Selective management of abdominal aortic aneurysms in a prospective measurement program

Purpose: The purpose of this study was to clarify the treatment of patients with small abdominal aortic aneurysms (AAAs) less than 5 cm in diameter and those believed to be unfit for operation with AAAs 5 cm diameter or greater.Methods: Four hundred ninety two patients with AAAs less than 5 cm when first seen were entered in a prospective measurement program by ultrasonography or computed tomography scan (exclusively after 1988) every 6 months. A decision regarding operative fitness was made when the AAA was 5 cm. Patients then underwent operation if fit or continued follow-up if their AAA was larger than 5 cm but they were unfit. A further group of 91 patients with aneurysms 5 cm or greater when first seen but unfit for repair were entered in the prospective measurement program.Results: In the group with AAAs less than 5 cm at entry, operation was performed in 201 patients as a result of increase in AAA size to 5 cm or greater (157), AAA expansion of more than 0.5 cm in 6 months (24), or for other reasons (20). Of those with AAAs smaller than 5 cm at entry, 291 have not undergone operation at a mean follow-up of 42 months. Expansion was significantly related to aneurysm size at entry and was highest in the 4.5 to 4.9 cm group at 0.7 cm/year. In the group of patients deemed unfit for operation with 5 cm AAAs [as a graduate of the less than 5 cm group at entry (85 patients) or first seen with AAA greater than 5 cm (91 patients)], 10 ruptures have occurred. Of these patients with ruptured AAAs, six had AAAs between 5.0 and 5.6 cm.Conclusions: Because of the risk of rupture demonstrated in our series in AAAs 5 cm or slightly greater and the progressive increase in expansion to a mean of 0.7 cm/year in those AAAs between 4.5 and 4.9 cm at entry, recommendation for elective operation in patients with AAAs between 4.5 and 5.0 cm should be strongly considered in a fit patient. (J VASC SURG1996;23:213-22.)     

Nonoperative management with selective delayed surgery for large abdominal aortic aneurysms in patients at high risk

OBJECTIVE: An accepted fact is that abdominal aortic aneurysms (AAAs) larger than 5.5 cm should undergo elective repair. However, subsets of these patients have serious comorbid conditions, which greatly increase operative risk. This study evaluated the outcomes of periods of protracted nonoperative observational management with selective delayed surgery in patients at high risk with large infrarenal and pararenal AAAs. METHODS: Among 226 patients with AAAs more than 5.5 cm, we selected 72 with AAAs from 5.6 to 12.0 cm (mean, 7.0 cm) for periods of nonoperative management because of their prohibitive surgical risks. Comorbid factors included a low ejection fraction of 15% to 34% (mean, 22%) in 18 patients, 1 second forced expiratory volume less than 50% (mean, 38%) in 25, prior laparotomy in 10, and morbid obesity in 22. Follow-up examination was complete in the 72 patients for the 6 to 76 months (mean, 23 months) that they underwent nonoperative treatment. Fifty-three patients ultimately underwent operation because of AAA enlargement or onset of symptoms after 6 to 72 months (mean, 19 months) of nonoperative treatment. RESULTS: Of the 72 selected patients, 54 (75%) are living and 18 (25%) are dead. Seven patients who underwent only nonoperative treatment presently survive after 28 to 76 months (mean, 48 months). Of the 18 deaths, AAA rupture occurred in only three patients (4%) who were observed for 12, 31, and 72 months before rupture. Nine other deaths (13%) occurred after 6 to 72 months from comorbidities unrelated to the AAA. Six of the 53 patients who underwent delayed operation died within 30 days of operation (11% mortality rate). The mortality rate for the 154 good-risk patients with an AAA who underwent prompt open or endovascular repair was 2.2%. CONCLUSION: These data indicate that some patients with large AAAs and serious comorbidities are acceptably managed for long periods (6 to 76 months) with nonoperative means. Substantial delays of 12 to 76 months resulted in an AAA rupture rate of only 4%, and 13% of these patients (nine of 72) died of comorbidities unrelated to AAA rupture or surgery. Mortality rate in this group of patients, when operated, was 11% (six of 53). These findings support the selective use of nonoperative management in some patients with large AAAs and serious comorbidities.     

Expansion rates and outcomes for the 3.0-cm to the 3.9-cm infrarenal abdominal aortic aneurysm

