Endovascular abdominal aortic aneurysm repair

Aortic Endovascular Stent IIIb Endoleak Combined With Sealed Aneurysm Rupture Mimicking a Paravertebral Retroperitoneal Tumor

The aim of this paper is to present the unique case of a sealed ruptured abdominal aortic aneurysm (AAA) with simultaneous type IIIb endoleak of an endovascular stent, mimicking a paravertebral retroperitoneal tumor. A 75-year-old male was referred to the tumor service of our tertiary orthopaedic department suffering from intractable low back pain with an onset of six months. He had undergone repair of an infrarenal AAA with an endovascular stent 5 years ago. Imaging studies depicted a large retroperitoneal mass adjacent to L2 and L3 vertebrae. The stent’s metal cage had no signs of wear or migration. The pathology report of a CT-guided core-needle biopsy he had undergone before his referral raised suspicion about possible AAA rupture. CT-angiography confirmed the existence of a ruptured AAA, accompanied by retroperitoneal blood loss and a (possibly) failed stent. The IIIb eroded stent was openly removed and a Y-type allograft was used to repair the defect. The patient reported immediate relief and was uneventfully discharged. He demised 4 years later due to reasons unrelated to the hereby reported condition. Increased awareness is warranted when dealing with anterior lumbar spine or retroperitoneal lesions. A close cooperation between a vascular and an orthopaedic/spine surgeon must always be sought.

Review of Malpractice Lawsuits in the Diagnosis and Management of Aortic Aneurysms and Aortic Dissections

OBJECTIVE

Aortic aneurysms and dissections are prevalent causes of morbidity and mortality. The management of aortic pathologies may be called into question in malpractice suits. Malpractice claims were analyzed to understand common reasons for litigation, medical specialties involved, patient injuries, and outcomes.

METHODS

Litigation cases in the Westlaw database from September 1st, 1987 to October 23 rd, 2019 were analyzed. Search terms included "aortic aneurysm" and "aortic dissection." Data on plaintiff, defendant, litigation claims, patient injuries, misdiagnoses, and case outcomes were collected and compared for aortic aneurysms, aortic dissections, and overall cases.

RESULTS

A total of 346 cases were identified, 196 involving aortic aneurysms and 150 aortic dissections. Physician defendants were emergency medicine (29%), cardiology (20%), internal medicine (14%), radiology (11%), cardiothoracic (10%) and vascular surgery (10%). Litigation claims included "failure to diagnose and treat" (61%), "delayed diagnosis and treatment" (21%), "post-operative complications after open repair" (10%) and "negligent post-operative care" (10%). Patients with aneurysms presented with abdominal (63%) and back pain (37%), while dissections presented with chest pain (78%), abdominal pain (15%), and shortness of breath (14%). Misdiagnoses included gastrointestinal (12%), other cardiovascular (9%), and musculoskeletal conditions (9%), but many were not specified (58%). Overall, 83% of cases were wrongful death suits. Injuries included loss of consortium (23%), emotional distress (19%), and bleeding (17%). In 53% of the cases, the jury ruled in favor of the defendant. 25% of cases ruled for the plaintiff. 22% of cases resulted in a settlement. The mean rewarded for each case was $1,644,590.66 (SD: $5,939,134.58; Range: $17,500-$68,035,462).

CONCLUSION

For aortic pathologies, post-operative complications were not prominent among the reasons why suits were brought forth. This suggests improvements in education across all involved medical specialties may allow for improved diagnostic accuracy and efficient treatment, which could then translate to a decrease in associated litigation cases.

The Fluid-Dynamics of Endo Vascular Aneurysm Sealing (EVAS) System failure

Purpose

The main objective of this work is to investigate hemodynamics phenomena occurring in EVAS (Endo Vascular Aneurysm Sealing), to understand if and how they could lead to type 1a endoleaks and following re-intervention. To this aim, methods based on computational fluid mechanics are implemented as a tool for checking the behavior of a specific EVAS configuration, starting from the post-operative conditions. Pressure and velocity fields are detailed and compared, for two configurations of the Nellix, one as attained after correct implantation and the other in pathological conditions, as a consequence of migration or dislocation of endobags.

Methods

The computational fluid dynamics (CFD) approach is used to simulate the behavior of blood within a segment of the aorta, before and after the abdominal bifurcation. The adopted procedure allows reconstructing the detailed vascular geometry from high-resolution computerized tomography (CT scan) and generating the mesh on which the equations of fluid mechanics are discretized and solved, in order to derive pressure and velocity field during heartbeats.

Results

The main results are obtained in terms of local velocity fields and wall pressures. Within the endobags, velocities are usually quite regular during the whole cardiac cycle for the post-implanted condition, whereas they are more irregular for the migrated case. The largest differences among the two cases are observed in the shape and location of the recirculation region in the rear part of the aorta and the region between the endobags, with the formation of a gap due to the migration of one or both of the two. In this gap, the pressure fields are highly different among the two conditions, showing pressure peaks and pressure gradients at least four times larger for the migrated case in comparison to the post-implanted condition.

Conclusions

In this paper, the migration of one or both endobags is supposed to be related to the existing differential pressures acting in the gap formed between the two, which could go on pushing the two branches one away from the other, thus causing aneurysm re-activation and endoleaks. Regions of flow recirculation and low-pressure drops are revealed only in case of endobag migration and in presence of an aneurysm. These regions are supposed to lead to possible plaque formation and atherosclerosis.

