Risk Of Rupture In Patients Research Articles

くも膜下出血における既知の未破裂脳動脈瘤破裂症例の増加─単一施設における経時的検討─

Japan now has a large number of centers that can perform magnetic resonance imaging. Further, the brain check-up system has also improved considerably. Thus, many unruptured intracranial aneurysms (UIA) have been diagnosed recently, and some of these are treated in an evidence-based manner. However, with the increase in the diagnosis of UIA, cases of rupture of UIA are supposed to be increasing. To test this hypothesis, we compared cases of rupture of UIA with subarachnoid hemorrhage (SAH) treated at Tokyo Dental College Ichikawa General Hospital between January 2002 and December 2006 (the early period) with those between January 2007 and December 2011 (the latter period). UIA was previously diagnosed in 1 of 100 SAH cases (1.0%) in the early period and in 11 of 132 SAH cases (8.3%) in the latter period. This difference was significant. We evaluated the following risk factors in patients with rupture of UIA in both groups: UIA location, size, bleb, UIA multiplicity, history of hypertension, habit of smoking, and family history of SAH. Most patients in both groups had several of the evaluated risk factors, and all cases of rupture occurred in female patients in the both periods. On the other hand, two patients in the latter group presented with only one risk factor. Our results suggest that the number of cases of rupture of previously diagnosed UIA have increased recently. To prevent the occurrence of rupture, we recommend that female UIA patients with several risk factors be treated with the obliteration of UIA. Further, clinicians should be alert to the risk of rupture in patients with only one risk factor, and periodic follow-up might be essential for such cases.

The Effect of Carotid Plaque Morphology on Longitudinal Fibrous Cap Stress Levels

Background and Purpose: Rupture of vulnerable carotid atherosclerotic plaques is a major cause of stroke. Stress levels may reflect risk of rupture in patients with carotid atherosclerotic plaques. Features thought to influence the risk of plaque rupture include the degree of stenosis, lipid-rich necrotic core (LR-NC) size, and thickness of the protective fibrous caps. We used computational models to investigate the effect of these variables on fibrous cap stress levels. Methods: Two-way coupled fluid-structure interaction longitudinal 2D simulations were performed on a bifurcation model based on idealized geometry derived from a symptomatic patient. Models with varying degrees of stenosis (50%-95%), fibrous cap thicknesses (0.05-1 mm), and LR-NC sizes (2 × 1 mm-6 × 3 mm) were simulated. The stress distribution for each model was calculated and peak principal stresses extracted. Regression analysis was used for assessing the relationship between the variables and stress levels. Results: Mechanical stresses increased with decreasing fibrous cap thicknesses ( β= -0.905, p Conclusions: Thin-capped plaques with large atheromas, known predictors of plaque vulnerability, were shown to exhibit the greatest mechanical stress levels.

Annual rupture risk of abdominal aortic aneurysm enlargement without detectable endoleak after endovascular abdominal aortic repair

Whether abdominal aortic aneurysm (AAA) enlargement after endovascular aneurysm repair (EVAR), without an identifiable endoleak, is a risk factor for AAA rupture remains controversial. To our knowledge, studies including large patient numbers investigating this topic have not been done. Therefore, a considerable number of conversions to open AAA repair have been performed in this patient group. This study evaluated AAA rupture risk in patients without detectable endoleaks but with AAA enlargement after EVAR treatment. Baseline characteristics and follow-up data were collected prospectively by case record forms. Follow-up visits were scheduled at 1, 3, 6, 12, 18, and 24 months, and annually thereafter. The follow-up assessment included clinical examination and imaging studies. Patients were divided into three groups according to the degree of shrinkage or enlargement of the aneurysm. Group A included patients with >8 mm aneurysm shrinkage, group B consisted of patients with ≤ 8 mm shrinkage to ≤ 8 mm enlargement, and group C patients had an aneurysm enlargement of >8 mm. The basis for this analysis was 6337 patients who were enrolled prospectively in the European Collaborators on Stent-Graft Techniques for Aortic Aneurysm Repair (EUROSTAR) database between 1996 and 2006. Group A included 691 patients; group B, 5307 patients; and group C, 339 patients. Ruptures occurred in 3 patients in group A, in 14 patients in group B, and in 9 patients in group C. The annual rate of rupture in group C was <1% in the first 4 years but accelerated to 7.5% up to 13.6% in the years thereafter. The mortality rate of elective conversion to open AAA repair was 6.0%. The risk of rupture in patients with an AAA enlargement of 8 mm after EVAR, without detectable endoleaks, is <1% in the first 4 years. No ruptures were seen in patients with AAA enlargement without detectable endoleaks who were not treated with Vanguard stent grafts (Boston Scientific Corp, Natick, Mass) and had AAA diameters <70 mm. For this group, conversion to open repair might not be mandatory, and regular follow-up can be advised instead. After 4 years of follow-up, this study observed an increased annual rupture risk, which might indicate the need for conversion; however, groups are small, and follow-up bias could play a role.

