potential of these complications or consideration of staged repair is recommended. Short-term reintervention rates are low, but longer follow-up and greater patient numbers are needed to determine procedural durability and applicability.

Effect of chronic dissection on early and late outcomes after descending thoracic and thoracoabdominal aneurysm repair

OBJECTIVE

Although chronic aortic dissection (CD) has traditionally been considered a predictor of perioperative morbidity and mortality after descending thoracic/thoracoabdominal aneurysm repair (thoracoabdominal aortic aneurysm [TAA]), recent reports have rejected this assertion. Still, few contemporary studies document late outcomes after TAA for CD, which is the goal of this study.

METHODS

From August 1987 to December 2005, 480 patients underwent TAA; 73 (15%) CD and 407 (85%) degenerative aneurysms (DA). Operative management consisted of a clamp-and-sew technique with adjuncts in 53 (78%) CD and 355 (93%) DA patients (P < .001). Epidural cooling was used to prevent spinal cord injury (SCI) in 51 (70%) CD and 214 (53%) DA patients (P = .007). Study end points included perioperative SCI/mortality, freedom from reintervention, and long-term survival.

RESULTS

CD patients were younger (mean age 64.5 years CD vs 72.5 years DA, P < .001) and more frequently had a family history of aneurysmal disease (23% CD vs 6% DA, P < .001). Forty-three (59%) CD patients had elective TAA (vs 322 (79%) DA, P = .001). Eleven (15%) CD patients had Marfan's syndrome (vs 0% DA, P < .001), and 17 (23%) CD patients had a prior arch or ascending aortic repair (vs 16 [4%] DA, P < .001). CD patients were more likely to have Crawford type I & II thoracoabdominal aneurysms (44 [60%] vs 120 [29%] DA, P < .001), while only two (3%) CD patients had type IV aneurysms (vs 99 [24%] DA). There was no difference in perioperative mortality between the two groups (11% CD vs 8.6% DA, P = .52), nor was there a difference in flaccid paralysis, which occurred in five (7%) CD and 22 (5%) DA patients (P = .92). At 5 years, 70% of CD patients were free from reintervention versus 74% of DA (P = .36). The actuarial survival was 53% and 32% at 5 and 10 years for CD versus 47% and 17% for DA (P = .07).

CONCLUSIONS

Despite increased operative complexity, CD does not appear to increase perioperative SCI or mortality after TAA when compared with DA. Long-term freedom from aneurysm-related reintervention is similar for both groups as is survival, despite patients with CD being of younger age at presentation.

[Open surgical therapy of thoracoabdominal aortic aneurysms and chronic expanding aortic dissections: analysis of perioperative prognostic factors]

AIM OF THE STUDY

The aim of the study was to investigate perioperative prognostic factors and long-term outcome following conventional open repair (COR) of thoracoabdominal aortic aneurysms (TAAA) and chronic expanding aortic dissections (CEAD).

PATIENTS AND METHODS

Between March 1993 and December 2005, 92 patients underwent elective COR for TAAA or CEAD in our institution. Passive distal aortic perfusion during cross-clamping was used in 36 patients (39%). Medical records and imaging studies of all patients were reviewed. Follow-up included history, physical examination and CT or MR angiography. Median follow-up was 40 months (range 1-139 months).

RESULTS

Intraoperative, 30-day and in-hospital mortality rates were 2%, 8% and 12%, respectively. The estimated survival rate after 5 years was 70% and 43% of all deaths were cardiac related. The paraplegia rate was 10%, the rate of patients developing chronic renal failure requiring hemodialysis was 3% and 21% of patients required surgical revision. In multivariate analyses the need for surgical revision (OR: 8.465; CI: 0.802-89.318; p=0.024) and postoperative elevated serum transaminase values (OR: 1.009; CI: 1.002-1.017; p=0.017) independently predicted 30-day mortality. Peripheral arterial disease (OR: 4.41; CI:1.672-11.611; p=0.003), intraoperative complications such as disseminated intravasal coagulation and asystole (OR: 4.28; CI: 1.128-16.267; p=0.033), postoperative elevated bilirubin values >2.5 mg/dl (OR: 1.06; CI: 1.009-1.112; p=0.019), and postoperative ventilation >7 days (OR: 7.79; CI: 2.499-24.246; p<0,0001) independently predicted long-term mortality.

