Effect of intraluminal thrombus on abdominal aortic aneurysm wall stress

PURPOSE: Abdominal aortic aneurysms (AAAs) rupture when the wall stress exceeds the strength of the vascular tissue. Intraluminal thrombus may absorb tension and reduce AAA wall stress. This study was performed to test the hypothesis that intraluminal thrombus can significantly reduce AAA wall stress. METHODS: AAA wall stresses were determined by axisymmetric finite element analysis. Model AAAs had external diameters ranging from 2.0 to 4.0 cm. Model parameters included: AAA length, 6 cm; wall thickness, 1.5 mm; Poisson's ratio, 0.49; Young's modulus, 1.0 MPa; and luminal pressure, 1.6 x 10(5) dyne/cm2. Stresses were calculated for each model without thrombus, and then were recalculated with thrombus filling 10% of the AAA cavity. Calculations were repeated as thrombus size was increased in 10% increments and as thrombus elastic modulus increased from 0.01 MPa to 1.0 MPa. Maximum wall stresses were compared between models that had intraluminal thrombus and the unmodified models. Stress reduction greater than 25% was considered significant. RESULTS: The maximum stress reduction of 51% occurred when thrombus with elastic modulus of 1.0 MPa filled the entire AAA cavity. Stresses were reduced by only 25% as modulus decreased to 0.2 MPa. Similarly, decreasing thrombus size by 70% resulted in stress reduction of only 28%. Large AAAs experienced greater stress reduction than small AAAs (48% vs 11%). CONCLUSION: Intraluminal thrombus can significantly reduce AAA wall stress.     

Topical anesthesia: Proxymetacaine versus Amethocaine for clear corneal phacoemulsification

BACKGROUND: The risk of rupture of large abdominal aortic aneurysms (AAAs) remains uncertain. This study aimed to provide data to help decide whether or not to operate on high-risk patients. METHODS: Clinicians were asked to refer all patients with an AAA, even if unfit or elderly. One hundred and ninety-two patients with an intact AAA of 5 cm or greater in diameter were seen in 9 years; 59 had no elective operation and follow-up data were available for 57 at a minimum of 2 years. Initial AAA diameters were 5.0-5-9 cm (n=25) and 6.0 cm or more (n=32). Survival curves were constructed for both groups. RESULTS: At the end of the study 50 of 57 patients had died. Median survival was 18 (range 1-90) months. Twenty (35 per cent) suffered rupture at a median interval of 18 (range 1-38) months. The risk of rupture within 3 years was 28 (95 per cent confidence interval 12-49) per cent for 5.0-5.9-cm AAAs and 41 (24-59) per cent for AAAs of 6 cm or greater. In 133 elective AAA operations in fit patients the 30-day mortality rate was 3 per cent. CONCLUSION: The risk of rupture within 3 years of diagnosis of an AAA of 5 cm or greater exceeds the expected operative mortality rate for fit patients. However, the majority of patients unfit for surgery died from other causes, and only a few would have benefited from aneurysm repair.     

Activation of coagulation and fibrinolysis in patients with abdominal true aortic aneurysm associated with disseminated intravascular coagulation

Two cases of abdominal true aortic aneurysm (AAA) associated with disseminated intravascular coagulation (DIC) were reported. Case 1 was an 81-year-old male who was admitted because of hematoma on the left leg and in whom was found by MRI an aortic aneurysm of 14 cm in diameter. Coagulation studies indicated DIC by revealing thrombocytopenia, hypofibrinogenemia and increased level of FDP. DIC was well controlled by surgical repair of the aneurysm after the administration of a small dose of heparin. Case 2 was a 60-year-old male who was admitted because of lumbago and hematoemesis and in whom was found by CT and echography an aortic aneurysm of 5.5 cm in diameter. Coagulation studies indicated DIC by revealing thrombocytopenia and an increased level of FDP. On the 2nd hospital day, he suddenly died due to the rupture of the aortic aneurysm. In most of 9 cases with AAA without DIC, plasma levels of thrombin-antithrombin III complex, plasmin-alpha 2 plasmin inhibitor complex and FDP-D dimer were also elevated. These findings indicate that the coagulation and fibrinolysis systems were generally activated in patients with AAA, and that DIC tends to occur in patients with a giant aortic aneurysm or an impending ruptured aneurysm.     

