The objective of this review is to show different types of treatment for abdominal aortic aneurysms (AAA) - compare and evaluate the effectiveness of the treatments.

1. The department of Medical engineering
Stent implantation methods for
treatment of abdominal aortic
aneurysms (AAA)
Journal of Endovascular Therapy
Lecturer: Dr. Zehava Blachman
Name: Or Hananel
Date: 18.6.2015

2. 1. Abstract
Abdominal aortic aneurysm (AAA), associated with the expansion of a new
section of the aorta. As the aneurysm grows larger the ratio between the
diameter and the surface area and the pressure on the side, because of the
greater risk of outbreak or tear (rupture) as when inflated balloon too. Aneurysms
are usually caused by damage to the blood vessel wall. Is generally from
atherosclerosis caused by the accumulation of cholesterol and other fatty
deposits lining the blood vessels.
This paper reviews different methods for treating abdominal aortic aneurysm, the
paper gathers several articles that divided to two different approach treatments,
and compare them regarding the advantage and disadvantage of each one.
The paper relay on research conducted on 22,830 patients that had a open
repair procedure and 22.830 patients had a endovascular repair procedure. The
main medical aspects are rates of death, medical complications, and surgical
complications.
In the review there is comparison between 4 different companies that each one
developed a technology for noninvasive treatments.
The parameters for the comparison are: stent placement, surgeon skills,
invasiveness, surgery time, modularity.

3. 2. Introduction
Anatomy
Aorta is the main blood vessels leading from the heart blood throughout the
body. Aorta leaves the room left up, going through arched back and to the left,
above the heart and pulmonary artery, and down the front of the spine to the
abdomen. Over the course aortic arteries divergent body until finally, below the
navel, it splits into two iliac arteries. According to the structure is divided into the
aorta into three parts: the ascending aorta, which goes from the heart up, aortic
arch and descending aorta, which is above the diaphragm called the thoracic
aorta and abdominal aorta below it.
Figure 1 - showing the aorta in the human body

4. Pathology
Aneurysms of the aorta are usually caused by damage to the wall of the aorta. Is
generally from atherosclerosis, which is caused by the accumulation of
cholesterol and other fatty deposits on the vessel. This condition is more
common in men, and age-related diseases aggravated presence, such as
hypertension, diabetes and smoking. However, there are situations in which
there is a congenital weakness in the walls of blood vessels in the body. In these
situations, may develop aneurysms of the aorta younger people - in their younger
years. Weakness in the wall of the aorta can lead to expansion of the artery,
rupture and life-threatening bleeding without precursors. At risk for abdominal
aneurysm include: men over 65, current or former smokers, relatives of people
with aortic aneurysm, heart patients and patients with atherosclerosis. There
aortic aneurysms by more than 3% of people over age 60, and is a cause of
death in - 1/250 of people over age 50. You can find abdominal aortic aneurysm
before fatal complication appears very easily by a single ultrasound examination,
simple and non-invasive. Indeed, because of the recognition that the diagnosis
omission of Western countries, including the United States and England, were
led national programs to detect early aortic aneurysms in the population.
3. Objective
The objective of this review is to show different types of treatment for abdominal
aortic aneurysms (AAA) - compare and evaluate the effectiveness of the
treatments.
4. Methods
4.1 Searching strategy
Literature search was performed in Internet database Google Scholar
using the following key words: Endovascular, Open Repair,
Transabdominal Repair, Abdominal Aortic Aneurysm, AAA, Stent graft.
No limitation was applied during the search. All relevant articles were
initially selected by title and abstract.

5. 4.2 Review and comparison
The main comparison between endovascular and trans-abdominal
repair were reviewed from different articles and compared to each
other in a table. An additional comparison was made among different
companies with high technology advancing solution, the source of
each solution was taken from the official website of the company.
5. Review
Open repair procedure
The infrarenal aorta can be approached via a transabdominal midline or
paramedian incision, or via a retroperitoneal approach. The paravisceral and
thoracic aorta are approached via a left-sided posteriolateral thoracotomy incision
in approximately the 9th intercostal space. The Surgery preformed under a
general endotracheal anesthesia. The aneurysm may be exposed through either
a long midline incision for the transperitoneal approach or an oblique flank
incision for the retroperitoneal approach.
In a nutshell, open repair of an abdominal aortic aneurysm involves an incision of
the abdomen to directly visualize the aortic aneurysm. The procedure is
performed in an operating room under general anesthesia. The surgeon will
make an incision in the abdomen either lengthwise from below the breastbone to
just below the navel or across the abdomen and down the center. Once the
abdomen is opened, the aneurysm will be repaired by the use of a long cylinder-
like tube called a graft that acting like artificial artery.
Endovascular repair procedure
Also known as EVAR, is a minimally invasive (without a large abdominal
incision), with a regional anesthesia (epidural or spinal anesthesia), a small
incision is made in each groin to visualize the femoral arteries in each leg or one
leg (contingent on the technology). With X-ray images for guidance, a stent-graft
will be inserted through the femoral artery and advanced up into the aorta to the
site of the aneurysm. A stent-graft is a long cylinder-like tube made of a thin

