christinalee_research paper_final

Running head: ENDOVASCULAR AND OPEN REPAIRS OF POPLITEAL ANEURYSMS

A Comparison of the Effectiveness of Endovascular and Open Repairs of Popliteal Aneurysms

Research Paper

Submitted to Kennesaw Mountain High School

by

CHRISTINA LEE

Kennesaw, GeorgiaDecember 2014

ENDOVASCULAR AND OPEN REPAIRS OF POPLITEAL ANEURYSMS

Abstract

Popliteal artery aneurysms (PAAs) pose a significant threat of limb loss due to the high rates of

thromboembolic complications. The goal of this qualitative exploratory case study was to

compare the post-operative complication rates of open bypass repairs and endovascular stent

graft repairs of PAAs in order to determine if an endovascular repair or open repair results in a

lower post-operative complication rate. To assess the post-operative complications rates for

open bypass repairs and endovascular stent graft repairs, I utilized an online database to examine

each patient’s history and record the age, gender, type of PAA repair, and the presence or lack of

the following: post-operative infection, post-operative endoleaks, post-operative thrombosis,

post-operative stenosis, and necessary reintervention for a poorly functioning stent graft or

bypass. My convenience sample included all endovascular stent graft and open bypass repairs of

PAAs from January 2010 to December 2012 at a vascular surgical office in a large suburban

county in Georgia. Within these confines, surgeons performed 10 open bypass repairs and 13

endovascular stent graft repairs on 16 males from the ages 62 to 85. In this study, the relative

post-operative complication rates differed for each procedure, prompting the need for further

research on the matter. With further research, new evidence could support that one treatment

results in a lower post-operative complication rate, and doctors may be encouraged to select the

safer repair with knowledge of the lower post-operative complication rate. For the purposes of

this study, I defined the safer repair as the repair that resulted in fewer post-operative

complications


Acknowledgements

Thank you to all of the following for your eagerness to help me excel and succeed throughout the

course of this research:

Dr. David Hafner, M.D.

Mrs. Kelly Ingle

Ms. Kristen Younker

Dr. Mimi Dyer, Ed. D.


Table of Contents

Introduction......................................................................................................................................1Statement of the Problem............................................................................................................1Purpose of the Study...................................................................................................................2Research Questions.....................................................................................................................3Definition of Key Terms.............................................................................................................4

Review of Literature........................................................................................................................5Causes of PAAs...........................................................................................................................5Risk Factors Associated with PAAs...........................................................................................6Diagnosing PAAs........................................................................................................................6Open Bypass Approach to Repairing PAAs...............................................................................7Endovascular Stent Graft Approach to Repairing PAAs............................................................8Findings of Past Studies Comparing Open and Endovascular Repairs.......................................8Limiting Factors in Past Studies.................................................................................................9Summary.....................................................................................................................................9

Research Method...........................................................................................................................10Population and Sample..............................................................................................................11Instrumentation.........................................................................................................................12Data Collection Procedure........................................................................................................12Analysis Plan.............................................................................................................................13Assumptions..............................................................................................................................13Limitations................................................................................................................................14Delimitations.............................................................................................................................14Ethical Assurances....................................................................................................................15Summary...................................................................................................................................15

Findings.........................................................................................................................................15Results.......................................................................................................................................16Evaluation of Findings..............................................................................................................18Summary...................................................................................................................................18

Implications, Recommendations, and Conclusions.......................................................................19Implications...............................................................................................................................20Recommendations.....................................................................................................................22Conclusion.................................................................................................................................23

References......................................................................................................................................24

Appendix A: All Collected Data....................................................................................................27

ENDOVASCULAR AND OPEN REPAIRS OF POPLITEAL ANEURYSMS 1

Introduction

A popliteal artery aneurysm (PAA) is an excessive localized enlargement of the artery

caused by a weakening of the medial layer of the popliteal vessel wall (DeBakey, 2013). PAAs

are the most common type of peripheral artery aneurysms, accounting for 70% to 80% of all

peripheral artery aneurysms (Antonello et al., 2005). PAAs pose a significant threat of limb loss

due to the high rates of thromboembolic complications (Curl et al., 2007). Limb salvage is

unlikely in symptomatic patients, especially those suffering from acute ischemia (Antonello et

al., 2005).

With the surgical treatment of PAAs, surgeons aim to isolate and exclude the aneurysm

and allow for the restoration of effective blood flow to the lower extremities (Antonello et al.,

2005). In the past, doctors have most commonly repaired PAAs through ligation and a medial or

posterior bypass (Lovegrove, Javid, Magee, & Galland, 2008). In 1994, the option of an

endovascular repair through the interposition of a palmaz stent covered with a

polytetrafluoroethylene (PTFE) graft became available (Cronenwett & Johnston, 2010). Since

the first endovascular repair in 1994, researchers have suggested in various reports that

endovascular repairs are equally as effective as open repairs (Lovegrove et al., 2008).