Non-surgical treatment of abdominal aortic aneurysms

Percutaneous placement of an endovascular stent, with and without coils, in the treatment of large AAA in animal models is feasible, safe and effective. The covered stent sealed off AAA immediately after stent placement, however, it interrupted blood flow into arteries in the area covered by the stent. The uncovered stent prevented further expansion of the aneurysm and also significantly decreased the incidence of rupture. The long-term patency of branch arteries by the uncovered stent supported the possibility of safely using this approach in humans. Furthermore, either covered stent or uncovered stent with additional coils have the potential for treatment of acute aneurysm rupture or leaking. Most importantly, the aneurysm lumen in our model was gradually replaced by collagen after stent placement which further reduces the risk of aneurysm rupture: and this healing process was enhanced by the addition of coils. If proven safe and effective for humans as well, this technique has the potential for substantially reducing the morbidity and mortality associated with AAA.     

The relaxation of residual stresses with postweld heat treatment in a high-performance weld measured with neutron diffraction

The residual stresses in a cylindrical weldment of HP-9-4-30 steel were measured with neutron diffraction in the as-welded (AW) state and after postweld heat treatment (PWHT). Large residual stresses are present in the interior of the material in the as-welded condition. The maximum principal stresses measured were found around the edges of the cap-pass heat-affected zone and reached up to 1045 MPa (76 pct of the base metal yield strength) in the as-welded condition. The principal stress directions for the residual stress tensors do not in general follow the hoop, axial, and radial axes of the weld and change from position to position within the weld, although the highest values are generally in the hoop direction. The postweld heat treatment relaxed the largest residual stresses, with the maximum value being 30 pct of the base metal yield stress. The need for position-dependent stress-free standards and the implications of stress gradients over the measurement volumes are discussed.     

Ultrastructural, stereological evaluation of satellite cells derived from musculus soleus in rats kept in hypokinesia conditions

OBJECTIVES: Selection for surgery of patients with abdominal aortic aneurysm (AAA) depends on an assessment of risk from operation compared with risk from aneurysm rupture. A study was performed to assess the levels of co-morbidity and to see whether co-morbidity was different in people with a normal aorta after ultrasonographic examination than in those with an aneurysmal aorta. SETTING AND METHODS: Over a two year period 5392 people (2341 men, 3051 women) aged 65-80 were screened using B-mode linear ultrasound, with maximum measurements taken of transverse, anteroposterior diameters, or both. All subjects were given a questionnaire seeking a history of angina, stroke, claudication, myocardial infarct, respiratory problems, and diabetes. RESULTS: 218 men and women were found to have an AAA of 3 cm or greater. The results of the questionnaire were analysed using logistic regression whereby all the co-morbid conditions were adjusted for each other and for smoking, sex, and age. The only conditions which were significantly associated with AAA in both sexes were myocardial infarction with an odds ratio (OR) of 1.66 (95% confidence interval (CI) 1.06 to 2.60) and claudication with an OR of 1.68 (95% CI 1.17 to 2.42). The association between angina and AAA was of borderline significance (OR = 1.52, 95% CI 1.00 to 2.30). Stroke was significantly associated only in women, with an OR of 3.71 (95% CI 1.42 to 9.69). Rates of diabetes and respiratory disease were not significantly different between people with AAA and normal aortas. CONCLUSIONS: These findings show there is significantly higher co-morbidity in people with ultrasound detected AAA, which might influence outcome from surgery and long term survival.     

Abdominal aortic aneurysm in the elderly

AIM: Complication-free abdominal aortic aneurysm is often asymptomatic and its diagnosis is therefore frequently coincidental. Abdominal aortic aneurysm (AAA) is often suddenly manifested during the rupture stage, resulting in the patient's death. The importance of early diagnosis is therefore clear, enabling optimal monitoring and correct management. EXPERIMENTAL DESIGN AND SUBJECTS: This retrospective study evaluated the incidence of AAA in 1304 over-65-year-olds in care. The authors examined the presence of AAA-related symptoms, risk factors and the concomitance of other pathologies. RESULTS: Four subjects were diagnosed with AAA, equivalent to 0.3% of the total population. All were male, smokers, with multidistrict atherosclerosis in association with other pathologies. CONCLUSIONS: The incidence of AAA in the population of over-65-year-olds examined was lower than that reported in the literature. This discrepancy was due to the fact that the abdominal aorta is not usually examined in clinical practice. However, the high mortality rate of AAA during rupture prompted the authors to evaluate this disorder in high-risk patients.     

