Biological responses differ considerably between endovascular and conventional aortic aneurysm surgery

Cytokines as biomarkers of inflammatory response after open versus endovascular repair of abdominal aortic aneurysms: a systematic review

The repair of an abdominal aortic aneurysm (AAA) is a high-risk surgical procedure related to hormonal and metabolic stress-related response with an ensuing activation of the inflammatory cascade. In contrast to open repair (OR), endovascular aortic aneurysm repair (EVAR) seems to decrease the postoperative stress by offering less extensive incisions, dissection, and tissue manipulation. However, these beneficial effects may be offset by the release of cytokines and arachidonic acid metabolites during intra-luminal manipulation of the thrombus using catheters in endovascular repair, resulting in systemic inflammatory response (SIR), which is clinically called post-implantation syndrome. In this systematic review we compared OR with EVAR in terms of the post-interventional inflammatory response resulting from alterations in the circulating cytokine levels. We sought to summarize all the latest evidence regarding post-implantation syndrome after EVAR. We searched Medline (PubMed), ClinicalTrials.gov and the Cochrane library for clinical studies reporting on the release of cytokines as part of the inflammatory response after both open/conventional and endovascular repair of the AAA. We identified 17 studies examining the cytokine levels after OR versus EVAR. OR seemed to be associated with a greater SIR than EVAR, as evidenced by the increased cytokine levels, particularly IL-6 and IL-8, whereas IL-1β, IL-10 and TNF-α showed conflicting results or no difference between the two groups. Polyester endografts appear to be positively correlated with the incidence of post-implantation syndrome after EVAR. Future large prospective studies are warranted to delineate the underlying mechanisms of the cytokine interaction in the post-surgical inflammatory response setting.

Paradoxical Neutrophil Elastase Release in Endovascular Abdominal Aortic Aneurysm Repair

Endovascular repair of abdominal aortic aneurysm potentially avoids problems associated with prolonged aortic cross-clamping that occurs with open repair, but it appears to have its own biologic consequences, which may relate to neutrophil elastase release. Blood samples of consecutive patients undergoing open or endovascular abdominal aneurysm repair were analyzed for neutrophil elastase/α1-antitrypsin complex and free elastase. Free elastase rose from baseline and fell quickly in open repair patients, returning to baseline by 144 hours. In the endovascular repair group, it continued to increase for up to 144 hours. Bound elastase increased to 24 hours, returning to baseline in endovascular repair patients by 72 hours, but remaining elevated in open repair patients at 144 hours. Open repair patients showed raised elastase/α1-antitrypsin complex and initial raised free elastase levels. High free elastase levels in endovascular repair patients may reflect less bound elastase and may paradoxically lead to a prolonged inflammatory postoperative response.

Neutrophil Respiratory Burst Activity and Pro- and Anti-inflammatory Cytokines in AAA Surgery: Conventional versus Endoluminal Treatment

Purpose:

To examine the inflammatory impact of endovascular and conventional surgery of abdominal aortic aneurysm (AAA) as assessed by the activation of neutrophils and serum levels of pro- and anti-inflammatory cytokines.

Methods:

Twenty-four patients undergoing AAA exclusion were treated with either endovascular (n = 14) or conventional (n=10) techniques. Clinical and hematological data, respiratory burst of neutrophils, and the expression of adhesion and activation molecules (CD18, CD11b, CD69, and HLA-DR) were analyzed by flow cytometry. The enzyme-linked immunosorbent assay technique was used to measure proinflammatory cytokine interleukin (IL)–8 and anti-inflammatory cytokines IL-1 receptor antagonist (IL-1RA) and transforming growth factor β1 (TGF-β1).

Results:

All patients, most of whom had normal cytokine values before surgery, were successfully treated. No significant changes were found in surface antigens. Basal respiratory burst was quite heterogeneous; in all cases respiratory burst activity decreased after surgery and remained low throughout the observation period. Despite marked interpatient differences, IL-1RA and IL-8 increased after surgery, whereas TGF-β1 decreased, although the variation achieved statistical significance only in the conventional group. Elevated IL-1RA returned to normal within 48 hours in the endoluminal group, whereas the level remained high in the conventional group in the last sample.

Conclusions:

Despite heterogeneity before surgery, the respiratory burst decreased for most of the patients regardless of the approach, and both techniques increased IL-1RA. Although both procedures seemed to decrease TGF-β1, the difference was significant only with the conventional approach. IL-1RA levels fell toward basal values quicker in the endograft patients, suggesting that the endoluminal approach was less aggressive.

Acute Inflammatory Reaction Associated with Endoluminal Bypass Grafts

Purpose:

Nonspecific inflammatory reactions characterized by local tenderness, fever, and flu-like discomfort have been seen in patients undergoing endoluminal graft placement in the abdominal aorta or the femoral arteries. We undertook a study to assess the clinical and laboratory parameters of this inflammation.

Methods:

Ten patients with femoropopliteal artery (n = 9) or aortic (n = 1) lesions were treated with EndoPro System 1 stent-grafts made of nitinol alloy and covered with a polyester (Dacron) fabric. Eleven patients implanted with a bare nitinol stent served as the control group.

Results:

In the stent-graft group, four patients showed clinical signs of acute inflammation manifested by fever and local tenderness. Three of these patients suffered thrombosis of the stent-grafts during the first month of follow-up. Plasma levels of interleukin-1β and interleukin-6 in all stent-graft patients were markedly increased 1 day after intervention (7.3 ± 2.8 versus 90.2 ± 34.1 pg/mL and 15.6 ± 5.8 versus 175.5 ± 66.3 pg/mL, respectively; p < 0.01). This was followed by an increase in fibrinogen (3.0 ± 0.2 versus 5.0 ± 0.2 g/L; p < 0.05) and C-reactive protein (14.6 ± 3.3 versus 77.5 ± 15.0 mg/L; p < 0.01) at 1 week. No direct correlation between the inflammatory markers and symptoms could be found. In vitro analysis showed that individual components of the stent-graft did not activate human neutrophils, whereas the intact stent-graft itself induced a marked neutrophil activation.

Conclusions:

The component of the self-expanding stent-graft responsible for the nonspecific inflammatory reaction was not identified in this study. It is likely that the stent-graft itself or some as yet unrecognized element of the device other than the Dacron fabric or metal alloy may be a potent in vivo inducer of cytokine reaction by neutrophils.

Biological Responses to Endovascular Treatment of Abdominal Aortic Aneurysms

Purpose:

To review the findings of two studies investigating the apparent differences in inflammatory responses demonstrated in patients undergoing endovascular as opposed to classic surgical treatment of abdominal aortic aneurysms (AAAs).

Methods:

The clinical course of seven patients treated with an endoluminal procedure (AAA-E) and seven patients undergoing conventional surgery (AAA-C) were compared (all men; ages 52 to 80 years). Blood samples were taken pre-, intra-, and postoperatively for up to 7 days. Inflammatory responses were assessed from measurement of interleukins (IL)-1 β, IL-6, IL-8, and tumor necrosis factor (TNF-α); complement proteins C1q, C4, C5a, and terminal complement complexes, C5b-C9; and C-reactive proteins. Granulocyte and monocyte surface adhesion molecule expression was determined indirectly using a panel of monoclonal antibodies against CD11a, CD11b, CD11c, CD18, and L-selectin in donor white blood cells exposed to patient plasma.

