Abdominal aortic aneurysm screening: an epidemiological point of view

[Embolization of the internal iliac artery during endovascular repair of abdominal aortic aneurysms]

An abdominal aortic aneurysm is one of frequently encountered cardiovascular diseases, which is often accompanied by an aneurysm of the common and/or internal iliac arteries. Recent trends are towards increased use of endovascular methods of treatment, associated with a certain risk for the development of type IIa endoleaks. This raises the question as to the necessity of embolization of the internal iliac artery while covering it with a stent graft. Our study included a total of 20 patients operated on for abdominal aortic aneurysms combined with aneurysms of the common and/or internal iliac arteries. In order to evaluate the obtained outcomes, the patients were divided into 4 groups depending on the intervention performed. The scope of the performed operations varied from endoprosthetic repair of an abdominal aortic aneurysm with coverage of one internal iliac artery without embolization to endoprosthetic repair of an abdominal aortic aneurysm with coverage of both internal iliac arteries with embolization. In the latter event, two-stage interventions were performed. The duration of follow up amounted to more than 3 years. We assessed the short- and long-term outcomes, with zero lethality and the absence of either specific or non-specific complications observed. Embolization increases the duration of the operation and X-ray exposure, as well as the amount of the contrast medium, thus casting doubt upon the necessity of carrying it out, since the immediate and remote results do not differ as compared with mere coverage of the internal iliac artery.

3D-Printed Tissue-Mimicking Phantoms for Medical Imaging and Computational Validation Applications

Abdominal aortic aneurysm (AAA) is a permanent, irreversible dilation of the distal region of the aorta. Recent efforts have focused on improved AAA screening and biomechanics-based failure prediction. Idealized and patient-specific AAA phantoms are often employed to validate numerical models and imaging modalities. To produce such phantoms, the investment casting process is frequently used, reconstructing the 3D vessel geometry from computed tomography patient scans. In this study the alternative use of 3D printing to produce phantoms is investigated. The mechanical properties of flexible 3D-printed materials are benchmarked against proven elastomers. We demonstrate the utility of this process with particular application to the emerging imaging modality of ultrasound-based pulse wave imaging, a noninvasive diagnostic methodology being developed to obtain regional vascular wall stiffness properties, differentiating normal and pathologic tissue in vivo. Phantom wall displacements under pulsatile loading conditions were observed, showing good correlation to fluid-structure interaction simulations and regions of peak wall stress predicted by finite element analysis. 3D-printed phantoms show a strong potential to improve medical imaging and computational analysis, potentially helping bridge the gap between experimental and clinical diagnostic tools.

[Effect of intraoperative parameters on survival in patients with ruptured abdominal aortic aneurysms]

Ruptured abdominal aortic aneurysm is one of the most urgent surgical conditions with high mortality that has not been changed in decades. Between 1991-2001 total number of 1058 patients was operated at the Institute for Cardiovascular Diseases of Clinical Centre of Serbia due to abdominal aortic aneurysm. Of this number, 288 patients underwent urgent surgical repair because of ruptured abdominal aortic aneurysm. The aim of this retrospective study was to show results of the early outcome of surgical treatment of patients with ruptured abdominal aortic aneurysm, and to define relevant intraoperative factors that influence their survival. There were 83% male and 17% female patients in the study, mean aged 67 years. Mean duration of surgical procedure was 190 minutes (75-420 min). Most common localization of aneurysm was infrarenal--in 74% of patients, then juxtarenal (12.3%). Suprarenal aneurysm was found in 6.8% of patients, as well as thoracoabdominal aneurysm (6.8%). Retroperitoneal rupture of aortic aneurysm was most common--in 65% of patients, then intraperotineal in 26%. Rare finding such as chronic rupture was found in 3.8%, aorto-caval fistula in 3.2% and aorto-duodenal fistula in 0.6% of patients. Mean aortic cross-clamping time was 41.7 minutes (10-150 min). Average intraoperative systolic pressure in patients was 106.5 mmHg (40-160 mmHg). Mean intraoperative blood loss was 3700 ml (1400-8500 ml). Mean intraoperative diuresis was 473 ml (0-2100 ml). Tubular graft was implanted in 53% of patients, aorto-iliac bifurcated graft in 32.8%. Aortobifemoral reconstruction was done in 14.2% of patients. These data refer to the patients that survived surgical procedure. Intrahospital mortality that included intraoperative and postoperative deaths was 53.7%. Therefore, 46.3% patients survived surgical treatment and were released from the hospital. Intraoperative mortality was 13.5%. Type of aneurysm had no influence on outcome of patients (p > 0.05), as well as type of rupture and level of aortic cross-clamping. Aortic cross-clamping time was significantly shorter in survivors, and longest in patients that died intraoperatively (p < 0.05). Intraoperative systolic tension value influenced the outcome in patients; it was significantly higher in survivors (p < 0.01). Interposition of tubular graft gave better results compared with aorto-iliac and aorto-femoral reconstruction (p < 0.01). Duration of surgery was significantly higher in patients with lethal outcome (p < 0.05), as well as intraoperative blood loss (p < 0.05). Intraoperative diuresis was significantly lower in patients with lethal outcome (p < 0.05). Ruptured abdominal aortic aneurysm still remains one of the most dramatic surgical states with very high mortality. Important intraoperative factors that influence the outcome of surgical treatment can be defined. Therapeutic efforts should be concentrated on those factors that are possible to correct, which would hopefully lead to better survival of patients. Nevertheless, screening for abdominal aortic aneurysm and elective surgical intervention before rupture occurs should be the best solution for this complex problem.