OBJECTIVE: This study was performed for the determination of the expansion rates and outcomes and for recommendations for the surveillance of the 3.0-cm to 3.9-cm abdominal aortic aneurysm (AAA). DESIGN: The study was observational with data from patients screened with ultrasound scanning for AAA at five Veterans Affairs Medical Centers for enrollment in the Aneurysm Detection and Management Trial. The eligibility requirements included: AAA from 3.0 cm to 3.9 cm in diameter and at least one repeat ultrasound scan more than 90 days after the initial screening. Patients also completed a questionnaire for demographic data and the determination of the presence of risk factors associated with AAA. The study endpoints included: 1, both mean and median expansion rates; 2, moderate expansion (>4 mm/year); 3, no expansion; 4, all causes of death; 5, AAA rupture; 6, expansion to 4 cm or more; 7, expansion to 5.0 cm or more; and 8, operative repair. RESULTS: Ultrasound scan screening results identified 1445 patients with 3.0-cm to 3.9-cm AAAs. Seven hundred ninety men met the ultrasound scan criterion of having at least two ultrasound scan studies during the study period, and these 790 men were used for this study. Mean AAA size was 3.3 cm, with an average follow-up period of 3.89 +/- 1.93 years. The median expansion rate was 0.11 cm/year. Expansion rates were significantly different (P <.001) between 3.0-cm and 3.4-cm cm AAA and 3.5-cm and 3.9-cm AAA. There were no reported AAA ruptures during the study period, although cause of death data were available in only 43% of the patients. Few 3.0-cm to 3.9-cm AAAs expanded to 5.0 cm or more during the study period. The patients with 3.0-cm to 3.9-cm AAAs who underwent operative repair during the study period were younger, had larger initial AAA diameters, and had more rapid expansion rates. CONCLUSION: AAAs of 3.0 cm to 3.9 cm expanded slowly, did not rupture, and rarely had operative repair or expanded to more than 5.0 cm in our study of male patients. Expansion rates and the incidence rate of operative repair are more common in the 3.5-cm to 3.9-cm AAA when compared with the 3.0-cm to 3.4-cm AAA.     

Conservative observational management with selective delayed repair for large abdominal aortic aneurysms in high risk patients

AIM: Abdominal aortic aneurysms (AAAs) larger than 5.5 cm should generally undergo elective repair. However, some of these patients have serious comorbid conditions, which greatly increase operative risk. This study evaluated the outcomes of nonoperative, observational management and selective delayed AAA repair in high-risk patients with large infrarenal and pararenal AAAs. METHODS: Among 226 patients with AAAs >5.5 cm, we selected 72 with AAAs 5.6-12.0 cm (mean 7.0 cm) for periods of nonoperative management because of their prohibitive surgical risks. Comorbid factors included a low ejection fraction of 15-34% (mean 22%) in 18 patients; FEV1 <50% (mean 38%) in 25; prior laparotomy in 10; and morbid obesity in 22. Follow-up was complete in the 72 patients for the 6-76 months (mean 23 months) that they were treated nonoperatively. Fifty-three patients ultimately underwent repair because of AAA enlargement or onset of symptoms after 6-72 months (mean 19 months) of observational treatment. RESULTS: Of the 72 selected patients, 54 (75%) are living and 18 (25%) are dead. Seven patients undergoing only nonoperative treatment presently survive after 28-76 months (mean 48 months). Of the 18 deaths, AAA rupture occurred in only 3 patients (4%) who had been observed for 12, 31, and 72 months before rupture. Nine other deaths (13%) occurred after 6-72 months from comorbidities unrelated to the patient's AAA. Six of the 53 patients undergoing delayed AAA repair died within 30 days of operation (11% mortality). The mortality for the 154 good risk AAA patients, who underwent prompt open or endovascular repair, was 2.2%. CONCLUSION: These data indicate that some patients with large AAAs and serious comorbidities are acceptably managed for long periods (6-76 months) by nonoperative means. Substantial delays of 12 to 76 months resulted in an AAA rupture rate of only 4%, while 13% of these patients (9 of 72) died of their comorbidities unrelated to AAA rupture or surgery and mortality in this group of patients, when operated on, was 11% (6 of 53). These findings support the selective use of nonoperative observational management in some patients with large AAAs and serious comorbidities.     

The cost-effectiveness of early surgery versus watchful waiting in the management of small abdominal aortic aneurysms

Purpose: The purpose of this study was to compare the relative cost-effectiveness of two clinical strategies for managing 4 to 5 cm diameter abdominal aortic aneurysms (AAAs): early surgery (repair 4 cm AAA when diagnosed) versus watchful waiting (monitor AAA with ultrasound size measurements every 6 months and repair if the diameter reaches 5 cm).Methods: We used a Markov decision tree to compute the expected survival in quality-adjusted life years (QALYs) for each strategy, based on literature-derived estimates for the probabilities of different outcomes in this model. We determined hospital costs for patients undergoing elective and emergency AAA repair at our center. With standard methods of cost accounting, we then calculated the additional cost per year of life saved by early surgery compared with watchful waiting (cost-effectiveness ratio, dollars/QALY).Results: Mean hospital costs for elective and emergency AAA repair were $24,020 and $43,208, respectively (1992 dollars). For our base-case analysis (60-year-old men with 4 cm diameter AAAs, with 5% elective operative mortality rate and 3.3% annual rupture rate), early surgery improved survival by 0.34 QALYs compared with watchful waiting, at an incremental cost of $17,404/QALY. Increased elective surgical mortality rate, decreased AAA rupture risk, and increased patient age all reduced the cost-effectiveness of early surgery. Future increases in elective operative risk, noncompliance with ultrasound follow-up and increased threshold size for elective AAA repair during watchful waiting all improved the cost-effectiveness of early surgery. Future increases in elective operative risk, noncompliance with ultrasound follow-up and increased threshold size for elective AAA repair during watchful waiting all improved the cost-effectiveness of early surgery.Conclusions: The cost effectiveness of early surgery for 4 cm diameter AAAs in carefully selected patients compares favorably with that of other commonly accepted preventive interventions such as hypertension screening and treatment. With an upper limit of $40,000/QALY as an "acceptable" cost-effectiveness ratio, early surgery appears to be justified for patients 70 years old or younger, if the AAA rupture risk is 3%/year or more and the elective operative mortality rate is 5% or less. Although not a substitute for clinical judgment, this cost-effectiveness analysis delineates the essential tradeoffs and uncertainties in treating patients with small AAAs. (J VASC SURG 1994;19:980–91.)     