CONCLUSION

Postoperative elevated liver values represent negative prognostic factors and may indicate a more standardized use of active shunt systems for organ perfusion.

Endovascular repair of thoracic aortic aneurysm

A thoracic aortic aneurysm (TAA) is a potentially life-threatening condition with structural weakness of the aortic wall, which can progress to arterial dilatation and rupture. Today, both an increasing awareness of vascular disease and the access to tomographic imaging facilitate the diagnosis of TAA even in an asymptomatic stage. The risk of rupture for untreated aneurysms beyond a diameter of 5.6 cm ranges from 46% to 74% and the two-year mortality rate is greater than 70%, with most deaths resulting from rupture. Treatment options include surgical and non-surgical repair to prevent aneurysm enlargement and rupture. While most cases of ascending aortic involvement are subject to surgical repair (partially with valve-preserving techniques), aneurysm of the distal arch and descending thoracic aorta are amenable to emerging endovascular techniques as an alternative to classic open repair or to a hybrid approach (combining debranching surgery with stent grafting) in an attempt to improve outcomes.

Recent advances in thoraco-abdominal aortic aneurysm repair

Thoraco-abdominal aortic aneurysm repair remains a formidable challenge to vascular surgeons. The traditional repair of thoraco-laparotomy with aortic cross-clamping is associated with a high morbidity and mortality despite significant advances in perioperative critical care, anaesthetic and surgical techniques. The advent of the endovascular revolution has shown a marked paradigm in the approach to all aneurysm repairs. As a logical progression from the open repair, the St Mary's visceral hybrid repair combines traditional open techniques (retrograde visceral and renal revascularisation via mid-line laparotomy) with endovascular stent grafting, thereby avoiding the need for thoracotomy and aortic cross-clamping. In specialist centres, the results have been encouraging and easily comparable to the open repair. The technique has been used in several centres around the world and represents a robust, transferrable method of repairing thoraco-abdominal aortic aneurysms. Stent-grafting technologies have reached a point of sophistication that wholly endovascular methods of repairing thoraco-abdominal aortic aneurysms are being performed in several centres around the world. Although these stent grafts have to be customised to the individual patient and are only suitable for certain types of aneurysmal anatomies, they represent the future of thoraco-abdominal aortic aneurysm repair. We review the history of thoraco-abdominal aortic aneurysm repair, the exciting advances in their treatment and discuss our approach to the management of thoraco-abdominal aortic aneurysms in the 21st century.

Outcome of open and endovascular repair in acute type B aortic dissection: a retrospective and observational study

Background

The aim of the study was to analyze surgical and endovascular results in the treatment of acute type B aortic dissection (B AAD).

Methods

Retrospective and observational analysis with patient inclusion between January 2001-December 2008 and follow-up ranged from 2 to 96 months (median = 47.2) was performed. Out of 51 consecutive patients with B AAD, 11 (21.6%) had to undergo open surgery (OS) and 13 (25.5%) endovascular treatment (TEVAR).

Results

There was a significantly difference in early mortality in the TEVAR group (0/13,0%) vs OS group (4/11,36.4%, P < 0.05) and in the incidence of paraplegia/paraparesis (OS 2,28.6% vs TEVAR 1,7.7%, P < 0.05), renal failure (OS 3, 42.8% vs TEVAR 1, 7.7%, P < 0.05), respiratory failure (OS 2,28.6% vs TEVAR 1,7.7%, P < 0.05) and cerebrovascular accident (OS 1,14.3% vs TEVAR 0,0%, P < 0.05). The late mortality at a follow-up was 30.8% (4/13) in the TEVAR group and 42.8% (3/7) in the OS group, respectively (P = not significant). The cumulative survival rate after 1, 3 and 8 years was 93%, 84%, and 69% in the TEVAR group and 86%, 71% and 57% in the OS group, respectively. Endoleaks were diagnosed in 2/13 endovascular patients (15.4%).