[Effect of preoperative factors on survival in patients with ruptured aneurysms of the abdominal aorta]

Between 1991-2001 total number of 1058 patients was operated at the Institute of Cardiovascular Diseases of Serbian Clinical Centre due to abdominal aortic aneurysm. Of this number, 288 patients underwent urgent surgical treatment because of ruptured abdominal aortic aneurysm. The aim of this retrospective study was to show results of the early outcome of the surgical treatment of patients with ruptured abdominal aortic aneurysm, and to define relevant preoperative factors that influenced their survival. There were 83% male and 17% female patients in the study, mean aged 67 years. Intrahospital mortality that included intraoperative and postoperative deaths was 53.7%. Therefore, 46.3% patients survived surgical treatment and were released from hospital. Intraoperative mortality was 13.5%. Statistics showed that the gender and the age did not have any influence on mortality of our patients, as well as their co morbid conditions (p > 0.05). Clinical parameters at admission in hospital such as state of consciousness, systolic blood pressure, cardiac arrest and diuresis significantly influenced the outcome of treatment, as well as laboratory findings such as levels of hematocrit, hemoglobin, white blood cells, urea and creatinin (p < 0.05; p < 0.01). Ruptured abdominal aortic aneurysm still remains one of the most dramatic surgical states with very high mortality reported. We assume that important preoperative factors that influence the outcome of surgical treatment can be defined, but there is no single parameter which can certainly predict the lethal outcome after surgery. Also, the presence of co morbid conditions does not significantly influence the outcome of treatment in these patients. Therefore, urgent operation should not be withheld in most of the patients with ruptured abdominal aortic aneurysm.

Aortic emergencies

Prompt recognition of actual or impending aortic emergencies is essential to the effective practice of emergency medicine. Understanding the pathophysiologic principles and awareness of the potential subtleties in the clinical presentations of aortic dissection, aneurysm, and occlusive disease are prerequisites to this task. Knowledge of current diagnostic modalities is also important if these entities are to be identified rapidly and managed efficiently to maximize the potential for a good patient outcome. Awareness of the potential complications of these conditions and the necessary interventional and resuscitative measures that might be called for in the appropriate clinical setting are likewise essential requirements for the EP. Appropriate surgical consultation and mobilization of operative resources form the backbone of appropriate management in the patient who has an aortic emergency.

Abdominal aortic aneurysms. Surgical treatment

The purpose of this chapter is to provide a brief overview of the current place of open surgical repair for abdominal aortic aneurysms with respect to the factors influencing clinical decision-making, the operative techniques most frequently used, and some of the complications commonly encountered in the postoperative period.

Community mortality after ruptured abdominal aortic aneurysm is unrelated to the distance from the surgical centre

BACKGROUND

Ruptured abdominal aortic aneurysm (RAAA) carries a high community mortality. Raigmore Hospital, Inverness serves Highland Region, an area the size of Wales with a population of 204,000. The aim of this retrospective review was to determine the community mortality and hospital mortality rates from RAAA in Highland Region and to assess whether distance travelled had any significant impact on survival.