Statement of the Problem

If PAAs are ineffectively treated, post-operative complications can include, but are not

limited to, loss of patency of the graft or vein, thrombosis– which may lead to acute limb

ischemia– development of arterial ulcers, and infection of the incision site (Cronenwett &

Johnston, 2010). Other indirect factors that may influence the effectiveness of an endovascular

repair or open repair is the length of hospital stay and length of use of anesthesia (Antonello et

al., 2005). It is unclear whether an endovascular repair or an open repair results in a higher rate


of post-operative complications (Cronenwett & Johnston, 2010). The problem associated with

this study is whether an endovascular repair or an open repair of PAAs results in the lowest

percentage of post-operative complications. Due to the wide variety of complications that can

occur if the PAA is not effectively treated, it is imperative that surgeons are aware of the optimal

procedure for repairing PAAs (Mosquera, 2013). If a significant difference exists between the

post-operative complication rates of endovascular stent graft repairs and open bypass repairs, the

public and medical field should be informed, thereby ensuring the effective treatment of PAAs in

the future. If an endovascular repair or open repair does result in fewer post-operative

complications and the medical field and public remains unaware of such a difference, medical

professionals may continue to treat patients in an ineffective and unnecessarily hazardous

manner.

Purpose of the Study

The purpose of this qualitative exploratory case study was to determine if an

endovascular repair is a more effective treatment for PAAs than an open repair. I catalogued and

calculated percentages for the respective number of post-operative infections, post-operative

endoleaks, post-operative thrombosis, post-operative stenosis, and necessity for reintervention

for endovascular stent graft repairs and open bypass repairs. I utilized the resulting trends and

patterns to draw casual conclusions or generalizations about the population. I obtained data from

October to November 2014 using patient records from the Vascular Surgical Associates patient

database at WellStar Kennestone Regional Medical Center. The data included the age, gender,

type of PAA repair, and the presence or lack of the following: post-operative infection, post-

operative endoleaks, post-operative thrombosis, post-operative stenosis, and necessary

reintervention for a poorly functioning stent graft or bypass. I compared the relative post-


operative complication rates of the two procedures by calculating the relative percentages of

each post-operative complication to determine if there was a difference. If the endovascular or

open repair resulted in a lower post-operative complication rate, I will assert that it is the safer

procedure. As information concerning the safety of each procedure becomes more available,

surgeons will be more likely to perform the procedure that results in the least number of post-

operative complications for their patients ("Physicians Oaths," n.d.).

Research Questions

The following are research questions for the study of endovascular and open repairs of

PAAs.

Q1. What is the post-operative complication rate, as determined by post-operative

infections of the surgical site, of open repairs of PAAs?


infections of the surgical site, of endovascular repairs of PAAs?


endoleak rate, of open repairs of PAAs?


endoleak rate, of endovascular repairs of PAAs?


thrombosis, of open repairs of PAAs?


thrombosis, of endovascular repairs of PAAs?


stenosis, of open repairs of PAAs?



stenosis, of endovascular repairs of PAAs?

Q9. What is the post-operative complication rate, as determined by the necessity for

reintervention, of open repairs of PAAs?

Q10. What is the post-operative complication rate, as determined by the necessity for

reintervention, of endovascular repairs of PAAs?

Q11. How do the post-operative complication rates of open repairs and endovascular

repairs compare?

Q11a. Which PAA treatment results in the fewest number of post-operative

complications?

Definition of Key Terms

Arteriosclerosis. A chronic disease characterized by abnormal thickening and hardening

of the arterial walls with resulting loss of elasticity (“Arteriosclerosis,” 2014).

Ischemia. A deficient supply of blood to a body part that is due to obstruction of the

inflow of arterial blood ("Ischemia," 2014).

Aneurysm. The widening of an artery that develops from a weakness or destruction of

the medial layer of the blood vessel (DeBakey, 2013).

Ligation. The surgical process of tying up an anatomical channel such as a blood vessel

("Ligation," 2014).

Medial. Lying or extending toward the median axis of the body (“Medial,” 2014).

Posterior. Situated behind the human body or its parts (“Posterior,” 2014).

Morbidity. A diseased state or symptom (“Morbidity,” 2014).

Patency. The state of being open or exposed ("Patency," 2014).


Stenosis. A narrowing or constriction of the diameter of a bodily passage or orifice

("Stenosis," 2014).

Thrombosis. The formation or presence of a blood clot within a blood vessel

("Thrombosis," 2014).

Distal. Located away from the center of the body ("Distal," 2014).

Autologous. Derived from the same individual (“Autologous,” 2014).