Variables that affect the expansion rate and outcome of small abdominal aortic aneurysms

Seventy-three patients with small (less than 6 cm in diameter) abdominal aortic aneurysms (AAAs) were selected for nonoperative management and followed up with sequential ultrasound size measurements. Fifty-four men and 19 women, 51 to 89 years of age (mean 70 years), had an initial mean AAA size of 4.1 cm (anteroposterior) x 4.3 cm (lateral) diameter, with a calculated elliptic cross-sectional area of 14.3 cm2. After a mean of 37 months of follow-up, AAA area increased at a mean rate of 20% per year (3 cm2 yr; 0.4 to 0.5 cm/yr diameter). Expansion rate was not affected by initial aneurysm size. During follow-up, only 3 patients (4%) required urgent operation (1 died), 26 patients (36%) died of non-AAA causes, and 26 patients (36%) underwent elective AAA repair because of progressive size increase (1 died). Elective operations were performed at the rate of 10% per year, when mean AAA size had increased to 22 cm2 (5.1 cm in diameter). Multiple regression analysis of clinical parameters available at presentation indicated that subsequent elective AAA repair was predicted by younger age at diagnosis and larger initial aneurysm size. As anticipated, patients who underwent surgery had more rapid aneurysm expansion (5.3 cm2/yr) compared with patients who did not undergo surgery (1.6 cm2/yr; p less than 0.05). This difference was caused by more rapid expansion during later follow-up intervals among patients selected for operation and was not predicted by the change in aneurysm size observed during initial ultrasonographic follow-up. Final aneurysm size was predicted by initial size, duration of follow-up, and both systolic and diastolic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vivo analysis of mechanical wall stress and abdominal aortic aneurysm rupture risk

OBJECTIVE: The purpose of this study was to calculate abdominal aortic aneurysm (AAA) wall stresses in vivo for ruptured, symptomatic, and electively repaired AAAs with three-dimensional computer modeling techniques, computed tomographic scan data, and blood pressure and to compare wall stress with current clinical indices related to rupture risk. METHODS: CT scans were analyzed for 48 patients with AAAs: 18 AAAs that ruptured (n = 10) or were urgently repaired for symptoms (n = 8) and 30 AAAs large enough to merit elective repair within 12 weeks of the CT scan. Three-dimensional computer models of AAAs were reconstructed from CT scan data. The stress distribution on the AAA as a result of geometry and blood pressure was computationally determined with finite element analysis with a hyperelastic nonlinear model that depicted the mechanical behavior of the AAA wall. RESULTS: Peak wall stress (maximal stress on the AAA surface) was significantly different between groups (ruptured, 47.7 +/- 6 N/cm(2); emergent symptomatic, 47.5 +/- 4 N/cm(2); elective repair, 36.9 +/- 2 N/cm(2); P =.03), with no significant difference in blood pressure (P =.2) or AAA diameter (P =.1). Because of trends toward differences in diameter, comparison was made only with diameter-matched subjects. Even with identical mean diameters, ruptured/symptomatic AAAs had a significantly higher peak wall stress (46.8 +/- 4.5 N/cm(2) versus 38.1 +/- 1.3 N/cm(2); P =.05). Maximal wall stress predicted risk of rupture better than the LaPlace equation (20.7 +/- 5.7 N/cm(2) versus 18.8 +/- 2.9 N/cm(2); P =.2) or other proposed indices of rupture risk. The smallest ruptured AAA was 4.8 cm, but this aneurysm had a stress equivalent to the average electively repaired 6.3-cm AAA. CONCLUSION: Peak wall stresses calculated in vivo for AAAs near the time of rupture were significantly higher than peak stresses for electively repaired AAAs, even when matched for maximal diameter. Calculation of wall stress with computer modeling of three-dimensional AAA geometry appears to assess rupture risk more accurately than AAA diameter or other previously proposed clinical indices. Stress analysis is practical and feasible and may become an important clinical tool for evaluation of AAA rupture risk.     

