Characteristics and outcome amongst young adults suffering from out-of-hospital cardiac arrest in whom cardiopulmonary resuscitation is attempted.

OBJECTIVES: Amongst patients suffering from out-of-hospital cardiac arrest, young adults represent a minority. However, these victims suffer from the catastrophe when they are in a very active phase of life and have a long life expectancy. This survey aims to describe young adults in Sweden who suffer from out-of-hospital cardiac arrest and in whom cardiopulmonary resuscitation (CPR) is attempted in terms of characteristics and outcome. DESIGN: Prospective and descriptive design. SUBJECTS AND METHODS: Young adults (18-35 years) who suffered from out-of-hospital cardiac arrest in whom CPR was attempted and who were included in the Swedish Cardiac Arrest Registry between 1990 and 2004. MAIN OUTCOME MEASURES: Survival to 1 month. RESULTS: In all, 1105 young adults (3.1% of all the patients in the registry) were included, of which 29% were females, 51% were nonwitnessed and 15% had a cardiac aetiology. Only 17% were found in ventricular fibrillation, 53% received bystander CPR. The overall survival to 1 month was 6.3%. High survival was found amongst patients found in ventricular fibrillation (20.8%) and those with a cardiac aetiology (14.8%). Ventricular fibrillation at the arrival of the rescue team remained an independent predictor of an increased chance of survival (odds ratio: 7.43; 95% confidence interval: 3.44-16.65). CONCLUSION: Amongst young adults suffering from out-of-hospital cardiac arrest and in whom CPR was attempted, a minority survived to 1 month. Subgroups with a higher survival could be defined (patients found in ventricular fibrillation and patients in whom there was a cardiac aetiology). However, only one independent predictor of an increased chance of survival could be demonstrated, i.e. ventricular fibrillation at the arrival of the rescue team.

Association between interval between call for ambulance and return of spontaneous circulation and survival in out-of-hospital cardiac arrest.

AIM: To describe the association between the interval between the call for ambulance and return of spontaneous circulation (ROSC) and survival in out-of-hospital cardiac arrest. PATIENTS: All patients suffering an out-of-hospital cardiac arrest in whom cardiopulmonary resuscitation (CPR) was started, included in the Swedish Cardiac Arrest Registry (SCAR) for whom information about the time of calling for an ambulance and the time of ROSC was available. RESULTS: Among 26,192 patients who were included in SCAR and were not witnessed by the ambulance crew, information about the time of call for an ambulance and the time of ROSC was available in 4847 patients (19%). There was a very strong relationship between the interval between call for an ambulance and ROSC and survival to one month. If the interval was less than or equal to 5 min, 47% survived to one month. If the interval exceeded 30 min, only 5% (n = 35) survived to one month. The vast majority of the latter survivors had a shockable rhythm either on admission of the rescue team or at some time during resuscitation. CONCLUSION: Among patients who have ROSC after an out-of-hospital cardiac arrest, there is a very strong association between the interval between the call for ambulance and ROSC and survival to one month. However, even if this delay is very long (> 30 min after calling for an ambulance), a small percentage will ultimately survive; they are mainly patients who at some time during resuscitation have a shockable rhythm. The overall percentage of patients for whom CPR continued for more than 30 min who are alive one month later can be assumed to be extremely low.

Major differences in 1-month survival between hospitals in Sweden among initial survivors of out-of-hospital cardiac arrest.

AIM: To explore the rate of survival to hospital discharge among patients who were brought to hospital alive after an out-of-hospital cardiac arrest in different hospitals in Sweden. PATIENTS AND METHODS: All patients who had suffered an out-of-hospital cardiac arrest which was not witnessed by the ambulance crew, in whom cardiopulmonary resuscitation (CPR) was started and who had a palpable pulse on admission to hospital were evaluated for inclusion. Each participating ambulance organisation and its corresponding hospital(s) required at least 50 patients fulfilling these criteria. RESULTS: Three thousand eight hundred and fifty three patients who were brought to hospital by 21 different ambulance organisations fulfilled the inclusion criteria. The number of patients rescued by each ambulance organisation varied between 55 and 900. The survival rate, defined as alive 1 month after cardiac arrest, varied from 14% to 42%. When correcting for dissimilarities in characteristics and factors of the resuscitation, the adjusted odds ratio for survival to 1 month among patients brought to hospital alive in the three ambulance organisations with the highest survival versus the three with the lowest survival was 2.63 (95% CI: 1.77-3.88). CONCLUSION: There is a marked variability between hospitals in the rate of 1-month survival among patients who were alive on hospital admission after an out-of-hospital cardiac arrest. One possible contributory factor is the standard of post-resuscitation care.