Review of Literature

Arteries generally have thick walls that are excellent for withstanding normal blood

pressures; however, smoking, hypertension, or heart disease may compromise the strength of the

arterial wall and cause an aneurysm to form ("What Is an Aneurysm?," 2011). An aneurysm is a

widening of an artery caused by a weakening of the arterial wall ("What Is an Aneurysm?,"

2011). Rarely, aneurysms form in the popliteal artery (Mohan et al., 2006). The popliteal artery

is located behind the knee and connects the superficial femoral artery in the thigh to the

tibioperoneal trunk in the calf ("Popliteal Artery Aneurysm," n.d.; Knipe & Jones, n.d.). The

normal diameter of a popliteal artery varies from 0.5 to 1.1 centimeters; however, the

development of a PAA can cause the artery to widen to 2.0 to 4.0 centimeters (Cronenwett &

Johnston, 2010). PAAs only affect about 1% of the general population yet PAAs account for

70% to 80% of all peripheral artery aneurysms (Mohan et al., 2006; Cronenwett & Johnston,

2010). PAAs are most common in elderly men (95%) with a median age of 71 (Mosquera,

2013).

Causes of PAAs

The exact cause of PAAs remains unclear (Cronenwett & Johnston, 2010). Hamish et al.

(2006) identified arteriosclerosis as the dominant associated factor. Arteriosclerosis can form


lesions in the arterial wall ("Arteriosclerosis / Atherosclerosis," n.d.). The turbulent blood flow

along such lesions causes the arterial wall to weaken and dilate the artery (Hamish et al., 2006).

The constant motion and associated kinking of the knee may also contribute to the formation of

an aneurysm in the popliteal artery (Hamish et al., 2006).

Risk Factors Associated with PAAs

PAAs can lead to considerable morbidities and are the cause of one in every 5000

hospital admissions (Siauw, Koh, & Walker, 2006). While this particular type of aneurysm does

not pose a high risk of rupturing, it can suddenly thrombose and obstruct blood flow to the lower

leg and foot. The thrombosis may cause severe ischemia which can result in the necessary

amputation of the afflicted limb (Mosquera, 2013). Thirty-six percent of symptomatic patients

ultimately require an amputation, usually as a result of treatment failure (Siauw et al., 2006).

Approximately 60% of PAA patients are symptomatic upon first presentation; 30% present acute

limb ischemia and another 11% present with generalized pain caused by local compression of the

nerves or veins behind the knee (Siauw et al., 2006). Cronenwett and Johnston (2010) believed

that a positive correlation exists between the size of the enlarged aneurysm and the incidence of

symptoms. However, Kirkpatrick et al. (2004) and Ebaugh et al. (2003) argued that aneurysm

size has no bearing on the presence or lack of symptoms.

Diagnosing PAAs

Correctly diagnosing PAAs can be difficult due to their infrequency. Specialists at major

vascular centers only treat approximately five PAAs per year (Hamish et al., 2006). Forty

percent of patients present with asymptomatic PAAs, and healthcare professionals generally

diagnose them by accident (Antonello et al., 2005). It is easier to correctly identify a PAA in a

symptomatic patient; however, the probability of limb salvage in symptomatic patients is greatly


decreased (Cronenwett & Johnston, 2010). Doctors may utilize duplex ultrasonagraphy to image

and diagnose a PAA (Cronenwett & Johnston, 2010). Palpating the popliteal space can also be

effective for diagnosing a PAA though it is an unreliable method (Cronenwett & Johnston,

2010). Once a medical professional confirms a PAA, he utilizes more detailed imaging in order

to indentify the appropriate treatment method for the individual patient (Cronenwett & Johnston,

2010). Common imaging techniques include contrast-enhanced arteriography, magnetic

resonance angiogram (MRA), and computed tomography angiography (CTA) (Cronenwett &

Johnston, 2010).

Open Bypass Approach to Repairing PAAs


and allow for the restoration of effective blood flow to the lower extremities (Cronenwett &

Johnston, 2010). The first open bypass repair was performed in 1785 by John Hunter, and the

procedure has been generally considered an excellent choice for PAA repairs ever since

(Cronenwett & Johnston, 2010). An open bypass repair for PAAs involves the ligation of the

aneurysm and interposition of a bypass graft to maintain healthy blood flow to the lower leg and

foot (Cronenwett & Johnston, 2010). The bypass, which is made of a PTFE prosthetic graft or

autologous vein, connects the superficial femoral artery or common femoral artery to the distal

popliteal artery or peroneal artery (Huang et al., 2007). Surgeons select the inflow and outflow

sites on a case-by-case basis depending upon the patient anatomy and size of the PAA (Hamish

et al., 2006). Hamish et al. (2006) and Huang et al. (2007) agreed that utilization of the

autologous vein poses lower risks of post-operative complications in comparison to the

utilization of a prosthetic graft. If the patient is classified low-risk in terms of operative health,

surgeons will opt to harvest the great saphenous vein (GSV) for use as the autologous vein for


the bypass graft (Cronenwett & Johnston, 2010).