Thermal Relaxation of Residual Stresses in Nickel-Based Superalloy Inertia Friction Welds

This article describes an experimental study aimed at characterizing the extent of residual stress relaxation during thermal treatment of inertia friction-welded alloy 720Li nickel-based superalloy welded tubular rings. In the as-welded condition, yield level tensile hoop stresses were found by neutron diffraction in the weld region along with axial bending stresses (tensile toward the inner diameter (ID)/compressive toward the outer). The evolution of these residual stress levels during postweld heat treatment (PWHT) was mapped experimentally over the weld cross section. After 8 hours of PWHT, the axial stresses relaxed by 70 pct, whereas the hoop stresses reduced by only 50 pct. Some scatter of residual stress evolution was found between samples, particularly for the axial stress direction. This was attributed to substandard tooling to grip the rings. The results on subscale samples were transferred to a full-scale aeroengine (650-mm diameter) compressor drum assembly that was postweld heat treated for 8 hours. It was found that the residual stresses, particularly in the axial direction, were noticeably lower in this full-scale weld component compared to the subscale weld heat treated for the same time. The differences seem to be best rationalized by the different standards of jigging used during joining these two types of welds.     

Chronic rupture of abdominal aortic aneurysms

INTRODUCTION: Rupture of abdominal aortic aneurysms (RAAA) can take place in one of the 4 following ways: 1. "Open" rupture in the free peritoneal cavity; 2. "Closed" rupture with formation of retroperitoneal haematoma; 3. Rupture into surrounding cavity structures, such as veins and bowels; 4. In rare cases rupture is effectively "sealed of" by the surrounding tissue reaction, and retroperitoneal haematoma is "chronically" contained [1]. The terms "sealed" [2], "spontaneously healed" [3], "leakig" [4] RAAA, were also used in the previous papers connected to this situation. The "sealed" rupture was first described by Szilagyi and associates in 1961 [2]. In their case the rupture was small and haemorrhage was effectively encircled by the tissue surrounding the aortic wall. The slow rate of blood loss contributed to the patient's haemodinamically stable condition. Christenson et al. reported a case of "spontaneously healed" RAAA [3]. Rosenthal and associates described 2 patients who had aortic aneuryms that ruptured several months before repair and contributed to the term "leaking AAA" [4], while Jones et al. introduced the term "chronic contained rupture" [1]. The aim of this paper is the presentation of 5 such patients. CASE REPORT: Between December 1, 1988 and May 30, 1997 411 patients with abdominal aortic aneurysms (AAA) have been operated at our institute. Of this number 137 (33%) had RAAA, while 5 patients (12%) had a contained RAAA (CRAAA). CRAAA were found in 3 male and two female patients, average age 62 years. All of them had a previously proved AAA and initial symptoms lasted for days or months before the admission. In all patients haematocrit, pulse rate and arterial tension during the admission, were normal. All typical signs of RAAA were absent in these patients. Patient 1. A 56-year-old man, smoker, with previous history of arterial hypertension had an isolated episode of abdominal pain and collapse 30 days before the admission. Physical examination revealed a pulsatile abdominal mass. Doppler ultrasonography identified an infrarenal AAA, with right lobular extraaneurysmal mass which displaced the inferior vena cava (ICV). Angiographically (Figure 1a) an unusual saccular intrarenal AAA was detected, while simultaneous cavography (Figure 1b) confirmed the-dislocated inferior vena cava to the right. The intraoperative finding showed infrarenal CRAAA with organized retroperitoneal haematoma between AAA, ICV and duodenum. After aortic cross clamping and aneurysmal opening, the rupture at the right posterior aneurysmal wall was discovered. The partial aneurysmactomy and aortobilliar bypass procedure with bifurcated knitted Dacron graft (16 x 8 mm), were performed. The patient recovered very well. After a 4-year follow-up period the graft is still patent. Patient 2. A 72-year-old woman with low back pain, fever and disuric problems was urgently admitted to the Institute of Urology and Nephrology. The standard urological examination (X-ray, intravenous pyelography, retrograde urography, kidney Duplex ultrasonography) excluded urological diseases. However, intrarenal AAA an a giant aneurysm of the right common iliac artery, were found. The proximal dilatation of the right excretory urinary system was also found by retrograde urography. The patient was transported to our Institute 20 days after the initial symptoms. Translumbar aortography (Figure 3) showed the right common iliac artery aneurysm and gave the false negative picture of normal abdominal aorta because of parietal thrombosis of AAA. The intraoperative finding showed chronic rupture of the posterior wall of the right common artery aneurysm. The retroperitoneal haematoma compressed the right ureter. Both aneurysm have been resected and replaced by bifurcated Dacron graft (16 x 8 mm). The patient recovered successfully. After a 2-year period of follow-up the graft is still patent. Patient 3. (ABSTRACT TRUNCATED)     