Characteristics and outcome among children suffering from out of hospital cardiac arrest in Sweden.

AIM: To evaluate the characteristics, outcome and prognostic factors among children suffering from out of hospital cardiac arrest in Sweden. METHODS: Patients aged below 18 years suffering from out of hospital cardiac arrest which were not crew witnessed and included in the Swedish cardiac arrest registry were included in the survey. This survey included the period 1990-2001 and 60 ambulance organisations covering 85% of the Swedish population (8 million inhabitants). RESULTS: In all 457 children participated in the survey of which 32% were bystander witnessed and 68% received bystander CPR. Ventricular fibrillation was found in 6% of the cases. The overall survival to 1 month was 4%. The aetiology was sudden infant death syndrome in 34% and cardiac in 11%. When in a multivariate analysis considering age, sex, witnessed status, bystander CPR, initial rhythm, aetiology and the interval between call for, and arrival of, the ambulance and place of arrest only one appeared as an independent predictor of an increased chance of surviving cardiac arrest occurring outside home (adjusted odds ratio 8.7; 95% CL 2.2-58.1). CONCLUSION: Among children suffering from out of hospital cardiac arrest in Sweden that were not crew witnessed, the overall survival is low (4%). The chance of survival appears to be markedly increased if the arrest occurs outside the patients home compared with at home. No other strong predictors for an increased chance of survival could be demonstrated.

Can we define patients with no chance of survival after out-of-hospital cardiac arrest?

OBJECTIVE: To evaluate whether subgroups of patients with no chance of survival can be defined among patients with out-of-hospital cardiac arrest. PATIENTS: Patients in the Swedish cardiac arrest registry who fulfilled the following criteria were surveyed: cardiopulmonary resuscitation (CPR) was attempted; the arrest was not crew witnessed; and patients were found in a non-shockable rhythm. SETTING: Various ambulance organisations in Sweden. DESIGN: Prospective observational study. RESULTS: Among the 16,712 patients who fulfilled the inclusion criteria, the following factors were independently associated with a lower chance of survival one month after cardiac arrest: no bystander CPR; non-witnessed cardiac arrest; cardiac arrest occurring at home; increasing interval between call for and arrival of the ambulance; and increasing age. When these factors were considered simultaneously two groups with no survivors were defined. In both groups patients were found in a non-shockable rhythm, no bystander CPR was attempted, the arrest was non-witnessed, the arrest took place at home. In one group the interval between call for and arrival of ambulance exceeded 12 minutes. In the other group patients were older than 80 years and the interval between call for and arrival of the ambulance exceeded eight minutes. CONCLUSION: Among patients who had an out-of-hospital cardiac arrest and were found in a non-shockable rhythm the following factors were associated with a low chance of survival: no bystander CPR, non-witnessed cardiac arrest, the arrest took place at home, increasing interval between call for and arrival of ambulance, and increasing age. When these factors were considered simultaneously, groups with no survivors could be defined. In such groups the ambulance crew may refrain from starting CPR.

Prediction of development of fatigue during a simulated ambulance work task from physical performance tests.

The aims of this study were (1) to identify which physical performance tests could best explain the development of fatigue during a simulated ambulance work task, (2) to investigate the effect of height and weight and (3) to investigate in what respects these findings differ between female and male ambulance personnel. Forty-eight male and 17 female ambulance personnel completed a test battery assessing cardio-respiratory capacity, muscular strength and endurance, and co-ordination. The subjects also completed a simulated ambulance work task -- carrying a loaded stretcher. The work task was evaluated by development of fatigue. Univariate and multiple regression analyses were used to investigate to what extent the tests in the test battery were able to explain the variance of developed fatigue. The explained variance was higher for female than for male ambulance personnel (time > 70% of HRpeak: R2 = 0.75 vs 0.10, accumulated lactate: R2 = 0.62 vs 0.42, perceived exertion: R2 = 0.75 vs 0.10). Significant predictors in the models were VO2max, isometric back endurance, one-leg rising, isokinetic knee flexion and shoulder extension strength. Height, but not weight, could further explain the variance. The high physical strain during carrying the loaded stretcher implies the importance of investigating whether improved performance, matching the occupational demands, could decrease the development of fatigue during strenuous tasks.