Endovascular Stent Graft Approach to Repairing PAAs

In 1994, the option of an endovascular repair through the interposition of a palmaz stent

covered with a PTFE graft became available (Cronenwett & Johnston, 2010). Since the first

endovascular repair in 1994, researchers have suggested in various reports that endovascular

repairs are equally as effective as open repairs, or possibly even more effective (Lovegrove et al.,

2008). The most commonly used stent graft is the Hemobahn graft (W. L. Gore & Associates,

Flagstaff, Arizona; Antonello et al., 2005). The Hemobahn graft is built with a unique self-

expanding nitinol stent (Antonello et al., 2005). The nitinol stent within the Hemobahn graft has

a wide range of flexibility and radial stiffness, making it a good candidate for a bypass placed

behind the constantly flexing knee joint (Antonello et al., 2005).

In an endovascular approach, surgeons make a small incision in the groin, and feed a

catheter through the superficial femoral artery to the popliteal artery ("Endovascular Stent Graft,"

n.d.). Surgeons feed the stent graft into the catheter and position it by using contrast dye and x-

ray imaging ("Endovascular Stent Graft," n.d.). Once correctly positioned, the surgeon deploys

the stent graft and expands the graft with a balloon to ensure a tight seal to the arterial walls

above and below the PAA ("Endovascular Stent Graft," n.d.). If the stent graft is not long

enough, the surgeon may have to insert and overlap multiple grafts (Tielliu et al., 2010).

However, surgeons should avoid overlapping the graft as doing so increases the chances of

kinking or thrombosing in the graft (Tielliu et al., 2010).

Findings of Past Studies Comparing Open and Endovascular Repairs

Within the medical community, there is debate over the relative superiority of

endovascular stent graft repairs and open bypass repairs (Cronenwett & Johnston, 2010). Each


procedure has different types of post-operative complications and recovery times (Cronenwett &

Johnston, 2010). Taurino et al. (2013) concluded that as long as the surgeon correctly ligates the

aneurysm, a patient who receives an open bypass repair will experience a low rate of post-

operative complications. Conversely, Rosenthal, Matsuura, Clark, Kirby, and Knoepp (2000)

believed the endovascular approach is the appropriate repair in all cases because the

endovascular repair does not require the long incisions required for the open bypass repair,

avoids most wound complications due to the small size of the incision made in the groin, and

usually results in a substantially shorter stay in the hospital. Mohan et al. (2006) and Antonello

et al. (2005) compromised after their studies and agreed that both procedures were good for

various reasons. However, the authors believed that as technology in grafts advances, the

endovascular approach will become the superior repair (Mohan et al. 2006; Antonello et al.

2005). Lovegrove et al. (2008) concluded that neither procedure is superior, and that each

patient needs to be examined on an individual basis in order to determine which procedure is

appropriate per the patient’s anatomy, current health, and lifestyle and will result in the fewest

post-operative complications.

Limiting Factors in Past Studies

Unfortunately for researchers, PAAs are rare and therefore finding data on enough PAA

patients to calculate statistically significant results can be difficult (Siauw et al., 2006). Many of

the studies on this topic contain data that cover a 10 to 20 year time span. A time span of this

length adds numerous confounding variables into the data due to advances in medicine and the

learning curve placed on new procedures (Curl et al., 2007).

Summary

PAAs are the most common type of peripheral artery aneurysm. Surgeons commonly


perform endovascular stent graft repairs and open bypass repairs for PAA repair (Cronenwett &

Johnston, 2010). While a PAA does not pose a high risk of rupturing, it can suddenly thrombose

and obstruct blood flow to the lower leg and foot. The thrombosis may cause severe ischemia

which can result in the necessary amputation of the afflicted limb (Mosquera, 2013). Correctly

diagnosing PAAs can be difficult due to their infrequency (Hamish et al., 2006), however

medical professionals may use duplex ultrasonagraphy to quickly image and diagnose a PAA

(Cronenwett & Johnston, 2010). Once a medical professional confirms a PAA, he may utilize

more detailed imaging in order to indentify the appropriate treatment method for the individual

patient (Cronenwett & Johnston, 2010). With the surgical treatment of PAAs, surgeons aim to

isolate and exclude the aneurysm and allow for the restoration of effective blood flow to the

lower extremities (Cronenwett & Johnston, 2010). An open bypass repair for PAAs involves the

ligation of the aneurysm and interposition of a bypass graft to maintain healthy blood flow to the

lower leg and foot (Cronenwett & Johnston, 2010). In an endovascular approach, a surgeon

makes a small incision in the groin, and feeds a catheter through the superficial femoral artery to

the popliteal artery ("Endovascular Stent Graft," n.d.). The surgeon positions the stent graft

inside the PAA, and the graft acts as an internal bypass for blood flow ("Endovascular Stent

Graft," n.d.). Unfortunately for researchers, PAAs are rare and therefore finding data on enough

PAA patients to calculate statistically significant results can be difficult (Siauw et al., 2006).

Research Method

A qualitative exploratory case study was the proposed research method for this study. An

exploratory case study is appropriate when the researcher cannot provide a clear or single set of

outcomes for the treatment (Yin, 2003). It is unclear whether an endovascular repair or an open

repair results in a higher rate of post-operative complications (Cronenwett & Johnston, 2010).