A unique method of closure for an aortocaval fistula in association with a ruptured abdominal aortic aneurysm: report of a case

We report herein the case of a 78-year-old man in whom an aortocaval fistula caused by spontaneous rupture of an abdominal aortic aneurysm (AAA) was successfully treated by a unique surgical technique. The aortocaval fistula had been revealed by an aortography after the patient presented with high-output heart failure. During the operation, massive bleeding from the fistula was evident. The fistula measured 2 cm in diameter, and was located between the right posterior wall of the AAA and the inferior vena cava (IVC). Direct suturing of the defect in the IVC failed to close the fistula because the tissue around it would not hold together due to degeneration. However, the bleeding was finally able to be controlled by plugging the fistula with isolated and properly trimmed omentum packed within the excluded aneurysmal sac. Unfortunately, the patient died due to respiratory failure on the 201st postoperative day. A pathological autopsy revealed that the aortocaval fistula had been closed by fibrous tissue and that the IVC was patent. Although such a drastic operative measure to repair an aortocaval fistula has never before been reported, it could be an alternative when direct closure proves unsuccessful.     

A Comparison of Residual Stress Development in Inertia Friction Welded Fine Grain and Coarse Grain Nickel-Base Superalloy

The effect of the base material microstructure on the development of residual stresses across the weld line in inertia friction welds (IFWs) of high-strength nickel-base superalloy RR1000 was studied using neutron diffraction. A comparison was carried out between tubular IFW specimens generated from RR1000 heat treated below (fine grain (FG) structure) and above (coarse grain (CG) structure) the γ′-solvus. Residual stresses were mapped in the as-welded (AW) condition and, after a postweld heat treatment (PWHT), optimized for maximum alloy strength. The highest tensile stresses were generally found in the hoop direction at the weld line near the inner diameter of the tubular-shaped specimens. A comparison between the residual stresses generated in FG and CG RR1000 suggests that the starting microstructure has little influence on the maximum residual stresses generated in the weld even though different levels of energy must be input to achieve a successful weld in each case. The residual stresses in the postweld heat treated samples were about 35 pct less than for the AW condition. Despite the fact that the high-temperature properties of the two parent microstructures are different, no significant differences in terms of stress relief were found between the FG and CG RR1000 IFWs. Since the actual weld microstructures of FG and CG RR1000 inertia welds are very similar, the results suggest that it is the weld microstructure and its associated high-temperature properties rather than the parent material that affects the overall weld stress distribution and its subsequent stress relief.     