Does lipoprotein(a) inhibit elastolysis in abdominal aortic aneurysms?

PURPOSE: to test the hypothesis that there is a negative association between serum levels of lipoprotein(a) (Lp(a)) and elastin-derived peptides (EDP) as well as matrix metalloproteinase (MMP)-9 activation in the aneurysm wall in patients with asymptomatic abdominal aortic aneurysms (AAA). MATERIAL AND METHODS: from 30 patients operated for asymptomatic AAAs, preoperative serum samples and AAA biopsies were collected. Lp(a) (mg/L) and EDP (ng/ml) in serum were measured by enzyme linked immunosorbent assays. MMP-9 activity (arbitrary units) in the AAA wall was measured by gelatin zymography and the ratio: active MMP-9/total MMP-9 were calculated. RESULTS: there was a significant negative correlation (Spearman's rho) between serum levels of Lp(a) and EDP (r= -0.707, p<0.001), as well as the share of activated MMP-9 (r= -0.461, p=0.01) in the AAA wall. CONCLUSION: this preliminary study indicate that Lp(a) inhibit elastolysis in asymptomatic AAA.

Serum concentrations of elastin-derived peptides in patients with specific manifestations of atherosclerotic disease.

OBJECTIVE: To measure serum concentrations of elastin-derived peptides (S-EDP) in patients with aneurysmal, occlusive and ulcerative manifestations of atherosclerotic disease. MATERIALS AND METHODS: S-EDP concentrations were measured by a competitive enzyme-linked immunosorbent assay in 10 patients with infrarenal aneurysms 5cm in diameter (AAA), 10 patients with distal aortic occlusive disease (AOD), 10 patients with symptomatic carotid stenosis (>or=70%) and plaque ulceration (SCS) and a control group of 10 patients with no similar specific manifestations of atherosclerotic disease (NAM). RESULTS: S-EDP concentrations (median, range) were significantly higher in patients with AAA (42ng/ml, 35-52, p<0.001) and SCS (49ng/ml, 37-60, p<0.001) but not AOD (28ng/ml, 22-38, p=0.240) compared to NAM (26ng/ml, 19-36) patients. CONCLUSION: Increased concentrations of S-EDP were associated with aneurysmal and ulcerative, but not occlusive, manifestations of atherosclerosis.

Intestinal pHi studied with continuous saline tonometry during ischaemia and reperfusion in the pig.

OBJECTIVE: To evaluate continuous saline tonometry for detection of progressive intestinal ischaemia and reperfusion in a porcine model. DESIGN: In eight anaesthetised pigs, small bowel mucosal pCO2 was recorded by means of two identical equipments for continuous saline tonometry and a standard tonometry balloon during ischaemia and reperfusion. RESULTS: Both systems of saline tonometry functioned stably during the four hour protocol ischaemia, although not significant until after 45 min for one of the tonometers. CONCLUSION: The equipment for continuous saline tonometry has a good reactivity, an accuracy comparable with standard tonometry.

Presence of Chlamydia pneumoniae in abdominal aortic aneurysms is not associated with increased activity of matrix metalloproteinases.

OBJECTIVE: to test the hypothesis that the presence of Chlamydia pneumoniae (C. pneumoniae) in the wall of abdominal aortic aneurysms (AAA) is associated with increased activity of matrix metalloproteinase (MMP)-2 and/or MMP-9. DESIGN: case-control study. MATERIAL AND METHODS: in a series of 40 patients with AAA > or =5cm in maximal cross-sectional diameter, C. pneumoniae-DNA was identified in the aneurysm wall by nested PCR in 14 (35%) patients. Another 14 C. pneumoniae-DNA-negative AAA patients from the same series, matched for gender and aneurysm diameter, were used as controls. In each group there were 7 asymptomatic (aAAA) and 7 ruptured (rAAA) aneurysms. MMP-2 and -9 activity was estimated in AAA wall biopsies by gelatin zymography. RESULTS: patients with a C. pneumoniae-DNA-positive aneurysm wall specimen showed an over-all lower activity of MMP-2 and MMP-9 (pro- and active enzyme) compared to the C. pneumoniae-DNA negative patients. However, there were no statistically significant differences in MMP activity between the two groups of patients with aAAA. Among patients with rAAA both pro-MMP-9 (p=0,026) and active-MMP-9 (p=0.007) were significantly lower in C. pneumoniae-DNA-positive patients compared to C. pneumoniae-DNA-negative patients, whereas there were no significant differences in pro-MMP-2 or active-MMP-2. CONCLUSION: this preliminary study does not support the hypothesis that the presence of C. pneumoniae in the AAA wall is associated with increased activity of MMP-2 and MMP-9.

