Endovascular Abdominal Aortic Aneurysm Repair: Part I

Retrograde branched extension limb assembling stent of pararenal abdominal aortic aneurysm: A longitudinal hemodynamic analysis for stent graft migration

PURPOSE

Pararenal abdominal aortic aneurysms (PRAAAs) are a life-threatening disease, and hemodynamic analysis may provide greater insight into the effectiveness and long-term outcomes of endovascular aneurysm repair (EVAR). However, the lack of patient-specific boundary conditions on the periphery compromises the accuracy. Windkessel (WK) boundary conditions coupled to hemodynamic follow-up models of a PRAAA patient, aims to provide insights into the link between hemodynamics and poor prognosis.

METHOD

One PRAAA patient underwent EVAR and reintervention after one branch of stent-graft (SG) had migrated. Totally five computational follow-up models were studied. Patient-specific flow data acquired via ultrasound were used to define the boundary conditions in the ascending aorta and the following three branches. Coupled zero-dimensional WK models representing the distal vasculature were used to define the outlet boundary conditions under the abdomen.

RESULTS

Flow divisions of the main SG branches were 40.7% and 24.7%, respectively. Time-averaged wall shear stress and oscillatory shear index (OSI) increased at the junction connected the SG branch and the stent leading to the right common iliac artery (RCIA) where the stent migrated. The OSI and relative residence time (RRT) value in superior mesenteric artery increased notably after the migration, the RRT continuously increased following the reintervention.

CONCLUSION

Unbalanced flow, resulting in locally high-speed flow, high WSS and OSI might significantly affect stent stability. Results suggest that diameters and interconnection design of stents in complex cases should take the flow division into consideration and computational simulations might be considered as a tool for intervention protocol design.

Comparison of endovascular and open repair of ruptured abdominal aortic aneurysm in the United States in the past decade

PURPOSE

The purpose of this study is national-level comparison of the endovascular (EVAR) and open repair (OAR) of ruptured abdominal aortic aneurysm (AAA) in the United States from 2001 to 2010.

METHODS

The data were obtained from nationwide inpatient sample from the Department of Health and Human Services. Ruptured AAA treated by OAR or EVAR were selected using combination ICD-9 codes.

RESULTS

There were 42,126 cases of ruptured AAA of which 8,140 (19.3%) were repaired by EVAR. EVAR patients were older (74.1 vs. 72.8 years, p < 0.001) and had higher incidence of comorbidities compared with OAR group. EVAR patients had lower in-hospital mortality (25.9 vs. 39.1%, p < 0.001) and shorter hospital stay (10.4 vs. 13.7 days, p < 0.001). More patients were discharged home following EVAR (36.8 vs. 21.5%, p < 0.001). There was reduced need for institutional rehabilitation following EVAR (26.3 vs. 29.1%, p < 0.001). Females had significantly higher mortality compared with males after both EVAR (32.2 vs. 24.1%, p < 0.001) and OAR (46.2 vs. 36.9%, p < 0.001). The hospital mortality (41.3-25.8%, p < 0.001) and mean length of stay (11.8-9.7 days, p < 0.01) of EVAR steadily improved over the study period.

CONCLUSIONS

National level comparison of data from the past decade shows that in suitable cases, EVAR for ruptured AAA is associated with reduced hospital mortality, shorter hospital stay, and reduced need for rehabilitation. EVAR outcomes showed consistent improvement with time. Regardless of the type of repair, women had higher mortality compared with men.

Nationwide trends in abdominal aortic aneurysm repair and use of endovascular repair in the emergency setting

PURPOSE

To analyze nationwide trends in abdominal aortic aneurysm (AAA) repair and the use of endovascular abdominal aortic aneurysm repair (EVAR) in the emergency setting.

MATERIALS AND METHODS

Data were obtained from the Nationwide Inpatient Sample (NIS) using the International Classification of Diseases, Ninth Revision-Clinical Modification (ICD-9-CM) codes for open and endovascular repairs from 2001-2009. Trends in outcome parameters and hospital charges were compared.

RESULTS

The number of emergency EVAR procedures increased from 382 in 2001 to 1,247 in 2009 (P < .001). During the study period, length of hospital stay associated with total number of EVAR procedures decreased from 3.8 days to 3.4 days (P < .05), and the in-hospital mortality decreased from 2.4% to 2% (P = .32). From 2001-2009, mean hospital charges associated with EVAR increased from $50,630 to $91,401 (74% increase), whereas charges associated with open repairs increased from $54,578 to $128,925 (136% increase). The proportion of patients needing rehabilitation or nursing home placement after EVAR increased from 5.8% to 7.7% (P < .01), and need for home health increased from 6.9% to 10.5% (P < .01).

CONCLUSIONS

There was a significant increase in the number of emergency EVAR procedures during the study period; however, the overall in-hospital mortality associated with EVAR remained unchanged, and the length of hospital stay showed a decreasing trend. The total hospital charges for EVAR were lower than the charges for open abdominal aneurysm repair throughout the study period; the difference in charges between the procedures showed a significant increasing trend with time.

Novel technique for endovascular salvage of a folded aortic endograft

Endovascular aneurysm repair (EVAR) has been established as a safe and effective treatment modality for infrarenal abdominal aortic aneurysms. Endograft migration resulting in a proximal type I endoleak can be one of the most difficult challenges following EVAR. Often, this precludes endovascular treatment and necessitates conversion to open surgical repair. We report a case of a high-risk patient who presented with impending abdominal aortic aneurysm rupture as a result of endograft migration following EVAR performed 5 years prior. The endograft had folded over on itself within the aneurysm sac and was successfully repaired using a total endovascular approach.