Results:

In six of the AAA-E patients, blood pressure decreases were recorded during the introduction of the device. Elevated body temperature was sustained for 2 to 5 days postoperatively in the AAA-E group. IL-6 levels were significantly higher in AAA-C patients (p < 0.0005), while TNF-α release was recorded in the AAA-E group only. CD11b, CD11c, and CD18 molecules on both granulocytes and monocytes were significantly upregulated 60 minutes after the endovascular procedure compared to conventional surgery.

Conclusions:

Endovascular aortic aneurysm repair apparently induces a significant inflammatory response, mainly involving TNF-α release, which differs from open AAA repair. These inflammatory responses, which may be related to the observed intraprocedural blood pressure decreases, could be caused by cell activation arising from intra-aneurysmal device manipulation.

Regional Anesthesia for Endovascular Treatment of Abdominal Aortic Aneurysms

Purpose:

To investigate the feasibility of regional anesthesia for endovascular repair of abdominal aortic aneurysms (AAAs).

Methods:

Since February 1995, 21 patients (17 men and 4 women; median age 67 years, range 49 to 80) have been treated with endovascular technique for true infrarenal AAA using Mialhe Stentor bifurcated grafts. A single dose of spinal anesthesia combined with epidural anesthesia was used in all procedures. Electrocardiography and arterial blood pressure were monitored.

Results:

No cases of emboli, hematoma, or graft migration were seen, and there were no reoperations or conversions to open operation. Arterial blood pressure was stable at a satisfactory level from induction of anesthesia throughout the procedure, and there was no period of clinically significant hypotension during any implantation. One patient died on the second postoperative day from cardiac and renal insufficiency. Three endoleaks were observed during the procedure; one healed spontaneously within 5 weeks, and the other two were repaired by endovascular techniques after 1 and 4 months, respectively. During follow-up, one patient died at 6 months from pancreatic carcinoma.

Conclusions:

The application of regional anesthesia is feasible for endovascular treatment of AAA. The arterial blood pressure remained stable throughout the procedure, and all patients, with two exceptions, were mobilized on the first day and placed on a regular diet. Based on these early results, it appears that regional anesthesia is feasible, effective, and safe for endovascular AAA repair.

Routine clinical markers of the magnitude of the systemic inflammatory response after elective operation: a systematic review

BACKGROUND

Operative injury to the body from all procedures causes a stereotypical cascade of neuroendocrine, cytokine, myeloid, and acute phase responses. This response has been examined commonly by the use of cortisol, interleukin-6 (IL-6), white cell count, and C-reactive protein (CRP). We aimed to determine which markers of the systemic inflammatory response were useful in determining the magnitude of injury after elective operations.

METHODS

A systematic review of the literature was performed using surgery, endocrine response, systemic inflammatory response, cortisol, IL-6, white cell count, and CRP. For each analyte the studies were grouped according to whether the operative injury was considered to be minor, moderate, or major and then by the operative procedure.

RESULTS

A total of 164 studies were included involving 14,362 patients. The IL-6 and CRP responses clearly were associated with the magnitude of operative injury and the invasiveness of the operative procedure. For example, the peak CRP response increased from 52 mg/L with cholecystectomy to 123 mg/L with colorectal cancer resection, 145 mg/L with hip replacement, 163 mg/L after abdominal aortic aneurysm repair, and 189 mg/L after open cardiac surgery. There also appeared to be a difference between minimally invasive/laparoscopic and open procedures such as cholecystectomy (27 vs 80 mg/L), colorectal cancer resection (97 vs 133 mg/L), and aortic aneurysm repair (132 vs 180 mg/L).

CONCLUSION

Peak IL-6 and CRP concentrations consistently were associated with the magnitude of operative injury and operative procedure. These markers may be useful in the objective assessment of which components of Enhanced Recovery after Surgery are likely to improve patient outcome and to assess the possible impact of operative injury on immune function.

Impact of graft composition on the systemic inflammatory response after an elective repair of an abdominal aortic aneurysm

Purpose

The present study aimed to evaluate the risk factors and the role of graft material in the development of an acute phase systemic inflammatory response, and the clinical outcome in patients who undergo endovascular aneurysm repair (EVAR) or open surgical repair (OSR) of an abdominal aortic aneurysm (AAA).

Methods

We retrospectively evaluated the risk factors and the role of graft material in an increased risk of developing systemic inflammatory response syndrome (SIRS), and the clinical outcome in patients who underwent EVAR or OSR of an AAA.

Results

A total of 308 consecutive patients who underwent AAA repair were included; 178 received EVAR and 130 received OSR. There was no significant difference in the incidence of SIRS between EVAR patients and OSR patients. Regardless of treatment modality, SIRS was observed more frequently in patients treated with woven polyester grafts. Postoperative hospitalization was significantly prolonged in patients that experienced SIRS. In multivariate analyses, the initial white blood cell count (P = 0.001) and the use of woven polyester grafts (P = 0.005) were significantly associated with an increased risk of developing SIRS in patients who underwent EVAR. By contrast, the use of woven polyester grafts was the only factor associated with an increased risk of developing SIRS in patients who underwent OSR, although this was not statistically significant (P = 0.052).

Conclusion

The current study shows that the graft composition plays a primordial role in the development of SIRS, and it leads to prolonged hospitalization in both EVAR and OSR patients.

Antiplatelet Treatment and Prothrombotic Diathesis Following Endovascular Abdominal Aortic Aneurysm Repair

Prothrombotic diathesis expressed by elevated levels of coagulation-specific biomarkers has been reported in patients with abdominal aortic aneurysm (AAA) and after AAA endovascular repair (EVAR). This study investigates the effect of antiplatelet agents (APLs) on the prothrombotic diathesis in the post-EVAR period. Forty elective EVAR patients had thrombin–antithrombin complex, d-dimer, fibrinopeptide A, and high-sensitivity C-reactive protein measured before, at 24 hours, 1 month, and 6 months after EVAR. Patients receiving APLs postoperatively were compared with those not receiving APLs. All biomarkers were above the normal limits preoperatively and increased significantly 24 hours postoperatively followed by a drop at 1 and 6 months. No statistically significant changes were noted among patients receiving APLs in comparison with those not receiving APLs. The preoperative and postoperative prothrombotic diathesis of AAA following EVAR was confirmed in line with other reports. There was however no significant alteration of the examined biomarkers in patients receiving APLs.

Changes in inflammatory response after endovascular treatment for type B aortic dissection

This present study aims to investigate the changes in the inflammatory markers after elective endovascular treatment of Type B aortic dissection with aneurysm, as related to different anatomical features of the dissection flap in the paravisceral perfusion. Consecutive patients with type B aortic dissections with elective endovascular stent graft repair were recruited and categorized into different groups. Serial plasma levels of cytokines (Interleukin-1β, -6, -8, -10, TNF-α), chemokines (MCP-1), and serum creatinine were monitored at pre-, peri- and post-operative stages. The length of stent graft employed in each surgery was retrieved and correlated with the change of all studied biochemical parameters. A control group of aortic dissected patients with conventional medication management was recruited for comparing the baseline biochemical parameters. In total, 22 endovascular treated and 16 aortic dissected patients with surveillance were recruited. The endovascular treated patients had comparable baseline levels as the non-surgical patients. There was no immediate or thirty day-mortality, and none of the surgical patients developed post-operative mesenteric ischaemia or clinically significant renal impairment. All surgical patients had detectable pro-inflammatory mediators, but none of the them showed any statistical significant surge in the peri-operative period except IL-1β and IL-6. Similar results were obtained when categorized into different groups. IL-1β and IL-6 showed maximal levels within hours of the endovascular procedure (range, 3.93 to 27.3 higher than baseline; p = 0.001), but returned to baseline 1 day post-operatively. The change of IL-1β and IL-6 at the stent graft deployment was statistically greater in longer stent graft (p>0.05). No significant changes were observed in the serum creatinine levels. In conclusion, elective endovascular repair of type B aortic dissection associated with insignificant changes in inflammatory mediators and creatinine. All levels fell toward basal levels post-operatively suggesting that thoracic endovascular aortic repair is rather less aggressive with insignificant inflammatory modulation.