Conclusions

TEVAR group had a significantly reduction in early mortality and postoperative complications. No significant differences were found in terms of cumulative survival at follow-up. On this basis TEVAR could be considered an option in the treatment of these complex cases with all proper reservation especially related to the small sample sizes examined.

Complex Abdominal Aortic Pathologies: Operative and Midterm Results after Pararenal Aortic Aneurysm and Type IV Thoracoabdominal Aneurysm Repair

The aim of the study was to describe the clinical outcome of pararenal aortic aneurysm (PAAA) and type IV thoracoabdominal aneurysm (TAAA) repair, with special consideration placed on disease-related complications and midterm follow-up. Data were collected retrospectively between 1997 and 2004 for patients with PAAA or type IV TAAA repair. Comorbidities, operative details, and early and late outcome were analyzed to predict disease-related complications. During the study period, 63 patients (33 PAAAs, 30 type IV TAAAs) underwent aortic repair. The 30-day mortality rate of 7.9% was acceptable for complex aortic entities compared with other series. The morbidity for cardiac events was 3.2%, for pulmonary complications 17.5%, and the need for reoperation was 14.3%. With regard to disease-related complications, two patients (3.2%) required dialysis and one patient (1.6%) developed paraplegia (spinal cord ischemia) after type IV TAAA repair. Complex aortic repair for PAAAs and type IV TAAAs showed acceptable perioperative mortality, morbidity, and midterm survival rates. Patients with type IV TAAAs suffered more major complications, such as postoperative dialysis or spinal cord ischemia.

Hybrid repair of thoracoabdominal aneurysms: a combined endovascular and open approach

Thoracic endografting is emerging as an alternative option in the surgical management of patients who have thoracoabdominal aortic aneurysms (TAAA) or aortic dissection. Due to the high morbidity and mortality rates associated with open TAAA repair, vascular surgeons are searching for innovative methods to repair such aneurysms. A combined endovascular and open approach, otherwise known as the hybrid repair, involves aortic "debranching" (renal and mesenteric revascularization) to create a landing zone for the endograft. Although operative mortality with hybrid is equivalent to mortality found with open repair, reported paralysis rates are reduced. Limited data regarding hybrid graft patency and durability are available. Vascular nurses play a vital role in patient education pre and postoperatively; therefore, they should know the risks and benefits associated with both open and hybrid TAAA repair as well as the risk associated with TAAA rupture. Nurses caring for patients after hybrid repair should possess astute assessment skills in monitoring for postoperative complications. Close observation for stroke, paralysis, renal insufficiency/failure, bowel ischemia/dysfunction, lower extremity ischemia and basic hemodynamics is essential for favorable outcomes. Vascular nurses should provide surgery-specific instruction regarding lengths of stay, expected outcomes, activity restrictions, CT-scan follow-up and possible complications after surgery, including warning signs. In the evolving field of endovascular surgery, vascular nurses must remain current on new innovative techniques being used, such as thoracic endografting.

Optimal End-Organ Protection for Thoracic and Thoracoabdominal Aortic Aneurysm Repair Using Deep Hypothermic Circulatory Arrest

BACKGROUND

Despite the advent of numerous protective strategies, thoracic and thoracoabdominal aortic replacement remains a high risk. While mortality rates have improved over the last 15 years, the incidence of adverse outcomes (including stroke, renal failure, and paraplegia, as well as death) remains at 13% to 30% in all published series. The use of deep hypothermic cardiopulmonary bypass with circulatory arrest has been associated with high morbidity in the past; however, we report a single surgeon's experience of improved end-organ protection with low morbidity and mortality utilizing this technique.

METHODS

One hundred seventy-three consecutive patients with descending thoracic and thoracoabdominal aneurysms were operated on between April 1995 and March 2005. Hypothermic (15 degrees C) cardiopulmonary bypass with circulatory arrest and open proximal anastomosis were utilized in all subjects. Visceral arteries were uniformly reimplanted as an island while additional renal artery bypasses were performed as required. Lower intercostals and lumbar arteries were aggressively reimplanted or preserved at the aortic anastomosis. No other adjuncts for spinal cord protection were routinely employed.