METHODS

Data were retrieved from hospital records, the Registrar General for Scotland and the Information and Statistics Division of the National Health Service in Scotland about patients diagnosed with RAAA between 1992 and 1999.

RESULTS

Of 198 patients with RAAA, 131 (66 per cent) were transferred to Raigmore Hospital while the other 67 (34 per cent) died in a community hospital or at home. Of those reaching Raigmore 109 (83 per cent) had surgery, of whom 65 (60 per cent) survived. The overall community mortality rate was 67 per cent while the hospital mortality rate was 50 per cent. The hospital and community mortality rates for patients living within 50 miles of Raigmore Hospital were 60 and 67 per cent respectively, compared with 26 and 68 per cent for those living more than 50 miles away.

CONCLUSION

Distance from Raigmore Hospital had no significant impact on community mortality from RAAA.

Elevated plasma levels of matrix metalloproteinase-9 in patients with abdominal aortic aneurysms: a circulating marker of degenerative aneurysm disease

PURPOSE

Matrix metalloproteinase-9 (MMP-9) is abundantly expressed in abdominal aortic aneurysms (AAAs), where it plays a pivotal role in connective tissue destruction. Elevated plasma concentrations of MMP-9 (MMP-9PL) also have been reported in patients with AAAs, but it is unclear if this can distinguish patients with AAAs from those with atherosclerotic occlusive disease (AOD). The purpose of this study was to further define the utility of elevated MMP-9PL levels in the diagnosis and evaluation of AAAs, and to examine if changes in MMP-9PL can be used as a functional biomarker of degenerative aneurysm disease.

MATERIALS AND METHODS

Peripheral venous blood was obtained from 25 patients with AAAs, 15 patients with AOD, and five normal control subjects. MMP-9PL levels were determined by an enzyme-linked immunosorbent assay. In four patients undergoing open AAA repair, MMP-9PL levels were directly compared with the amount of MMP-9 produced in aortic tissue. Six additional patients undergoing operative AAA repair were followed for 3-10 months to determine how treatment affected elevated MMP-9PL concentrations.

RESULTS

Mean (+/- SE) MMP-9PL was 36.1 +/- 7.7 ng/mL in normal control subjects, 54.7 +/- 10.5 ng/mL in patients with AOD, and 99.4 +/- 17.4 ng/mL in patients with AAAs (P < .05 versus normal control subjects and patients with AOD). Elevated MMP-9PL levels (> 87.8 ng/mL) were found in 12 of 25 (48%) patients with AAA but in only one of 15 (7%) patients with AOD (P < .05). MMP-9PL levels did not correlate significantly with either age, gender, or aneurysm diameter, although there was a trend toward the highest values in male patients with large AAAs. Production of MMP-9 in aneurysm tissues paralleled MMP-9PL levels, and elevated MMP-9PL levels decreased by 92.7% +/- 3.2% after surgical AAA repair.

CONCLUSIONS

Elevated MMP-9PL levels were observed in approximately one half of patients with AAAs and less than 10% of those with AOD (positive predictive value of 92.3%), but normal MMP-9PL levels had limited utility in excluding the presence of an aortic aneurysm (negative predictive value, 52%). MMP-9PL levels in patients with AAAs appeared to directly reflect the amount of MMP-9 produced within aneurysm tissue, and MMP-9PL levels decreased substantially after aneurysm repair. Measures of circulating MMP-9 may provide a biologically relevant marker of connective tissue metabolism in patients with AAAs.

MMP inhibition in abdominal aortic aneurysms. Rationale for a prospective randomized clinical trial

