Scientific paperThe natural history of abdominal aortic aneurysms
Abstract
This study examines the rate of expansion of abdominal aortic aneurysms and the risk of rupture in relation to their size. To assess these variables, we conducted a prospective study of 300 consecutive patients who presented over a 6-year interval with abdominal aortic aneurysms (AAA) that were initially managed nonoperatively. The mean age of the patients was 70.4 years, and 211 (70%) were men. The mean initial aneurysm diameter was 4.1 cm.
Among the 208 patients who underwent more than one ultrasound or computed tomographic (CT) scan, the diameter of the aneurysm increased by a median of 0.3 cm per year. The 6-year cumulative incidence of rupture was 1% and 2% among patients with aneurysms less than 4.0 cm and 4.0 to 4.9 cm in diameter, respectively (p > 0.05). In comparison, the 6-year cumulative incidence of rupture was 20% among patients with aneurysms greater than 5.0 cm in diameter (p < 0.004).
We conclude that (1) abdominal aortic aneurysms expand at a median rate of 0.3 cm per year; and (2) the risk of rupture of abdominal aortic aneurysms less than 5.0 cm is substantially lower than the risk of rupture of aneurysms 5.0 cm or more in diameter.
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Ascending thoracic aortic aneurysm is associated with the risk of dissection or rupture, creating life-threatening conditions. Current surgical intervention guidelines are mostly diameter based. Recently, many studies proposed to incorporate other morphological parameters into the current clinical guidelines to better prevent severe adverse aortic events like rupture or dissection. The purpose of this study is to gain a better understanding of the relationship between morphological parameters and hemodynamic parameters in ascending aortic aneurysms using fluid-solid-interaction analysis on patient-specific geometries. Our results suggest that ascending aortic volume may be a better indicator for surgical intervention as it shows a stronger association with pathogenic hemodynamic conditions.
Thoracic aortic disease in women: Sex disparities in etiology, presentation, and outcomes
2021, Vascular Disease in Women: An Overview of the Literature and Treatment RecommendationsMultiple studies have observed statistically significant differences among men and women regarding thoracic aortic disease. Women presenting with acute aortic dissection present at an older age than men may present without typical onset of severe pain and are more likely to present with congestive heart failure and/or altered mental status. Women are also more likely to present for medical evaluation in a delayed fashion. In-hospital mortality, hemodynamic instability, and cardiac tamponade occur at higher frequency in women with aortic dissection. Female sex was also predictive for long-term death in chronic type B dissection. Female thoracic aortic aneurysm patients present at an older age with COPD, and the presence of concomitant thoracic and abdominal aortic aneurysms is observed more commonly in female patients. Women unequivocally present differently than men with thoracic aortic disease. These disparities must be studied to generate sex-specific screening and surveillance protocols for women.
Variability in aneurysm sac regression after endovascular aneurysm repair based on a comprehensive registry of patients in Eastern Ontario
2019, Journal of Vascular SurgeryAlthough the absence of aneurysm-related mortality, postimplantation rupture, and reintervention after endovascular aneurysm repair (EVAR) is desirable, it may not necessarily reflect successful aneurysm sac exclusion. Sac regression may be a more sensitive marker for EVAR success and may be influenced by factors beyond the presence or absence of an endoleak. The objective of this study is to determine the rate of overall long-term sac regression after EVAR and the influence of nonanatomic factors, and endograft devices used at our center.
This retrospective cohort study included all EVARs performed for intact and ruptured abdominal aortic aneurysms (AAAs) at a university teaching hospital. Preoperative, operative, and follow-up data were collected using clinical and radiologic institutional databases. Preoperative and post-EVAR sac diameters were determined by a blinded observer in accordance with Society for Vascular Surgery guidelines. Absolute and relative sac regression was determined at the following intervals: 0 to 6 months, 6 to 12 months, 12 to 18 months, 18 months to 2 years, 2 to 5 years, 5 to 10 years, and more than 10 years.
From 1999 to 2015, 1060 patients underwent EVAR for an AAA at the Ottawa Hospital. Procedures were performed using a total of nine unique endograft devices, with five devices (Cook Zenith, n = 398; Medtronic Endurant, n = 375; Medtronic Talent, n = 183; Cook Zenith LP, n = 52; and Terumo Anaconda, n = 23) used in 97% of the procedures. The mean preoperative AAA diameter was 61.2 mm, with no detectable differences between endograft devices with respect to age, preoperative AAA diameter, or rupture diagnosis. Overall mean sac regression increased from -1.3 mm at 6 months, to -14.9 mm beyond 10 years. The majority of sac regression was achieved within 2 years. Only 90 of the 1060 patients (8.5%) experienced sac expansion of greater than 5 mm at some point during their follow-up period. Kaplan-Meier analyses revealed statistically significant device-specific variability in sac regression rates, even in the absence of an endoleak. Cox proportional hazard modeling demonstrated that age less than 75 years (hazard ratio [HR], 1.4; P = .001), female sex (HR, 1.4; P = .003), absence of type I endoleak (HR, 4.6; P < .0001), AAA greater than 70 mm (HR, 1.6; P < .0001), and both the Zenith (HR, 2.0; P < .0001) and Endurant (HR, 1.7; P = .001) devices were associated with shorter time to more than 5 mm sac regression.
This study demonstrated a pattern of sac diameter change after EVAR, with the majority of sac regression occurring within the first 2 years. Variability in sac regression was influenced by nonanatomic variables including age, sex, original AAA diameter, and specific endograft device, even after controlling for the presence or absence of an endoleak. The biophysical relationship between specific endograft design and materials, and sac regression is yet to be determined.
