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Everything you need to know about Computed Tomography (CT) & CT Scanning

Vascular: Tevar Imaging Pearls - Learning Modules | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Vascular ❯ TEVAR

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  • Post-stent CT findings
    Normal
    • Aneurysm sac decreases in size progressively
    Complications
    • Aneurysm size increasing (endoleak)
    • Change in stent positioning (migration, kinking)
    • Branch vessel compromise
    • Infection
    • Limb thrombosis
    • Aneurysm formation elsewhere in aorta
  • Type I Endoleak
    • Proximal or distal stent not in complete contact with aortic wall
    • Diameter of aorta too large at stent landing zone
    • Gap between stent and aortic wall allows blood to flow into aneurysm sac
  • “Type II endoleak is the most common endoleak. It is seen in 10% to 20% of patients at the completion of EVARs. The usual culprit is retrograde filling of an aneurysm sac by either a patent IMA or a lumbar artery. Fortunately, spontaneous resolution is noted in up to 50% to 60% of patients by 30 days.

    ”
Overview of aortic aneurysm management in the endovascular era.
Calero A, Illig KA.
Semin Vasc Surg. 2016 Mar;29(1-2):3-17

  • Type III Endoleak: Facts
    A Type III endoleak arises from poor seal between components or frank component separation.
    It is associated with aneurysm sac pressurization and increased risk of rupture. It must be treated when found.
    It can be treated with either a relining stent for poor seal or aorto-uni-iliac devices and femoral−femoral bypass for component separation
  • Type IV Endoleak: Facts
    Type IV endoleak refers to the diffuse contrast blush occasionally seen immediately after implantation. This is a reflection of porosity of graft material and is usually self-limited and does not require treatment.
  • “Renal ischemia remains a known compli- cation of FEVAR, with clinical studies showing variable rates of renal impairment after FEVAR of juxtarenal abdominal aortic aneurysms. Studies show that 11– 35% of patients experience a transient increase in serum creatinine levels (defined as a > 30% increase in serum creatinine level), and 0–4% of patients require temporary or permanent dialysis.” 
Incidence and Clinical Significance of Renal Infarct After Fenestrated Endovascular Aortic Aneurysm Repair 
Burke LMB et al.
AJR 2017; 208:885–890

  • “Our data show a gradual mild increase in baseline serum creatinine level in all patients undergoing FEVAR, regardless of whether the patient had a renal infarct. This finding mirrors a recent study from France , which found an increase in serum creatinine level during the first week after FEVAR.”

    
Incidence and Clinical Significance of Renal Infarct After Fenestrated Endovascular Aortic Aneurysm Repair 
Burke LMB et al.
AJR 2017; 208:885–890

  • Frequency of EVAR Failures

  • EVAR vs Open Procedure

  • Operator experience and familiarity with EVAR have improved during the past 20 years. These advances have resulted in decreased procedure times and blood loss and improved intraprocedural and perioperative complication rates. The incidence of type I and type III endoleaks has decreased, and the need for reintervention has declined. Aneurysm-related mortality rates after EVAR are lower now than in the past, and these results continue to improve. The most obvious innovation accounting for these improvements is the transition from use of physician-made devices to the use of industry-made devices.
  • Summary of Devices by Era

  • Types of Endoleaks
    • Type I        Flow from inadequate graft apposition at proximal or distal seal zones
    • Type II      Retrograde flow from aortic or iliac artery branches (ie, patent lumbar, inferior mesenteric, or internal iliac arteries)
  • Types of Endoleaks
    • Type III      Flow from inadequate graft to graft apposition at component junctions or from tears in the endograft fabric
    • Type IV      Flow through the pores of the fabric
  • “Late or secondary open conversions are defined as open operations performed more than 30 days after EVAR to address endoleaks not amenable to endovascular treatment, endograft migration, aneurysm rupture, graft occlusion, or infection of the endoprosthesis. By a review of 15 studies that included over 14,000 patients, the late conversion rate was 1.9%.”