Should endovascular surgery lower the threshold for repair of abdominal aortic aneurysms?

PURPOSE: Because endovascular repair of abdominal aortic aneurysms (AAAs) is less invasive, some investigators have suggested that this increasingly popular technique should broaden the indications for elective AAA repair. The purpose of this study was to calculate quality-adjusted life expectancy rates after endovascular and open AAA repair and to estimate the optimal diameter for elective AAA repair in hypothetical cohorts of patients at average risk and at high risk. METHODS: A Markov decision analysis model was used in this study. Assumptions were made on the basis of published reports and included the following: (1) the annual rupture rate is a continuous function of the AAA diameter (0% for <4 cm, 1% for 4.5 cm, 11% for 5.5 cm, and 26% for 6.5 cm); (2) the operative mortality rate is 1% for endovascular repair (excluding the risk of conversion to open repair) and 3.5% for open repair at age 70 years; and (3) immediate endovascular-to-open conversion risk is 5%, and late conversion rate is 1% per year. The main outcome measure in this study was the benefit of AAA repair in quality-adjusted life years (QALYs). The optimal threshold size (the AAA diameter at which elective repair maximizes benefit) was measured in centimeters. RESULTS: The benefit of endovascular repair is consistently greater than that of open repair, but the additional benefit is small-0.1 to 0.4 QALYs. For men in average health with gradually enlarging AAAs with initial diameters of 4 cm, endovascular surgery reduces the optimal threshold diameter by very little: from 4.6 to 4.6 cm (no change) at age 60 years, from 4.8 to 4.7 cm at age 70 years, and from 5.1 to 4.9 cm at age 80 years. For older men in poor health, endovascular surgery reduces the optimal threshold diameter substantially (8.1 to 5.7 cm at age 80 years), but the benefit of repair in this population is small (0.2 QALYs). CONCLUSION: For most patients, the indications for AAA repair are changed very little by the introduction of endovascular surgery. Only for older patients in poor health does endovascular surgery substantially lower the optimal threshold diameter for elective AAA repair.     

Endovascular aneurysm repair at 5 years: does aneurysm diameter predict outcome?

OBJECTIVE: The appropriate size threshold for endovascular repair of small abdominal aortic aneurysms (AAA) is unclear. We studied the outcome of endovascular aneurysm repair (EVAR) as a function of preoperative aneurysm diameter to determine the relationship between aneurysm size and long-term outcome of endovascular repair. METHODS: We reviewed the results of 923 patients treated in a prospective, multicenter clinical trial of EVAR. Small aneurysms were defined according to two size thresholds of 5.5 cm and 5.0 cm. Two-way analysis was used to compare patients with small aneurysms (<5.5 cm, n = 441) to patients with large aneurysms (> or =5.5 cm, n = 482). An ordered three-way analysis was used to compare patients with small AAA (<5.0 cm, n = 145), medium AAA (5.0 to 5.9 cm, n = 461), and large AAA (> or =6.0 cm, n = 317). The primary outcome measures of rupture, AAA-related death, surgical conversion, secondary intervention, and survival were compared using Kaplan-Meier estimates at 5 years. RESULTS: Median aneurysm size was 5.5 cm. The two-way comparison showed that 5 years after EVAR, patients with small aneurysms (<5.5 cm) had a lower AAA-related death rate (1% vs 6%, P = .006), a higher survival rate (69% vs 57%, P = .0002), and a lower secondary intervention rate (25% vs 32%, P = .03) than patients with large aneurysms (> or =5.5 cm). Three-way analysis revealed that patients with small AAAs (<5.0 cm) were younger (P < .0001) and were more likely to have a family history of aneurysm (P < .05), prior coronary intervention (P = .003), and peripheral occlusive disease (P = .008) than patients with larger AAAs. Patients with smaller AAAs also had more favorable aortic neck anatomy (P < .004). Patients with large AAAs were older (P < .0001), had higher operative risk (P = .01), and were more likely to have chronic obstructive pulmonary disease (P = .005), obesity (P = .03), and congestive heart failure (P = .004). At 5 years, patients with small AAAs had better outcomes, with 100% freedom from rupture vs 97% for medium AAAs and 93% for large AAAs (P = .02), 99% freedom from AAA-related death vs 97% for medium AAAs and 92% for large AAAs (P = .02) and 98% freedom from conversion vs 92% for medium AAAs and 89% for large AAAs (P = .01). Survival was significantly improved in small (69%) and medium AAAs (68%) compared to large AAAs (51%, P < .0001). Multivariate Cox proportional hazards modeling revealed that aneurysm size was a significant independent predictor of rupture (P = .04; hazard ratio [HR], 2.195), AAA-related death (P = .03; HR, 2.007), surgical conversion (P = .007; HR, 1.827), and survival (P = .001; HR, 1.351). There were no significant differences in secondary intervention, endoleak, or migration rates between small, medium, and large AAAs. CONCLUSIONS: Preoperative aneurysm size is an important determinant of long-term outcome following endovascular repair. Patients with small AAAs (<5.0 cm) are more favorable candidates for EVAR and have the best long-term outcomes, with 99% freedom from AAA death at 5 years. Patients with large AAAs (> or =6.0 cm) have shorter life expectancy and have a higher risk of rupture, surgical conversion, and aneurysm-related death following EVAR compared to patients with smaller aneurysms. Nonetheless, 92% of patients with large AAAs are protected from AAA-related death at 5 years. Patients with AAAs of intermediate size (5 to 6 cm) represent most of the patients treated with EVAR and have a 97% freedom from AAA-related death at 5 years.     