RESULTS

Sixty-three patients with isolated descending thoracic aortic aneurysms and 27 patients with extent I, 49 with extent II, 20 with extent III, and 14 with extent IV thoracoabdominal aortic aneurysms underwent operative repair. Ninety percent of cases were elective while 10% were urgent or emergent. There were seven hospital deaths, and the hospital mortality was 4.0%. Operative complications included stroke in seven patients (4.1%), paraplegia in four (2.4%), including 0 of 62 ambulatory patients with isolated thoracic aneurysm repairs, and acute renal failure requiring dialysis in two of 168 operative survivors that were not dialysis-dependent before surgery.

CONCLUSIONS

Deep hypothermic circulatory arrest allows replacement of complex aortic pathology with low mortality. End-organ protection is excellent with lower incidences of dialysis-dependent renal failure and paraplegia than are reported with other currently used surgical techniques.

Preservation of Renal Function Utilizing Hypothermic Circulatory Arrest in the Treatment of Distal Thoracoabdominal Aneurysms (Types III and IV)

Although left heart bypass and hypothermia are often used in the performance of type I and type II thoracoabdominal aneurysms (TAAs), most of these more distal aneurysms are done utilizing the clamp and sew technique. Renal failure occurs between 8.6% to 39% in recent series of patients following surgery for type III and IV TAAs. The purpose of this study was to determine whether the use of hypothermic circulatory arrest in these cases would serve to protect renal function. All patients were operated on using hypothermic circulatory arrest. The kidneys were perfused with cold blood during the procedures, and renal artery bypasses were aggressively used (when stenoses greater than 50% were observed). The series describes 33 consecutive patients with type III and IV TAAs who were operated on utilizing hypothermic circulatory arrest with a core temperature of 15 degrees centigrade. All visceral and renal arteries were individually perfused; 20 patients had bypass grafts of their renal artery stenoses. Although six patients had renal failure preoperatively, only one developed postoperative renal failure. This was the patient who was operated on as an emergency for severe abdominal pain, back pain, and acidosis who was also the only hospital death. Of the remaining five patients with elevated creatinines preoperatively, four had postoperative decrease of the serum creatinine. One patient developed paraparesis and one developed a stroke. The median length of stay was 8 days. Consideration should be given to the use of hypothermic circulatory arrest in type III and IV TAAs for the preservation of renal function and improved overall results.

Tracheostomy after major vascular surgery

OBJECTIVES

Major vascular surgery such as aortic aneurysm repair may be associated with prolonged in-patient hospitalization. Certain patients undergo a tracheostomy to aid in weaning from mechanical ventilation or for secretion management. The authors hypothesized that tracheostomy after aortic reconstruction for aneurysmal disease was associated with poor outcomes.

DESIGN

A retrospective, observational study.

SETTING

Vascular surgical intensive care unit (ICU) of a tertiary referral hospital.

PARTICIPANTS

Eighty-one patients who underwent a tracheostomy after open thoracoabdominal or abdominal aortic aneurysm (AAA) repair between 1993 and 2002.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 1,940 patients who underwent aneurysm repair, 81 (4.2%) had a tracheostomy during their index hospitalization. Of those patients, 40.7% did not survive to hospital discharge. Postoperative sepsis was associated with an increased mortality (relative risk 2.45, 95% confidence interval [CI] 1.22-4.90). Many developed postoperative renal failure and were more likely to die in the hospital (relative risk 1.53, 95% CI 1.00-2.33). The preoperative diagnosis of chronic obstructive pulmonary disease (COPD) was not associated with increased mortality (relative risk 0.471, 95% CI 0.23-0.96). Thirty-two (39.5%) patients were transferred from the ICU to a chronic ventilator dependency unit (CVDU).

