Variability of Origin of Splanchnic and Renal Vessels From the Thoracoabdominal Aorta.

OBJECTIVE: To analyze the variability of origin of the celiac trunk (CT), the superior mesenteric artery (SMA), the right renal artery (RRA), and the left renal artery (LRA) in terms of mutual distances, angle from the sagittal aortic axis (clock position), and ostial diameters on computed tomography angiographies (CTAs) in three groups of patients. METHODS: One hundred and fifty CTAs of 50 patients with a non-dilated thoracoabdominal aorta (group A), 50 with thoracoabdominal aneurysm (B), and 50 with infrarenal aneurysm (C) were reviewed. The measurements performed on CTAs, as well as the patients' age, sex, and body surface area, were analyzed. p values <.05 were considered statistically significant. RESULTS: The clock position of the CT and the SMA, the diameters of all vessels, and the distance of the CTeSMA followed a Gaussian distribution. In contrast, the clock position of the renal vessels did not follow a normal distribution, and nor did the distances of the SMA-RRA, SMA-LRA, RRA-LRA or the distances between the renal arteries and the aortic bifurcation. The same values did not differ significantly among the three groups, with the exception of the distances between the renal arteries and the aortic bifurcation, significantly greater in group C. The clock position of the LRA and the distances of the SMA-LRA, SMA-RRA, RRA-LRA and between both renal arteries and the aortic bifurcation showed a significant correlation with the increase of aortic diameter. CONCLUSION: The anatomic variability of the origin of both the CT and the SMA in terms of clock position and mutual distances followed a Gaussian distribution, regardless of group. The same applies to the ostial diameters of renal and visceral vessels. In contrast, the origin of the renal vessels had a statistically significant heterogeneity that seemed to be correlated with the increase of aortic diameter in the mesenteric and renal aortic region.

Ulnar artery aneurysm: case report and review of the literature.

AIM: We report a case of ulnar and palmar arch artery aneurysm in a 77 years old man without history of any occupational or recreational trauma, vasculitis, infections or congenital anatomic abnormalities. We also performed a computed search of literature in PUBMED using the keywords "ulnar artery aneurysm" and "palmar arch aneurysm". CASE REPORT: A 77 years old male patient was admitted to hospital with a pulsing mass at distal right ulnar artery and deep palmar arch; at ultrasound and CT examination a saccular aneurysm of 35 millimeters at right ulnar artery and a 15 millimeters dilatation at deep palmar arch were detected. He was asymptomatic for distal embolization and pain. In local anesthesia ulnar artery and deep palmar arch dilatations were resected. Reconstruction of vessels was performed through an end-to-end microvascular repair. Histological examination confirmed the absence of vasculitis and collagenopaties. In postoperative period there were no clinical signs of peripheral ischemia, Allen's test and ultrasound examination were normal. At follow-up of six months, the patient was still asymptomatic with a normal Allen test, no signs of distal digital ischemia and patency of treated vessel with normal flow at duplex ultrasound. CONCLUSION: True spontaneous aneurysms of ulnar artery and palmar arch are rare and can be successfully treated with resection and microvascular reconstruction.

[Chemical risk assessment]. / Modelli per la valutazione delle esposizioni.

Determination of the effect an agent has on health requires that the dose of the agent to a person be defined as accurately as possible. The correct estimation of exposure for occupational studies has received increasing attention in recent years and, as a result, a body of methodological literature has begun to take form. The importance of 'analysis and control of errors in exposure assessment, and integration with decision-making processes, is emphasized. This paper reviews the issues in the methodology of exposure assessment, particularly methods for quantitative retrospective assessment studies. The advantages of the use of validated statistical models are discussed.

Inflammatory abdominal aortic aneurysms. A 20-year experience.

AIM: The aim of the study was to report a 20-year single Institution experience, with the early and late outcomes of surgical treatment of inflammatory abdominal aortic aneurysms. METHODS: In a 20-year period, 2 275 consecutive patients underwent elective surgical repair for non-rupture abdominal aortic aneurysm. Fifty-two patients (2.3%) were classified as inflammatory abdominal aortic aneurysms. Early and late outcomes were analyzed. RESULTS: One patient died in the perioperative period, giving a mortality rate of 1.92%. One patient died from a pseudoaneurysm rupture 7 months after operation. Three patients developed an aortic pseudoaneurysm in the follow-up period (mean 12.1 years, range 1-20 years) and underwent a redo operation. CONCLUSION: Overall surgical outcome of these patients, in terms of short-term and long-term is good. A high rate of pseudoaneurysm formation was observed.