Abdominal aortic aneurysm rupture rates: A 7-year follow-up of the entire abdominal aortic aneurysm population detected by screening

Purpose: The goal of the current study was to identify the risk of rupture in the entire abdominal aortic aneurysm (AAA) population detected through screening and to review strategies for surgical intervention in light of this information. Methods: Two hundred eighteen AAAs were detected through ultrasound screening of a family practice population of 5394 men and women aged 65 to 80 years. Subjects with an AAA of less than 6.0 cm in diameter were followed prospectively with the use of ultrasound, according to our protocol, for 7 years. Patients were offered surgery if symptomatic, if the aneurysm expanded more than 1.0 cm per year, or if aortic diameter reached 6.0 cm. Results: The maximum potential rupture rate (actual rupture rate plus elective surgery rate) for small AAAs (3.0 to 4.4 cm) was 2.1% per year, which is less than most reported operative mortality rates. The equivalent rate for aneurysms of 4.5 to 5.9 cm was 10.2% per year. The actual rupture rate for aneurysms up to 5.9 cm using our criteria for surgery was 0.8% per year Conclusion: In centers with an operative mortality rate of greater than 2%, (1) surgical intervention is not indicated for asymptomatic AAAs of less than 4.5 cm in diameter, and (2) elective surgery should be considered only for patients with aneurysms between 4.5 and 6 cm in diameter that are expanding by more than 1 cm per year or for patients in whom symptoms develop. In centers with elective mortality rates of greater than 10% for abdominal aortic aneurysm (AAA) repair, the benefit to the patient of any surgical intervention for an asymptomatic AAA of less than 6.0 cm in diameter is questionable. (J Vasc Surg 1998;28:124-8.)     

Effect of beta-adrenergic blockade on the growth rate of abdominal aortic aneurysms

We retrospectively identified 136 patients with abdominal aortic aneurysms (AAAs) who were initially evaluated as outpatients. Twenty-seven of these patients met the following criteria for eligibility in the study: (1) roentgenographic documentation of an AAA larger than 3 cm, (2) at least two serial ultrasound size determinations over a minimum six-month interval, and (3) a documented medication history. Of these 27 patients, 12 received long-term beta-blockade, while 15 received no beta-blockade. The two groups were comparable with respect to age, sex, initial aneurysm size, mean systolic and diastolic blood pressure, and duration of follow-up (mean, 34 months). Among patients with beta-blockade, the mean growth rate was 0.17 cm/y. The rate for the controls was 0.44 cm/y. One patient of 12 (8%) in the beta-blocker group had a rate that exceeded the mean for the overall group compared with eight patients of 15 (53%) in the group with no beta-blockade. This difference was statistically significant. Thus, beta-blockade may be associated with a decreased AAA growth rate in this small, retrospective study.     

Endovascular vs open AAA repair: does size matter?

Since the natural tendency of the aorta is to increase in diameter and tortuosity with age and since abdominal aortic aneurysms (AAAs) increase in diameter and length over time, encroaching on the renal and hypogastric orifices, early repair of AAAs (when > or =4.0 cm) may allow greater applicability of the endovascular option because of more favorable aortoiliac morphology. Patients who present at an older age with larger AAAs should be more likely to be anatomically excluded from endovascular AAA repair. Over a 42-month period, 317 consecutive patients referred with aortoiliac aneurysms (infrarenal AAA > or =4.0 cm) were evaluated by one of the authors (SGL) for endovascular vs open repair based on computed tomography (CT) and angiographic imaging. The 10 anatomic exclusion criteria were those applicable to the Zenith endograft (Cook, Inc), which currently is the most anatomically inclusive of the aortic endografts in commercial use in the United States. Based on their aortoiliac morphology, 212 patients were excluded from endovascular repair and 105 were included as acceptable anatomic candidates. Age, AAA size, and the reason(s) for exclusion were recorded for each patient. By use of Student's t test and logistic and linear regression analyses, the groups were compared by age, AAA size, and age + size. There was no significant difference in patient age or AAA size distribution between the group of patients excluded from endovascular repair based on aortoiliac morphology compared to those who met the inclusion criteria. Patients with small AAAs (4.0-5.4 cm) had similar age distribution as those with large (> or =5.5 cm) AAAs. The majority of patients (87%) were excluded based on proximal aortic neck morphology. The presence of aortoiliac morphology that precludes endovascular repair is independent of patient age or AAA size at presentation. A patient presenting with a small (4.0-5.4 cm) AAA is not more likely to be a candidate for endovascular repair than a patient with a large AAA.     