Effect of GF120918, a potent P-glycoprotein inhibitor, on morphine pharmacokinetics and pharmacodynamics in the rat

PURPOSE: Studies have shown that 11% to 18% of patients with an abdominal aortic aneurysm (AAA) have a first-degree relative with an AAA. A familial pattern among patients with peripheral arterial aneurysms and arteriomegaly has not been reported. The objective of this study was to examine familial patterns among patients with peripheral arterial aneurysm and arteriomegaly and compare them with patterns among patients with AAA. METHODS: Pedigrees were constructed for first-degree relatives of patients who received the diagnosis of peripheral arterial aneurysm, arteriomegaly, or AAA from 1988 through 1996. The presence of aneurysms and risk factors was confirmed for patients and relatives by means of telephone interviews and review of hospital and physician records. RESULTS: Seven hundred three first-degree relatives older than 50 years were contacted for 140 probands with peripheral arterial aneurysm, AAA, or arteriomegaly. There were differences in risk factors for hernia and diabetes mellitus among the probands with peripheral arterial aneurysm, AAA, or arteriomegaly but none for relatives. Patients with peripheral arterial aneurysm (n = 40) had a 10% (4/40) familial incidence rate of an aneurysm, patients with AAA (n = 86) had a 22% (19/86) familial incidence rate, and patients with arteriomegaly (n = 14) had a 36% (5/14) familial incidence rate. AAA (24/28, or 86%) was the aneurysm diagnosed most commonly among first-degree relatives. Most aneurysms (85%) occurred among men. CONCLUSION: There appears to be a gradation of familial patterns from peripheral arterial aneurysm to AAA to arteriomegaly among patients with degenerative aneurysmal disease, and there appears to be a predominance among men. Relatives of patients with any of the 3 lesions-peripheral arterial aneurysm, AAA, arteriomegaly--most frequently have AAA. Relatives of patients with AAA, peripheral arterial aneurysm, or arteriomegaly may be screened by means of a physical examination for peripheral aneurysmal disease. Screening by means of ultrasound examination of the aorta should be limited to first-degree relatives of patients with aortic aneurysms or arteriomegaly.     

Analysis of the interdependent localization of vimentin and microtubules in neoplastic myoepithelial cells

Certain biological differences between men and women are relevant to the problem of AAA, and are widely accepted. Women unequivocally have smaller aortas. The size difference correlates with a variety of anthropomorphic measurements, but is most strongly associated with body surface area. In women the compliance of the aorta decreases in linear fashion with age, whereas in men the decrease in compliance is exponential with age. Women appear to be underrepresented in AAA surgical series (typically 18% to 20% of operative cases) compared with autopsy studies (29% to 32%), ultrasound screening studies (19% to 25%), and mortality studies (34% of the 14,982 deaths due to AAA in the US in 1988). Several lines of evidence suggest that women with AAA are less likely than men to be referred for surgery, and that, when referred, they have higher mortality rates. The reasons for these differences are unclear. The very factors that allow increased longevity in women may have an adverse effect on the ability to tolerate a major surgical stress. Wenger et al have suggested that psychosocial and economic factors may affect women's decisions to seek care, or their choice of therapeutic options. Lack of knowledge among practitioners of gender-related aortic size differences and overreliance on simplistic clinical paradigms that dictate operations for 5-cm diameter aneurysms and watchful waiting for 4- to 5-cm AAAs may result in unintended bias in patient selection. It may be that a 5-cm diameter AAA in a woman with a predicted normal aortic size of 1.4 cm represents a more advanced stage of disease than a 5-cm diameter AAA in a man with a normal aortic diameter of 2.5 cm. More precise and detailed algorithms are needed to permit clinicians to tailor decisions to patients' size, sex, and risk factors. Development of such algorithms requires expansion of clinical and epidemiological studies to include enough women to make precise risk estimates.     

Ruptured de novo aneurysm induced by ethyl 2-cyanoacrylate: case report

OBJECTIVE AND IMPORTANCE: We report a rare case of a ruptured de novo aneurysm induced by ethyl 2-cyanoacrylate. CLINICAL PRESENTATION: A 44-year-old woman had undergone microvascular decompression for a right-sided facial spasm. The preoperative vertebral angiogram did not show any aneurysmal dilation. The right anteroinferior cerebellar artery, which was compressing the exit zone of the facial nerve, was detached and fixed to the dura mater with ethyl 2-cyanoacrylate. Nine years later, the patient suffered a subarachnoid hemorrhage caused by the rupture of a newly developed aneurysm of the right anteroinferior cerebellar artery. INTERVENTION: The aneurysm was clipped 2 days after onset of the subarachnoid hemorrhage. It consisted of two bulges in the arterial wall on the proximal side of the meatal loop. One bulge was stuck to the dura mater of the pyramis by ethyl 2-cyanoacrylate, which had been used in the microvascular decompression 9 years previously. CONCLUSION: This is the first reported clinical case of a de novo aneurysm induced by a cyanoacrylate adhesive. Ethyl 2-cyanoacrylate can damage the arterial wall and induce a de novo aneurysm.     