Trigger Factors and Their Attributable Risk for Rupture of Intracranial Aneurysms

Little is known about activities that trigger rupture of an intracranial aneurysm. Knowledge on what triggers aneurysmal rupture increases insight into the pathophysiology and facilitates development of prevention strategies. We therefore aimed to identify and quantify trigger factors for aneurysmal rupture and to gain insight into the pathophysiology. During a 3-year period, 250 patients with aneurysmal subarachnoid hemorrhage completed a structured questionnaire regarding exposure to 30 potential trigger factors in the period soon before subarachnoid hemorrhage (hazard period) and for usual frequency and intensity of exposure. We assessed relative risks (RR) of rupture after exposure to triggers with the case-crossover design comparing exposure in the hazard period with the usual frequency of exposure. Additionally, we calculated population-attributable risks. Eight triggers increased the risk for subarachnoid hemorrhage: coffee consumption (RR, 1.7; 95% CI, 1.2-2.4), cola consumption (RR, 3.4; 95% CI,1.5-7.9), anger (RR, 6.3; 95% CI, 4.6-25), startling (RR, 23.3; 95% CI, 4.2-128), straining for defecation (RR, 7.3; 95% CI, 2.9-19), sexual intercourse (RR, 11.2; 95% CI, 5.3-24), nose blowing (RR, 2.4; 95% CI, 1.3-4.5), and vigorous physical exercise (RR, 2.4; 95% CI, 1.2-4.2). The highest population-attributable risks were found for coffee consumption (10.6%) and vigorous physical exercise (7.9%). We identified and quantified 8 trigger factors for aneurysmal rupture. All triggers induce a sudden and short increase in blood pressure, which seems a possible common cause for aneurysmal rupture. Some triggers are modifiable, and further studies should assess whether reduction of exposure to these factors or measures preventing sudden increase in blood pressure decrease the risk of rupture in patients known to have an intracranial aneurysm.

Analysis of aortic wall stress and rupture risk in patients with abdominal aortic aneurysm with a gender perspective

The most commonly used predictor of rupture of an abdominal aortic aneurysm (AAA) is the diameter; however, this does not estimate the true risk for each patient. Why women with AAAs have an increased growth rate, weaker aortic wall, and increased risk for rupture is yet unclear. It is likely that geometrical and biomechanical properties contribute to found gender differences. Several studies have shown that peak wall stress (PWS) and peak wall rupture risk (PWRR), predicted by a finite element (FE) analysis of AAAs derived from computed tomography (CT), is a better predictor of rupture than maximum diameter. The purpose of this study was to investigate if women with AAAs have an increased PWS and PWRR using an FE model compared to men. Fifteen men and 15 women (AAAs 4-6 cm) were included. AAA geometry was derived from CT scans, and PWS and PWRR were estimated using the FE method. Comparisons were made by t test and Mann-Whitney test. Mean age (women 73 years old vs men 71 years old) and mean AAA diameter was similar (49.7 mm vs 50.1 mm) for women and men. PWS did not differ for women 184 and men 198 kPa. PWRR was 0.54 (0.28-0.85) for women and 0.43 (0.24-0.66) for men, P = .06. This is the first analysis of stress and strength of the aneurysm wall with a gender perspective. The reported higher rupture risk for women has previously not been tested with geometrical and biomechanical properties. PWS did not differ, but the PWRR was slightly higher in women. However, the difference did not reach statistical significance, probably due to the small sample size. In summary, the results in the present study suggest that differences in biomechanical properties could be a contributing explanation for the higher rupture risk reported for female patients with AAAs.