Systemic inflammation, coagulopathy, and acute renal insufficiency following endovascular thoracoabdominal aortic aneurysm repair

OBJECTIVE

To characterize the inflammatory and coagulopathic response after endovascular thoracoabdominal aortic aneurysm (TAAA) repair and to evaluate the effect of the response on postoperative renal function.

METHODS

From July 2005 to June 2008, 42 patients underwent elective endovascular repair of a TAAA using custom designed multi-branched stent-grafts at a single academic institution. Four patients were excluded from the analysis. White blood cell count (WBC), platelet count, prothrombin time (PT), and creatinine were measured in all patients. In the last nine patients, interleukin-6 (IL-6), protein C, Factor V, d-dimers, cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL) levels were also measured. Change in lab values were expressed as a percentage of baseline values.

RESULTS

The 30-day mortality rate was 5% (2/38). All patients (n = 38) had a higher WBC (mean +/- SD: 139 +/- 80%, P < .0001), lower platelet count (56 +/- 15%, P < .0001), and higher PT (median: 17%, Interquartile range (IQR) 12%-22%, P < .0001) after stent-graft insertion. Twelve of 38 patients (32%) developed postoperative acute renal insufficiency (>50% rise in creatinine). Patients with renal insufficiency had significantly larger changes in WBC (178 +/- 100% vs 121 +/- 64%, P = .04) and platelet count (64 +/- 17% vs 52 +/- 12%, P = .02) compared with those without renal insufficiency. All patients (n = 9) had significant increases in NGAL (182 +/- 115%, P = .008) after stent-graft insertion. Six of nine patients (67%) had increased cystatin C (35 +/- 43%, P = .04) after stent-graft insertion, with a greater rise in those with postoperative renal insufficiency (87 +/- 32% vs 8 +/- 13%, P = .02). IL-6 levels were markedly increased in all patients (n = 9) after repair (9840 +/- 6160%, P = .008). Protein C (35 +/- 10%, P = .008) and Factor V levels (28 +/- 20%, P = .008) were uniformly decreased, while d-dimers were elevated after repair in all patients (310 +/- 213%, P = .008).

CONCLUSIONS

Leukocytosis and thrombocytopenia were uniform following endovascular TAAA repair, and the severity of the response correlated with post-operative renal dysfunction. Elevation of a sensitive marker of renal injury (NGAL) suggests that renal injury may occur in all patients after stent-graft insertion.

A Global Assessment of the Inflammatory Response Elicited Upon Open Abdominal Aortic Aneurysm Repair

The inflammatory response during elective open infrarenal abdominal aortic aneurysm repair and its impact on outcome is investigated. Twenty high-risk patients were enrolled, and blood samples were obtained at 8 perioperative time points. Endotoxin, cytokines (tumor necrosis factor-α and interleukin-1β, and interleukin-6), CD11b expression, and nitric oxide were measured. Peak endotoxin levels occurred within 30 minutes of reperfusion and were higher among patients developing complications. Interleukin-6 levels increased during reperfusion, reaching a peak on the first postoperative day. Interleukin-6 increase correlated with aortic clamp time and morbidity. CD11b expression increased 30 minutes after reperfusion, and this effect was greater among patients who developed complications. Endotoxin may be important in the pathogenesis of multiple organ dysfunction syndrome. Activated neutrophils may have a central role in tissue injury after reperfusion. Intraoperative CD11b upregulation may be an early marker for postoperative complications after infrarenal abdominal aortic aneurysm repair.

Postoperative evolution of inflammatory response in a model of suprarenal aortic cross-clamping with and without hemorrhagic shock. Systemic and local reactions

Surgery of the abdominal aorta generates a systemic inflammatory response (SIR), a source of operative morbidity-mortality. In the present work we attempted to evaluate the evolution of SIR in an experimental model that simulates elective and urgent surgery on the abdominal aorta. Fifteen mini-pigs divided into three groups were used. The animals were subjected to suprarenal aortic/iliac clamping and bypass with a Dacron-collagen prosthetic graft. Groups were as follows: (1) sham (only aortic dissection); (2) clamping and bypass; (3) hemorrhage of 40%, pre-clamping, and bypass. Determinations included (1) tumor necrosis factor-alpha (TNF-alpha) interleukin (IL)-1beta, IL-6, IL-10, interferon-gamma; (2) myeloperoxidase (MPO), superoxide anion (SOA), superoxide dismutase (SOD), and malondialdehyde (MDA); (3) nitrites; (4) iNOS, (5) cell adhesion molecules (ICAM-1, VCAM-1) at 24 hours, 48 hours, and on day 7; and (6) NFkappaB at 48 hours. Our results point to an increase in all inflammatory variables, corroborated by their molecular regulators such as the expression of CAMs, iNOS, and NFkappaB. The alterations tended to normalize by day 7, after reperfusion. The results point to the great importance of SIR at all levels (molecular, nuclear, cellular, and systemic) in situations such as elective and urgent abdominal aorta surgery and the role that control of this response could represent for the future of vascular surgery.

Consumption of mannan-binding lectin during abdominal aortic aneurysm repair

OBJECTIVE

Patients undergoing abdominal aortic aneurysm (AAA) repair are exposed to an ischaemia-reperfusion injury (IRI), which is in part mediated by complement activation. We investigated the role of the novel lectin pathway of complement during IRI in patients undergoing AAA repair.

METHODS

Patients undergoing elective open infrarenal AAA repair had systemic blood samples taken at induction of anaesthesia, prior to aortic clamping, prior to aortic declamping and at reperfusion. Control patients undergoing major abdominal surgery were also included. Plasma was assayed for levels of mannan-binding lectin (MBL) using ELISA techniques. Consumption of plasma MBL was used as a measure of lectin pathway activation.

RESULTS

Twenty-three patients undergoing AAA repair and eight control patients were recruited. No lectin pathway activation could be demonstrated in the control patients. AAA patients experienced a mean decrease in plasma MBL levels of 41% representing significant lectin pathway activation (p = 0.003).

CONCLUSION

Consumption of MBL occurs during AAA repair, suggesting an important role for the lectin pathway in IRI. Specific transient inhibition of lectin pathway activity could be of significant therapeutic value in patients undergoing open surgical AAA repair.

The Effect of Acute Normovolaemic Haemodilution on the Inflammatory Response and Clinical Outcome in Abdominal Aortic Aneurysm Repair—Results of a Pilot Trial

OBJECTIVES

To determine the effect of acute normovolaemic haemodilution (ANH) on the inflammatory response and clinical outcome in elective open abdominal aortic aneurysm (AAA) repair.

DESIGN

Randomised controlled clinical trial.

METHODS

Thirty-six patients were randomised to undergo ANH or act as controls. Cell salvage was permitted in both groups. Heterologous blood was transfused according to pre-determined triggers. Outcome measures were markers of the systemic inflammatory response in serum and urine observed at multiple time points, and clinical recovery.

