Introduction, AAA and treatment now Flashcards
What is an abdominal aortic aneurysm (AAA)?
- The aorta is dialated with a diameter > 3 cm.
Classifications of aneurysms
- Infrerenal, suprarenal, juxtarenal, iliac aneurysm
- Fusiform, saccular or dissected
- Asymptomatic, symptomatic or rupture (99% does not have any symptoms of aneurysm)
Describe characteristics of the epidemiology, diagnosis and screening of AAA.
- Epidemiology → 2-8% >65 years male population, 2% female.
- Epidemiology → around 5000 hospital admissions yearly in the Netherlands
- Risk factors → smoking age, hypertension, family, racial, diabetes.
- Screening → ultrasound
- When surgical treatment is advised → CTA (and one time CT-thorax)
Describe the aortic wall structure.
In general, like all arteries, the aortic wall consists of the tunica externa, tunica media and tunica intima.
- The tunica externa contains connective tissue.
- The tunica media contains the smooth muscle cells.
- The tunica intima contains endothelial cells.
What cells play a crucial role in AAA?
Vascular smooth muscle cells
What kind of (mutated) genes are usually involved in the development of AAA?
Mutations in genes of the mechano-transduction complex.
What hypothesis of the pathophysiology of AAA is there?
That risk factors (like smoking, age, and genes) influence smooth muscle cells. This influence of risk factors cause the function of smooth muscle cells to be disturbed, which causes weakening of the aortic wall.
How can smooth muscle cells be derived/isolated?
- Smooth muscle cells can be isolated from an AAA biopsy.
- There is also a live biobank which stores things like blood, tissue and urine, where smooth muscle cells can also be collected.
Why are there no screenings for aneurysms?
- Ethical considerations → knowing you have a disease i.e. aneurysm, but not knowing if it will cause harm.
- No medical treatment
- Only surgical treatment and follow-up is based on guidelines.
- Screenings not proven to be efficient.
Is screening possible when there is a risk for the development of an aneurysm?
Yes (e.g. population screening for AAA for all men age 65 years)
Name an example of a case where screening for AAA is necessary?
There is a connection between a popliteal aneurysm and AAAs. So in 39% of the cases where a person has a popliteal aneurysm, a newly diagnosed aneurysm is seen within 7 years of follow-up, of which 43% is AAA. So screening is highly recommended in this case.
When is surgical treatment for AAA indicated?
- In men, with an AAA of > 5,5 cm diameter.
- In women (with acceptable surgical risk), with an AAA of > 5 diameter.
- When rapid AAA growht is observed (>1 cm/year).
- Symptomatic AAA
For the repair of aneurysms above the renal system, there is a risk of ischaemia reperfusion injury. What needs to be done to prevent this?
Clamp the renal arteries.
Describe what Endovascular Aneurysm Repair (EVAR) is.
EVAR involves the placement of an expandable stent graft within the aorta to treat aortic disease without operating directly on the aorta.
Before EVAR was developed, there was standard open repair surgery of AAAs. What was done here to repair the AAA?
A large incision in the abdomen is made to expose the aorta. Once opened, a graft can be used to repair the aneurysm.
A study was performed to determine whether EVAR of open surgery was better. The study looked at several outcome variables, where among others the survival rate was studied.
What was the observed outcome?
That in the first few years after intervention (EVAR or open surgery), EVAR had slightly better survival results. However, after a certain amount of years (ca. 5/6 years) after the intervention, the survival results for EVAR and open surgery did not differ anymore (just a tiny bit).
A study was performed to determine whether EVAR of open surgery was better. The study looked at several outcome variables, where among others the amount of reinterventions was studied.
What was the observed outcome?
That the amount of secondary procedures i.e. reinterventions was higher for EVAR than for open surgery.
A study was performed to determine whether EVAR of open surgery was better. The study looked at several outcome variables, where among others the amount of reinterventions was studied. With this, the study also looked at what indications there were for the reintervention for EVAR and open surgery.
What was the observed outcome?
So we have already concluded that EVAR comes with a higher risk for reintervention. With this it was seen then especially the development of an endoleak or occlusions were higher due to EVAR compared to open surgery. Furthermore, there was also more graft infection and migration for EVAR compared to open surgery (wound infection and rupture are not significant)
Why is there no difference in survival between EVAR and open in regard to RAAA?
- Patients were already treated and then randomized
- Patients were already critically ill (multiple organ failure), so close monitoring
What is the biggest problem of AAA surgery?
Endoleak (type II endoleak mostly)
What is fenestrated EVAR (FEVAR)?
Fenestrated endografts were developed to treat patients with aneurysms with short proximal necks. Fenestrated grafts extend the proximal sealing zone from the infrarenal segment to the juxtarenal aorta using fenestrations (holes) in the graft or scallops (gaps in the upper graft fabric margin) to permit perfusion of the visceral vessels.
What is chimney endo sealing (CHEVAS)?
The chimney technique in endovascular aortic aneurysm repair (Ch-EVAR) involves placement of a stent or stent-graft parallel to the main aortic stent-graft to extend the proximal or distal sealing zone while maintaining side branch patency. Ch-EVAR can facilitate endovascular repair of juxtarenal and aortic arch pathology using available standard aortic stent-grafts, therefore, eliminating the manufacturing delays required for customised fenestrated and branched stent-grafts.
Think of reasons why you would use imaging techniques (e.g. MRI/PET/CTA/etc.) pre-, per-, and postoperatively for EVAR.