Risk factors for the formation and rupture of intracranial saccular aneurysms in Shimane, Japan

Background Prevention of aneurysmal subarachnoid hemorrhage (SAH) can be achieved by reducing risk factors, which include those for aneurysm formation and aneurysm rupture. However, neither of these 2 factors has been discussed separately so far. A case control study was undertaken in Shimane, Japan, to identify modifiable risk factors for the formation and rupture of aneurysms. Methods This study included 858 patients with ruptured aneurysms, 285 patients with unruptured aneurysms without a history of SAH, and 798 control subjects. Hypertension, diabetes mellitus, heart disease, hypercholesterolemia, cigarette smoking, and alcohol consumption were assessed as risk factors by using conditional logistic regression. Results After adjustment for other risk factors, hypertension was the most powerful risk factor for aneurysm formation, regardless of age and sex, followed by hypercholesterolemia, heart disease, and cigarette smoking, whereas diabetes mellitus and daily drinking were insignificant for aneurysm formation. Hypertension and daily drinking were not related to the risk of aneurysm rupture, regardless of age and sex, whereas cigarette smoking was associated with an increased risk of aneurysm rupture in patients 60 years or older and in men. In contrast, hypercholesterolemia was strongly associated with a decreased risk of rupture, regardless of age and sex, and in patients with small aneurysms (<5 mm). Diabetes mellitus and heart disease were also related to a decreased risk of rupture in patients 60 years or older and in women. Conclusion Identification of risk factors for aneurysm formation and rupture separately seems to be pivotal for reducing the incidence of SAH.

Ruptured splenic abscess as a cause of acute abdomen: Report of two cases and review of literature

When evaluating patients with severe acute abdominal pain, physicians and surgeons must consider common etiologies for acute abdomen such as appendicitis, diverticulitis, perforated viscus and vascular emergencies like ruptured aneurysm or bowel ischemia. In some patients, however, there is a more unusual cause of an abdominal emergency. In this article, we report two patients where an abdominal crisis was caused by rupture of a splenic abscess. Our review of the literature suggests that the risk of rupture in patients with splenic abscess is 10-20% and that the mortality rate for this condition could be greater than 50%. While there may be a role for percutaneous catheter drainage for some splenic abscesses, we conclude that the best treatment of ruptured splenic abscess is antibiotic therapy and splenectomy.

Importance of initial stress for abdominal aortic aneurysm wall motion: Dynamic MRI validated finite element analysis

Currently the transverse diameter is the primary decision criterion to assess rupture risk in patients with an abdominal aortic aneurysm (AAA). To obtain a measure for more patient-specific risk assessment, aneurysm wall stress, calculated using finite element analysis (FEA), has been evaluated in literature. In many cases, initial stress, present in the AAA wall during image acquisition, is not taken into account. In the current study the effect of initial stress incorporation (ISI) is determined by directly comparing wall displacements extracted from FEA and dynamic MRI.Ten patients with an aneurysm diameter >5.5cm were scanned with cardiac triggered MRI. Semi-automatic segmentation of the AAA was performed on the diastolic phase. The segmented in-slice contours were propagated through the remaining cardiac phases using an active contour model as to track wall displacements on MRI. Consequently, FEA with and without ISI (no-ISI) was performed using the diastolic geometry with simultaneously measured intra-aneurysm pressure values as boundary condition. Contours extracted from FEA were compared with MRI contours at corresponding cardiac phases by distance and relative area differences.The wall displacements from FEA with ISI show significant better correspondence with wall motion from MRI data in comparison with the no-ISI FEA (deviation in wall displacement 1.7% vs. 12.4%; p<0.001). Based on these results it can be concluded that incorporation of initial stress significantly improves wall displacement accuracy of FEA and therefore it should be incorporated in future analyses.

Higher maximum doses of oxytocin are associated with an unacceptably high risk for uterine rupture in patients attempting vaginal birth after cesarean delivery

The objective of the study was to more precisely estimate the effect of maximum oxytocin dose on uterine rupture risk in patients attempting vaginal birth after cesarean (VBAC) by considering timing and duration of therapy. A nested case-control study was conducted within a multicenter, retrospective cohort study of more than 25,000 women with at least 1 prior cesarean delivery, comparing cases of uterine rupture with controls (no rupture) while attempting VBAC. Time-to-event analyses were performed to examine the effect of maximum oxytocin dose on the risk of uterine rupture considering therapy duration, while adjusting for confounders. Within the nested case-control study of 804 patients, 272 were exposed to oxytocin: 62 cases of uterine rupture and 210 controls. Maximum oxytocin ranges above 20 mU/min increased the risk of uterine rupture 4-fold or greater (21-30 mU/min: hazard ratio [HR] 3.92, 95% confidence interval [CI], 1.06 to 14.52; 31-40 mU/min: HR 4.57, 95% CI, 1.00 to 20.82). These findings support a maximum oxytocin dose of 20 mU/min in VBAC trials to avoid an unacceptably high risk of uterine rupture.