RESULTS

Median 890 (range 670-1620) ml of blood was removed at ANH in 16 patients. There were no differences in peri-operative changes in neutrophil count ( P = 0.13), serum C-reactive protein ( P = 0.38), interleukin-6 ( P = 0.50), total antioxidant capacity ( P = 0.73), urinary secretion of albumin ( P = 0.97) or retinol binding protein ( P = 0.41). There were no differences in the mortality and morbidity rates, systemic inflammatory response syndrome, ITU or hospital stay.

CONCLUSIONS

ANH, when used in combination with cell salvage, made no impact on systemic inflammatory response and clinical outcome when compared to cell salvage alone after AAA repair. ANH cannot be recommended for routine use in patients undergoing abdominal aortic aneurysm surgery when cell salvage is available.

A prospective study of subclinical myocardial damage in endovascular versus open repair of infrarenal abdominal aortic aneurysms

BACKGROUND

Endovascular repair of abdominal aortic aneurysms (AAAs) is considered to be less invasive and better tolerated by the cardiovascular system than open repair. Our aim was to assess the true incidence of perioperative myocardial damage associated with endovascular vs open infrarenal AAA repair.

METHODS

Between July 1999 and June 2001, preoperative and postoperative serum troponin T (TnT) levels were measured in all patients presenting for elective AAA repair at Royal Prince Alfred Hospital. The incidence of myocardial damage was recorded on the basis of standard clinical, biochemical, and electrocardiographic changes or a subclinical increase of 50% or more in serum TnT. Patients were excluded if the TnT increase was associated with a significant increase of serum creatinine (> or =50%) with no other evidence of myocardial ischemia. The differences between the two groups were analyzed with the chi 2 test and odds ratios.

RESULTS

A total of 35 open and 112 endovascular AAA repairs were included in the study. There was no significant difference in age, sex, preoperative serum creatinine, or preoperative serum TnT between the two treatment groups. Seventeen patients had biochemical evidence of myocardial damage, which was clinically obvious in only one patient. Even though the incidence of previous myocardial infarction was significantly higher in patients undergoing endovascular repair (41%) than open repair (22%; P < .05), the overall incidence of myocardial damage (clinical or subclinical) was significantly higher in the open group compared with the endovascular group (8 [25%] of 32 vs 9 [8%] of 109, respectively; odds ratio, 3.7; 95% confidence interval, 1.28-10.49; P < .02).

CONCLUSIONS

There is a previously underestimated incidence of subclinical myocardial damage associated with surgery for infrarenal AAA which is lower after endovascular than open repair.

Ischaemia-Reperfusion Injury and Regional Inflammatory Responses in Abdominal Aortic Aneurysm Repair

OBJECTIVES

The inflammatory response to abdominal aortic aneurysm repair is likely to result in response to an ischaemia-reperfusion injury (IRI) to the lower-limbs and gastrointestinal tract. This paper reviews the pathogenesis of the inflammatory response to abdominal aortic aneurysm repair, with specific reference to the levels of evidence in the current literature regarding the potential origin of the inflammatory response.

DESIGN

Review article.

METHODS

The current literature (1966 to August 2003) was reviewed specifically for all articles employing techniques of regional blood sampling from the venous drainage of the lower limbs or gastrointestinal tract during abdominal aortic aneurysm repair.

RESULTS

Ten relevant studies were identified. These demonstrated that regional blood sampling techniques could be easily performed, and provided useful information regarding the potential sites of origin of the inflammatory response.

CONCLUSIONS

Regional blood sampling techniques provide useful information regarding the potential sites of origin of the inflammatory response. Current evidence suggests that both the lower limbs and gastrointestinal tract are clearly important in their roles, however more work is now required to compare directly the roles and contributions of the lower limbs and gastrointestinal tract to the inflammatory response during abdominal aortic aneurysm repair.

Increased nitrotyrosine production in patients undergoing abdominal aortic aneurysm repair

Background

Vascular inflammation is implicated in the pathogenesis of atherosclerosis and abdominal aortic aneurysm (AAA), and is thought to involve reactive species such as the nitric oxide-derived oxidant peroxynitrite. In the present study nitrotyrosine was measured as a stable marker of peroxynitrite production in vivo.

Methods

Perioperative blood samples were obtained from patients undergoing elective open or endovascular repair of an AAA and from patients with intermittent claudication, smoking aged-matched controls, non-smoking aged-matched controls and non-smoking young healthy controls. Plasma nitrotyrosine was measured by an enzyme-linked immunosorbent assay.

Results

The median plasma nitrotyrosine concentration in patients with an AAA (0·46 nmol nitrated bovine serum albumin equivalents per mg protein) was significantly higher than that in patients with intermittent claudication (0·35 nmol; P = 0·002), smoking controls (0·36 nmol; P = 0·001), non-smoking controls (0·35 nmol; P = 0·002) and young healthy controls (0·27 nmol; P &lt; 0·001). Nitrotyrosine concentrations increased during early reperfusion in open AAA repair, but not during endovascular repair. AAA exclusion from the circulation reduced levels to control values (P = 0·001).

Conclusion

Patients with an AAA had raised levels of circulating nitrated proteins compared with patients with claudication and controls, suggesting a greater degree of ongoing inflammation that was not related to smoking.

Intraoperative management: endovascular stents

This article discusses the current state of minimally invasive treatment options for a variety of vascular diseases. Advances that have been introduced over the last two decades have dramatically changed the practice of vascular surgery and anesthesia. The ability to treat pathology, using both intraluminal and extraluminal means,has provided vascular surgeons, interventional radiologists, and cardiologists with unique treatment options that were not available less than a decade ago. Peripheral interventions to treat vascular disease have exploded, from 90,000 in 1994 to more than 200,000 in 1997, and endovascular procedures now replace almost 50% of traditional open vascular operations.

Fever and inflammatory response as principal manifestation of chronic aortic type A dissection--a case report

Aortic dissection usually presents with sudden onset of severe pain. Unfortunately, in more than half of these patients, the diagnosis is missed on admission. If the patient survives, the aortic dissection becomes chronic, whereas the patient may have few or minor symptoms. A rare manifestation may be subfebrile temperatures and inflammatory response. The authors describe a patient in whom aortic dissection resulted in night sweats, weight loss, and subfebrile temperatures.

Cytokine activation and intestinal mucosal and renal dysfunction are reduced in endovascular AAA repair compared to surgery

PURPOSE

To compare endovascular (EVR) to open repair (OR) of abdominal aortic aneurysm (AAA) for cytokine activation, changes in the intestinal mucosal barrier, and renal dysfunction.

METHODS

In a prospective nonrandomized study, 15 patients admitted to a university hospital for elective infrarenal AAA repair (8 OR and 7 EVR) were recruited. Intestinal permeability was assessed preoperatively (PO), at day 1 (D1), and at day 3 (D3) after surgery using the lactulose/mannitol differential excretion (LMR) test. Renal damage was assessed from measurements of the urinary albumin:creatinine ratio (ACR); cytokine activation was based on the urinary concentration of tumor necrosis factor receptor p55 (TNF-Rp55) at the same time points. Serum creatinine and urea concentrations were measured preoperatively and daily for 5 days postoperatively.

RESULTS

A significant increase in LMR was found in the OR group at D1 and D3 compared to PO (p<0.05). The LMR increase at D3 was significantly greater in the OR group (p<0.01). A significant difference was observed in the percentage rise in ACR on D1 in the OR group compared to the EVR group (p<0.005). The urinary TNF-Rp55 concentration was significantly elevated in the OR group at D1 (p<0.05) and D3 (p<0.05) compared to baseline; in the EVR group, it was elevated at D1 (p<0.05) compared to PO. The difference was also significant for this marker between the 2 groups at D1 (p<0.01). No significant change was observed in the serum creatinine or urea concentrations in either group perioperatively.