    Late abdominal aortic endograft explants: Indications and outcomes
Phade SV et al.
Surgery Volume 150, Issue 4, October 2011, Pages 788–795
  • Device failures included
    • Migrations
    • Graft infolding
    • Fabric tears
    • Limb disconnections
    • Stent fractures
  • “The overall use of EVAR has risen sharply in the past 10 years (5.2% to 74% of the total number of AAA repairs) even though the total number of AAAs remains stable at 45,000 cases per year. In-hospital mortality rates for both ruptured and unruptured cases have fallen by more than 50% during this time period. Lower mortality rates and shorter LOS despite a 27%-36% higher cost of care continues to justify the use of EVAR over OAR. For patients with suitable anatomy, EVAR should be the preferred management of both ruptured and unruptured AAAs.”


    Epidemiology of aortic aneurysm repair in the United States from 2000 to 2010 
Dua A et al.
J Vasc Surg 2014;59:1512-7
  • “In 2000, 5.2% of all AAAs were repaired by EVAR (5.9% for unruptured and 0.8% of ruptured AAAs). By 2010, 74.0% of all AAAs were repaired by EVAR (77.8% for unruptured and 38.4% of ruptured AAAs). Although in-hospital mortality rates remained sta- ble for OAR in unruptured patients (3.8% to 4.8%; P > .05), it declined for EVAR (1.8%-2.1% to 0.9%; P 1⁄4 .001). Over the same time period, mortality rates for ruptured AAAs repaired by means of OAR decreased from 44.5% to 33.4% (P < .001); those patients undergo- ing EVAR had a similar decrease for in-hospital mortality rate (40.0%-40.8% to 19.8%; P < .001).”


    Epidemiology of aortic aneurysm repair in the United States from 2000 to 2010 
Dua A et al.
J Vasc Surg 2014;59:1512-7
  • “Endovascular repair is the treatment of choice for high-risk patients. A small but significant number of clinical failures were observed during the long-term follow-up.”


    Experience and outcomes after a decade of endovascular abdominal aortic aneurysm repair: a retrospective study from a community-based single center.
Kalteis M et al.
Ann Vasc Surg. 2012 Apr;26(3):330-7
  • “A total of 106 patients were treated in a period of 9 years. A Zenith stent-graft was used in 95% of cases. No deaths occurred during the first 30 days postsurgery. The complication rate was 4.7% (n = 5). The overall clinical and technical success rate at 30 days was 93.4%.”


    Experience and outcomes after a decade of endovascular abdominal aortic aneurysm repair: a retrospective study from a community-based single center.
Kalteis M et al.
Ann Vasc Surg. 2012 Apr;26(3):330-7
  • “After a mean follow-up period of 52 months (range, 13-112 months), the overall mortality rate was 25.4%. Aneurysm-related mortality was 2.1%. Rupture of the aneurysm occurred in four cases (4.3%). The final clinical failure rate was 13.8%.”


    Experience and outcomes after a decade of endovascular abdominal aortic aneurysm repair: a retrospective study from a community-based single center.
Kalteis M et al.
Ann Vasc Surg. 2012 Apr;26(3):330-7
  • “During the follow-up period, the mean diameter of the aneurysm decreased from 58.0 to 52.3 mm. However, expansion of the aneurysm was registered in 10 cases. Eleven patients had a primary endoleak, and another 11 secondary endoleaks occurred during the follow-up. The reintervention rate was 16.3%. The main reasons for repeat interventions were iliac limb occlusion (n = 5) and type 3 endoleak/limb disconnection (n = 4). Graft migration occurred in 3% of cases.”