6. metal framework (stent), while the graft portion is made of various materials such
as Dacron or polytetrafluoroethylene (PTFE) land may cover the stent. The stent
helps to hold the graft in place. The stent-graft is inserted into the aorta in a
collapsed position and placed at the aneurysm site. Once in place, the stent-graft
will be expanded, attaching to the wall of the aorta to support the wall of the
aorta. The aneurysm will eventually shrink down onto the stent-graft.
Open repair versus Endovascular
Several researches have been taken under consideration to determine which
procedure is preferable and pros and cons of each one. In the following lines we
will discuss the ratio between 3 main medical aspects that are taken from the
results of a research conducted on 22,830 patients that had a open repair
procedure and 22.830 patients had a endovascular repair procedure. The main
medical aspects are rates of death, medical complications, and surgical
complications.
Graph 1 shows the percentage medical complications developed in patients that
were under the supervision of the research. The complications that were studied
were myocardial infarction, pneumonia, acute renal failure, renal failure requiring
dialysis and deep-vein thrombosis or pulmonary embolism. The orange color
represents the open repair and the blue one represents the endovascular repair
according to the diseases.
Graph 1
0.0
5.0
10.0
15.0
20.0
Mycardial
infrac;on
Pneumonia Acute renal
failure
Renal failure
requiring
dialysis
Deep-vein
thrombosis or
pulmonary
embolism
Percent(%)
Medical complica=ons
Endovascular Repair
Open Repair

7. Graph 2 shows the surgical complications that accrued during the surgery. The
problems that were under examination were acute mesenteric ischemia,
reintervention for bleeding, Tracheostomy (incision in breathing canal) and
embolectomy (in operation to remove thrombosis).
Graph 2
In graph 3 we can see the follow up of the all the patients in the research during
4 years time period and suffered from severe rupture despite the operation.
Graph 3
0.0
0.5
1.0
1.5
2.0
2.5
Acute
mesenteric
ischemia
Reinterven;on
for bleeding
Tracheostomy Thrombectomy
Percent(%)
Surgical complica=ons
Endovascular Repair
Open Repair
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Year 1 Year 2 Year 3 Year 4
Percent(%)
Rupture for long term
Endovascular
Open Repair

8. Graph 4 shows the death ratio between both procedures.
Graph 4
The death fatalities are caused by the complications before and after the
operation as shown in graph 1,2,3.
In the last 10 years many development have been made in the field of EVAR and
significant improvements to the durability of the stents. This review details 4
companies that use different unique approaches and technology: LOMBARD
MEDICAL, JOTEC, BIFLOW and ENDOSPAN. We gather all the specification
from each one and compared between them.
Lombard Medical
The Aorfix Endovascular Stent Graft is designed to be flexible and to more easily
treat AAAs with severe bends or angles. This flexibility allows some patients to
be treated with a stent graft where open surgery was previously their only option.
Aorfix is also appropriate for patients who have AAAs with less severe bends or
angles.
This technology leap reducing the chances to suffer from endoleak after the
procedure, therefore death ratio is decreasing.
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Endovascular
Repair
Open Repair
Percent(%)
Death
Death