CONCLUSIONS

Endovascular AAA repair is associated with less cytokine production and less intestinal and renal dysfunction compared to the open approach.

Changes in TH1/TH2 immunity after endovascular and conventional infrarenal aortic aneurysm repair: its relevance for clinical practice

OBJECTIVE

to evaluate local surgical trauma induced by endovascular (TPEG) and conventional infrarenal aortic aneurysm repair (AAA-C), the inflammatory response and changes in cell-mediated and antibody-mediated immunity as illustrated by the type-1/type-2 T-helper (TH1/TH2) cell balance were investigated.

DESIGN

prospective study.

PATIENTS AND METHODS

sixteen patients were included, eight patients underwent AAA-C and eight TPEG. Venous peripheral blood samples were collected 24h preoperatively and 24, 48, 72h, 5 and 7 days postoperatively. Besides the WBC, intracellular TH1/TH2 cytokines (IFN-gamma/IL-4) and the cell surface markers HLA-DR on monocytes and CD23 on B cells were measured by four colour flow cytometry.

RESULTS

statistically significant higher values in the AAA-C group were demonstrated for neutrophiles. The TH1/TH2 immunobalance (expressed by forming the ratio of IFN-(gamma/IL-4 producing T cells as well as by the ratio of HLA-DR(pos) monocytes/CD23(pos) B-cells) showed a significant shift towards TH2 immunity in the AAA-C group whereas TPEG led to a significant lesser shift 24-72h after surgery (p < 0.05).

CONCLUSIONS

TPEG leads to a minor distortion of the TH1/TH2 immunobalance. This implies that TPEG is a less stressing procedure, that is especially beneficial in patients whose conditions are considered less suitable for AAA-C due to age and serious comorbidity.

Ischemic preconditioning before lower limb ischemia--reperfusion protects against acute lung injury

OBJECTIVE

Prolonged limb ischemia followed by reperfusion (I/R) is associated with a systemic inflammatory response syndrome and remote acute lung injury. Ischemic preconditioning (IPC), achieved with repeated brief periods of I/R before the prolonged ischemic period, has been shown to protect skeletal muscle against ischemic injury. The aim of this study was to ascertain whether IPC of the limb before I/R injury also attenuates systemic inflammation and acute lung injury in a fully resuscitated porcine model of hind limb I/R.

METHODS

This prospective, randomized, controlled, experimental animal study was performed in a university-based animal research facility with 18 male Landrace pigs that weighed from 30 to 35 kg. Anesthetized ventilated swine were randomized (n = 6 per group) to three groups: sham-operated control group, I/R group (2 hours of bilateral hind limb ischemia and 2.5 hours of reperfusion), and IPC group (three cycles of 5 minutes of ischemia/5 minutes of reperfusion immediately preceding I/R). Plasma was separated and stored at -70 degrees C for later determination of plasma tumor necrosis factor-alpha and interleukin-6 with bioassay as markers of systemic inflammation. Circulating phagocytic cell priming was assessed with a whole blood chemiluminescence assay. Lung tissue wet-to-dry weight ratio and myeloperoxidase concentration were markers of edema and neutrophil sequestration, respectively. The alveolar-arterial oxygen gradient and pulmonary artery pressure were indices of lung function.

RESULTS

In a porcine model, bilateral hind limb (I/R) injury significantly increased plasma interleukin-6 concentrations, circulating phagocytic cell priming, and pulmonary leukosequestration, edema, and impaired gas exchange. Conversely, pigs treated with IPC before the onset of the ischemic period had significantly reduced interleukin-6 levels, circulating phagocytic cell priming, and experienced significantly less pulmonary edema, leukosequestration, and respiratory failure.

CONCLUSION

Lower limb IPC protects against systemic inflammation and acute lung injury in lower limb I/R injury.

Endovascular approach to abdominal aortic aneurysms limits the postoperative systemic immune response

OBJECTIVES

endovascular repair of abdominal aortic aneurysms (E-AAA) has in recent years developed as an alternative to the conventional open repair (C-AAA). Adverse outcomes following the open approach may relate to immune cell activation and the systemic inflammatory response syndrome (SIRS) and organ failure but the benefits in this respect of the endovascular approach are unclear. This study evaluated this question and focused on T-cell activation and function.

DESIGN

prospective clinical study.

MATERIALS

twenty patients undergoing abdominal aortic aneurysm repair (12 C-AAA and 8 E-AAA).

METHODS

peripheral T-cell expression of surface markers CD69, CD62L and CD25 in vivo and Interleukin 2 (IL-2) and Interleukin-10 (IL-10) responses to the superantigen staphylococcal enterotoxin B (SEB) in vitro were measured preoperatively, 24 h and 1 week postoperatively.

RESULTS

there was no significant increase (p=0.23) in the incidence of SIRS in the open compared with the endovascular group. Enhanced T cell activation occurred following C-AAA and this was associated with significantly greater IL-2 production in response to SEB, with no change in IL-10 production.

CONCLUSIONS

E-AAA attenuates proinflammatory T-cell changes compared with C-AAA repair. A reduction in T-cell activation and impaired responsiveness to superantigen suggests that the immunological sequelae of the endovascular approach to aneurysm repair is more favourable than after the open approach with potentially less risk of adverse outcomes. Proof of this thesis will require a larger prospective study.

Overt colon ischemia after endovascular aneurysm repair: the importance of microembolization as an etiology

OBJECTIVE

The purpose of this study was to analyze the incidence, severity, and etiologic factors of the development of colon ischemia after endovascular aortoiliac aneurysm repair (EVAR).

METHODS

During the last 9 years we performed 278 elective EVARs using a variety of grafts. To facilitate these repairs, one hypogastric artery (HA) was coil embolized in 109 patients and both HAs were coil embolized in 13 patients. The preprocedural status of the inferior mesenteric, hypogastric, and iliac arteries as well as anatomical characteristics of the abdominal aortic aneurysm were determined arteriographically and by computerized tomographic scans. Postoperative colon ischemia was documented by colonoscopy or operative findings.

RESULTS

Colon ischemia occurred in eight patients (2.9%). Three patients with colon ischemia died and had evidence of widespread (cutaneous, renal, small bowel, and/or lower extremity) microembolization. One of these three had a colectomy and microscopic emboli were present. One other patient who required a colectomy also had pathologic evidence of colonic microembolization but survived. Four other patients with colon ischemia were treated conservatively and survived. In one patient, previous colectomy with interruption of mesenteric collaterals may have been a contributory cause of colon ischemia. Of the eight patients with colon ischemia, only one had unilateral HA occlusion, and none had bilateral HA occlusion. The other 121 patients with unilateral and bilateral HA occlusion had no evidence of colon ischemia.

CONCLUSIONS

Colon ischemia occurs after EVAR with an incidence approximating that of open repair. Colon ischemia was unrelated to HA interruption. Embolization appears to be a major cause of colon ischemia, although inadequate mesenteric collateral circulation may also play an etiologic role. Mortality with colon ischemia accompanied by widespread embolization was high, whereas colon ischemia without it was often mild and amenable to nonoperative management.

Pro- and anti-inflammatory cytokine release in open versus endovascular repair of abdominal aortic aneurysm

BACKGROUND

Pro- and anti-inflammatory cytokine release occurs with abdominal aortic aneurysm (AAA) repair although the relative contribution of each is currently poorly understood. Ischaemia-reperfusion injury is thought to play a greater role following open (OR) than endovascular (ER) repair, with resultant greater perioperative morbidity.