    Experience and outcomes after a decade of endovascular abdominal aortic aneurysm repair: a retrospective study from a community-based single center.
Kalteis M et al.
Ann Vasc Surg. 2012 Apr;26(3):330-7
  • “However, expansion of the aneurysm was registered in 10 cases. Eleven patients had a primary endoleak, and another 11 secondary endoleaks occurred during the follow-up. The reintervention rate was 16.3%. The main reasons for repeat interventions were iliac limb occlusion (n = 5) and type 3 endoleak/limb disconnection (n = 4). Graft migration occurred in 3% of cases.”


    Experience and outcomes after a decade of endovascular abdominal aortic aneurysm repair: a retrospective study from a community-based single center.
Kalteis M et al.
Ann Vasc Surg. 2012 Apr;26(3):330-7
  • IMPORTANCE:To our knowledge, long-term outcomes of open and endovascular (EVAR) repairs of abdominal aortic aneurysms (AAAs) have not been studied on a population level outside a controlled trial setting.


    Survival After Endovascular vs Open Aortic Aneurysm Repairs.
Chang DC, Parina RP, Wilson SE
JAMA Surg. 2015 Sep 2:1-7. doi: 10.1001/jamasurg.2015.2644. [Epub ahead of print]
  • OBJECTIVE: To determine long-term outcomes of EVAR vs open repair on a population level.
    DESIGN, SETTING, AND PARTICIPANTS: Analysis 
of the longitudinally linked California Office of 
 Statewide Health Planning and Development inpatient database from 2001 to 2009. Median follow-up was 3.3 years.
    EXPOSURES: Endovascular vs open repairs.

    MAIN OUTCOMES AND MEASURES: Mortality and
 complications at 30 days, as well as long-
             term mortality and complications up to 9 years.
  • “In this observational study, a total of 23 670 patients were studied, with 52% receiving EVAR. Endovascular repair was associated with improved 30-day outcomes (all-cause mortality, readmission, surgical site infection, pneumonia, and sepsis), as well as significantly improved survival until 3 years postoperatively. After 3 years, mortality was higher for patients who underwent an EVAR repair. No significant difference in long-term mortality was observed for the entire cohort on adjusted analysis (hazard ratio, 0.99; 95% CI, 0.94-1.04; P = .64). Endovascular repair was found to be associated with a significantly higher rate of reinterventions and AAA late ruptures.”


    Survival After Endovascular vs Open Aortic Aneurysm Repairs.
Chang DC, Parina RP, Wilson SE
JAMA Surg. 2015 Sep 2:1-7. doi: 10.1001/jamasurg.2015.2644. [Epub ahead of print]
  • “The survival advantage for EVAR repair in a statewide population is maintained for 3 years. After 3 years, EVAR repair was associated with higher mortality; however, these mortality differences did not reach statistical significance over the entire study period. Reintervention and late AAA rupture rates are higher after EVAR repair.”


    Survival After Endovascular vs Open Aortic Aneurysm Repairs.
Chang DC, Parina RP, Wilson SE
JAMA Surg. 2015 Sep 2:1-7. doi: 10.1001/jamasurg.2015.2644. [Epub ahead of print]
  • “Although the readmission rate at 30 days was similar between EVAR repair and OAR, intervention for aneurysm-related complications, such as leak, was higher for EVAR repair at each interval from 6 months to 5 years, reaching 7% at 5 years. During this interval, computed tomographic angiography is done on an annual basis to detect endoleaks, which are usually type II and have an incidence initially of approximately 20%.”


    Survival After Endovascular vs Open Aortic Aneurysm Repairs.
Chang DC, Parina RP, Wilson SE
JAMA Surg. 2015 Sep 2:1-7. doi: 10.1001/jamasurg.2015.2644. [Epub ahead of print]
  • “Endovascular repair and open repair resulted in similar long-term survival. The perioperative survival advantage with endovascular repair was sustained for several years, but rupture after repair remained a concern. Endovascular repair led to increased long-term survival among younger patients but not among older patients, for whom a greater benefit from the endovascular approach had been expected.”