Rupture of abdominal aortic aneurysm: concurrent comparison of outcome of those occurring after endovascular repair versus those occurring without previous treatment in an 11-year single-center experience

OBJECTIVE: The purpose of this single-center study was to compare findings at presentation and surgical outcome in patients in whom abdominal aortic aneurysms (AAAs) ruptured after endovascular repair and patients in whom AAAs ruptured before any treatment, over a defined period. METHODS: From May 1992 to September 2003, 1043 patients underwent elective repair of intact infrarenal AAAs. Endovascular repair was performed in 609 patients, and open repair in 434 patients. Eighteen of 609 patients (3%) who underwent endovascular AAA repair required treatment because of rupture of the aneurysm after a mean of 29 months (group 1). During the same 11-year period, another 91 patients without previous treatment required urgent repair of a ruptured AAA (group 2). Rupture was diagnosed at contrast material-enhanced computed tomography or by presence of extramural extravasation of blood at open repair. Except for a higher incidence of women in group 2, patients in both groups were similar with regard to demographics and clinical characteristics but differed in findings at presentation. Eight patients in group 1 had a known endoleak before AAA rupture, whereas contrast-enhanced computed tomography, performed in 15 patients at presentation, demonstrated an endoleak in all. Hypotension (systolic blood pressure <100 mm Hg) was noted at presentation in 4 of 18 patients (22%) in group 1 and 76 of 91 patients (84%) in group 2. All patients underwent open repair via a transperitoneal approach, except for 4 patients in group 1 and 3 patients in group 2 who underwent endovascular repair of ruptured AAAs. RESULTS: The proportion of patients with hypotension at presentation in group 1 (4 of 18) was significantly less than in group 2 (76 of 91; P < .01). The difference in perioperative (30 day) mortality rate in group 1 (3 of 18; 16.6%) compared with group 2 (49 of 91; 53.8%) was also significant (P < .01). The outcome in group 1 was therefore superior to that in group 2. CONCLUSIONS: This study confirms that endovascular AAA repair complicated by endoleak does not prevent rupture. The data suggest, however, that rupture, when it occurs in these circumstances, may not be accompanied by such major hemodynamic changes and high mortality as rupture of an untreated AAA. Further long-term follow-up and analysis in a larger group of patients are required to confirm the apparent intermediate level of protection afforded by failed endovascular repair, which does not prevent rupture but enhances survival after operation to treat rupture, possibly by ameliorating the hemodynamic changes associated with the rupture process.     

Size and location of thrombus in intact and ruptured abdominal aortic aneurysms

PURPOSE: This study compared the volume and morphology of intraluminal thrombus (ILT) in intact and ruptured abdominal aortic aneurysms (AAAs). METHODS: ILT volume in 67 intact AAAs and in 31 ruptured AAAs was assessed by using computed tomography (CT) angiography to measure the major and minor diameter of the outer wall and lumen of AAA as outlined by contrast at multiple sites. ILT thrombus morphology was recorded by AutoCAD 2000 software. Four equidistant images traced from the CT scan were recorded along the length of AAA. Thrombus volume was categorized as anterior-eccentric if the calculated area of thrombus was greater anteriorly, posterior-eccentric if greater posteriorly, eccentric-equal if the difference between the anterior and posterior thrombus was 相似文献   

Anatomic characteristics of ruptured abdominal aortic aneurysm on conventional CT scans: Implications for rupture risk