246: Higher maximum doses of oxytocin are associated with an unacceptably high uterine rupture risk during VBAC

Prior studies have examined the relationship between maximum oxytocin dose and uterine rupture risk in patients attempting vaginal birth after cesarean (VBAC). We sought to more precisely estimate this risk by considering timing and duration of oxytocin dose

Risk of Rupture of Unruptured Intracranial Aneurysms in Relation to Patient and Aneurysm Characteristics

We updated our previous review from 1996 on the risk of rupture of unruptured intracranial aneurysms, aiming to include the newly published articles. We reviewed all studies from our former meta-analysis and performed a Medline search for new studies published after 1996. We calculated overall risks of rupture for studies with a mean follow-up time of <5, 5 to 10, and >10 years. Relative risks (RR) were calculated by comparing the risk of rupture in patients with and without potential risk factors. We aimed to perform multivariable analyses of the different risk factors with meta-regression analysis. We included 19 studies (10 new) with 4705 patients and 6556 unruptured aneurysms (follow-up 26 122 patient-years). The overall rupture risks were 1.2% (follow-up <5 years), 0.6% (follow-up 5 to 10 years), and 1.3% (follow-up >10 years). In the univariable analysis, statistically significant risk factors for rupture were age >60 years (RR 2.0; 95% confidence interval [CI], 1.1 to 3.7), female gender (RR 1.6; 95% CI, 1.1 to 2.4), Japanese or Finnish descent (RR 3.4; 95% CI, 2.6 to 4.4), size >5 mm (RR 2.3; 95% CI, 1.0 to 5.2), posterior circulation aneurysm (RR 2.5; 95% CI, 1.6 to 4.1), and symptomatic aneurysm (RR 4.4; 95% CI, 2.8 to 6.8). Meta-regression analysis yielded implausible results. Age, gender, population, size, site, and type of aneurysm should be considered in the decision whether to treat an unruptured aneurysm. Pooled multivariable analyses of individual data are needed to identify independent risk factors and to provide more reliable risk estimates for individual patients.

The Long‐Term Relationship of Wall Stress to the Natural History of Abdominal Aortic Aneurysms (Finite Element Analysis and Other Methods)

For the past four decades, abdominal aortic aneurysm (AAA) rupture risk has been estimated using maximum aneurysm diameter. Although this works relatively well in general, clinicians know that some aneurysms rupture at an unusually small size, while others grow to exceptionally large sizes without rupture. We have demonstrated that finite element analysis (FEA) of AAA wall stress using three-dimensional computed tomography (CT) reconstructions is better than diameter for differentiating AAAs near the time of rupture, and that wall stress is superior to AAA diameter for predicting rupture risk in patients under observation. This article summarizes our current work, future areas of investigation, and issues related to "translational" research for FEA of aortic aneurysms.

How Time Affects the Risk of Rupture in Appendicitis

Increasing time between symptom onset and treatment may be a risk factor for a ruptured appendix, but little is known about how the risk changes with passing time. This study aimed to determine the changes in risk of rupture in patients with appendicitis with increasing time from symptom onset to treatment to help guide the swiftness of surgical intervention. We conducted a retrospective chart review of physician office, clinic, emergency room, and inpatient records of a random sample of 219 of 731 appendicitis patients operated on between 1996 and 1998 at 2 inner-city tertiary referral and municipal hospitals. Conditional risks of rupture were calculated using life table methods. Logistic regression was used to assess factors associated with rupture, and linear regression was used to assess factors affecting time from first examination to treatment. Rupture risk was < or = 2% in patients with less than 36 hours of untreated symptoms. For patients with untreated symptoms beyond 36 hours, the risk of rupture rose to and remained steady at 5% for each ensuing 12-hour period. Rupture was greater in patients with 36 hours or more of untreated symptoms (estimated relative risk [RR]=6.6; 95% CI: 1.9 to 8.3), age 65 years and older (RR=4.2; 95% CI: 1.9 to 6.1), fever > 38.9 degrees C (RR=3.6; 95% CI: 1.2 to 5.7), and tachycardia (heart rate > or = 100 beats/minute; RR=3.4; 95% CI: 1.8 to 5.4). Time between first physician examination and treatment was shorter among patients presenting to the emergency department (median, 7.1 hours versus 10.9 hours; p<0.0001), and those for whom a physician's leading diagnostic impression was appendicitis (6.3 hours versus 11.3 hours; p<0.0001). Patients sent for CT scan experienced longer times to operation (18.6 hours versus 7.1 hours; p<0.0001). Risk of rupture in ensuing 12-hour periods rises to 5% after 36 hours of untreated symptoms. Physicians should be cautious about delaying surgery beyond 36 hours from symptom onset in patients with appendicitis.

