Screening for abdominal aortic aneurysms: single centre randomised controlled trial

Objective To determine whether screening Danish men aged 65 or more for abdominal aortic aneurysms reduces mortality.Design Single centre randomised controlled trial.Setting All five hospitals in Viborg County, Denmark.Participants All 12 639 men born during 1921-33 and living in Viborg County. In 1994 we included men born 1921-9 (64-73 years). We also included men who became 65 during 1995-8.Interventions Men were randomised to the intervention group (screening by abdominal ultrasonography) or control group. Participants with an abdominal aortic aneurysm > 5 cm were referred for surgical evaluation, and those with smaller aneurysms were offered annual scans.Outcome measures Specific mortality due to abdominal aortic aneurysm, overall mortality, and number of planned and emergency operations for abdominal aortic aneurysms.Results 4860 of 6333 men were screened (attendance rate 76.6%). 191 (4.0% of those screened) had abdominal aortic aneurysms. The mean follow-up time was 52 months. The screened group underwent 75% (95% confidence interval 51% to 91%) fewer emergency operations than the control group. Deaths due to abdominal aortic aneurysms occurred in nine patients in the screened group and 27 in the control group. The number needed to screen to save one life was 352. Specific mortality was significantly reduced by 67% (29% to 84%). Mortality due to non-abdominal aortic aneurysms was non-significantly reduced by 8%. The benefits of screening may increase with time.Conclusion Mass screening for abdominal aortic aneurysms in Danish men aged 65 or more reduces mortality.     

Early and late results of resection of abdominal aortic aneurysms.

Resection of the abdominal aortic aneurysm is being performed with decreasing operative mortality and morbidity. Among 190 patients undergoing this procedure at the Ottawa Civic Hospital between 1970 and 1975, 53 (28%) had a ruptured aneurysm and 137 (72%), a nonruptured aneurysm. Mean age of the patients was 66.2 years. Concomitant disease was frequent, 73% of patients having two or more associated diseases; the average number of associated diseases per patient was 2.25. Operative mortality in the group with ruptured aneurysms was 51%, and in the group with nonruptured aneurysms, 4%. Postoperative morbidity was 85% among those with a ruptured aneurysm, 67% among those with imminent rupture before operation and 34% among the others with a nonruptured aneurysm. Graft complications occurred in 15% of those with a ruptured aneurysm and 9% of those with a nonruptured aneurysm. Among survivors of the operation 73% and 81% of those with a ruptured and a nonruptured aneurysm, respectively, are known to be alive. In both groups causes of late death included infection or thrombosis of the graft and mesenteric thrombosis, as well as causes unrelated to the operation. Surgical management of the abdominal aortic aneurysm is advocated in all but patients at poor risk for operation who have asymptomatic aneurysms less than 6 cm in diameter.     

The Helsinki Rat Microsurgical Sidewall Aneurysm Model

Experimental saccular aneurysm models are necessary for testing novel surgical and endovascular treatment options and devices before they are introduced into clinical practice. Furthermore, experimental models are needed to elucidate the complex aneurysm biology leading to rupture of saccular aneurysms.Several different kinds of experimental models for saccular aneurysms have been established in different species. Many of them, however, require special skills, expensive equipment, or special environments, which limits their widespread use. A simple, robust, and inexpensive experimental model is needed as a standardized tool that can be used in a standardized manner in various institutions.The microsurgical rat abdominal aortic sidewall aneurysm model combines the possibility to study both novel endovascular treatment strategies and the molecular basis of aneurysm biology in a standardized and inexpensive manner. Standardized grafts by means of shape, size, and geometry are harvested from a donor rat''s descending thoracic aorta and then transplanted to a syngenic recipient rat. The aneurysms are sutured end-to-side with continuous or interrupted 9-0 nylon sutures to the infrarenal abdominal aorta.We present step-by-step procedural instructions, information on necessary equipment, and discuss important anatomical and surgical details for successful microsurgical creation of an abdominal aortic sidewall aneurysm in the rat.     

Abdominal Aortic Aneurysms—Unusual Clinical Manifestations

Misleading symptoms were responsible for failure to make the diagnosis of symptomatic abdominal aortic aneurysm in 15 patients. The presenting complaints appeared to be specific for other diseases, such as genitourinary disease, diverticulitis, intra-abdominal neoplasm and functional large intestinal disorders. A correct diagnosis was ultimately made in 12 patients and aneurysmectomy was performed. In three patients, who died of ruptured aneurysm, the diagnosis was not made until postmortem examination.An awareness of the atypical symptoms of aneurysms, careful physical examination and appropriate x-ray studies will lead to the diagnosis of symptomatic aortic aneurysms. Early resection will result in a lower mortality rate.     