METHODS

Thirty-two patients undergoing OR (n = 16) and ER (n = 16) of AAA were studied. Systemic venous (SV) blood was taken at induction (baseline), 0 h (last clamp off), 4, 24, 72 and 144 h, and femoral venous (FV) blood (indwelling catheter; lower torso venous effluent) at 0, 4 and 24 h. The cytokines interleukin (IL) 6, IL-8 and IL-10 were measured in these samples.

RESULTS

In OR, SV and FV IL-6 increased from baseline to a peak at 24 h (SV 589 pg/ml (P = 0.001 versus baseline) and FV 848 pg/ml (P = 0.05)) before declining at 144 h. In ER, there was a similar pattern but the increase was smaller (24 h: SV 260 pg/ml (P = 0.003 versus baseline) and FV 319 pg/ml (P = 0.06)) at all equivalent timepoints compared with OR. IL-8 peaked earlier (4 h) from baseline in both groups before declining by 144 h, and significant differences between SV and FV were seen only in the OR group. IL-10 levels peaked in both groups at 24 h before declining at 144 h, and there were no significant locosystemic differences between the groups.

CONCLUSION

Venous pro-inflammatory cytokine changes (IL-6) are consistent with significantly greater lower-torso reperfusion injury in patients undergoing OR. Smaller responses were seen after ER (IL-6 and IL-8), although both groups showed a similar anti-inflammatory response (IL-10); this pro- and anti-inflammatory imbalance may account for the increased morbidity associated with OR.

Hypogastric artery embolization in endovascular abdominal aortic aneurysm repair

PURPOSE

Iliac artery anatomy is a central factor in endoluminal abdominal aortic aneurysm therapy. It serves as the conduit for graft deployment and as the region of distal graft seal. Thirty-eight percent of iliac vessels in our patients require special treatment because of aneurysms, tortuosity, or small size. Bilateral hypogastric artery exclusion has been avoided because of concerns of colorectal ischemia, hip/buttock claudication, and impotence. We suggest that elective, staged, bilateral hypogastric embolization can be performed safely with reasonably low morbidity and can expand the anatomic boundaries for stent-graft abdominal aortic aneurysm repair.

METHODS

This study was performed as a retrospective chart review of patients requiring hypogastric artery embolization for endovascular repair of abdominal aortic aneurysms between June 1998 and June 2000. Patients with otherwise appropriate anatomy and common iliac artery aneurysms were informed of the option for stent-graft repair with internal iliac artery embolization with its risks of impotence, hip/buttock claudication, and bowel ischemia. Patients underwent unilateral or staged bilateral coil embolizations of their proximal hypogastric arteries with an approximate 1-week interval between procedures. Hospital and office records were reviewed; phone interviews were performed. Follow-up ranged from 1 to 12 months.

RESULTS

During a 24-month period, 65 patients underwent endovascular abdominal aortic aneurysm repair; 18 patients (28%) required hypogastric artery embolization. Seven (39%) of these patients underwent bilateral embolization. There were no episodes of clinically evident bowel ischemia. Lactate levels were normal in all measured patients. Postoperative fevers (> 101.0 degrees F) were documented in 10 (56%) of 18 patients. The average white blood cell count was 12.8 x 10(9)/L (range, 8.5-22.9). There were no positive blood culture results. The return to the full preoperative diet occurred in 1 to 3 days. Hip/buttock claudication occurred in approximately 50% of patients with persistent but improved symptoms at 6 months. Eighty-seven percent of patients had preoperative erectile dysfunction. Only two patients noted worsening of erectile function postoperatively.

CONCLUSIONS

Preliminary results indicate that bilateral hypogastric artery embolization can be performed, when necessary, with reasonable morbidity in patients undergoing stent-graft abdominal aortic aneurysm repair.

The Inflammatory Response and its Consequence for the Clinical Outcome Following Aortic Aneurysm Repair

OBJECTIVE

to review published studies on the outcome of the inflammatory response after abdominal aortic aneurysm (AAA) repair.

METHODS

a literature search on PubMed was performed. All studies that determined the inflammatory response (cytokine release) after AAA repair were included. The results of the studies and differences between open and endoluminal repair were compared and evaluated.

RESULTS

seventeen studies were identified. In most studies the investigated cytokines were TNF-alpha and IL-6. Determination of IL-1 beta, IL-8, TNFsr1 and TNFsr2 were less often performed. TNF-alpha may reflect, but not strictly predict, the clinical outcome in patients with ruptured AAA. IL-6 levels correlate well with the surgical trauma per se. Variations in recorded cytokine release during endovascular AAA repair may depend on the times of blood sampling.

CONCLUSION

both open and endovascular AAA repair provoke a cytokine response. This response is greater during open repair than during endovascular aortic aneurysm exclusion.

Extraperitoneal Approach Reduces Neutrophil Activation, Systemic Inflammatory Response and Organ Dysfunctionin Aortic Aneurysm Surgery

OBJECTIVES

to compare the effects of transperitoneal and extraperitoneal approaches on systemic inflammatory response, neutrophil activation and organ dysfunction in elective abdominal aortic aneurysm (AAA) repair.

PATIENTS AND METHODS

twenty patients admitted for elective infrarenal AAA repair were prospectively randomised into transperitoneal (n =10) or extraperitoneal ( n =10) groups. Neutrophil activation was assessed by measuring the plasma levels of neutrophil elastase/alpha(1)-anti-trypsin complexes before surgery, intraoperatively and at 6 h, 12 h, 24 h and then daily after surgery. Venous blood samples for estimation of liver function tests, full blood counts, urea and electrolytes and arterial samples for blood gas analysis were taken daily from preoperatively to day 5 after surgery. Multiple organ dysfunction (MOD) and systemic inflammatory response (SIR) scores were calculated daily.

RESULTS

the concentrations of neutrophil elastase/alpha(1)-anti-trypsin complexes were significantly higher in the transperitoneal group at 6 h after surgery compared to the extraperitoneal group (799(455-921) ng/ml (median(i.q.r.)) vs 307(171-395) ng/ml, p<0.005), and at 12 h (397(364-936) ng/ml vs 319(134-352) ng/ml, p <0.05). The MOD scores were significantly higher in the transperitoneal group in comparison to the extraperitoneal group at day 1 (2.5(2-3.3) vs 1(0-1), p<0.001) and day 2 (2.5(2-3.3) vs 1(0-1), p <0.001). The SIR scores were also significantly higher at day 1 (1(0-2) vs 0, p <0.01), day 2 (1.5(0-2.3) vs 0, p <0.01), and day 3 (1(0-1) vs 0, p <0.05).

CONCLUSIONS

neutrophil activation, systemic inflammatory response and organ dysfunction are increased in elective AAA repair when a transperitoneal approach is used. This may be related to intestinal manipulation and mesenteric traction which are reduced in the extraperitoneal approach.

Regional Tissue Metabolism During Open or Endovascular Abdominal Aortic Aneurysm Surgery

OBJECTIVE

to investigate differences in regional tissue metabolism between open and endovascular aneurysm repair utilising a microdialysis technique.

MATERIALS

eight patients receiving endovascular stent grafts (STENT) and six patients undergoing open aortic surgery (OPEN) for abdominal aortic aneurysms were studied prospectively but non-randomised.

METHOD

microdialysis catheters placed subcutaneously in the pectoral and calf region, respectively.