Case report of adventitial cystic disease of the popliteal artery presented with the ''dog-leg'' sign.

Adventitial cystic disease of the popliteal artery constitutes an infrequent cause of claudication in non-atherosclerotic young or middle-aged population. Here, we report the case of a 43-year-old female with adventitial cystic disease of the popliteal artery causing left lower leg claudication, detected by duplex scanning. The angio-CT showed the "dog-leg" sign, typical of the aneurysm of the popliteal artery. Surgery was performed through the posterior approach. The cyst and the affected segment of the artery were successfully excised and replaced with an autogenous saphenous vein graft. In 1 year follow-up the graft is patent and the patient is completely asymptomatic.

Duplex scanning on admission prevents unnecessary carotid endarterectomies.

AIM: This retrospective single Institution study, aims to evaluate the performance of duplex scanning on admission of patients with carotid artery disease to avoid unnecessary carotid endarterectomies. METHODS: From 1 January 1997 until 31 Decem-ber 2004, 1 504 patients were admitted to our Institution to undergo carotid endarterectomy. A duplex scan on admission was performed in all of them. RESULTS: A total of 1 369 from these patients (91%) underwent surgery, while 135 (9%) were dismissed because there was no indication for surgical treatment. They were put in conservative treatment and periodic duplex control appointments. CONCLUSIONS: In 9% of the patients, unnecessary carotid endarterectomy was avoided.

Retrograde aorto-mesenteric by-pass grafting as treatment option of recurrent chronic mesenteric ischemia after thrombosed superior mesenteric artery stenting. Report of a case.

We report a case of early stent failure in a patient with chronic mesenteric ischemia and its treatment with a retrograde aorto-mesenteric by-pass. The patient was initially treated with angioplasty and stenting. Seven months after the procedure complete thrombosis of the stent was achieved. A retrograde aorto-mesenteric by-pass was performed. After two years the patient remains asymptomatic and color Duplex scan confirm the patency of the graft.

The challenge of gate cannulation during endovascular aortic repair: A hypothesis of simplification.

AIM: One of the technical problems which can be encountered during the endovascular repair (EVAR) of abdominal aortic aneurysms, is represented by the challenge of cannulation of the contralateral gate after the opening of the main body of the endograft, especially in case of tortuous aorta-iliac anatomy. Aim of this work is to propose a hypothesis of simplification, verifying the possibility to maximize the area available for the cannulation of the contralateral gate by simulating an oblique distal end of the leg of the most used devices, without affecting the correct sealing between the main body and the iliac extension. METHODS: Data about the contralateral gate of the main body of endografts most used for EVAR were analyzed. The elliptical sectional area resulting from the simulation of the oblique cut was calculating with some geometric formulas. Then the gain of "disposable area" for the cannulation of the contralateral gate was calculated as a percentage of the elliptical area resulting in maximum distal oblique cut, with respect to the nominal circular area of the base. RESULTS: The only endografts which could undergo an oblique cut without losing the sealing between the main body and the contralateral limb were the Incraft, the Treovance and the Ovation, for which it would be possible to obtain a surface gain up to 84%, 22.8% and 14.4% respectively (being 9.8% in case of Ovation with the main body 29 and 34). A simulation of oblique cut was also performed on the endografts which currently do not allow to do so without a loss of sealing, assuming to lengthen the contralateral gate of an arbitrary measure of 10mm. In these cases, the percentage of surface gain was greater for endoprostheses which had a smaller diameter of the contralateral leg. CONCLUSIONS: The oblique cut of the contralateral gate allowed a gain of the surface available for the cannulation, however it was not applicable to all models of currently available endoprostheses, unless of a loss of sealing between the main body and the contralateral iliac limb.

PHCCC, a specific enhancer of type 4 metabotropic glutamate receptors, reduces proliferation and promotes differentiation of cerebellar granule cell neuroprecursors.