The detection of<Emphasis Type="Italic">Chlamydia pneumoniae</Emphasis> in aneurysm of abdominal aorta and in normal aortic wall of organ donors

Sixty patients underwent surgery due to abdominal aortic aneurysms; the group included 30 patients with asymptomatic aneurysm and 30 with ruptured aneurysm. A control group comprised 30 organ donors. Surgical specimens derived from aneurysm or aorta fragments were investigated for Chlamydia pneumoniae DNA using PCR. In asymptomatic aneurysms, DNA was found in 9 cases (29%), and in ruptured aneurysms in 14 cases (49%). In the control group, C. pneumoniae DNA was not detected in an aortic wall. These results suggest that healthy aortic wall is not susceptible to chlamydial infection. A large number of aneurysm infections implies C. pneumoniae role in proteolysis and degradation of the aneurysm wall. The biological effect of this process may cause an enlargement of the aneurysm.     

Long Telomeres in Blood Leukocytes Are Associated with a High Risk of Ascending Aortic Aneurysm

Ascending aortic aneurysm is a connective tissue disorder. Even though multiple novel gene mutations have been identified, risk profiling and diagnosis before rupture still represent a challenge. There are studies demonstrating shorter telomere lengths in the blood leukocytes of abdominal aortic aneurysm patients. The aim of this study was to measure whether relative telomere lengths are changed in the blood leukocytes of ascending aortic aneurysm patients. We also studied the expression of telomerase in aortic tissue samples of ascending aortic aneurysms. Relative lengths of leukocyte telomeres were determined from blood samples of patients with ascending aortic aneurysms and compared with healthy controls. Telomerase expression, both at the level of mRNA and protein, was quantified from the aortic tissue samples. Mean relative telomere length was significantly longer in ascending aortic aneurysm blood samples compared with controls (T/S ratio 0.87 vs. 0.61, p<0.001). Expressions of telomerase mRNA and protein were elevated in the aortic aneurysm samples (p<0.05 and p<0.01). Our study reveals a significant difference in the mean length of blood leukocyte telomeres in ascending aortic aneurysm and controls. Furthermore, expression of telomerase, the main compensating factor for telomere loss, is elevated at both the mRNA and protein level in the samples of aneurysmal aorta. Further studies will be needed to confirm if this change in telomere length can serve as a tool for assessing the risk of ascending aortic aneurysm.     

Preoperative evaluation of a patient for abdominal aortic aneurysm repair

Coexistent cardiovascular disease is common in patients presenting for repair of aortic aneurysms. However, preoperative cardiac evaluation prior to abdominal aortic aneurysm (AAA) surgery remains contentious with significant variations in practice between countries, institutions and individual anesthetists. The following case report raises some everyday issues confronting clinical anesthetists.     

Ultrasound screening for clinically occult abdominal aortic aneurysm.

In a review of the records of 74 patients who had undergone repair of an abdominal aortic aneurysm at a community hospital between 1977 and 1983 we found that the aneurysm had been undiagnosed before rupture in 35%; these patients had an operative death rate of 50%, whereas elective repair carried a death rate of 4%. The characteristic patient was an obese man over the age of 55 years with hypertension, coronary artery disease, cerebrovascular disease or peripheral vascular disease. Ultrasound examination was performed in 45 patients with these characteristics, and six aneurysms were diagnosed. Either surgery or computed tomography confirmed the diagnosis. The rate of false-negative results was estimated by review of the charts of 100 men over the age of 55 years who had undergone abdominal ultrasonography for other indications: no undetected aneurysms were discovered over 3 years of follow-up. Routine screening in this high-risk group would improve the rate of diagnosis of this potentially fatal condition before rupture and offer the patient the lower mortality rate associated with elective surgery.     

Diagnosis and management of 528 abdominal aortic aneurysms.

Between 1960 and 1979 528 patients with abdominal aortic aneurysms presented to the university department of surgery. Of these, 222 (42%) were elective cases, 72 acute (14%), 174 had ruptured (33%), and four had had a spontaneous aortoduodenal fistula (1%). In all these patients resections were undertaken, but in another 56 patients (11%) the aneurysm was not resected. A review of these cases showed that 91% had symptoms at their first presentation; abdominal pain and backache being most common. The diagnosis could be established in 91% by the presence of pulsatile abdominal mass on clinical examination. The operative mortality for elective resection was 8%, for acute 19%, for ruptured cases 42%, and for spontaneous aortoduodenal fistula 50%. After successful resection the overall five-year survival was 65% by the life table method, and there was no significant difference between elective, acute, and ruptured cases. This five-year survival after resection compares favourably with the expected 76% survival of a similar normal population, and was considerably better than that for conservatively treated patients. As most cases have symptoms, and diagnosis may be established easily by routine physical examination in 91%, the prognosis for this condition could be considerably improved by increased awareness of its existence and early referral for treatment as an elective surgical procedure.     