CONCLUSIONS

Tracheostomy in patients after aortic reconstruction for aneurysmal disease is associated with a high incidence of in-hospital mortality. Patients who survive to ICU discharge are likely to be transferred to a CVDU for further respiratory management. The preoperative diagnosis of COPD is associated with improved survival, whereas postoperative sepsis is associated with an increased mortality. These observations should be considered when counseling patients and their families regarding tracheostomy after aortic surgery.

Update on Thoracic Aortic Endovascular Grafting Using the Medtronic Talent Device

This article provides a brief update on the current status of the treatment of thoracic aortic pathology using the Medtronic Talent device. Preoperative evaluation and selection criterion along with study design are described for the recently completed Phase II VALOR Trial (Evaluation of the Medtronic AVE Talent Thoracic Stent Graft System for the Treatment of Thoracic Aneurysms). In addition, the results of several recent series for the treatment of degenerative aneurysm and more complex aortic pathology such as transection, rupture and acute and chronic dissection are reviewed.

Coagulation Disorders and Blood Product Use in Patients Undergoing Thoracoabdominal Aortic Aneurysm Repair

Repair of thoracoabdominal aortic aneurysms (TAAA) is associated with major blood loss, often exceeding the patient's intravascular volume, and complex intraoperative and postoperative coagulopathies necessitating large-volume transfusion of blood products. Abnormalities sufficient to cause thrombocytopenia or clinically important prolongation of clotting parameters are rarely present before surgery in elective aneurysms but are more common with ruptured aneurysms. The finding of intraoperative and postoperative deficiencies of clotting factors, along with thrombin generation and activation of the thrombolytic system, is reflective of massive blood losses, visceral ischemia, and massive transfusions. An aggressive strategy of transfusion of blood products is critical to the prevention of clinically significant coagulopathy during surgery. Adjuncts to reduce blood losses and blood product use include low-dose aprotinin or epsilon -aminocaproic acid, intraoperative blood salvaging, and acute normovolemic hemodilution. In TAAA repair, an average blood loss of 5000 to 6000 mL and average transfusion of allogeneic blood products of 50 to 60 U are to be anticipated.

Thoracoabdominal aortic aneurysm repair after prior aortic surgery

PURPOSE

The purpose of this study was to determine whether the morbidity and mortality of surgery for thoracoabdominal aortic aneurysm (TAAA) in patients with prior aortic surgery are increased.

METHODS

The results for all patients undergoing operation for TAAA at a single institution were reviewed.

RESULTS

Over a 10-year interval, 279 patients (136 women and 143 men) underwent aortic replacement for TAAA. The mean patient age was 68 years (range, 34-90). The extent of aortic replacement was relatively evenly distributed: type I (91), type II (54), type III (78), or type IV (56). Of these 279 patients, 76 (27%) had undergone prior aortic surgery. Prior infrarenal AAA was the most common prior procedure (56, 20%). Reoperation for prior failed TAAA repair was performed in 20 (7%) patients. A history of Marfan syndrome was highly associated with the need for remedial TAAA procedures (P <.0001). Overall 30-day mortality was 11.4% (32). Mortality was independent of prior aortic surgery (P =.98), prior AAA (P =.84), prior TAAA (P =.61), and gender (P =.18). Postoperative complications were seen in 67 (24%) patients and were more likely in patients who had undergone prior AAA surgery (P =.008). TAAA repair in patients with recurrent TAAA was not associated with higher morbidity (P =.33). Paraplegia (10) occurred in type I (3), type II (2), and type III (5) aneurysms but not in type IV (0), and its development was associated with higher mortality (P =.01). Prior aortic surgery was not found to be predictive of paraplegia (P =.90), although 30% of patients who developed paraplegia had a history of prior AAA repair.

CONCLUSIONS

Aortic reoperation for TAAA is required in a significant number of patients, particularly those with Marfan syndrome. Therefore, ongoing surveillance of the residual aorta is mandatory. Postoperative complications are more likely to occur in patients after prior infrarenal aortic replacement, but mortality is not significantly increased. Special technical considerations exist for remedial procedures after failed TAAA repair to provide protection for the spinal cord, kidneys, and viscera. Patients with failed TAAA procedures or progression of aneurysmal extent should be offered reoperation when indicated.