Exposure of immature rat cerebellar granule cell cultures to the type 4 metabotropic glutamate (mGlu4) receptor enhancer N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC) reduced [3H]thymidine incorporation. Its action was sensitive to the growth conditions and was attenuated by two mGlu4 receptor antagonists. An antiproliferative action of PHCCC was also seen in cultures from wild-type, but not mGlu4, knock-out mice. At least in rat cultures, PHCCC was not neurotoxic and enhanced neuritogenesis. Although PHCCC reduced the increase in cAMP formation and phospho-AKT levels induced by forskolin, none of these transduction pathways significantly contributed to the reduction of [3H]thymidine incorporation. Interestingly, PHCCC reduced the expression of Gli-1, a transcription factor that mediates the mitogenic action of Sonic hedgehog. Finally, we treated newborn rats with PHCCC either intracerebrally (infusion of 5 nmol/2 microl in the cerebellar region once every other day) or systemically (5 mg/kg, i.p., once daily) from postnatal days 3-9. Local infusion of PHCCC induced substantial changes in the morphology of the developing cerebellum. In contrast, systemic injection of PHCCC induced only morphological abnormalities of the cerebellar lobule V, which became visible 11 d after the end of the treatment. These data suggest that mGlu4 receptors are involved in the regulation of cerebellar development.

Plasma levels of metalloproteinases-3 and -9 as markers of successful abdominal aortic aneurysm exclusion after endovascular graft treatment.

BACKGROUND: Structural alterations of aortic wall resulting from degradation of matrix proteins by matrix metalloproteinases (MMPs) characterize abdominal aortic aneurysms (AAAs). No studies have compared circulating levels of MMPs after endovascular graft (EVG) exclusion in comparison with open surgical repair (OSR) in patients affected by AAA. METHODS AND RESULTS: An abdominal angiography and CT scan were performed in all patients at the time of enrollment. A spiral CT scan was performed at 6 months to detect presence of endoleaks. MMP-3 and MMP-9 levels were measured before EVG (n=30) and OSR (n=15) treatments and at 1, 3, and 6 months of follow-up by a sandwich ELISA technique. Healthy volunteers (n=10) were used as control subjects. Immunohistochemical staining for MMP-9 and MMP-3 was performed on tissue samples from surgical cases. Both MMP-9 and MMP-3 mean basal levels were significantly higher in patients affected by AAA than in control subjects (32.3+/-20.7 ng/mL for EVG and 28+/-9.9 ng/mL for OSR versus 8.9+/-2.5 ng/mL, 2P<0.05; 18.3+/-9.7 ng/mL and 26.7+/-10.8 ng/mL versus 8.2+/-5.3 ng/mL, 2P<0.001). In the OSR group, both MMP-9 and MMP-3 mean levels decreased after surgery (28+/-9.9 ng/mL at basal versus 14.7+/-6.6 ng/mL at 6 months, 2P<0.001; 26.7+/-10.8 versus 12+/-5.3 ng/mL; 2P<0.001). In the EVG group, a statistically significant difference at 6-month follow-up in MMP-9 and MMP-3 mean plasma values was detected in patients who had endoleakage in comparison with patients without endoleakage (44.3+/-20.7 versus 14.6+/-7.0 ng/mL, 2P<0.005; 25+/-11.5 versus 10.3+/-5.4 ng/mL, 2P<0.005). CONCLUSIONS: After EVG exclusion, MMP-9 and MMP-3 levels decreased to a level similar to that of patients undergoing OSR. In addition, a lack of decrease in MMP levels after EVG exclusion may help in identifying patients who will have endoleakage and consequent aneurysm expansion caused by continuous sac pressurization during follow-up.

[Neuropsychological study of 12 patients with pure degenerative cerebellar disease]. / Evaluación cognitiva en 12 pacientes con enfermedad cerebelosa degenerativa pura.