OBJECTIVE: The purpose of this study was to analyze anatomic characteristics of patients with ruptured abdominal aortic aneurysms (AAAs), with conventional two-dimensional computed tomography (CT), including comparison with control subjects matched for age, gender, and size. METHODS: Records were reviewed to identify all CT scans obtained at Dartmouth-Hitchcock Medical Center or referring hospitals before emergency AAA repair performed because of rupture or acute severe pain (RUP group). CT scans obtained before elective AAA repair (ELEC group) were reviewed for age and gender match with patients in the RUP group. More than 40 variables were measured on each CT scan. Aneurysm diameter matching was achieved by consecutively deleting the largest RUP scan and the smallest ELEC scan to prevent bias. RESULTS: CT scans were analyzed for 259 patients with AAAs: 122 RUP and 137 ELEC. Patients were well matched for age, gender, and other demographic variables or risk factors. Maximum AAA diameter was significantly different in comparisons of all patients (RUP, 6.5 +/- 2 cm vs ELEC, 5.6 +/- 1 cm; P <.0001), and mean diameter of ruptured AAAs was 5 mm smaller in female patients (6.1 +/- 2 cm vs 6.6 +/- 2 cm; P =.007). Two hundred patients were matched for diameter, gender, and age (100 from each group; maximum AAA diameter, 6.0 +/- 1 cm vs 6.0 +/- 1 cm). Analysis of diameter-matched AAAs indicated that most variables were statistically similar in the two groups, including infrarenal neck length (17 +/- 1 mm vs 19 +/- 1 mm; P =.3), maximum thrombus thickness (25 +/- 1 mm vs 23 +/- 1 mm, P =.4), and indices of body habitus, such as [(maximum AAA diameter)/(normal suprarenal aorta diameter)] or [(maximum AAA diameter)/(L3 transverse diameter)]. Multivariate analysis controlling for gender indicated that the most significant variables for rupture were aortic tortuosity (odds ratio [OR] 3.3, indicating greater risk with no or mild tortuosity), diameter asymmetry (OR, 3.2 for a 1-cm difference in major-minor axis), and current smoking (OR, 2.7, with the greater risk in current smokers). CONCLUSIONS: When matched for age, gender, and diameter, ruptured AAAs tend to be less tortuous, yet have greater cross-sectional diameter asymmetry. On conventional two-dimensional CT axial sections, it appears that when diameter asymmetry is associated with low aortic tortuosity, the larger diameter on axial sections more accurately reflects rupture risk, and when diameter asymmetry is associated with moderate or severe aortic tortuosity, the smaller diameter on axial sections more accurately reflects rupture risk. Current smoking is significantly associated with rupture, even when controlling for gender and AAA anatomy.     

Prognosis of patients turned down for conventional abdominal aortic aneurysm repair in the endovascular and sonographic era: Szilagyi revisited?

PURPOSE: The United Kingdom Small Aneurysm study has demonstrated the low risk of rupture in aneurysms less than 5.5 cm in diameter. With the advent of endoluminal techniques, patients considered unfit to undergo laparotomy are now considered for endovascular repair. However, the natural history of aneurysms larger than 5.5 cm remains uncertain, especially when severe comorbidity is present. In our center, we prospectively maintain records of all patients for whom elective aneurysm surgery was refused. This study documented the outcome of all patients referred with abdominal aortic aneurysms (AAAs) larger than 5.5 cm in diameter who were turned down for elective open repair and determined the cause of death and risk of rupture in all patients. METHODS: Details of all patients with AAAs from January 5, 1989, to January 5, 1999, were recorded, and demographic details on all patients with AAAs larger than 5.5 cm were collected. Copies of death certificates were obtained from the Office of National Statistics, local in-hospital patient records, and general practitioner records. Results of postmortem examinations were also obtained. Aneurysms were stratified according to their size at presentation (5.5-5.9 cm, 6.0-7.0 cm, and > 7.0 cm), and the reasons no intervention was made were documented. RESULTS: A total of 106 patients were turned down for elective aneurysm surgery in the 10-year period (10.6 per year). The mean age of the patients was 78.4 years (SD, 7.4), and 70 were men and 36 were women. At the end of the study, 76 patients (71.7%) had died. Overall, the 3-year survival rate was 17%. Patients with AAAs larger than 7.0 cm lived a median of 9 months. A ruptured aneurysm was certified as a cause of death in 36% of the patients with an AAA of 5.5 to 5.9 cm, in 50% of the patients with an AAA of 6 to 7.0 cm, and 55% of the patients with an AAA larger than 7.0 cm. Reasons given for not intervening were patient refusal (31 cases), the patient being "unfit for surgery" (18 cases), the "advanced age" of the patient (18 cases), cardiac disease (9 cases), cancer (9 cases), respiratory disease (6 cases), and other (15 cases). CONCLUSION: Although we recognize the problems with death certification, we found that rupture was a significant cause of death in patients with an untreated AAA that was larger than 5.5 cm. Although little difference in outcome was observed in aneurysms in the 5.5 to 7.0 cm size range, patients with an AAA that was larger than 7.0 cm seemed to have a much poorer prognosis.     

Abdominal aortic aneurysms: screening,epidemiology and open surgical repair

Abdominal Aortic Aneurysm (AAA) is a dilatation of the infra-renal abdominal aorta to greater than 3 cm. Population screening is offered to men in their 65th year in the UK. Patients with small AAAs (<5.5 cm) are entered into surveillance programs and should have cardiovascular risk factors managed aggressively. An AAA with ≥5.5 cm diameter should be considered for surgical repair to prevent rupture. Open surgical repair has proven to be a durable treatment for AAA and while less often performed than endovascular aneurysm repair (EVAR) it remains a common approach in the surgical management of AAA. While associated with higher short-term risks than EVAR, the long-term outcomes are similar and many younger patients have a preference for open repair as routine follow-up is not required.     

Endovascular repair of small abdominal aortic aneurysms: a paradigm shift?