9. JOTEC
With E-vita ABDOMINAL XT, JOTEC provides an abdominal stent graft system
that – based on the latest catheter technology – makes even difficult vascular
anatomies passable, thus enabling endovascular treatment of abdominal aortic
aneurysms. The reason this technology is reviewed in this paper is due to 3
dominant characteristics:
Smooth delivery - the hydrophilic coating facilitates the introduction and advance
of the stent graft even in narrow and tortuous vessels.
Highest flexibility - the multi-zone catheter specifically developed for E-vita
ABDOMINAL XT is particularly flexible, enabling safe push- ability and precise
track ability even in strongly tortuous vessels. The catheter’s working length is 55
cm.
Precise release - the Squeeze-to- Release mechanism allows for gradual or
continuous release at minimum effort.
With this kind of catheter the doctors can achieve better results and reduced the
procedure time.
BIFLOW
BIFLOW Medical is developing a unique side-branch stent to be used during
percutaneous procedures in endovascular stent grafting. During the procedure,
the side-branch stent is introduced in a secondary artery. It penetrates the main
graft in the main artery, and then it opens for total sealing. This enables easier,
shorter, and less costly procedures. The BiFlow stent presents significantly lower
risk to the patient.
In every person the renal position is different thus making it hard to manufacture
one type of implant for everyone, they invent special system that enables to
install the main stent graft and adjust the renal opening according to each
individual unique blood vessels by piercing the graft with side-branch stent.

10. ENDOSPAN
ENDOSPAN develops advanced low profile stent-grafts systems for the
treatment of aneurysms and dissection throughout the aorta: infarenal, visceral
and thoracic. Endospan’s Horizon takes a different approach, enabling a single-
sided procedure, transforming the procedure into a shorter, simplified, and more
flexible procedure that need less technical expertise. The HORIZON AAA stent-
graft is constructed in a bottom-up sequence, providing more stability.
The uniqueness of ENDOSPAN is that the entrance to the body is made by one
cut only in the femoral artery in different from other applications that need two or
more incisions. This technique requires less operational skills from the medical
stuff and therefore decrease the amount of medical complications.
Summarizing table (table 1) of technology elements.
# LOMBARD JOTEC BIFLOW ENDOSPAN OPEN REPAIR
Material Nitinol,
polyester
Nitinol,
polyester
Nitinol, polyester Nitinol, polyester Polyester
Stent placement Fixation with
hook uses a
balloon to
expand.
Regular
fixation with
hooks.
By placing stents
in renal and
hooks.
Hooks and artery
support.
Sewing stent into the
artery.
Surgeon skills Medium, using
two catheters
and balloon.
Medium, using
two catheters,
easy
technology.
Medium, using 3
different catheters
and balloon
Medium, using 3
catheters, without
balloon.
Requires high skill of
the doctor.
Invasiveness Minimal
invasive, entry
on both
arteries.
Minimal
invasive, entry
on both
arteries.
Minimal invasive,
entry on both
arteries.
Minimally invasive,
single artery entry.
Highly invasive, open
surgery.
Surgery time 2-4(hr) 2-4(hr) 2-4(hr) 2-4(hr) 4-6(hr)
Modularity Flexible and
adapts over
time.
Wide variety of
sizes and
dimensions.
Suitable for
different anatomy
because renals
are not a factor.
Adapts With 3
different parts.
Precise match to the
artery.
Table 1 – Comparison among treatment methods

11. 6. Discussion
In the review we presented two kinds of procedures for abdominal aortic
aneurysm treatments. The comparison was between two researches that
followed on patients that needed surgery for aneurysm treatment.
The procedure of open repair itself is highly dangerous and can lead to severe
complications like critical bleeding, infections and liquids accumulation. The
healing from the surgery is more prolong than the endovascular and consist of
many hours or lying in bed. In doctors eyes the procedure is more complex and
requires a high skills.
Has shown in the graph mentioned above in the short term we can see that the
complication and the rates of death is higher in open repair then endovascular,
On the contrary for the long term we can see that the open repair is more reliable
through time and the chances for ruptures after the first 2 years is lower.
In my perspective lower death rate is the most important criterion that needed to
pay attention to. In every case that was studied the open repair has higher
probability to develop complication in the tested subjects.
We reviewed 4 different companies that have technology in the field of
endovascular and compared the most valuable parameters:
Material – all the technologies use nitinol and polyester except the open repair
that is use only polyester.
Stent placement - open repair due to because the graft is sewed directly to the
aorta.
Surgeon skills – JOTEC due to catheter abilities and the stent is consist only by 2
parts without the need of inflate a balloon.
Invasiveness – ENDOSPAN due to only one incision.
Surgery time – all the treatments were the same except the open repair that is
longer.
Modularity – open repair due to perfect compatibility between the graft and the
artery.

12. 7. Conclusions
Despite all the advantages in open repair it is recommended for younger people
to take the open repair treatment, because it is more reliable trough time. For
mature patients it is more recommended to use the endovascular treatment.
It is important to mention that open repair has high risks because the trauma the
body suffers from.
8. References
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