Renin-angiotensin system blockade does not attenuate abdominal aortic aneurysm growth, rupture rate, or perioperative mortality after elective repair
2018, Journal of Vascular SurgeryThe objective of this study was to summarize the literature regarding the effects of renin-angiotensin system blockade (RASB) using angiotensin-converting enzyme inhibitors (ACEis) or angiotensin receptor blockers (ARBs) on human abdominal aortic aneurysm (AAA) growth, rupture, and perioperative mortality.
We conducted a systematic review in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Our review protocol was registered at the International Prospective Register of Systematic Reviews (CRD42016054082). We searched the Cochrane Central Register of Controlled Trials database, MEDLINE, and Embase from inception to 2017 for studies examining the effects of ACEi or ARB treatment on AAA growth, rupture, or perioperative mortality. Review, abstraction, and quality assessment were conducted in duplicate, and a third author resolved discrepancies. We assessed study quality using the Cochrane and Newcastle-Ottawa scales. We used random-effects models to calculate pooled mean differences and odds ratios (ORs) with 95% confidence intervals (CIs). Heterogeneity was quantified using the I2 statistic.
Our search yielded 525 articles. One randomized and seven observational studies involving 35,448 patients were included. Inter-rater agreement was excellent (κ = 0.78), and risk of bias was low to moderate. All studies investigated ACEis, three studies investigated ARBs, and two studies included a composite RASB group consisting of ACEi or ARB users. Five studies assessed AAA growth, two assessed rupture rate, and one reported 30-day mortality after elective open repair. There was no difference in AAA growth rate between RASB and control (mean difference, 0.03 mm/y; 95% CI, −0.40 to 0.46; P = .88; I2 = 60%). No protective effect of RASB (OR, 0.92; 95% CI, 0.72, 1.16; P = .47; I2 = 90%) was demonstrated for AAA rupture. Finally, RASB increased 30-day mortality in patients undergoing elective open AAA repair (OR, 5; 95% CI, 1.4, 27) according to a single well-adjusted study.
RASB does not appear to affect AAA growth and rupture rate but increases elective perioperative mortality. The small number of heterogeneous, retrospective studies and limited long-term follow-up preclude a definitive dismissal of RASB as pharmacotherapy for AAA. Prospective, long-term data are needed to clarify the effect of RASB on AAA growth, rupture, and perioperative mortality.
ACR Appropriateness Criteria<sup>®</sup> Pulsatile Abdominal Mass Suspected Abdominal Aortic Aneurysm
2017, Journal of the American College of RadiologyClinical palpation of a pulsating abdominal mass alerts the clinician to the presence of a possible abdominal aortic aneurysm (AAA). Imaging studies are important in diagnosing and categorizing the extent of the aneurysm and may aid in treatment planning. The consensus of the literature supports the use of ultrasound as the initial screening test in patients with suspected AAA. Population-based ultrasound screening studies have been recommended and have proved effective for male patients > 65 years of age. For diagnosis and pre-intervention evaluation, either multidetector CT or CT angiography is the optimal choice for detailed characterization of the aneurysm. MR angiography may be substituted if CT cannot be performed (for example, because the patient is allergic to iodinated contrast material). Invasive angiography has little role in the diagnosis of AAA and PET and CT remain experimental in patients with suspected aneurysms.
The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.
The natural history of splanchnic artery aneurysms and outcomes after operative intervention
2016, Journal of Vascular SurgerySplanchnic artery aneurysms (SAAs) are uncommon, and standards for surveillance and intervention are lacking. The goal of this study was to review our 20-year experience with managing SAAs.
The Research Patient Data Registry at the Massachusetts General Hospital was queried, and all patients with SAAs identified by axial imaging from 1994 to 2014 were included. Aneurysms were stratified into two cohorts: those that underwent early intervention (<6 months after lesion discovery) and those that received surveillance. Primary study end points included aneurysm growth or rupture during surveillance and patient 30-day morbidity or mortality after aneurysm repair.
There were 264 SAAs identified in 250 patients. In 166 patients, 176 SAAs (66.6%) were placed into the surveillance cohort; 38 SAAs (21.6%) did not have subsequent axial imaging and were considered lost to follow-up. Mean aneurysm size in the surveillance cohort at first imaging study was 16.28 mm (8-41 mm), and mean surveillance time was 36.1 months (2-155 months); 126 SAAs (91.3%) remained stable in size over time, and 8 SAAs (5.8%) required intervention for aneurysm growth after a mean of 24 months. There were no ruptures in the surveillance cohort. There were 88 SAAs (33.3%) repaired early. Mean size of SAAs that were repaired early was 31.1 mm (10-140 mm). For intact SAAs, 30-day morbidity and mortality rates after repair were 13% and 3%, respectively. In the early repair cohort, 13 SAAs (14.7%) were ruptured at presentation. The 30-day morbidity and mortality rates after rupture were 54% and 8%, respectively. Five ruptured SAAs (38%) were anatomically located in the pancreaticoduodenal arcade. On univariate analysis, pancreaticoduodenal aneurysms were strongly associated with rupture (P = .0002).
Small SAAs (≤25 mm) are not prone to significant expansion and do not require frequent surveillance imaging. Imaging every 3 years for small SAAs is adequate. Aneurysms of the pancreaticoduodenal arcade and gastroduodenal aneurysms are more likely to rupture and therefore warrant a more aggressive interventional approach.
- 1
From the Department of Surgery, University of Ottawa, Ottawa Civic Hospital, Ottawa, Ontario, Canada.