The use of left heart bypass in the repair of thoracoabdominal aortic aneurysms: current techniques and results

The surgical repair of thoracoabdominal aortic aneurysms (TAAA) remains challenging. The prevention of spinal cord ischemic complications requires a multidisciplinary approach. The protective effect of left heart bypass (LHB), particularly regarding spinal cord ischemia, during the repair of extensive TAAA is evaluated here. Data from 1,250 consecutive patients who underwent the repair of extent I or extent II TAAA over a 16-year period was prospectively entered into a database. LHB was used in 666 (53.3%) patients. This group was retrospectively compared with 584 (46.7%) patients who had undergone surgery without the use of LHB. A total of 1,173 (93.8%) patients were 30-day survivors. Paraplegia or paraparesis developed postoperatively in 68 (5.5%) patients. In patients with extent I TAAA, paraplegia and paraparesis rates in the LHB cohort (9 of 290, 3.1%) and those without LHB (13 of 313, 4.2%) were statistically similar (P=0.866). The latter was observed despite the fact that longer clamp times were used in the LHB group. In patients with extent II TAAA, the LHB group had a statistically significant lower incidence of paraplegia or paraparesis (17 of 375, 4.5%) compared with the non-LHB group (29 of 259, 11.2%; P=0.019). In our experience, we identified LHB as protective for reducing the risk of postoperative paraplegia and paraparesis in patients who underwent the repair of extent I and extent II TAAA, the latter statistically significant.

Estimating group mortality and paraplegia rates after thoracoabdominal aortic aneurysm repair

BACKGROUND

Most clinical studies regarding thoracoabdominal aortic aneurysm (TAAA) surgery are retrospective comparisons involving heterogeneous groups of patients. Risk models that evaluate susceptibility bias enhance interpretation of these intergroup comparisons. The purpose of this analysis was to derive group risk models for mortality and paraplegia after TAAA repair.

METHODS

Data regarding 1,220 consecutive patients undergoing TAAA repair were analyzed via multiple logistic regression with stepwise model selection. Categorical preoperative risk factors that predicted 30-day mortality and paraplegia were used to develop risk models.

RESULTS

Fifty-eight patients (4.8%) died within 30 days and 56 patients (4.6%) developed paraplegia or paraparesis. Predictors of mortality were rupture, renal insufficiency, symptomatic aneurysms, and Crawford extent II repairs. Extent of repair and acute presentation were predictors of paraplegia. The derived risk models estimated mortality and paraplegia rates that correlated well with actual frequencies reported in other contemporary series (regression slopes = 0.87 and 1.06, respectively).

CONCLUSIONS

The derived risk models accurately estimate paraplegia and mortality rates in groups of patients. Prospective model validation will be required to confirm their accuracy.

Thoracoabdominal aortic aneurysm repair: a prospective cohort study of 121 cases

Between October 1990 and June 2001, 121 patients underwent surgery for thoracoabdominal aortic aneurysm (TAAA)-99 procedures were elective and 22 were for ruptured aneurysms. Between October 1990 and September 1997, the clamp-and-go technique was used for all aneurysms (43 patients), and from October 1997, clamp-and-go was reserved for type IV TAAAs, and atriofemoral bypass (AFB) was used for types I, II, and III (78 patients). Overall hospital mortality was 21.4% (26/121)-12% for the elective group and 64% for the ruptured group. Hospital mortality was associated with age (67 years in survivors vs. 73 years in nonsurvivors, p = 0.03), FEV1<2 L (RR 4.1, p = 0.01), CSF drainage (RR 5.0, p = 0.03), type II aneurysms vs. other aneurysms (RR 3.7, p = 0.02), and relative inexperience (mean rank in the series was 52 in survivors vs. 30 in nonsurvivors, p = 0.01). The overall incidence of neurologic deficits due to spinal cord ischemia was 6.2% (paraplegia in 4.4%). Temporary dialysis was necessary in 13% of patients, and chronic dialysis in 2%. In long-term follow-up of patients undergoing elective repair, 5-year survival was 80% and median survival was 7.9 years. Mortality and neurologic deficits have improved over time as a consequence of either increased surgical experience, the adoption of a protocolized strategy for repair, or secular improvements in ICU care. Long-term survival after elective TAAA repair is excellent.