Surgery of abdominal aortic aneurysm and concomitant disease of the digestive tract

The incidence of intra-abdominal diseases associated with abdominal aortic aneurysm is increasing, and it is difficult to decide whether to operate the abdominal disease first, the aneurysm first or both simultaneously. Variables used in decision analysis include type, stage and life expectancy of the cancer, rupture rate of abdominal aortic aneurysm. Symptomatic lesion should be treated first. Absolute indication for operation initially on the aneurysm is the presence of symptoms of rupture. Aortic abdominal aneurysmectomy combined with surgical removal of an intestinal disease may present severe risks as infection of the graft and anastomotic leakage, especially during lower abdominal surgery. In this paper authors present four cases of AAA which had intra-abdominal surgical disease. They were treated by one-stage operation with no complications. Criteria to assess timing of surgical treatment of abdominal surgical diseases concomitant to AAA are discussed.     

Administration of progesterone before oocyte retrieval negatively affects the implantation rate

BACKGROUND: Recent studies have demonstrated the effectiveness of endovascular grafting with aneurysm shrinkage following total exclusion of the abdominal aortic aneurysm (AAA). However, little is known about the effect of the preexisting thrombus (PT) on changes in aneurysm size following endovascular grafting. Therefore, this study is designed to determine the effect of PT on aneurysm size following endovascular grafting. METHODS: Blinded measurements of preoperative, postoperative, and 1-year computed tomographic scans of 44 patients undergoing endovascular grafting for AAA were performed. PT fraction was determined by the formula This was normalized for preoperative AAA growth. Pearson correlations were performed with AAA minor diameter change over the first year. RESULTS: There was no statistically significant relationship between PT fraction and rate of aneurysm size change (all patients, r = 0. 196 and P = 0.207). When patients with persistent leaks were excluded, the r = 0.234 and P = 0.170 also were not statistically significant. CONCLUSIONS: The amount of PT bears no important relationship to the response of the aneurysm following endovascular repair. Failure of aneurysms to shrink after endovascular treatment should not be attributed to large PT, but should prompt a thorough investigation for incomplete exclusion of the AAA. Long-term studies are needed to validate the efficacy of this new form of treatment.     

Andersen''s syndrome: a distinct periodic paralysis

PURPOSE: To develop a stable, transluminally created abdominal aortic aneurysm (AAA) within a live animal model. MATERIALS AND METHODS: Eight mongrel dogs were utilized to evaluate a new, catheter-based technique for the creation of an AAA. With use of a standard angioplasty balloon and a balloon-expandable intravascular metallic stent, the infrarenal abdominal aorta was overdilated to twice its measured diameter into a fusiform shape AAA in eight dogs. At 30 days, aortography was performed, the dogs were killed, and the aorta was resected and evaluated for histopathology. RESULTS: Seven of the eight dogs that underwent transluminal AAA creation survived the initial procedure. A stable, fusiform AAA was successfully created in these seven dogs. At 30 days, repeat angiography and histologic examination confirmed that the seven AAAs were still twice the diameter of the normal aorta (a four-fold increase in luminal area), that the branch arteries remained patent, and that the lumen was endothelialized. One of the eight dogs was killed 9 hours after the procedure because of inability to awaken from anesthesia. Gross and histopathologic results in this one dog also demonstrated an intact aorta containing an AAA. CONCLUSIONS: A stable, infrarenal AAA model can be successfully created in the canine species with use of standard catheter-based techniques and equipment. This model can be used to test emerging endovascular treatments of AAA.     