Therefore, an exploratory case study was suitable for this study. A qualitative case study is most

suitable for studies in which the compiled data are limited but detailed (Leedy & Ormrod, 2005).

Therefore, a qualitative case study was suitable for this study. In this study, I evaluated the

endovascular stent graft repair and open bypass repair on multiple parameters– the relative rates

of post-operative infection, post-operative endoleaks, post-operative thrombosis, post-operative

stenosis, and necessity for reintervention. I collected all cases of PAA repairs from January 2010

to December 2012 at a vascular surgical office in a large suburban county in Georgia through

convenience sampling. When sampling by convenience, the researcher only collects data that

are easily available rather than randomly collecting data that are representative of the population

as a whole (Leedy & Ormrod, 2005). The limited time given to complete this study, the

limitations of medical privacy, and the low rates of occurrences of PAAs made a convenience

sampling method the only practical data collection method. Due to the limited available sample,

each case consisted of one PAA repair and corresponding results. Consequently, one patient

may have consisted of multiple cases if the patient had more than one PAA repair or required

reintervention of a stent graft or bypass.

Population and Sample

When researchers utilize convenience sampling to collect data, they cannot apply the

observed trends to a larger population (Leedy & Ormrod, 2005). Since the method of data

collection was convenience sampling, I could not apply the results of this study to the total

population of PAA repairs. The population in this study was limited to all PAA repairs

performed by a vascular surgical office in a large suburban county in Georgia. The convenience

sample included all endovascular stent graft and open bypass repairs of PAAs from January 2010

to December 2012 at a vascular surgical office in a large suburban county in Georgia. Within


these confines, surgeons performed 10 open bypass repairs and 13 endovascular stent graft

repairs on 16 males from the ages 62 to 85 years.

Instrumentation

I utilized the online database of Vascular Surgical Associates’ patients, Allscripts

Professional EHR with Citrix Clinical Modules. A Vascular Surgical Associates secretary culled

patient records and identified 16 patients who had undergone endovascular stent graft repairs or

open bypass repairs for PAAs and compiled a list of those patients. I employed the online

database to access the identified patient records and evaluate their treatments of PAAs.

Data Collection Procedure

In this qualitative exploratory case study, I collected the convenience sample by

gathering information on PAA repairs from the online database, Allscripts Professional EHR. A

secretary at Vascular Surgical Associates utilized search criteria to locate qualified patient’s

records. The secretary searched for all patients diagnosed with PAAs (database code 442.3) who

had undergone open bypass repairs or endovascular stent graft repairs (database codes 37226,

35152, and 35151) within the service dates January 1, 2010 through December 31, 2012.

Sixteen patients matched these criteria and the secretary provided their patient numbers to me. I

logged onto a doctor’s computer in the Vascular Surgical Associates office in Marietta, Georgia

and logged into Allscripts Professional EHR clinical module using the doctor’s credentials. I

utilized the patient numbers to pull digital patient charts and gather data concerning their PAA,

treatment of the PAA, and post-operative complications. I examined each patient’s history and

recorded the age, gender, type of PAA repair, and the presence or lack of the following: post-

operative infection, post-operative endoleaks, post-operative thrombosis, post-operative stenosis,

and necessary reintervention for a poorly functioning stent graft or bypass. I collected data


intermittently over the course of 4 weeks.

Analysis Plan

I grouped data for each procedure and examined each endovascular stent graft repair or

open bypass repair as an individual case in this qualitative exploratory case study. Examining

the data in this way resulted in 23 total cases: 10 open bypass repairs and 13 endovascular stent

graft repairs performed on 16 males from the ages 62 to 85. I catalogued and calculated

percentages for the respective number of post-operative infections, post-operative endoleaks,

post-operative thrombosis, post-operative stenosis, and necessity for reintervention for each

procedure. Researchers cannot compute statistical analysis with small samples (Leedy &

Ormrod, 2005). Due to the rarity of PAAs and the resulting small number of cases available for

analysis through Vascular Surgical Associates, I could not compute statistical analysis with this

data set. According to the protocol for qualitative analysis, researchers may only observe trends

and patterns with small data sets (Leedy & Ormrod, 2005). I utilized the trends and patterns

observed in this study to draw casual conclusions or generalizations about the population.

Assumptions

A necessary assumption was that the doctors, physician’s assistants, and surgeons at

Vascular Surgical Associates correctly diagnosed patients with PAAs. This assumption is

acceptable because all employees at Vascular Surgical Associates who may have diagnosed the

patients are trained professionals. It was also necessary to assume that patient records were

accurate concerning basic patient information, history, PAA treatment, and post-operative care of

the PAAs. I warranted this assumption because health care professionals make it a priority to

truthfully and accurately record patient information, and insurance companies require accurate

information for their coverage. For the purposes of this study, I assumed that all surgeons


performed the endovascular stent graft repairs and open bypass repairs to the same standards and

with the same amount of care. I made this assumption because of the standardized procedural

protocol that exists for both repairs. I also assumed that all post-operative complications relate

directly to the repair of a PAA with an endovascular stent graft or an open bypass, instead of an

outstanding medical condition or failure to follow post-operative orders from the surgeons.

