Endovascular repair of ruptured abdominal aortic aneurysms: A systematic review and meta-analysis

ObjectivesThe perioperative mortality for people with ruptured abdominal aortic aneurysms (RAAA) has not changed for two decades. Of patients who survive long enough to undergo open repair for ruptured aneurysms, half die (48%; 95% confidence interval [CI] 46 to 50). Randomized trials have shown that endovascular aneurysm repair (EVAR) for nonruptured abdominal aortic aneurysms decreases perioperative mortality compared with open repair. EVAR may similarly benefit patients with RAAA. We aimed to summarize studies of patients undergoing EVAR for ruptured aneurysms.MethodsTwo reviewers searched Medline and EMBASE databases from 1994 to July 2006, Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effectiveness, the Cochrane Central Register of Controlled Trials, Best Evidence 1994 to 2006, reference lists, clinical trial registries, and conference proceedings; we also contacted authors. All published and unpublished studies in which a group of people with ruptured aneurysms, assessed objectively by imaging, was treated with EVAR (REVAR) were eligible. We used the generic inverse variance function of the REVMAN software to pool results for death in hospital. Sensitivity analyses, using prespecified subgroups, explored heterogeneity between studies.ResultsPooled mortality in 18 observational studies describing 436 people who underwent REVAR was 21% (95% CI 13 to 29); however, 90% of the heterogeneity between studies was not explained by chance alone. Surgical volume explained substantial heterogeneity. According to study-specific criteria, 47% (95% CI 39 to 55) of people with ruptured aneurysms were potentially eligible for REVAR.ConclusionsMortality in people who underwent REVAR is lower than that in historical reports of unselected people undergoing open repair. Further investigation is needed to determine whether the difference in mortality is attributable to patient selection alone or to this new approach to treatment

Comparison of indirect radiation dose estimates with directly measured radiation dose for patients and operators during complex endovascular procedures

BackgroundA great deal of attention has been directed at the necessity and potential for deleterious outcomes as a result of radiation exposure during diagnostic evaluations and interventional procedures. We embarked on this study in an attempt to accurately determine the amount of radiation exposure given to patients undergoing complex endovascular aortic repair. These measured doses were then correlated with radiation dose estimates provided by the imaging equipment manufacturers that are typically used for documentation and analysis of radiation-induced risk.MethodsConsecutive patients undergoing endovascular thoracoabdominal aneurysm (eTAAA) repair were prospectively studied with respect to radiation dose. Indirect parameters as cumulative air kerma (CAK), kerma area product (KAP), and fluoroscopy time (FT) were recorded concurrently with direct measurements of dose (peak skin dose [PSD]) and radiation exposure patterns using radiochromatic film placed in the back of the patient during the procedure. Simultaneously, operator exposure was determined using high-sensitivity electronic dosimeters. Correlation between the indirect and direct parameters was calculated. The observed radiation exposure pattern was reproduced in phantoms with over 200 dosimeters located in mock organs, and effective dose has been calculated in an in vitro study. Scatter plots were used to evaluate the relationship between continuous variables and Pearson coefficients.ResultseTAAA repair was performed in 54 patients over 5 months, of which 47 had the repair limited to the thoracoabdominal segment. Clinical follow-up was complete in 98% of the patients. No patients had evidence of radiation-induced skin injury. CAK exceeded 15 Gy in 3 patients (the Joint Commission on Accreditation of Healthcare Organizations [JCAHO] threshold for sentinel events); however, the direct measurements were well below 15 Gy in all patients. PSD was measured by quantifying the exposure of the radiochromatic film. PSD correlated weakly with FT but better with CAK and KAP (r = 0.55, 0.80, and 0.76, respectively). The following formula provides the best estimate of actual PSD = 0.677 + 0.257 CAK. The average effective dose was 119.68 mSv (for type II or III eTAAA) and 76.46 mSv (type IV eTAAA). The operator effective dose averaged 0.17 mSv/case and correlated best with the KAP (r = 0.82, P < .0001).ConclusionFT cannot be used to estimate PSD, and CAK and KAP represent poor surrogate markers for JCAHO-defined sentinel events. Even when directly measured PSDs were used, there was a poor correlation with clinical event (no skin injuries with an average PSD >2 Gy). The effective radiation dose of an eTAAA is equivalent to two preoperative computed tomography scans. The maximal operator exposure is 50 mSv/year, thus, a single operator could perform up to 294 eTAAA procedures annually before reaching the recommended maximum operator dose

Perioperative cardiac events in endovascular repair of complex aortic aneurysms and association with preoperative studies