Analysis of thermal residual stress in a thick-walled ring of duralcan-base Al-SiC functionally graded material

A ring-cutting test and an elastic theory were applied to evaluate the macroscopic residual stress in a thick-walled ring made of Al-SiC functionally graded material (FGM). The FGM ring specimens, with outer diameter 90 mm, radial thickness approximately 8.4 to 10 mm, and width 30 mm, were fabricated by the centrifugal casting method from an ingot of Duralcan F3D.20S of Al-20 vol pct SiC master composite. Because of a difference in centrifugal forces of SiC particles and of molten aluminum alloy, the rings had a graded composition of SiC particles in the radial direction. The volume fractions of SiC particles in each ring specimen varied in the range of 0 to 43 vol pct from the inner to the outer surface of the ring, depending on the applied mold spin speed. A ring diametral compression test was performed to validate an analytical formula based on the curved beam theory that can account for the graded properties of the material. Excellent agreement between the theory and the experiment was found. The residual stress was found to be generated by a cooling of Δt=140 K, which was from half the melting point corresponding stress-free condition to the ambient temperature. The hoop residual stresses in the FGM ring varied in the range of −50 to +35 MPa and from tension at the inner surface to compression at the outer surface because of the graded composition. With an increase in wall thickness and/or composition gradation, the residual stresses were found to increase.     

Cyanamide-induced granulocytopenia

BACKGROUND: The appropriate management of patients who are older than 80 years of age and who present with an abdominal aortic aneurysm (AAA) remains controversial. While it appears that elective repair can be performed safely, appropriate management of these patients in the emergency situation is unclear. The purpose of the present study was to examine the results obtained in treating this elderly group in the elective and emergency setting, by operation and conservative techniques at St George Hospital, Kogarah. METHODS: Between January 1987 and December 1994 85 patients older than 80 years of age were treated for AAA. These patients were divided into four groups: I, elective presentation/no surgery; II, elective presentation/elective surgical repair; III, emergency presentation/surgical repair; and IV, emergency presentation/conservative treatment. We examined age, sex, size of AAA, mode of presentation, type of treatment, length of survival and cause of death. RESULTS: The mean age of the total group (n = 85) of patients was 84 years (range: 80-94). The mean AAA diameter for this group was 5.6 cm (95% CI: 5.2-6 cm). The diameters for group I (n = 40), II (n = 22), III (n = 16) and IV (n = 7) were 4.9 cm (4.4-5.5, 95% CI), 5.7 (4.9-6.5 CI), 7.0 (6.1-7.7 CI) and 6.2 (5.2-7.2 CI), respectively. The median survival for groups I, II, III and IV was 18, 38.5, 0.25 and 0 months, respectively. Group II had a longer survival than any other group (P = 0.015), and group IV had a shorter survival than the total group (P = 0.001). However, the length of survival was no different for III versus IV (P = 0.146). Deaths in each group were due to the following reasons. I: cardiopulmonary events (14), rupture (3), malignancy/sepsis (3); II: cardiopulmonary events (3), rupture (thoracic aneurysm) (2), malignancy (I); III: rupture (10), malignancy (I); and (IV): rupture (6), malignancy (1). CONCLUSIONS: Elective surgical repair offers the best management option for AAA in patients older than 80 years of age. Death may still occur from progression of aneurysmal disease at other sites. An aggressive surgical approach to the management of haemodynamically unstable patients in this age group is of questionable benefit.     

Factors associated with psychotic symptoms in Alzheimer''s disease

BACKGROUND: The incidence of abdominal aortic aneurysm (AAA) has increased steadily during the past 30 years. METHODS: Trends in the incidence and surgical intervention for AAA in Western Australia were reviewed for the interval 1985-1994. A population-based health database was used to link morbidity and mortality records of all patients aged 55 years or more who died from rupture or were admitted and treated surgically for AAA. Three groups were separated for analysis: patients with a ruptured AAA, those admitted for elective repair and those admitted as an emergency with an acute (non-ruptured) aneurysm. RESULTS: There was a decline in the incidence of both emergency and elective procedures for AAA after 1992. While the mortality rate from ruptured AAA has also fallen since 1991, the overall case fatality rate for ruptured AAA has fallen by only 1.3 per cent (from 80.7 to 79.3 per cent). CONCLUSION: The decline in mortality rate and emergency procedures may result from a fall in the incidence of ruptured AAA, due to an increasing rate of elective surgery before 1992. The decline in elective procedures from 1992 may be due to a fall in the prevalence of AAA owing to high rates of elective surgery, or to a fall in the incidence of the disease itself.