INTRODUCTION: The cerebellum has been traditionally associated with motor control learning and performance. However, since 1970 a growing body of clinical and experimental evidences has suggested that the cerebellum may be involved in nonmotor cognitive functions as well. OBJECTIVE: To explore the presence of eventual cognitive impairment in non-demented patients with isolated degenerative cerebellar diseases. PATIENTS AND METHODS: Twelve patients with the diagnosis of selective degenerative cerebellar disorders, either inherited or sporadic, were selected (mean age: 40.42 +/- 13.49 years; mean education level: 9.92 +/- 3.99 years; duration of illness: 12.13 +/- 11.27 years, MMSE: 26.75 +/- 1.5) and evaluated through a standardized neuropsychological tests battery. Normalized Z scores were estimated and compared against 0, employing the t test for one sample. RESULTS: Significant cognitive deficits were found in the following domains: executive, visuo-spatial, memory and attention functions. Performance on the Wisconsin test showed a significative number of perseverative errors. Memory deficits included verbal learning and free recall difficulties, with good recognition of the material presented. CONCLUSIONS: The findings of this study are consistent with the role of the cerebellum as modulator of mental functions. The cognitive deficits resulting from cerebellar pathology may be related with the disruption of cerebello-cortical connexions involving a complex network which includes the prefrontal region, suggesting that the cerebellum may process cortical information coming from different areas linked with the control of cognition.

Initial experience with the inspire MD C-Guard stent in the treatment of carotid artery disease.

OBJECTIVE: One of the main issue concerning the treatment of carotid artery stenosis is about the use of stents which could offer the best navigability through the lesion and the smallest "maximum unprotected circular area", ensuring the lower risk of neurological complication both intraprocedurally and in the long term. Recently, the Inspire MD technology (Tel Aviv, Israel) presented the new stent Inspire MD C-Guard, a bare-metal stent covered by a micron level mesh (MicroNet).We report our experience about the use of this novel stent in the endovascular treatment of carotid artery stenosis, with some technical considerations. METHODS: Data about patients in whom the Inspire MD C-Guard was used for the treatment of carotid artery diseases were retrospectively collected and analyzed. RESULTS: The procedure was completed in all patients without any intraoperative complications. Postoperative course was uneventful in all cases and no complications have been recorded till now. CONCLUSIONS: In our limited experience, the Inspire MD C-Guard has proven to be a safe stent for the treatment of carotid artery diseases. However large studies are needed to better explain strengths and weaknesses of this device.

Treatment of significant carotid artery stenosis in 1824 patients.

AIM: We report our experience of thirteen years of treatment of significant carotid artery stenosis. METHODS: Data of all consecutive patients who came to our Division for a significant carotid artery stenosis from January 1999 to January 2012 were collected about patients' demographic, cardiovascular risk factors, neurological symptoms and treatment (carotid endarterectomy, carotid artery stenting or best medical therapy). Retrospective review was performed and the occurrence of death, major cerebrovascular events (major stroke, minor stroke) and myocardial infarction (MI) were recorded both at 30-day and at long-term. Analysis was performed among groups by means of JMP 5.1(®). RESULTS: Of 1824 patients who were admitted to our Department for a significant carotid stenosis, 582 were unsuitable for surgery and underwent carotid artery stenting (CAS, Group A). Three hundred and seventy-three of them were symptomatic (64.1%). Carotid endarterectomy (CEA) was performed in 1030 patients (Group B), 741 (71.9%) of them were symptomatic. The remaining patients (Group C) were treated using best medical therapy (BMT). At 30-day CEA compared to CAS and BMT was associated with higher risk of MI (2.1% vs. 0.2%, and 0.4% respectively, P<0.05), most of all in asymptomatic patients. CEA had a higher risk of cranial nerve injuries than CAS (3.3% vs. 0%, P<0.001). Both risk of death and major neurological complications were similar among the three groups in both symptomatic and asymptomatic patients. At long-term, risk of stroke after CEA was similar to that after CAS, both for symptomatic and asymptomatic patients, while risk of 1-year stroke in Group C was higher than in Group A (P<0.001) and in Group B (P<0.001), for both symptomatic and asymptomatic patients. Risk of long-term MI was similar among the three groups. Mortality at long term in symptomatic patients was higher after CAS than after CEA (P=0.001). Also long-term mortality in Group C was higher than in Group A and B (both P<0.001) but only for asymptomatic patients. A procedure that lasted for more than 60 minutes, patients who had no prior Magnetic Resonance Angiography (MRA) or Computed Tomographic Angiography (CTA) study of the aortic arch were independent risk factors for major neurological complications after CAS. Symptomatic patients were likely to have more major neurological complications in the long term if they were treated with BMT only. CONCLUSION: In our experience, CAS offered a valid alternative for both symptomatic and asymptomatic patients who were poor candidates for CEA, with results that compared favourably to those of CEA both at 30-day and at long-term. Patients who couldn't be operated on neither with CAS nor with CEA had a lower risk of MI at 30-day but a higher risk of stroke during the first year, especially if they had previously experienced neurological symptoms.