RESULTS

microdialysate glucose levels increased in the OPEN group on the day of surgery. Microdialysate lactate levels increased transiently in the leg in the STENT group. In the OPEN group lactate increased in the leg after aortic cross-clamping. Glycerol decreased in the pectoral region in the STENT group after surgery, but remained elevated in the OPEN group.

CONCLUSION

we found indications that the metabolic impact of the two aortic procedures differ. This may be of clinical importance when selecting patients for either open aortic surgery or endovascular stentgrafting.

Differences in renal response between endovascular and open repair of abdominal aortic aneurysms

OBJECTIVES

to determine the difference in renal and systemic response between open and endovascular aneurysm repair.

MATERIALS AND METHODS

we studied prospectively 22 patients undergoing open repair (OR) and 15 patients undergoing endovascular repair (ER). Blood and urine samples were taken preoperatively (T0) and before clamping of the aorta or femoral artery (T1) and 5 min (T2), 1 h (T3), 6 h (T4), 24 h (Day 1) and 48 h (Day 2) after declamping. Albumin/creatinin ratio (AC ratio) in urine, serum albumin, serum creatinin, serum C-reactive protein and serum lactate were determined.

RESULTS

the urinary AC ratio in ER was significantly lower than in OR (p<0.001). In both groups the rise in urine albumin/creatinin ratio after declamping (T2, T3) was significant (p<0.001). C-reactive protein was raised significantly at day 1 and 2 in both groups (p<0.001) with no difference between the groups. Serum lactate values were significantly higher in OR. There was a significant increase in serum lactate 6 h after declamping in the ER group.

CONCLUSIONS

after endovascular repair renal damage is less compared to open repair. There is a significant systemic reaction to the endovascular repair causing mild, short-lasting damage to the kidney. This systemic response is most probably induced by a combination of ischaemia reperfusion injury and the surgical trauma of the procedure. Other possible explanations are discussed.

Response of inflammatory markers to balloon angioplasty in peripheral arterial occlusive disease

OBJECTIVES

To study the inflammatory response to balloon angioplasty (PTA).

DESIGN

Prospective study.

MATERIALS

Blood samples were drawn for cytokine analysis from 10 patients undergoing PTA before, after 60 min and 6 h after the balloon inflation. Adhesion molecules were analysed in 14 patients undergoing PTA and in seven patients undergoing angiography only. Arterial samples were taken in eight patients, before PTA, immediately after and 15 min later. Venous samples were taken in six patients and in the group undergoing angiography only. The sampling was before, 60, 90 and 120 min after the procedure. As controls served 15 patients with no signs of peripheral arterial disease.

METHODS

Cytokines (IL-6, TNF-alpha) were analysed using ELISA. Adhesion molecule expression on WBC was measured by flow cytometry.

RESULTS

A significant increase of IL-6 in the sample taken 6 h after the last balloon inflation was seen in five patients. TNF-alpha was raised only in one patient. The group of patients with peripheral arterial occlusive disease (PAOD) expressed pre-interventionally a higher level of adhesion molecules on WBC compared to the controls. The expression of adhesion molecules (CD11b/CD18) was significantly decreased after PTA.

CONCLUSION

Only a very limited cytokine response is caused by PTA reflecting the small surgical trauma. PTA results in a downregulation of detectable CD11b/CD18 expression on WBC in the circulation, which may reflect removal of activated cells through adhesion and extravasation.

Endovascular AAA repair attenuates the inflammatory and renal responses associated with conventional surgery

PURPOSE

To quantify the inflammatory and renal parameters in comparative cohorts of patients undergoing surgical or endovascular repair of abdominal aortic aneurysms (AAAs).

METHODS

Forty-three patients (41 men; ages 58-81 years) underwent endovascular or conventional aneurysm surgery according to aortic morphology. All patients received a standard general anesthetic and had 12 serial blood and urine samples collected during the perioperative period. Samples underwent analysis for the cytokines interleukin (IL) 1beta tumor necrosis factor-alpha (TNF-alpha), and IL-6. White cell and platelet activation were estimated indirectly by measuring sL-selectin and 11-dehydrothromboxane B2, respectively. The urinary albumin:creatinine ratio (ACR) and N-acetyl-beta-D-glucosaminidase (NAG) activity were estimated to assess renal injury. Fibrinogen and fibrinogen degradation products were calculated to assess activation of the clotting cascade.

RESULTS

Twenty-three patients underwent endovascular AAA repair and 20 had conventional surgery. Concentrations of IL-6 (p < 0.002) and TNF-alpha (p < 0.0004) were significantly higher in the conventional group. The ACR (p < 0.002) and urinary NAGs (p < 0.0009) were also significantly higher in this group, suggesting greater renal injury. Platelet activity was significantly greater in the endovascular group (p < 0.01), perhaps indicating thrombus organization within the aneurysm sac.

CONCLUSIONS

These data suggest that the inflammatory response associated with conventional aneurysm repair is largely obviated by endovascular techniques. This may potentially translate to a lower incidence of multiple organ failure after endovascular surgery.

Early inflammatory response after elective abdominal aortic aneurysm repair: a comparison between endovascular procedure and conventional surgery

OBJECTIVE

To determine the nature of and to compare the inflammatory responses induced by (1) endovascular and (2) conventional abdominal aortic aneurysm (AAA) repair.

MATERIAL AND METHODS

Twelve consecutive patients undergoing elective infrarenal AAA repair were prospectively studied. Seven patients were selected for endovascular procedures (the EAAA group); five patients underwent open surgery (the OAAA group). Three control patients undergoing carotid thromboendarterectomy were also included. Serial peripheral venous blood samples were collected preoperatively, immediately after declamping or placement of the endograft, and at hours 1, 3, 6, 12, 24, 48, and 72. Acute phase response expression of peripheral T lymphocyte and monocyte activation markers and adhesion molecules (flow cytometry), soluble levels of cell adhesion molecules (enzyme-linked immunosorbent assay), cytokine (tumor necrosis factor alpha, interleukin-6, and interleukin-8) release (enzyme-linked immunosorbent assay), and liberation of complement products (nephelometry) were measured.

RESULTS

Regarding acute phase response, the EAAA and OAAA groups showed significant increases in C-reactive protein (P <.001 and P =.001), body temperature (P =.035 and P =.048), and leukocyte count (P <.001 and P <.001). Similar time course patterns were observed with respect to body temperature (P =.372). Statistically significant different patterns were demonstrated for C-reactive protein (P =.032) and leukocyte count (P =.002). Regarding leukocyte activation, a significant upregulation of peripheral T lymphocyte CD38 expression was observed in the OAAA group only (P =.001). Analysis of markers such as CD69, CD40L, CD25, and CD54 revealed no perioperative fluctuations in any group. Regarding circulating cell adhesion molecules, the EAAA and OAAA groups displayed significant increases in soluble intercellular adhesion molecule-1 (P =.003 and P =.001); there was no intergroup difference (P =.193). All groups demonstrated high soluble von Willebrand factor levels (P =.018, P =. 007, and P =.027), there being no differences in the patterns (P =. 772). Otherwise, soluble vascular cell adhesion molecule-1, soluble E-selectin, and soluble P-selectin did not appear to vary in any group. Regarding cytokine release, although a tendency toward high tumor necrosis factor alpha and interleukin-8 levels was noticed in the EAAA group, global time course effects failed to reach statistical significance (P =.543 and P =.080). In contrast, interleukin-6 showed elevations in all groups (P =.058, P <.001, and P =.004). Time course patterns did not differ between the EAAA and OAAA groups (P =.840). Regarding complement activation, the C3d/C3 ratio disclosed significant postoperative elevations in the EAAA and OAAA groups (P =.013 and P =.009). This complement product release was reduced in the EAAA group (P <.001).