Chinese Herbal Medicine as a Potential Treatment of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is an irreversible condition where the abdominal aorta is dilated leading to potentially fatal consequence of aortic rupture. Multiple mechanisms are involved in the development and progression of AAA, including chronic inflammation, oxidative stress, vascular smooth muscle (VSMC) apoptosis, immune cell infiltration and extracellular matrix (ECM) degradation. Currently surgical therapies, including minimally invasive endovascular aneurysm repair (EVAR), are the only viable interventions for AAAs. However, these treatments are not appropriate for the majority of AAAs, which measure <50 mm. Substantial effort has been invested to identify and develop pharmaceutical treatments such as statins and doxycycline for this potentially lethal condition but these interventions failed to offer a cure or to retard the progression of AAA. Chinese herbal medicine (CHM) has been used for the management of cardiovascular diseases for thousands of years in China and other Asian countries. The unique multi-component and multi-target property of CHMs makes it a potentially ideal therapy for multifactorial diseases such as AAA. In this review, we review the current scientific evidence to support the use of CHMs for the treatment of AAA. Mechanisms of action underlying the effects of CHMs on AAA are also discussed.

Considerations for patients undergoing endovascular abdominal aortic aneurysm repair

Endovascular aneurysm repair has taken over open surgery as the primary strategy for treatment of patients with abdominal and thoracic aneurysms. The minimally invasive nature of these techniques requires alterations in preoperative workup, intraoperative management, and familiarity with unique complications that can occur. Familiarity from the anesthetic standpoint of endovascular techniques, including treatment of patients with fenestrated, chimney, snorkel, and periscope grafts, is necessary for the contemporary cardiac anesthesiologist.

Wall stress reduction in abdominal aortic aneurysms as a result of polymeric endoaortic paving

Polymeric endoaortic paving (PEAP) may improve endovascular repair of abdominal aortic aneurysms (AAA) since it has the potential to treat patients with complex AAA geometries while reducing the incidence of migration and endoleak. Polycaprolactone (PCL)/polyurethane (PU) blends are proposed as PEAP materials due to their range of mechanical properties, thermoformability, and resistance to biodegradation. In this study, the reduction in AAA wall stress that can be achieved using PEAP was estimated and compared to that resulting from stent-grafts. This was accomplished by mechanically modeling the anisotropic response of PCL/PU blends and implementing these results into finite element model (FEM) simulations. We found that at the maximum diameter of the AAA, the 50/50 and 10/90 PCL/PU blends reduced wall stress by 99 and 98%, respectively, while a stent-graft reduced wall stress by 99%. Our results also show that wall stress reduction increases with increasing PEAP thickness and PCL content in the blend ratio. These results indicate that PEAP can reduce AAA wall stress as effectively as a stent-graft. As such, we propose that PEAP may provide an improved treatment alternative for AAA, since many of the limitations of stent-grafts have the potential to be solved using this approach.

Polymeric endoaortic paving: Mechanical, thermoforming, and degradation properties of polycaprolactone/polyurethane blends for cardiovascular applications

Polymeric endoaortic paving (PEAP) is a process by which a polymer is endovascularly delivered and thermoformed to coat or "pave" the lumen of the aorta. This method may offer an improvement to conventional endoaortic therapy in allowing conformal graft application with reduced risk of endoleak and customization to complex patient geometries. Polycaprolactone (PCL)/polyurethane (PU) blends of various blend ratios were assessed as a potential material for PEAP by characterizing their mechanical, thermoforming and degradation properties. Biaxial tension testing revealed that the blends' stiffness is similar to that of aortic tissue, is higher for blends with more PCL content, and may be affected by thermoforming and degradation. Tubes of blends were able to maintain a higher diameter increase after thermoforming at higher PCL content and higher heating temperatures; 50/50 blend tubes heated to 55 °C were able to maintain 90% of the diameter increase applied. Delamination forces of the blends ranged from 41 to 235 N m⁻². In a Pseudomonas lipase solution, the 50/50 blend had a 94% lower degradation rate than pure PCL, and the 10/90 blend exhibited no degradation. These results indicate that PEAP, consisting of a PCL/PU blend, may be useful in developing the next generation of endoaortic therapy.

Persistent chronic peri-aortitis (‘inflammatory aneurysm’) after abdominal aortic aneurysm repair: systematic review of the literature

Abstract

Data on the outcome of aneurysmal chronic peri-aortitis (‘inflammatory aneurysm’) after open surgical aneurysm repair are few and contradictory. To what extent this inflammatory process is reversed after endovascular aneurysm repair (EVAR) is even more unclear. The objective of this review was to study the outcome of peri-aortic fibrosis (PAF) and ureteral obstruction in patients with aneurysmal chronic peri-aortitis treated with open surgery or EVAR. Medical literature was searched for pertinent articles on the outcome of PAF and ureteral obstruction after open surgery or EVAR from 1970 through October 2007. Studies were included if specific follow-up data were available on outcomes of interest. A total of 19 studies were included comprising 478 patients (open surgical, n = 426; EVAR, n = 52). Age, sex and percentage of patients with ureteral obstruction (31% vs 37%) did not differ between groups. Regression of PAF occurred more frequently after open surgery compared to EVAR (86% vs 60%; p < 0.0001). Complete regression of PAF was more frequent after open surgery compared to EVAR (52% vs 14%; p < 0.0001). After excluding patients in whom concurrent ureterolysis was performed, the frequency of persistent ureteral obstruction remained lower in patients treated surgically compared to patients treated with EVAR, albeit not statistically significant (32% vs 56%; p = 0.09). In conclusion, although open surgery is superior to EVAR in achieving regression of chronic peri-aortitis, the frequency of persistent PAF and/or ureteral obstruction is not negligible. Additional medical and/or urological treatment should be considered in selected cases of aneurysmal chronic peri-aortitis.