BackgroundEndovascular repair of complex aortic aneurysms (CAAs) can be performed in high-risk individuals, yet is still associated with significant morbidity, including spinal cord ischemia, cardiac complications, and death. This analysis was undertaken to better define the cardiac risk for CAA.MethodsA prospective database of patients undergoing thoracoabdominal or juxtarenal aortic aneurysm repair with branched and fenestrated endografts was used to retrospectively determine the number of cardiac events, defined as myocardial infarction (MI), atrial fibrillation (AF), and ventricular arrhythmia (VA), that occurred ≤30 days of surgery. Postoperative serial troponin measurements were performed in 266 patients. Any additional available cardiac information, including preoperative echocardiography, physiologic stress tests, and history of cardiac disease, was obtained from medical records. The efficacy of preoperative stress testing and the association of various echo parameters were evaluated in the context of cardiac outcomes using univariable and multivariable logistic regression models.ResultsBetween August 2001 and December 2007, 395 patients underwent endovascular repair of a thoracoabdominal or juxtarenal aortic aneurysm. The incidence of AF, VA, and 30-day cardiac-related death was 9%, 3%, and 2%, respectively. Overall 30-day mortality was 6%. Univariable analysis showed the presence of mitral annulus calcification was associated with MI (odds ratio [OR], 3.5; 95% confidence interval [CI], 0.9-13.8; P = .07). Left atrium cavity area, ejection fraction, left ventricle mass, and left ventricular mass index were univariably associated with the presence of VA. Multivariable analysis showed only the left atrium cavity area was independently associated with VA (OR, 1.2; 95% CI, 1.0-1.5; P = .07). Stress test was done in 179 patients. Negative stress test results occurred in 152 (85%), of whom 9 (6%) sustained an MI during the 30-day perioperative course. MI occurred in 2 of the 27 patients (7%) who had a positive stress test result.ConclusionsEndovascular repair of CAA can be performed in high-risk individuals but is associated with significant cardiac risk. It remains difficult to risk stratify patients using preoperative stress testing. Echo evaluation may help to identify patients who may be more likely to develop ventricular arrhythmias in the postoperative period and thus warrant closer monitoring. Postoperative troponin monitoring of all patients undergoing repair of CAA is warranted given the overall risk of MI

A patient-specific multi-modality abdominal aortic aneurysm imaging phantom

PURPOSE: Multimodality imaging of the vascular system is a rapidly growing area of innovation and research, which is increasing with awareness of the dangers of ionizing radiation. Phantom models that are applicable across multiple imaging modalities facilitate testing and comparisons in pre-clinical studies of new devices. Additionally, phantom models are of benefit to surgical trainees for gaining experience with new techniques. We propose a temperature-stable, high-fidelity method for creating complex abdominal aortic aneurysm phantoms that are compatible with both radiation-based, and ultrasound-based imaging modalities, using low cost materials. METHODS: Volumetric CT data of an abdominal aortic aneurysm were acquired. Regions of interest were segmented to form a model compatible with 3D printing. The novel phantom fabrication method comprised a hybrid approach of using 3D printing of water-soluble materials to create wall-less, patient-derived vascular structures embedded within tailored tissue-mimicking materials to create realistic surrounding tissues. A non-soluble 3-D printed spine was included to provide a radiological landmark. RESULTS: The phantom was found to provide realistic appearances with intravascular ultrasound, computed tomography and transcutaneous ultrasound. Furthermore, the utility of this phantom as a training model was demonstrated during a simulated endovascular aneurysm repair procedure with image fusion. CONCLUSION: With the hybrid fabrication method demonstrated here, complex multimodality imaging patient-derived vascular phantoms can be successfully fabricated. These have potential roles in the benchtop development of emerging imaging technologies, refinement of novel minimally invasive surgical techniques and as clinical training tools

Factors Affecting Radiation Injury

Introduction During the past several decades, the number of diagnostic tests and procedures that require the administration of radiation has increased dramatically. Understanding which factors affect radiation injury and how to mitigate these to protect patients has become critical for physicians to understand. Informed consent for these procedures has to include a discussion of the risks of radiation. Methods Factors that affect radiation injury, as well as ways to mitigate these, are discussed. Informed consent is also reviewed. Results Technical factors of the radiation delivery and patient factors both influence the dose of radiation received. Minimizing exposure is critical, and close examination of the patient is warranted to diagnose radiation injury. True informed consent includes a frank discussion of the radiation risks as well as the benefits of the procedure. Conclusion Minimizing patient radiation exposure and accurately diagnosing radiation injury are key skills with which any physician ordering or performing tests or procedures requiring the use of radiation needs to be familiar. Informed consent includes a discussion of the risks as well as the benefits of the proposed radiation exposure