While this assumption may have decreased the validity of the study, it was necessary in order to

make generalizations or draw casual conclusions. There was no way to quantify a patient’s

noncompliance, and most patients do not report their noncompliance to doctors, thus the doctors

did not record the information the patients’ charts.

Limitations

Patient confidentiality, sampling method, and sample size limited this study. The

restraints of patient confidentiality prevented the collection of data from patient records not

directly affiliated with Vascular Surgical Associates. This necessitated convenience sampling

and led to a small sample size for endovascular repairs and open repairs. Convenience sampling

made it impossible to generalize the results of this study beyond patients treated at the

experiment location. Researchers cannot compute statistical analysis on small samples and,

without statistical data, they can only draw casual conclusions (Leedy & Ormrod, 2005).

Therefore, I drew only casual conclusions from the data in this study.

Delimitations

For the purpose of this study, I did not consider patient history and current medical

conditions. Although a history of smoking, drug abuse, alcoholism, hypertension, blood clotting

disorders, or heart disease can affect the effectiveness of an open bypass repair or endovascular

stent graft repair, time restraints prevented the collection and analysis of this data.


Ethical Assurances

I closely followed ethical guidelines associated with medical research. I maintained

patient identity and confidentiality. I completed all necessary Wellstar and Vascular Surgical

Associates paperwork prior to commencing data collection and followed all Wellstar and

Vascular Surgical Associates research protocols during data collection. I carefully and precisely

collected all data to ensure the correct data retained its original association to particular patients

and procedures. I did not falsify any data. I reported and referenced all information truthfully.

Summary

A qualitative exploratory case study was the proposed research method for this study.

The population in this study was limited to all PAA repairs performed by a vascular surgical

office in a large suburban county in Georgia. The convenience sample included all endovascular

stent graft repairs and open bypass repairs of PAAs from January 2010 to December 2012 at a

vascular surgical office in a large suburban county in Georgia. Within these confines, surgeons

performed 10 open bypass repairs and 13 endovascular stent graft repairs on 16 males from the

ages 62 to 85. I utilized an online database to examine each patient’s history and record the age,

gender, type of PAA repair, and the presence or lack of the following: post-operative infection,

post-operative endoleaks, post-operative thrombosis, post-operative stenosis, and necessary

reintervention for a poorly functioning stent graft or bypass. I catalogued and calculated

percentages for the respective number of post-operative infections, post-operative endoleaks,

post-operative thrombosis, post-operative stenosis, and reinterventions for each. I qualitatively

analyzed the results and made generalizations about endovascular stent graft repairs and open

bypass repairs.

Findings


The goal of this research was to compare the post-operative complication rates of open

bypass repairs and endovascular stent graft repairs of PAAs in order to determine if an

endovascular repair or open repair results in a lower post-operative complication rate, thus

indicating that one procedure is safer. In this study, the relative post-operative complication

rates differed for each procedure, prompting the need for further research on the matter. With

further research, evidence could be found to support that one treatment is safer than the other,

and doctors may be encouraged to select the safer repair with knowledge of the lower post-

operative complication rate. For the purposes of this study, I defined the safer repair as the

repair that resulted in fewer post-operative complications. To assess the post-operative

complications rates for open bypass repairs and endovascular stent graft repairs, I utilized an

online database to examine each patient’s history and record the age, gender, type of PAA repair,

and the presence or lack of the following: post-operative infection, post-operative endoleaks,

post-operative thrombosis, post-operative stenosis, and necessary reintervention for a poorly

functioning stent graft or bypass. I catalogued and calculated percentages for the respective

number of post-operative infections, endoleaks, thrombosis, stenosis, and necessity for

reintervention for each procedure. I employed these percentages to determine if one procedure

resulted in a lower post-operative complication rate.

Results

A total of 23 cases were included in the sample. I detailed all collected data in Table 1

and Table 2. Of which, 10 were open bypass repairs, and 13 were endovascular stent graft

repairs. The age range of patients was 62-85 years, and the average age was 73.81 years. The

sample consisted of only males. Ten percent of open bypass repairs resulted in infection (one

out of ten cases). Conversely, 7.69% of endovascular stent graft repairs resulted in infection


(one out of 13 cases). Zero percent of open bypass repairs resulted in endoleaks (zero out of ten

cases). 15.38% of endovascular stent graft repairs resulted in endoleaks (two out of 13 cases).

Thirty percent of open bypass repairs resulted in thrombosis (three out of ten cases). 38.46% of

endovascular stent graft repairs resulted in thrombosis (five out of 13 cases). Thirty percent of

open bypass repairs resulted in stenosis (three out of ten cases). 15.38% of endovascular stent

graft repairs resulted in stenosis (two out of 13 cases). Thirty percent of open bypass repairs

required reintervention (three out of ten cases). 23.07% of endovascular stent graft repairs

required reintervention (two out of 13 cases). I summarized a comparison of the percentages in

Figure 1.