CONCLUSIONS

The current study indicated that both endovascular and coventional AAA repair induced significant inflammatory responses. Our findings showed that there were no large differences between the procedures with respect to circulating cell adhesion molecule and cytokine release. Moreover, the endoluminal approach produced a limited response in terms of acute phase reaction, T lymphocyte activation, and complement product liberation. This might support the concept that endovascular AAA repair represents an attractive alternative to open surgery. Given the relatively small sample size, further larger studies are required for confirmation of our observations.

The inflammatory response following treatment of abdominal aortic aneurysms: a comparison between open surgery and endovascular repair

OBJECTIVES

to compare the inflammatory response following endovascular and conventional AAA repair.

DESIGN

prospective study.

PATIENTS AND METHODS

ten patients were selected for open surgery (OPEN) and ten for endovascular (ENDO) AAA repair. Leukocytes, platelets, myeloperoxidase, lactoferrin, beta-thromboglobulin, C-reactive protein (CRP), interleukin 6 (IL-6), tumour necrosis factor alpha (TNF-alpha) and complement activation products were measured before, during and after surgery.

RESULTS

in the OPEN group the median hospital stay was longer (6 vs. 12 days, p=0.001) and more patients required transfusion (p=0.02). IL-6 and CRP increased postoperatively, most in OPEN (p<0.01). Platelet counts decreased after the first angiography in ENDO (p<0.01) and before aortic cross-clamping in OPEN (p<0.05). The decrease was larger in OPEN (p=0.02). Leukocyte counts decreased after the first angiography in ENDO, and thereafter increased (p=0.001). An equivalent increase was observed in OPEN after declamping (p=0.001). Leukocyte and platelet degranulation products increased after the first angiography in ENDO and after declamping in OPEN. Changes in complement activation products were small. TNF-alpha did not change significantly.

CONCLUSION

endovascular AAA repair caused significant leukocyte and platelet activation. Based on the timing of activation this could be caused by radiographic contrast media.

Sigmoid ischemia and the inflammatory response following endovascular abdominal aortic aneurysm repair

PURPOSE

To assess the relationship between sigmoid colonic perfusion, endotoxemia, and cytokine generation in patients undergoing elective open repair (OR) or endovascular repair (EVR) of infrarenal abdominal aortic aneurysms (AAA).

METHODS

Ten patients (9 males; average age 67.6 +/- 2.5 years, mean aneurysm diameter 6.9 +/- 0.6 cm) undergoing OR were compared to 10 patients (all males; average age 70.3 +/- 2.6 years, mean aneurysm diameter 6.5 +/- 0.5 cm) whose repair was performed using the EVR technique. The partial pressure of the carbon dioxide gap (PCO2gap = tissue PCO2 - arterial PCO2) of the sigmoid colonic mucosa was measured using a silicone tonometer to evaluate bowel perfusion. Blood samples were collected into pyrogen-free heparinized tubes for quantification of plasma concentrations of endotoxin, tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6) before, during, and after aortic repair.

RESULTS

Patients in the OR group had a significantly greater increase in PCO2gap, suggesting a greater degree of bowel ischemia compared to the EVR group. This was associated with significantly greater postoperative concentrations of endotoxin, TNF-alpha, and IL-6 in the OR group. A significant correlation was found between PCO2gap, IL-6, and postoperative core temperature.

CONCLUSIONS

The results suggest that the degree of bowel ischemia, endotoxemia, and cytokine generation following elective infrarenal AAA reconstruction may be reduced if the endovascular technique is used instead of conventional surgery.

Endovascular repair of abdominal aortic aneurysms: where do we stand?

Endovascular repair of abdominal aortic aneurysms has evolved dramatically within the past few years. In light of the potential to reduce morbidity and mortality associated with open surgical repair, endoluminal grafting offers therapeutic options to patients who are not surgical candidates because of comorbidities. With the development of bifurcated devices, more complex aneurysms may be treated by endovascular grafting. Although successful placement of endovascular grafts requires a pronounced learning curve, including appropriate patient selection, midterm results seem consistent with those of traditional open repair of aneurysms. This review describes the current indications, minimal requirements, different devices and associated techniques, and potential complications of endoluminal repair of abdominal aortic aneurysms. Future aspects of endoluminal grafting are also discussed.

Cardiovascular and catecholamine responses during endovascular and conventional abdominal aortic aneurysm repair

OBJECTIVES

To compare changes in plasma catecholamines, acid-base status and cardiovascular dynamics in patients undergoing endovascular or conventional infrarenal abdominal aortic aneurysm (AAA) repair under standard general anaesthesia.

DESIGN

Prospective cohort study.

MATERIALS

30 patients scheduled for elective infrarenal AAA repair.

METHODS

Plasma epinephrine and norepinephrine concentrations, acid-base status and cardiovascular measurement were compared before surgery, and 5 min after aortic clamping and clamp release (conventional group) or occlusion and release (endovascular group) in patients undergoing endovascular (n = 15) or conventional AAA repair (n = 15).

RESULTS

Arterial pH (p < 0.005) and base deficit (p < 0.05) increased, and plasma bicarbonate decreased (p < 0.005) during aortic cross-clamping in the conventional group. pH decreased further (p < 0.005), and base deficit and pCO2 increased (both p < 0.005) after clamp release. These changes were significantly greater than during endovascular repair, in whom within-group changes were not statistically significant. Values were similar in the two groups 30 min after reperfusion. Plasma epinephrine concentrations increased during conventional surgery (p < 0.05) and were greater than in the endovascular group (p < 0.05). Plasma norepinephrine concentrations increased during surgery in both groups but the changes were not statistically significant.

CONCLUSIONS

Plasma catecholamine concentrations, changes in cardiovascular variables and acid-base status were increased during conventional compared with endovascular AAA repair.

Cytokine and fibrinogen response in patients undergoing open abdominal aortic aneurysm surgery

OBJECTIVES

To assess whether open abdominal aortic aneurysm (AAA) surgery influences cytokines and fibrinogen.

METHODS

Twenty-three consecutive patients operated on for AAA were compared to 11 operated controls and 20 age-matched controls. Cubital blood was sampled pre-, intra- and postoperatively and femoral blood also sampled intraoperatively.

RESULTS

Preoperatively, interleukin (Il)-6 was elevated in AAA patients. During aortic clamping, Il-6, Il-10 and monocyte chemoattractant protein-1 (MCP-1) increased significantly (p < 0.001, p < 0.01 and p < 0.05 respectively) while soluble interleukin-2 receptor (sIl-2R) and fibrinogen decreased significantly (p < 0.001 for both). After aortic declamping, Il-6, Il-10 and MCP-1 had further significant increases compared with levels during aortic clamping while sIl-2R had a further non-significant and fibrinogen a significant decrease (p < 0.05 in cubital and p < 0.001 in femoral blood). One week postoperatively Il-6, Il-10 and MCP-1 had all decreased but were still significantly elevated compared with baseline values while sIl-2R and fibrinogen showed an increase in comparison with baseline (p < 0.001 for both). Intraoperative levels of Il-6 and Il-10 showed a significant co-variation with the magnitude of operative trauma.

CONCLUSIONS

These data indicate that open AAA surgery induces a profound inflammatory and coagulative response which persists at one week postoperatively.