Chronic aortic dissection not a risk factor for neurologic deficit in thoracoabdominal aortic aneurysm repair

OBJECTIVE

chronic aortic dissection has long been considered a risk factor for neurologic deficit following thoracoabdominal aortic aneurysm (TAA) surgery. We reviewed our experience with regard to aneurysm extent and the use of adjunct, (distal aortic perfusion/cerebrospinal fluid drainage), and examined the impact of these factors on neurologic deficit among chronic dissection and non-dissection cases.

METHODS

between February 1991 and March 2001, we repaired 800 aneurysms of the descending thoracic and thoracoabdominal aorta. Seven hundred and twenty-nine cases were elective; 196 chronic dissection, 533 non-dissection. 182/729 (24.9%) were TAA extent II. Among these, 61/182 (33%) involved chronic dissection. Adjunct was used in 507/729 (69.6%). We conducted detailed multivariate analyses to isolate the impact of chronic aortic dissection on neurologic morbidity, with other important risk factors taken into account.

RESULTS

overall, 32/729 (4.4%) patients had neurologic deficit upon awakening; 7/196 (3.6%) in chronic dissections, and 25/533 (4.7%) in non-dissections. Adjunct had a major effect, reducing neurologic deficit in TAA extent II from 10/36 (27.8%) to 10/146 (6.9%) (p=0.001). However, in univariate and multivariate analysis, chronic dissection did not increase the risk of neurologic deficit, regardless of extent or mode of treatment.

CONCLUSION

in contrast to previous reports, we determined that chronic aortic dissection is not a risk factor in TAA patients.

Aneurysmal expansion of the visceral patch after thoracoabdominal aortic replacement: an argument for limiting patch size?

INTRODUCTION

Thoracoabdominal aortic replacement requires visceral vessel revascularization and is usually performed with Crawford's inclusion technique or a large Carrel patch. This segment of retained native aorta may be prone to recurrent aneurysmal disease. We reviewed our experience with patients in whom aneurysmal expansion of the visceral patch was detected.

METHODS

The records of 107 patients undergoing thoracoabdominal aortic replacement operations performed or followed up at the Johns Hopkins Hospital between 1992 and 2000 were reviewed. All patients had visceral patches created for type II, III, or IV aneurysms. Visceral patches were considered aneurysmal if the maximal diameter of the aortic prosthesis and patch was 4.0 cm or more.

RESULTS

Patch aneurysmal expansion (mean, 5.4 cm) was detected in eight patients (7.5%). All three women had connective tissue disorders (mean age, 36 years), and all five men had atherosclerotic disease (mean age, 73 years). Five patients were symptom free with their aneurysms detected by surveillance computed tomography scans; two patients had back pain prompting computed tomography scans; and one patient presented with an emergency patch rupture. Aneurysmal patches were successfully revised in three patients. Two patients died in the operating room, and three patch aneurysms (< 5 cm) are still being observed. The mean time to the detection of aneurysmal expansion was 6.5 years after the original operation. Therapy consisted of replacement of a segment of the thoracoabdominal aortic graft and refashioning a smaller patch, including only the visceral artery orifices with separate attachment of the left and possibly right renal artery.

CONCLUSIONS

Although Crawford's inclusion method of visceral patch construction is generally durable, patients undergoing thoracoabdominal aortic replacement require yearly surveillance for the detection of aneurysmal expansion of the visceral patch. We recommend limiting visceral patch size at the original operation by routinely excluding the orifice of the left renal artery. Patients at high risk for recurrent aneurysmal expansion, such as those with connective tissue disorders, will benefit from creating small visceral patches and possibly implanting both renal arteries separately during the original operation.