Recent reports have documented poor long-term results following endovascular aneurysm repair (EVAR) of large abdominal aortic aneurysms (AAA). EVAR of small AAAs may result in improved long-term results compared to large AAAs. It is not known whether the frequency of anatomic suitability for EVAR is increased for small compared to large AAAs. This study compared the anatomic suitability of large and small AAAs for EVAR in an unselected patient population. Radiology reports for all computed tomography (CT) scans in a single hospital over a recent 3-year period were reviewed. AAAs diagnosed by contrasted CT scans with cuts >7 mm were excluded. Suitability for EVAR was determined by neck diameter, length, and angulation. In addition, iliac diameters and common iliac distal landing zone lengths were determined. Computerized 3-dimensional (3D) reconstruction was used to measure neck angulation and total aortic tortuosity. One hundred ninety-one patients were found to have AAAs with adequate CT scans for evaluation. Suitability for EVAR was highest in patients with AAA diameters of 3-4 cm and declined with increasing size of the AAA. Dividing AAAs into sizes greater than or less than 5.5 cm revealed that small AAAs had significantly longer necks, less neck angulation, longer common iliac landing zones, and less total aortic tortuosity. Multivariable analysis revealed that maximal aortic diameter was the only independent predictor of suitability for EVAR (p = 0.005, odds ratio 1.67, CI 95% = 1.17 to 2.38). The odds ratio predicts that with each 1 cm increase in size, the likelihood of suitability decreased by 5.3-fold. Small AAAs have less complex anatomy with longer aortic necks, less neck angulation, and less tortuosity. The poor outcomes following the treatment of large AAAs is thought to be due to complex anatomy. EVAR of less anatomically challenging small AAAs may improve long-term outcomes.     

A comparison of the mortality rate after elective repair of aortic aneurysms detected either by screening or incidentally.

OBJECTIVE: to compare predicted and actual mortality rates, using POSSUM scoring, after elective repair of abdominal aortic aneurysms (AAAs) detected from the Gloucestershire Aneurysm Screening Programme and those discovered incidentally. METHODS: a sample of 276 men undergoing elective AAA repair in Gloucestershire between 1991 and 1998 was studied. AAAs were either detected from the screening programme or were discovered incidentally and referred from other sources. Mortality data relating to these patients have been recorded prospectively. POSSUM scoring was performed retrospectively from patients> notes in both groups and related to outcome (30 day and in-hospital mortality). POSSUM and P-POSSUM methodology were used to compare observed and predicted mortality rates. RESULTS: in the 276 men who had elective AAA repair, the overall mortality rate was 7%. Mortality was lower in screen-detected AAAs (3/111, 3%) than AAAs discovered incidentally (16/175, 9%) (p=0.05). Preoperative physiology scores were significantly lower in men with a screen-detected AAA (median 19, range 13-29 versus 21, 12-41, p<0.001). POSSUM operative scores were similar between the groups. Actual versus predicted death ratios in the sample group were more accurate using POSSUM (ratio 0.93) than P-POSSUM (2.38) analysis. CONCLUSIONS: men with a screen-detected AAA had a lower mortality rate after elective repair than in those detected incidentally; lower preoperative physiology scores suggested they were fitter (as well as younger). In this study POSSUM analysis more accurately predicted outcome than P-POSSUM.     

Hyperhomocysteinaemia is associated with the rate of abdominal aortic aneurysm expansion.

OBJECTIVES: Previous literature has suggested an association between AAA and the presence of elevated plasma homocysteine levels (HCY). Homocysteine can stimulate elastolysis in the arterial media via activation of elastase and matrix metalloproteinases. No evidence in the literature exists correlating aneurysm expansion and HCY. The study objective is to identify whether the rate of AAA expansion is related to HCY. METHODS: 108 patients undergoing surveillance for AAA were identified at our vascular surgical unit. AAA size and growth rate were assessed by serial ultrasonographic measurements. Fasting total HCY levels were measured using fluorescence polarisation immunoassays. Demographic details and atherosclerotic risk factors were noted all AAA patients. A multivariate analysis was performed for growth rate vs. HCY, hypertension and hypercholesterolaemia. The correlation between AAA growth rate, AAA size and HCY levels were calculated. RESULTS: 60% of patients with AAA had some degree of hyperhomocysteinaemia (> 15 micromol/l). Multivariate analysis showed HCY to be the only significant factor affecting AAA growth rate. A positive correlation was demonstrated between HCY levels and AAA growth rate using a linear regression model (R=0.28, p=0.003). Median growth rate among patients with hyperHCY was double that of patients with normal HCY (0.5 mm/month vs. 0.25 mm/month, p=0.003). A growth rate of > 10 mm/year was seen in 25% of hyper HCY patients and in only 2% of patients with normal HCY. In addition patients with hyper HCY and larger AAAs (> 4 cm) had a growth rate twice as fast as patients with hyper HCY and AAAs < 4 cm. CONCLUSIONS: A correlation between HCY and growth rate exists, although this is weak due to the multifactorial aetiology of AAAs. HyperHCY patients have faster expansion rates than patients with normal HCY, with significant numbers demonstrating rapid expansion (> 10 mm/year) and therefore an increased risk of rupture.