Long term relative survival after surgery for abdominal aortic aneurysm in Western Australia: population based study

Objective: To determine the long term relative survival of all patients who had surgery for abdominal aortic aneurysm in Western Australia during 1985-94. Design: Population based study. Setting: Western Australia. Subjects: All patients who had had surgery for abdominal aortic aneurysm in Western Australia during 1985-94. Main outcome measures: Morbidity and mortality data of patients admitted and surgically treated for abdominal aortic aneurysm in Western Australia during 1985-94. Elective, ruptured, and acute non-ruptured cases were analysed separately. Independent analyses for sex and patients aged 80 years or more were also undertaken. Postoperative (>30 days) relative survival was assessed against age and sex matched controls. Results: Overall, 1475 (1257 men, 218 women) cases were identified. The crude five year survival after elective surgery, including deaths within 30 days of surgery, was 79% for both men and women. When compared with a matched population the five year relative survival after elective surgery was 94.9% (95% confidence interval 89.9% to 99.9%) for men but only 88.0% (76.3% to 99.7%) for women. The five year relative survival of those aged 80 years and over was good: 116.6% (89.1% to 144.0%) compared with 92.4% (87.7% to 97.0%) for those under 80 years of age (men and women combined). Cardiovascular disease caused 57.8% of the 341 deaths after 30 days. Conclusion: In a condition such as abdominal aortic aneurysm, which occurs in elderly patients, relative survival is more clinically meaningful than crude survival. The five year relative survival in cases of elective and ruptured abdominal aortic aneurysm was better in men than in women. This is probably because of greater comorbidity in women with abdominal aortic aneurysm and this deserves more attention in the future. The long term survival outcome in octogenarians supports surgery in selected cases.

Key messages

• Background mortality for conditions such as abdominal aortic aneurysm in elderly patients needs to be taken into account when assessing long term survival after surgery
• Relative survival methodology can correct for background mortality
• The five year relative survival for patients surviving beyond 30 days of elective surgery for abdominal aortic aneurysm was 95% for men and 88% for women
• For octogenarians, five year survival after elective surgery was greater than that expected of an age matched population
• Age over 80 years should not preclude consideration for elective surgery for abdominal aortic aneurysm

     

Survivors of ruptured abdominal aortic aneurysm: the iceberg's tip.

In four and a half years 25 patients in one community suffered a ruptured abdominal aortic aneurysm. Eleven died at home, nine died without operation in hospital, and only five had the aneurysm removed. There were four survivors. A further seven patients might have lived had they had a prompt operation. The average operative mortality for ruptured aneurysms among series reported in British journals is 53%, but the survivors are a small minority of the total number of people in the community whose aneurysms rupture. No basis could be found for the view that replacing an aortic aneurysm with a straight graft (while leaving behind aneurysmal common iliac arteries) lowers the operative mortality. On the contrary, oversimplifying the operation may be hazardous.     

Increasing incidence of aortic aneurysms in England and Wales.

The numbers of patients being admitted to hospital with aortic aneurysms have increased recently. A study was carried out to try to find out whether this was a true increase in incidence or whether it could be attributable to more accurate diagnosis and better surgical techniques. From analyses of routine statistics it was found that from 1950 to 1984 age standardised mortality rose 20-fold in men to 47.1 per 100,000 population and 11-fold in women to 22.2 per 100,000 and that this was mainly due to more deaths from abdominal aneurysms. Hospital admissions of men with abdominal aneurysms were found to have increased steadily from 1968 to 1983, but the increase for women admitted did not begin until 1978. An increase in both emergency and elective admissions and only a marginal fall in deaths in hospital (from 45% to 39%) suggest that admissions for abdominal aneurysms increased across a wide range of severity of disease. It is concluded for the following reasons that the true incidence of aortic aneurysms, particularly abdominal aneurysms, has been increasing in England and Wales: the trends are not wholly compatible with advances in diagnosis and surgery, there are inconsistencies by age and sex, and increases have occurred in the number of complicated as well as uncomplicated cases.     