Risk of uterine rupture in patients with a prior cesarean complicated by febrile morbidity

Risk of uterine rupture in patients with a prior cesarean complicated by febrile morbidity

Measurement of aortic compliance in abdominal aortic aneurysms before and after open and endoluminal repair: preliminary results.

To assess aortic wall compliance as a portent of rupture risk in patients with abdominal aortic aneurysms. In this pilot study, 38 patients (32 men; median age 78 years, range 63-95) underwent an ultrasound scan: 20 pre-repair and 24 post-repair (18 endovascular [EVR] and 6 open). Six patients from the pre-repair group were included in a post repair study after EVR. Cine loop images were analyzed offsite using wall tracking software, which measured aortic diameter changes during cardiac cycles. Brachial blood pressure was measured, and elastic modulus (Ep) and stiffness (beta) were calculated. Preop Ep and beta were determined at the neck, inflection points (IP), and mid sac levels. Postop Ep and beta were calculated in mid sac only for technical reasons. Preoperative Ep and beta were significantly higher at IP compared with neck (median Ep 24.22 versus 12.95 N/cm(2), p<0.003; median beta 16.27 versus 8.65, p<0.003). At the mid sac, Ep and beta were also significantly higher compared with neck: Ep 26.41 versus 12.95 N/cm(2), p=0.001; beta 17.94 versus 8.65, p=0.001. The values for IP and mid sac were Ep 24.22 versus 26.41 N/cm(2), p=0.64; beta 16.27 versus 17.94, p=0.64. In the postop cases (n=24), Ep and beta in successful endovascular repair (n=12) were significantly higher than in open repair, respectively: median Ep 34.31 versus 12.33 N/cm(2), p<0.001; median beta 23.18 versus 8.24, p<0.001. Patients with endoleaks or endotension (n=6) had significantly elevated Ep and beta compared with those without endoleaks (n=12): median Ep 79.79 versus 34.31 N/ cm(2), p=0.002; median beta 51.52 versus 23.18, p<0.002. Six patients scanned before and after EVR showed a decrease of Ep and beta in 3, no change in 1, and an increase in 2. An increase greater than 2 fold was noted in a patient with a gross type II endoleak. This pilot study shows that estimates of aortic wall compliance agree well with known values for wall stress distribution. EVR leaves patients with greater wall stiffness than those undergoing open repair, a situation accentuated by endoleaks. Wall compliance and stiffness measurement promises to be useful for the evaluation of success of endovascular repair.

Non-operative Management of High-Risk Patients with Abdominal Aortic Aneurysm

Objectives: to determine the risk of rupture in patients with large non-operated abdominal aortic aneurysms (AAAs).Methods: in 128 patients admitted over a 5-year period with an intact AAA, and who did not have a surgical repair were included, initial maximum antero-posterior AAA diameter was related to survival and cause of death.Results: at the end of follow-up 27/52 (52%) patients with AAA <55 mm were alive compared to 17/62 (27%) patients with AAA ≥55 mm. Six (12%) in the former and 18 (29%) in the latter group had an AAA-related death. However, non-AAA-related death was commoner in both groups.Conclusion: these findings support a role for non-operative management in high-risk patients with large AAAs.

The risk of rupture in untreated aneurysms: the impact of size, gender, and expansion rate.

The purpose of this study was to establish the risk of rupture as related to size of abdominal aortic aneurysm (AAA), gender, and expansion of the aneurysm. Between 1976 and 2001, 476 patients with conditions considered unfit for surgery with AAA 5.0 cm or more were followed with computed tomographic scans every 6 months until rupture, surgery, death, or deletion from follow-up. Surgery was performed for rupture (n = 22), improved medical condition (n = 37), increase in size (n = 95), symptoms (n = 17), and other reasons (n = 24). Fifty ruptures occurred during the follow-up period. The average risk of rupture (and standard error) in male patients with 5.0-cm to 5.9-cm AAA was 1.0% (0.01%) per year, in female patients with 5.0-cm to 5.9-cm AAA was 3.9% (0.15%) per year, in male patients with 6.0-cm or greater AAA was 14.1% (0.18%) per year, and in female patients with 6.0-cm or greater AAA was 22.3% (0.95%) per year. The risk of rupture in male patients with AAA 5.0 to 5.9 cm is low. The four-time higher risk of rupture in female patients with AAA 5.0 to 5.9 cm suggests a lower threshold for surgery be considered in fit women. The data regarding risk of rupture in patients with AAA 6.0 cm or more may allow more appropriate decision analysis for surgery in patients with unfit conditions with large AAA.