Abdominal aortic aneurysms (AAAs) represent a chronic degenerative condition associated with a life-threatening risk of rupture. The evolution of AAAs is thought to involve the progressive degradation of aortic wall elastin and collagen, and increased local production of several matrix metallo-proteinases (MMPs) has been implicated in this process. We have previously shown that tetracycline derivatives and other MMP inhibitors suppress aneurysm development in experimental animal models of AAA. Doxycycline also reduces the expression of MMP-2 and MMP-9 by human vascular wall cell types and by AAA tissue explants in vitro. To determine whether this strategy might have a role in the clinical management of small AAA, we examined the effect of doxycycline on aortic wall MMP expression in vivo. Patients were treated with doxycycline (100 mg p.o. bid) for 7 days prior to elective AAA repair, and aneurysm tissues were obtained at the time of surgery (n = 5). Tissues obtained from an equal number of untreated patients with AAA were used for comparison. By reverse transcription-polymerase chain reaction and Southern blot analysis, MMP-2 and MMP-9 were both found to be abundantly expressed in the aneurysm wall. Preoperative treatment with doxycycline was associated with a 3-fold reduction in aortic wall expression of MMP-2 and a 4-fold reduction in MMP-9 (p < 0.05 compared to untreated AAA). These preliminary results suggest that even short-term treatment with doxycycline can suppress MMP expression within human AAA tissues. Given its pleiotropic effects as an MMP inhibitor, doxycycline may be particularly effective in suppressing aortic wall connective tissue degradation. While it remains to be determined whether MMP inhibition will have a clinically significant impact on aneurysm expansion, it is expected that this question can be resolved by a properly designed prospective randomized clinical trial.

Reduced capacity to inhibit elastase in abdominal aortic aneurysm

BACKGROUND

Loss of elastin in the aortic wall is an early event in abdominal aortic aneurysm (AAA). An imbalance in the protease-antiprotease system is proposed to be one of the factors that promote connective tissue destruction. We hypothesize that plasma from AAA patients will have a reduced inhibitory capacity in comparison to normal controls.

MATERIALS AND METHODS

Using an assay we developed, plasma (10 microliters), collected from AAA patients (n = 14) and normal controls (n = 13), was added to the elastase inhibition assay containing succinylated elastin substrate. The reaction was initiated with 13.9 units porcine pancreatic elastase (PPE). Elastase activity in the presence and absence of plasma was compared. Plasma elastase was also determined using the Merck PMN-elastase kit.

RESULTS

The relative activity of exogenous elastase (%) in the presence of AAA plasma (n = 14, mean age 73.4 years +/- 1.7 SEM) was 42.59% +/- 4.3 SEM, while that in the presence of control plasma (n = 13, mean age 73.9 years +/- 2.1 SEM) was 10.23% +/- 2.1 SEM (P < 0.0001). Analysis of plasma elastase (microgram/L) indicated that there was no significant difference between normal (n = 9, 207.33 microgram/L +/- 58.67 SEM) and AAA (n = 9, 145.34 microgram/L +/- 29.54 SEM) (P = 0.359).

CONCLUSION

There is a significant reduction in the plasma inhibitory capacity of elastase in AAA patients in comparison to normal controls, though plasma elastase level was not significantly different. The data presented here give experimental evidence to the protease-antiprotease imbalance in AAA patient plasma and may lead to the development of a measurable parameter to monitor AAA.

Routine ultrasound screening for abdominal aortic aneurysm among 65- and 75-year-old men in a city of 200,000 inhabitants

Unruptured abdominal aortic aneurysm (AAA) is seldom recognized. Thus it is difficult to know whether the incidence of AAA in the general population is high enough to warrant routine screening at least in men after a certain age. Ultrasound screening studies to evaluate the incidence of AAA have been carried out in several English-speaking and Scandinavian countries. The purpose of this report is to describe the results of a study carried out in Belgium. All 65- and 75-year-old men living in the city of Liege, Belgium, were given the opportunity to undergo a free ultrasound examination. Only 41% of the target population was examined. AAA defined as abdominal aortic diameter of >30 mm was observed in 28 subjects (incidence: 3.8%). Mean abdominal aortic diameter was 34.7 mm. A diameter >29 mm was observed in 33 subjects (incidence 4.5%). Mean abdominal aortic diameter was 30.4 mm. On the basis of epidemiological data collected, a high-risk population for AAA was identified. Arterial hypertension (p < 0.05), previous coronary artery surgery (p < 0.05), and smoking (p < 0.06) were more common in subjects with than without AAA. The overall cost of screening was $18.175. The cost per AAA diagnosed was $551.00.