Treatment options for visceral artery aneurysms: ten year experience.

AIM: Open surgical repair (OSR) and endovascular techniques (ET) are both described in the literature for treating visceral artery aneurysms (VAAs). Aim of this study is to report a two-center experience of patients treated for a VAA using either OSR or ET, analyzing perioperative outcomes. METHODS: Clinical data of 32 VAAs in 32 patients treated between January 2001 and May 2011 were retrospectively reviewed and outcomes analyzed. RESULTS: Eighteen patients were men (56.3%). Median age was 64 years (range 26-79). Sixteen aneurysms were symptomatic: half of them were ruptured causing hemoperitoneum or gastrointestinal bleeding. ET were employed in 19 cases (59%) using covered stents (7 patients), coil embolization (5), plug placement (1), thrombin injection (2) and multiple associated techniques (4). OSR consisted in aneurysmectomy with end to end anastomoses (5 patients) or interposition graft (1), aneurysm ligation (4), splenectomy (2). One patient died during open surgery for hemoperitoneum due to VAA rupture (3%). OSR and ET had similar perioperative complication rates (5.2% vs. 15.3%, P=0.76). OSR had a longer in-hospital stay than ET (8 vs. 4 days, P=0.04). The presence of pancreatitis and alcohol abuse were more frequent in patients who presented with VAAs rupture. Clinical presentation with hemoperitoneum or aneurysm rupture were associated with higher mortality, regardless of the type of treatment. CONCLUSION: Both OSR and ET offered a safe way to treat VAAs in our experience.

Endovascular treatment of hepatic artery aneurysm in a patient with Ehlers-Danlos syndrome. Case report.

Ehlers-Danlos syndrome (EDS) is a rare, variably inherited disorder affecting connective tissue. Patients with EDS often develop aneurysms of the thoracic and abdominal aorta as well as the visceral arteries. We report our experience with an elective endovascular exclusion of an hepatic artery aneurysm in a 26-year-old female patient with EDS type IV. A balloon-expandable 4x26 mm stent-graft was placed in the common hepatic artery, excluding the aneurysm. The follow-up at the 2, 6 and 18 months showed the patency of the common hepatic artery, the absence of endo-leak and the right location of the stent-graft. In EDS patients, the endovascular treatment could be preferable to open surgery because of the minimum trauma.

Midterm experience with the endovascular treatment of isolated iliac aneurysms.

AIM: The aim of this retrospective, single institution study was to describe our 4-year experience with the endovascular repair of isolated iliac artery aneurysms. METHODS: Between May 1997 and June 2001, 16 patients (15 males; mean age 64+/-9 years), were treated with covered stent grafts. Twelve of the endovascular procedures were performed under epidural and 4 under local anaesthesia. The percutaneous approach was employed in 13 cases and the femoral artery had to be exposed in 3 cases that demanded simultaneous revascularization of the peripheral circulation (n=2) or required a 16 F sheath to employ a Baxter Lifepath stent graft (n=1). The mean size of the iliac aneurysms was 4.5 cm (range 3.5 to 5.2 cm). Four aneurysms involved the hypogastric ostium in absence of any distal neck. RESULTS: All the patients underwent initially successful endovascular treatment of isolated iliac aneurysms and were followed from 3 to 52 months (mean 18 months). No procedural deaths and no acute or late graft thrombosis occurred. The perioperative complications included 1 dissection of the external iliac artery that required a further endovacular procedure and 1 case of endovascular leak fed to the hypogastric artery. A CT scan 4 months later showed spontaneous thrombosis of aneurysm and no further leakage. Two patients had undergone combinated femoro-popliteal arterial bypass. CONCLUSION: In our early clinical experience the use of self-expandable covered stent graft successful treated isolated iliac artery aneurysms. Endovascular repair is a safe and effective technique with good midterm results in patients at standard and high risk.

Combined slurry and solid-phase bioremediation of diesel contaminated soils.