Percentage of cases with in-

fection

Percentage of cases with endoleak

Percentage of cases with thrombosis

Percentage of cases with stenosis

Percentage of cases requiring reintervention

0

5

10

15

20

25

30

35

40

45

Open bypass repair

Endovascular stent graft repair

Figure 1. Comparison of post-operative complication rates of open bypass repairs and endovascular stent graft repairs for PAAs.

Figure 1 depicts that open bypass repairs resulted in higher post-operative complication

rates than endovascular stent graft repairs in three of the five categories: infection, stenosis, and

necessity of reintervention. Endovascular stent graft repairs resulted in higher post-operative

complication rates than open bypass repairs in the two of the five categories: endoleaks and


thrombosis.

Evaluation of Findings

Researchers cannot compute statistical analysis with small samples (Leedy & Ormrod,

2005). Therefore, I could not compute statistical analysis with the data in this study. According

to the protocol for qualitative analysis, researchers may only observe general trends and patterns

in the data (Leedy & Ormrod, 2005). Open bypass repairs resulted in higher post-operative

complication rates than endovascular stent graft repairs in three of the five categories, while

endovascular stent graft repairs resulted in higher post-operative complication rates than open

bypass repairs in two of the five categories. Convenience sampling and a small sample size can

lead to error (Leedy & Ormrod, 2005), and consequently there was an expected amount of error

within the data. It is possible that sampling error attributed to the differences in the post-

operative complication rates. Lovegrove et al. (2008) concluded that neither procedure results in

a higher post-operative complication rate, and that a surgeon should examine each patient

individually in order to determine which procedure is appropriate per the patient’s anatomy,

current health, and lifestyle. Mohan et al. (2006) and Antonello et al. (2005) agreed that neither

procedure was safer; however, as technology in grafts advances, the endovascular approach will

become the superior repair.

Summary




indicating that one procedure is safer. Researchers cannot compute statistical analysis with small

samples (Leedy & Ormrod, 2005). Therefore, I could not compute statistical analysis with the


data in this study. According to the protocol for qualitative analysis, researchers may only

observe general trends and patterns in the data (Leedy & Ormrod, 2005). A total of 23 cases

were included in the sample. Of which, 10 were open bypass repairs, and 13 were endovascular

stent graft repairs. Open bypass repairs resulted in higher post-operative complication rates than

endovascular stent graft repairs in three of the five categories: infection, stenosis, and necessity

of reintervention. Endovascular stent graft repairs resulted in higher post-operative complication

rates than open bypass repairs in the two of the five categories: endoleaks and thrombosis.

Implications, Recommendations, and Conclusions


and allow for the restoration of effective blood flow to the lower extremities (Antonello et al.,

2005). Within the medical community there is debate regarding the relative superiority of

endovascular stent graft repairs and open bypass repairs (Cronenwett & Johnston, 2010). The

goal of this research was to compare the post-operative complication rates of open bypass repairs

and endovascular stent graft repairs of PAAs in order to determine if an endovascular repair or

open repair results in a lower post-operative complication rate, thus indicating that one procedure

is safer. A qualitative exploratory case study was the research method for this study. I utilized

an online database to examine each patient’s history and record the age, gender, type of PAA

repair, and the presence or lack of the following: post-operative infection, post-operative

endoleaks, post-operative thrombosis, post-operative stenosis, and necessary reintervention for a

poorly functioning stent graft or bypass. A total of 23 cases were included in the sample. I

detailed all collected data in Table 1 and Table 2. Of which, 10 were open bypass repairs, and 13

were endovascular stent graft repairs. The overall age range of patients was 62-85 years, and the

average age was 73.81 years. Researchers cannot compute statistical analysis with small


samples (Leedy & Ormrod, 2005). Therefore, I could not compute statistical analysis with the

data in this study. According to the protocol for qualitative analysis, researchers may only

observe general trends and patterns in the data (Leedy & Ormrod, 2005).

Implications

In this study, I utilized an online database to examine each patient’s history and record

the age, gender, type of PAA repair, and the presence or lack of the following: post-operative

infection, post-operative endoleaks, post-operative thrombosis, post-operative stenosis, and

necessary reintervention for a poorly functioning stent graft or bypass. I catalogued and

calculated percentages for the respective number of post-operative infections, post-operative

endoleaks, post-operative thrombosis, post-operative stenosis, and reinterventions. I observed

general trends in the data and made generalizations about endovascular stent graft repairs and

open bypass repairs.