Proteolysis of the abdominal aortic aneurysm wall and the association with rupture.

PURPOSE: to investigate proteolysis of the abdominal aortic aneurysm (AAA) wall and the association with rupture. METHODS: levels of matrix metalloproteinases (MMP-2 and MMP-9) and tissue inhibitor of metalloproteinases (TIMP-1 and TIMP-2) were measured in the walls of medium-sized (5-7 cm in diameter) ruptured AAA (rAAA) (n =30) and large (> or = 7 cm in diameter) asymptomatic AAA (aAAA) (n=30). RESULTS: MMP-2 levels (median, range) were significantly higher in the walls of large aAAA (165 ng/g AAA tissue, 50-840) than from medium-sized rAAA (110 ng/g AAA tissue, 47-547, p=0.007). MMP-9 levels were significantly higher in the walls of medium-sized rAAA (107 ng/g AAA tissue, 19-582) than from large aAAA (55 ng/g AAA tissue, 11-278, p=0.012). TIMP-1 and TIMP-2 levels were equivalent. There was a positive correlation between MMP-2 and the diameter of aAAA (r=0.54, p=0.002), but a negative correlation with MMP-9 (r= -0.44, p=0.017). No significant correlations were found between aAAA diameter and TIMP-1 or TIMP-2. CONCLUSION: AAA rupture is associated with higher levels of MMP-9. There is no association with TIMP-1 or TIMP-2 levels. MMP-2 levels are positively, whereas MMP-9 levels are negatively, correlated with aAAA size. MMP-9 may play a role in the progression towards rupture, whereas MMP-2 may play a role in expansion.

In vitro degradation of aortic elastin by Chlamydia pneumoniae.

OBJECTIVES: to investigate whether Chlamydia pneumoniae (C. pneumoniae) may increase elastin degradation in the aortic wall. MATERIALS AND METHODS: eighteen full thickness aortic wall samples from non-aneurysmal infrarenal abdominal aortas were collected from autopsies. Two adjacent and equally large pieces were cut out of each aortic sample. From each sample, one piece was incubated in a HEp-2 cell culture infected with C. pneumoniae and the other piece was incubated in an uninfected HEp-2 cell culture. The incubation time was one week at 35 degrees C. The concentration of elastin-derived peptides (EDP) (ng/ml) in the medium of each cell culture was measured in duplicate. For each paired sample, delta-EDP (EDP in HEp-2 cell culture infected with C. pneumoniae- EDP in uninfected HEp-2 cell culture) was calculated. RESULT: there was a significantly increased degradation of aortic elastin, estimated by EDP concentrations in cell culture conditioned medium, when aortic wall samples were incubated in C. pneumoniae cultures compared with uninfected cultures (p=0.025, Wilcoxon signed ranks test). CONCLUSION: these results indicate that there is a relationship between the presence of C. pneumoniae and increased elastin degradation in the aortic wall in vitro. This suggests C. pneumoniae in the aortic wall directly or indirectly leads to the degradation of aortic elastin.

Validation of a novel method for continuous saline tonometry in a porcine model.

Only intermittent and semi-continuous tonometric measurement of gastric and intestinal pHi is possible with the equipment available today. Earlier we developed a system for continuous saline tonometry and tested it in vitro. To assess the in vivo reliability of this method for continuous gastrointestinal saline tonometry, a standard tonometer for measurement of intestinal pCO2 and corresponding pHi was modified to allow continuous perfusion of physiological saline in a closed system and tested in a porcine model. In 11 anaesthetized and haemodynamically stable pigs, two continuous tonometry balloons were inserted into the distal small bowel, and a standard tonometry balloon was used as reference. To test long-term function of the continuous tonometers the research protocol lasted for eight hours. The two continuous saline tonometers performed well, and after an equilibration time of three hours the mean pHi values were stable between 7.35 and 7.43 and between 7.32 and 7.39 respectively. The standard tonometer measured stable pHi values. These preliminary studies indicate that continuous saline tonometry performs well over eight hours with a small bias and a good precision.