Abdominal aortic aneurysms: recent experience with 210 patients.

In the 6 1/2 years ending June 1977, 210 patients with abdominal aortic aneurysms underwent operation at Toronto Western Hospital; 160 aneurysms (76%) were unruptured and 50 (24%) were ruptured. In the patients with unruptured aneurysms the mean age was 68 years; the oldest was 91, and 12 were more than 80 years of age. The overall hospital mortality was 5.6%. Death in hospital occurred in 1 (1.2%) of the 83 asymptomatic patients, 4 (7.4%) of the 54 symptomatic patients and 4 (17.0%) of the 23 patients for whom operation was considered urgent. In the patients with ruptured aneurysms the mean age was 71 years; the oldest was 90, and five were more than 80 years of age. The overall hospital mortality was 54%. The morbidity and mortality were analysed; in particular the reasons for the markedly variable hazard of operations for the three categories of unruptured aneurysm were sought. The surgical literature is confusing because of the interchanging use of the words unruptured, elective and symptomless. The current philosophy management and technique of operation in a large cardiovascular surgery service with many trainees are presented and a plea is made for a standardized and simplified operation, always performed with three assistants helping the operating surgeon.     

Population based randomised controlled trial on impact of screening on mortality from abdominal aortic aneurysm

Objective To assess whether screening for abdominal aortic aneurysms in men reduces mortality.Design Population based randomised controlled trial of ultrasound screening, with intention to treat analysis of age standardised mortality.Setting Community based screening programme in Western Australia.Participants 41 000 men aged 65-83 years randomised to intervention and control groups.Intervention Invitation to ultrasound screening.Main outcome measure Deaths from abdominal aortic aneurysm in the five years after the start of screening.Results The corrected response to invitation to screening was 70%. The crude prevalence was 7.2% for aortic diameter ≥ 30 mm and 0.5% for diameter ≥ 55 mm. Twice as many men in the intervention group than in the control group underwent elective surgery for abdominal aortic aneurysm (107 v 54, P = 0.002, χ² test). Between scheduled screening and the end of follow up 18 men in the intervention group and 25 in the control group died from abdominal aortic aneurysm, yielding a mortality ratio of 0.61 (95% confidence interval 0.33 to 1.11). Any benefit was almost entirely in men aged between 65 and 75 years, where the ratio was reduced to 0.19 (0.04 to 0.89).Conclusions At a whole population level screening for abdominal aortic aneurysms was not effective in men aged 65-83 years and did not reduce overall death rates. The success of screening depends on choice of target age group and the exclusion of ineligible men. It is also important to assess the current rate of elective surgery for abdominal aortic aneurysm as in some communities this may already approach a level that reduces the potential benefit of population based screening.     

Clinical experience in 1040 patients with double-velour knitted Dacron vascular prostheses: With particular reference to dilatation and aneurysm formation

Recent reports of dilatation and aneurysm formation in Dacron fabric grafts have prompted us to review our experience with 1040 patients who received Meadox-Cooley double-velour knitted grafts over a 47-month period. Bifurcation grafts were used in 398 patients with aorto-femoral occlusive disease and in 203 patients with aortoiliac occlusive disease. Straight tube grafts were implanted in 310 patients with abdominal aortic aneurysms. Small caliber straight tube grafts were used for femoral-femoral bypass in 112 patients. The remaining 17 patients received double-velour grafts for restoration of the renal (14) and superior mesenteric (3) artery circulation. In a review of patients, no dilatation or aneurysm formation was disclosed by clinical examination, sonography or aortography.     

Protection of Renal Function During Surgery of the Abdominal Aorta

The operative and postoperative urinary output of 55 patients who underwent surgery for ruptured abdominal aortic aneurysms, unruptured abdominal aortic aneurysms, and aorto-iliac occlusive disease was recorded. There were five cases of postoperative anuria among 28 patients who received no free fluid in the immediate preoperative period. No case of anuria occurred in 27 patients who received either: (1) a water load of 5% dextrose in water or (2) 20% mannitol solution. The patients who received mannitol had a markedly greater operative and postoperative urinary output.Intravenous infusion of mannitol is recommended during the preoperative and operative period in patients with ruptured aneurysms of the abdominal aorta.     