This work investigates, at a laboratory and pilot-scale, the influence of various operating parameters on the combined slurry and solid-phase bioremediation technique for a diesel contaminated soil. For slurry-phase bioreactors (SPB), it has been found that, as far as famine conditions are attained at the end of the react cycle, a low hydraulic retention time and a low slurry recycle ratio allows for a better utilization of the reactor volume. A 7-day slurry-phase bioreactor treatment has been shown to provide enough contaminant removal allowing the soil drawn from the slurry-phase bioreactors to be fed effectively to the solid-phase bioreactors (SoPB) for completing the soil cleanup. However, an important improvement of the solid-phase bioreactor performance has been found using soil additives, namely sand and surfactants. While the first soil additive improves pile porosity and consequently oxygen diffusion, the latter increases contaminant bioavailability.

In vitro tests to evaluate potential biological activity in natural substances.

The biological activity of polysaccharides from the mycelia of 40 Basidiomycetes was studied using an uncommon toxicity test technique, the planaria bioassay, and the better known potato disk bioassay. The results showed the utility of this duo of 'in vitro' tests as a preliminary screening of the toxicity of substances that are present in aqueous fungal extracts.

[Implementation of parliamentary act D. Lgs 25/02 and definition of "moderate risk"]. / Applicazione del D.Lgs 25/02 e definizione di "rischio moderato".

This paper describes the position of the Joint Working Group of the Italian Association of Industrial Hygienists (AIDII), the Italian Society of Occupational Health and Industrial Hygiene (SIMLII) and the Italian Society of Toxicology (SITOX) on "Analysis of Parliamentary Act D.Lgs 25/02 and role of the Scientific Societies in the definition of Limit Values". The positive aspects of the new law which implements the European Directive 98/24 are discussed, including the abolition of the rigid periodicity of medical examinations as stated by the old rule D.P.R. 303/56. The Authors also address various parts of the law which appear to be unclear and controversial and highlight the expected difficulties arising for the employers and the safety and health professionals during the application of this new piece of legislation. Moreover, a number of discrepancies are noted between the new Italian law and the original Directive or other current Italian rules such as i. the translation of the term "slight risk", as from the original Directive, into "moderate risk", and the resulting non compulsoriness of health surveillance and biological monitoring of the workers in presence of a "moderate risk", ii. the concurrent exclusion, under the same circumstances, of the occupational physician from risk assessment procedures and iii. the upward modification of the previously established (D.Lgs 277/91) occupational exposure limits for lead. Moreover, the Authors examine and criticize--both in semantic and in toxicological terms--a recent proposal for the definition of "moderate risk" made by an ad hoc Consulting Committee of the Labour Ministry, in which the term "moderate" has been interpreted either as "low" or as "irrelevant for health effects", clearly two very different meanings. Besides, it would be inappropriate to define the conditions of a moderate risk based only on the level of exposure to the chemical (expressed as a fraction of the corresponding limit value), without considering the two other components of risk assessment for that chemical (hazard and susceptibility). Even worse would be the use of simplified models based on "algorithms", which might be useful in a preliminary phase of risk assessment, but easily could lead to an under- or over-estimation of risk, particularly when used by non professionals. In conclusion, the Working Group recommend that the new law be amended in order to clarify its most controversial aspects, whose misinterpretation could severely jeopardize the protection of the workers' safety and health at work.

[Intestinal and colonic ischaemia in the surgery of subdiaphragmatic aorta]. / Ischemia intestinale e colite ischemica nella chirurgia dell'aorta sottodiaframmatica.

Ischemic colitis resulting in colonic infarction after aortic reconstruction is a highly lethal complication. The etiology and pathogenesis of this condition demonstrate that in many instances it may be prevented. Early recognition, particularly of the transmural ischemic injury is essential. Numerous techniques used during surgery for assessing the adequacy of colonic perfusion have been evaluated and found to be inaccurate in terms of predicting colonic ischemia. The purpose of this study is to assess the main monitoring technique for prediction of ischemic colitis during aortic surgery as: colonic mesenteric Doppler signal, inferior mesenteric arteries stump pressure, sigmoidal intramucosal pH and measurement of mucosal capillary haemoglobin oxygen saturation by reflectance spectrophotometry. A 15-year experience with 1912 patients undergoing abdominal aortic reconstruction was reviewed to determined both the incidence of intestinal ischemia and the clinical anatomic, and technical factors associated with this complication of aortic surgery