Therapeutic potential of tetracycline derivatives to suppress the growth of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) represent a potentially lethal disorder associated with aging and atherosclerosis. Although current management of AAA is predicted on early detection and elective surgical repair, routine screening for AAA is infrequent, because most AAA are too small to warrant repair when first detected and because there are no therapeutic approaches proven to suppress aneurysm expansion. Basic research on this problem suggests that chronic inflammation and increased local production of elastin-degrading proteinases play prominent roles in the process of aneurysmal degeneration. Members of the matrix metalloproteinases (MMP) family appear to be the most prominent elastases produced in human AAA, suggesting that unique therapeutic targets might exist for aneurysm disease. Studies using a representative animal model for AAA support this view, providing a means for further development of pharmacological approaches to suppress aneurysm expansion. Indeed, recent work indicates that tetracycline derivatives have the potential to interrupt the progressive connective tissue destruction that occurs in AAA, by virtue of their non-antimicrobial properties as MMP inhibitors, and they do so at clinically achievable dose schedules. These findings support the view that MMPs are potentially important pharmacotherapeutic targets in AAA and, moreover, that tetracyclines might be useful in suppressing aneurysm expansion in vivo. Because tetracycline derivatives offer a number of distinct advantages as MMP inhibitors for patients with small AAA, prospective clinical trials of this novel therapeutic strategy can be anticipated in the near future.

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.

Results of aortic screening in the brothers of patients who had elective aortic aneurysm repair

BACKGROUND

Brothers of patients with an abdominal aortic aneurysm (AAA) are at high risk. In the present study brothers of patients who underwent elective AAA surgery were invited for aneurysm screening and the psychological consequences studied.

METHODS

All brothers over the age of 50 years were invited for abdominal ultrasonography. They were asked to complete a standard psychological well-being questionnaire both before, and 3 months after screening.

RESULTS

Some 571 brothers were identified: 251 were dead, 35 lived abroad, 16 could not be contacted for other reasons, 46 refused to participate and 13 were already known to have an AAA. Some 210 subjects (37.8 per cent) accepted the offer of screening. A new AAA was detected in 26 (12.3 per cent, 95 per cent confidence interval 8-18 per cent) of the men screened resulting in an overall prevalence of 18 per cent (95 per cent confidence interval 13-26 per cent). Eight (3.8 per cent) aneurysms were 5 cm or more in diameter and elective surgery was performed in five patients (2.4 per cent). The psychological dimensions of well-being (depression, anxiety, energy, and positive well-being) had not changed significantly 3 months after screening.

CONCLUSION

The prevalence of AAA in brothers of patients with AAA is far higher than in the overall male population of the same age. Screening does not seem to have a negative influence on psychological well-being.

An empirical study of nursing in patients undergoing two different procedures for abdominal aortic aneurysm repair

Specialized vascular nursing has to meet the challenge presented through progress and modern developments in vascular surgery. Endovascular techniques are becoming more widespread and are now available for diseases that previously have required extensive surgery. A comparative study was carried out in two groups of patients with infrarenal abdominal aortic aneurysms (N = 50), either by means of the traditional open surgical approach or by the new endovascular stented graft technology. Four problems were compared in both groups of patients: (1) length of hospital stay, (2) dependency on nursing, (3) patients mobility after surgery, and (4) analgesic requirements. Data were obtained from a designated data sheet. Analysis of the data obtained helped us in our service to optimize the nursing process for patients undergoing major aortic surgery for open, as well as endovascular, procedures, especially regarding the nursing anamnesis and nursing diagnosis.

Epidemiology and potential for prevention of abdominal aortic aneurysm

BACKGROUND

Ruptured abdominal aortic aneurysm (AAA) is a common cause of death which is preventable by elective repair of an asymptomatic AAA.

METHODS

The literature was reviewed with emphasis on epidemiological studies and population-based screening surveys.

RESULTS AND CONCLUSION

The prevalence of small AAA ranges between 3 and 8 per cent. The incidence of asymptomatic AAA seems to be increasing, although exact incidence estimates vary. The most important risk factors for AAA are male sex, age, family history and smoking. Hypertension is associated with a mildly increased risk, but diabetes is not associated with any increase. Primary prevention of AAA is not a realistic option. There is no evidence of an effective medical treatment to prevent growth of small AAAs, although trials with propranolol are under way. The only intervention to prevent death from aneurysm is elective repair of the asymptomatic lesion. Screening for asymptomatic AAA can reduce the incidence of rupture. However, further studies are needed to determine the cost effectiveness of screening compared with that of other health programmes.