Serum levels of elastin-derived peptides in patients with ruptured and asymptomatic abdominal aortic aneurysms.

OBJECTIVE: to determine whether serum elastin-derived peptides (S-EDP), are lower in patients with ruptured abdominal aortic aneurysms (rAAA) than asymptomatic (aAAA). MATERIALS AND METHODS: serum samples were collected preoperatively from 45 consecutive patients with aAAA and 15 haemodynamically stable patients with rAAA. S-EDP (ng/ml) was measured by a competitive enzyme-linked immunosorbent assay (ELISA). RESULTS: S-EDP (mean +/- s.d.) was significantly lower in patients with rAAA (31.6 ng/ml +/- 6.8) than in patients with aAAA (39.4 ng/ml +/- 8.0 p=0.001). CONCLUSION: patients with rAAA had significantly lower levels of S-EDP than patients with aAAA. The possibility that S-EDP can be used to identify patients at increased risk of rupture requires further investigation.

Activity of matrix metalloproteinase-2 and -9 in abdominal aortic aneurysms. Relation to size and rupture.

OBJECTIVES: to investigate the activity of matrix metalloproteinase (MMP)-2 and -9 in asymptomatic abdominal aortic aneurysms (aAAAs) and ruptured abdominal aortic aneurysms (rAAAs). DESIGN: cross-sectional study. MATERIALS AND METHODS: MMP-2 and MMP-9 activity was estimated in biopsies from the anterior wall of 60 AAAs using gelatin zymography. There were 20 medium-sized (diameter 5<7 cm) aAAAs, 20 large (>57 cm) aAAAs and 20 rAAAs. MMP activity was quantified using a laser densitometer and expressed as arbitrary units (au). RESULTS: mean (SEM) MMP-9 activity was significantly lower in large aAAAs (1190 au +/-247) than in rAAAs (2647 au +/-498, p<0.05). There was no difference in MMP-2 activity. CONCLUSION: High MMP-9 activity in the AAA wall is associated with rupture.

Geriatric-based versus general wards for older acute medical patients: a randomized comparison of outcomes and use of resources.

BACKGROUND: The effects of residence in an acute geriatrics-based ward (AGW) with emphasis on early rehabilitation and discharge planning for older patients with acute medical illnesses were assessed. Outcome and use of resources were compared with those of patients treated in general medical wards (MWs). A per-protocol rather than intention-to-treat analysis was performed. METHODS: A randomized trial with 3-months follow-up. A total of 190 patients aged 70 years and older were randomized to an acute geriatrics-based ward, and 223 patients were randomized to general medical wards. RESULTS: The two groups were comparable at inclusion. However, after care in the AGW, 71% of patients could be discharged directly home compared with 64% of those treated in MWs (relative risk 1.17; 95% CI, 0.93-1.49). The length of stay was shorter in the AGW (mean 5.9 vs 7.3 days; P = .002). The proportion of patients in geriatric or other hospital wards or in nursing homes did not differ, but the proportion of AGW patients in sheltered living tended to be lower (P = .085). At the follow-up, case fatality, ADL function, psychological well-being, need for daily personal assistance, drug consumption, need for readmission to hospital, and total health care costs after discharge did not differ between the two groups. Poor global outcome was observed in 37% of AGW and 34% of MW patients. CONCLUSIONS: A geriatric approach with greater emphasis on early rehabilitation and discharge planning in the AGW shortened the length of hospital stay and may have reduced the need for long-term institutional living. This occurred despite patients in an acute geriatric ward not having better medical or functional outcome than older acute patients treated in general medical wards.

A new method for continuous tonometric pCO2 measurement--in vitro studies.