    Long-term comparison of endovascular and open repair of abdominal aortic aneurysm.
Lederle FA et al. 
N Engl J Med. 2012 Nov 22;367(21):1988-97
  • BACKGROUND: Whether elective endovascular repair of abdominal aortic aneurysm reduces long-term morbidity and mortality, as compared with traditional open repair, remains uncertain.
    METHODS: We randomly assigned 881 patients with asymptomatic abdominal aortic aneurysms who were candidates for both procedures to either endovascular repair (444) or open repair (437) and followed them for up to 9 years (mean, 5.2). Patients were selected from 42 Veterans Affairs medical centers and were 49 years of age or older at the time of registration.”

    Long-term comparison of endovascular and open repair of abdominal aortic aneurysm.
Lederle FA et al. 
N Engl J Med. 2012 Nov 22;367(21):1988-97
  • “Aneurysm rupture after repair was uncommon but occurred only in the endovascular-repair group, resulting in a significant between-group difference. We found no significant difference between the two groups with respect to number of secondary therapeutic procedures, number of postrepair hospitalizations, quality of life, or erectile dysfunction.”


    Long-term comparison of endovascular and open repair of abdominal aortic aneurysm.
Lederle FA et al. 
N Engl J Med. 2012 Nov 22;367(21):1988-97
  • “Furthermore, 4 of the 6 ruptures in our study, including 2 of 3 fatal ruptures, occurred in patients older than 70 years of age at study entry. Three of the 6 ruptures in our study occurred in patients who did not adhere to the recommended follow-up and endovascular procedures. Pending longer-term data, we therefore consider endovascular repair to be a reasonable option in patients younger than 70 years of age who are likely to adhere to medical advice.”
Long-term comparison of endovascular and open repair of abdominal aortic aneurysm.
Lederle FA et al. 
N Engl J Med. 2012 Nov 22;367(21):1988-97
  • “Our results suggest that endovascular repair continues to improve and is now an acceptable alternative to open repair even when judged in terms of long-term survival. However, our results also indicate that late rupture remains a concern and that endovascular repair does not yet offer a long-term advantage over open repair, particularly among older patients, for whom such an advantage was originally expected.”