Indications for surgical treatment of abdominal aortic aneurysms]

The results of the surgical treatment of 115 patients with the abdominal aortal aneurysms are presented. Indications to surgery depending on the stage of aneurysm, way of classification, and coexisting cardiological disorders have been discussed. Excellent and favorable results of surgery have been achieved in 70 patients (60.9%). Overall hospital mortality rate was 39.1%. Out of patients who underwent elective surgery 11.6% died, in the group operated urgently--43.3%, and in emergency situation 89.4% of the operated patients died. Percentage of patients with coexisting cardiological disorders amounted to 54%, 62%, and 80% respectively. A strict correlation of the results of surgery and duration of the disease, and consequently classification to the treatment, has been noted. Indications to the elective surgery are related to the size of aneurysm, rate of its enlargement, patient's age, and general health.     

Clopidogrel,a Platelet P2Y12 Receptor Inhibitor,Reduces Vascular Inflammation and Angiotensin II Induced-Abdominal Aortic Aneurysm Progression

Medial degeneration and inflammation are features of abdominal aortic aneurysms (AAAs). However, the early inflammatory event initiating aneurysm formation remains to be identified. Activated platelets release abundant proinflammatory cytokines and are involved in initial inflammation in various vascular diseases. We investigated the role of platelets in progression of AAA in vivo and in vitro. Histological studies of tissues of patients with AAA revealed that the number of platelets was increased in aneurysm sites along with the increased infiltration of T lymphocytes and augmented angiogenesis. In a murine model of AAA, apolipoprotein E-knockout mice infused with 1,000 ng/kg/min angiotensin II, treatment with clopidogrel, an inhibitor of platelets, significantly suppressed aneurysm formation (47% decrease, P<0.05). The clopidogrel also suppressed changes in aortic expansion, elastic lamina degradation and inflammatory cytokine expression. Moreover, the infiltration of macrophages and production of matrix metalloproteinases (MMPs) were also significantly reduced by clopidogrel treatment. In vitro incubation of macrophages with isolated platelets stimulated MMP activity by 45%. These results demonstrate a critical role for platelets in vascular inflammation and AAA progression.     

Aneurysm and Helicobacter pylori relationship: the seropositivity of CagA, VacA and other antigens of Helicobacter pylori in abdominal and ascending aortic aneurysms

Helicobacter pylori is thought to be related to atherosclerosis and aneurysm development. We aimed to detect virulance factors of H. pylori and examine the potential etiopathogenetic relationship between aortic aneurysm and H. pylori, 58 abdominal aortic aneurysm (AAA) and 38 ascending aortic aneurysm (AsAA) cases and 57 Healty control group (HCG) were included. We investigated H. pylori IgG by ELISA and virulance factors by Western-Blot (WB) method. No difference was found between AAA (67.24%), AsAA (73.68%) and HCG (57.89%) for H. pylori IgG (p > 0.05). A significant difference was found between AsAA (78.95%) and HCG (57.89%) for H.pylori IgG (p < 0.05) by ELISA and a significant difference was found only between AsAA (100%) and HCG (37.5%) for H. pylori IgG in the 45-55 age group by WB. A statistically significant difference was found between AAA and AsAA for VacA and CagA + VacA and CagA + VacA + UreA antigens and also a significant difference was found between AsAA and HCG for CagA + UreA antigens (p < 0.05). Finally, we suggest that H. pylori VacA has a more important role than CagA in the development of two aneurysms especially in ruptured AAA. New extended studies detecting H. pylori DNA are needed to detect the aetiopathogenesis between aneurysm types and H. pylori.     

Patient-specific initial wall stress in abdominal aortic aneurysms with a backward incremental method

Patient-specific wall stress simulations on abdominal aortic aneurysms may provide a better criterion for surgical intervention than the currently used maximum transverse diameter. In these simulations, it is common practice to compute the peak wall stress by applying the full systolic pressure directly on the aneurysm geometry as it appears in medical images. Since this approach does not account for the fact that the measured geometry is already experiencing a substantial load, it may lead to an incorrect systolic aneurysm shape. We have developed an approach to compute the wall stress on the true diastolic geometry at a given pressure with a backward incremental method. The method has been evaluated with a neo-Hookean material law for several simple test problems. The results show that the method can predict an unloaded configuration if the loaded geometry and the load applied are known. The effect of incorporating the initial diastolic stress has been assessed by using three patient-specific geometries acquired with cardiac triggered MR. The comparison shows that the commonly used approach leads to an unrealistically smooth systolic geometry and therefore provides an underestimation for the peak wall stress. Our backward incremental modelling approach overcomes these issues and provides a more plausible estimate for the systolic aneurysm volume and a significantly different estimate for the peak wall stress. When the approach is applied with a more complex material law which has been proposed specifically for abdominal aortic aneurysm similar effects are observed and the same conclusion can be drawn.