The available methods for tonometric pCO2 measurement only provide the possibility of performing intermittent registrations. A new method allowing continuous tonometric pCO2 measurement has been developed and tested in an in vitro model. A standard tonometer for intestinal pCO2 measurement was modified to allow continuous perfusion of the balloon with physiological saline solution in a closed system. The pCO2 in the system was determined in a specially constructed measurement chamber with a TCM20 percutaneous pCO2 monitor. In this in vitro model the tonometer balloon was placed in a saline bath with a constant pCO2 concentration and the measurements from the closed circulating system were compared with those obtained from a standard tonometer placed in the same bath. In 8 and 24 h experiments the circulating system measured the pCO2 value as accurately and reliably as traditional tonometry. This study indicates that the new method makes continuous monitoring of pCO2 possible.

Non-invasive assessment of intercompartmental fluid shifts in burn victims.

Two non-invasive methods (the bioimpedance technique, BIA, and the impression method, IM) were studied, to find out whether they are sensitive enough to detect and chronicle the development of the oedema and fluid resuscitation effects (Parkland formula) that occur secondary to a major burn. Ten patients with a total burned body surface area (TBSA) of more than 10% were included in this prospective study. Total body water (TBW), as measured by the resistance (BIA) or F(0) variable (IM), reached a maximum on day 2. The tissue fluid translocation (INT) variable (IM) followed a different course, increasing slowly to reach a maximum on day 6, when it was 40% higher than the 12 h value. TBW and the interstitial translocatable fluid were still increased 1 week post-burn. The non-invasive measurements of TBW (resistance by BIA and F(0) by IM) reflected the anticipated changes in TBW. The phase angle (BIA) indicative of cellular membrane effects of burn and sepsis had its lowest values at day 1.5, and stayed significantly low until day 4. Interestingly, the phase angle was lowest in the two cases that died subsequently. The different time course of the INT value (IM), which reflected the translocatable interstitial fluid volume in skin, may be the result of resuscitation fluid remaining in this compartment, due to the excess sodium content together with a possible change in tissue compliance secondary to the early total water peak on day 2.

A tactile sensor for detection of physical properties of human skin in vivo.

A spring loaded tactile sensor with displacement sensing has been evaluated for non-invasive assessment of physical properties, stiffness and elasticity, of human skin in vivo. The tactile sensor consists of a peizoelectric vibrator (61 kHz) with a vibration pickup, electronics and PC with software for measurement of the change in frequency when the sensor is attached to an object. Integrated with the tactile sensor is a displacement sensor that shows the compression of the spring that loads the sensor element against the object during measurement. Under certain conditions (e.g. fixed contact pressure) this change in frequency monitors the acoustic impedance of the object and is related to the stiffness of soft tissue. The experimental results on silicone gum and on healthy Japanese and Swedish women indicated that the instrument was able to detect changes in stiffness and elastic related properties of human skin, related to age, day-to-day variations and application of cosmetics. The instrument was concluded to be easy to handle and suitable for field work.

Chlamydia pneumoniae in human abdominal aortic aneurysms.

OBJECTIVES: To investigate the presence of Chlamydia pneumoniae DNA in the wall of infrarenal abdominal aortic aneurysms, and in the wall of non-aneurysmal infrarenal abdominal aortas. DESIGN: Case-control study. MATERIALS AND METHODS: The study group consisted of 40 patients operated transperitoneally for an infrarenal abdominal aortic aneurysm (IAAA) (eight females, 32 males; mean age 69 years, median age 68 years). Specimens from the aneurysm wall were taken peroperatively under sterile conditions. The control group consisted of 40 deceased persons without aortic aneurysms (14 females, 26 males; mean age 71 years, median age 70 years). Specimens from the non-aneurysmal infrarenal aortas (NIAA) were collected within 48 h after death. The specimens from both groups were frozen at -70 degrees C immediately after collection. A nested polymerase chain reaction (PCR) method, using two sets of primers designed to detect a fragment of the major outer membrane protein gene of C. pneumoniae, was used. RESULTS: The detection of C. pneumoniae-specific DNA was significantly higher in the study group (14/40 = 35%) than in the control group (2/40 = 5%); (p = 0.001). No clinical factor predicting the presence of C. pneumoniae in the aneurysm wall, could be found. CONCLUSION: Chlamydia pneumoniae was detected at a significantly higher frequency in the wall of IAAAs than in the wall of NIAAs. Although this finding does not prove that C. pneumoniae causes IAAAs, further studies on the possible role of C. pneumoniae in the pathogenesis of aneurysms should be performed.