    Long-term comparison of endovascular and open repair of abdominal aortic aneurysm.
Lederle FA et al. 
N Engl J Med. 2012 Nov 22;367(21):1988-97
  • TEVAR: Descending Aorta
    - Aneurysm
    - Penetrating ulcer
    - Dissection
    - IMH
    - Aortic Rupture
  • Descending Thoracic Aorta
    - Proximity of pathology to celiac artery
    - Celiac artery may be covered by stent
    - Preliminary arteriography to assess patency of the gastroduodenal artery, which provides collateral flow from the SMA after celiac occlusion. 
    - SMA stenosis may dictate SMA stent prior to TEVAR
  • Role of Radiologist
    - Critical pre-procedural analyses
    - Location and extent of the pathology
    - Requirement for branch vessel occlusion
    - Risk of spinal cord ischemia
    - Identify risk factors for deployment failure and endoleak
    - Angulation, tortuousity, calcification, caliber
    - Provide information to guide stent selection
    - Post-stent imaging
  • CT Post-TEVAR
    - Confirm stent positioning
    - Confirm exclusion of aortic pathology
    - Identify potential complications
    - endoleak
    - arterial branch occlusion
    - stent collapse
    - migration
  • Endoleaks
    - Type I: proximal or distal end of stent
    - typically enhance on the arterial phase
    - Type II: reperfusion by aortic branch
    - left subclavian (IIs)
    - intercostal or bronchial branch (IIo)
    - seen on arterial and venous phase 
    - Type III: defect in the graft material or at the junction of overlapping grafts
  • Retrograde Type A Dissection
    - Risk factors
    - Graft
    - those with proximal bare springs
    - Aorta
    - steeply angulated aortic arch with morphologically normal aorta
    - Both
    - compliance mismatch between the stent graft and aortic wall
  • Complications
    - Vascular
    - Pseudoaneurysm
    - Aortic leak
    - Dissection
    - Coronary ostial aneurysm
    - Periaortic   
    - Mediastinitis
    - Sternal dehiscence
  • “ CT imaging plays an important role in procedural planning for TAVI/TAVR and should be fully integrated component of any TAVI/TAVR program. The use of TAVI/TAVR  is multifaceted and should include the assessment of vascular access of the aortic valve, annulus, and root and orientation of the annulus plane.”
    SCCT expert consensus document on computed tomography imaging before transcatheter aortic valve implantation (TAVI)/ transcatheter aortic valve replacement (TAVR)
    Achenbach S et al.
    J Cardiovasc Comput Tomogr (2012) 6, 366-380
  • “ Contrast-enhanced CT imaging provides information on the suitability of the peripheral access vessels to accommodate the relatively large sheaths necessary to introduce the prosthesis. CT imaging also provides accurate dimensions of the ascending aorta, aortic root, and aortic annulus which are of importance for prosthesis sizing.”
    SCCT expert consensus document on computed tomography imaging before transcatheter aortic valve implantation (TAVI)/ transcatheter aortic valve replacement (TAVR)
    Achenbach S et al.
    J Cardiovasc Comput Tomogr (2012) 6, 366-380
  • TEVAR
    - Thoracic endovascular aortic repair
    - First reported in 1994 @ Stanford
    - Favorable outcomes and reduced complications compared to open repair
    - Between 1998 and 2007: 60% rise in thoracic aortic repair concomitant with 6-fold increase in TEVAR
  • Thoracic Aortic Segments
    1. Ascending thoracic aorta can be stented in select patients
    - Nonsurgical candidates
    - Experienced centers
    2. Arch coverage is complicated
    - Arch curvature, branches
    - Fenestrated, branched grafts
    3. Descending thoracic aorta (DTA)
  • Left Subclavian Coverage
    - Occlusion of the left subclavian artery may result in left upper extremity ischemia, stroke or paraplegia
    - Branches of the left vertebral artery perfuse the anterior spinal artery
    - Preoperative LSA bypass
    - Varying practice
  • Descending Thoracic Aorta
    1. Celiac artery coverage if aortic pathology involves abdominal aorta.
    - Need preliminary arteriography to confirm patency of the gastroduodenal artery, which provides collateral flow from the superior mesenteric artery after celiac occlusion. 
    2. SMA stenosis may dictate SMA stent
  • Role of Radiologist
    1. Critical pre-procedural analyses
    - Location and extent of the pathology
    - Requirement for branch vessel occlusion
    - Risk of spinal cord ischemia
    2. Identify risk factors for deployment failure and endoleak
    - Angulation, tortuousity, calcification, caliber
    3. Provide information to guide stent selection
    4. Post-stent imaging 
  • CT Post-TEVAR
    1. Confirm stent positioning
    2. Confirm exclusion of aortic pathology
    3. Identify potential complications
    - endoleak
    - arterial branch occlusion
    - stent collapse
    - migration 
  • Endoleaks
    1. 3-29%
    2. Risk factors include
    - Aortic morphology
    - Length of proximal landing zone
    - Patient age
    - Type of stent graft 
  • Endoleaks
    1. Type I: proximal or distal end of stent
    - typically enhance on the arterial phase
    2. Type II: perfusion of left subclavian (IIs) or intercostal or bronchial branch (IIo)
    - seen on arterial and venous phase 
    - Type III is a defect in the graft material or at the junction of overlapping grafts
  • Other Complications
    1. Migration occurs in 3% at 12 months
    2. Endograft infection is rare
    - may necessitate surgical intervention
    - high risk of mortality
    3. Stent collapse
    4. Retrograde type A dissection of ascending aorta proximal to the stent
    5. Aneurysm formation distal to descending aortic dissection
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