Concerning post-operative infection, 10% of open bypass repairs resulted in infection,

and 7.69% of endovascular stent graft repairs resulted in infection. A difference of 2.31% does

not imply a substantial difference between the two procedures. Researchers attributed these

similar rates of post-operative infection to the easy access to effective and inexpensive

antibiotics (Taurino et al., 2013). The similar rates contradict the conclusion made by Rosenthal

et al. (2000). Rosenthal et al. (2000) believed that the endovascular approach avoids most

wound complications because it does not require the long incisions required for the open bypass

repair. Regarding post-operative endoleaks, 0% of open bypass repairs resulted in endoleaks,

and 15.38% of endovascular stent graft repairs experienced endoleaks. Due to the ballooning

process involved in the insertion of an endovascular stent graft, a higher rate of post-operative

endoleaks is expected ("Endovascular Stent Graft," n.d.).


Of the total cases, 30% of open bypass repairs resulted in post-operative thrombosis of

the bypass, and 38.46% of endovascular stent graft repairs resulted in post-operative thrombosis

of the stent graft. Post-operative thrombosis of the stent graft is a common concern of vascular

surgeons and a high rate of post-operative thrombosis for endovascular repairs should be

expected ("Endovascular Stent Graft," n.d.). Conversely, post-operative thrombosis is not a

common occurrence in open bypasses (Cronenwett & Johnston, 2010). Nevertheless, 30% of

open bypass repairs resulted in post-operative thrombosis of the bypass. Such a starch

contradiction between the results of this study and the existing literature written by Cronenwett

and Johnson (2010) reveals the need for further research on the subject.

Concerning post-operative stenosis of the graft, 30% of open bypass repairs resulted in

post-operative stenosis of the bypass, and 15.38% of endovascular stent graft repairs resulted in

post-operative stenosis of the stent graft. I attribute the higher rate of post-operative stenosis in

open bypass repairs to the use of a prosthetic bypass instead of an autologous bypass. Hamish et

al. (2006) and Huang et al. (2007) agreed that utilization of the autologous vein poses lower risks

of post-operative complications in comparison to the utilization of a prosthetic graft.

Of the total cases reintervention, 30% of open bypass repairs required reintervention, and

23.07% of endovascular stent graft repairs required reintervention. The difference between these

two rates is the most significant of the study. While the other post-operative complications may

cause the patient undue difficulties and require extra treatment, therapy, or medication, the

necessity for reintervention requires an entire additional procedure that involves more anesthesia,

medication, recovery, and an additional stay in the hospital. For patients who are elderly and in

poor health, reintervention causes undue stress to their bodies (Cronenwett & Johnston, 2010).

The relative rates of a necessity for reintervention differed by 6.93%. A difference of nearly 7%


calls into question the claims made by Lovegrove et al. (2008) and Cronenwett & Johnston

(2010) who stated that there is no difference in post-operative complication rates or the necessity

for reintervention between open bypass repairs and endovascular stent graft repairs. The

contradictions between the results of this study and the existing literature written by Cronenwett

and Johnson and Lovegrove et al. reveal the need for further research on the subject.

Recommendations

Some of the general trends observed in this study contradict the observations made by

Rosenthal et al. (2000), Cronenwett and Johnston (2010), and Lovegrove et al. (2008). The most

extreme contradictions occurred in the post-operative thrombosis rates of open bypass repairs

and the relative difference between the rates of necessity for reintervention between open bypass

repairs and endovascular stent graft repairs. An experimental study that includes a large, random

sample alleviates the stress of confounding variables (Leedy & Ormrod, 2005), and hence should

be utilized to draw firm conclusions in the presence of the confounding variables inherent to a

medical study. Such a study could contain much needed statistically significant data that

researchers could formulate into concrete conclusions. Additionally, future researchers should

conduct studies that are not limited by patient confidentiality and lack of access to certain patient

records. With unlimited access to patient records, the researcher could discern the pre-operative

condition of the aneurysm. Researchers should asses the pre-operative size of the aneurysm and

the pre-operative thrombosis or stenosis since these could have confounding effects on the post-

operative complication rates. With unlimited access to patient records, it may be possible to

determine the compliance of each patient concerning his/ her own post-operative care. After the

treatment of PAAs, medical professionals prescribe most patients an anti-coagulant medication

and a certain amount of exercise to accomplish each day (Cronenwett & Johnston, 2010). While


some patients are compliant and follow the surgeon’s orders closely, others are non-compliant.

The patient’s compliancy with the surgeons orders have a direct result on the post-operative

complications the patient will experience. The ability to assess the compliance of each patient

will alleviate the effect of confounding variables on the final rates of post-operative complication

rates.

Conclusion




indicating that one procedure is safer. A qualitative exploratory case study was the research

method for this study. I utilized an online database to examine each patient’s history and record

the age, gender, type of PAA repair, and the presence or lack of the following: post-operative

infection, post-operative endoleaks, post-operative thrombosis, post-operative stenosis, and

necessary reintervention for a poorly functioning stent graft or bypass. Some of the general

trends observed in this study contradict the observations made by Rosenthal et al. (2000),

Cronenwett and Johnston (2010), and Lovegrove et al. (2008). The most extreme contradictions

occurred in the post-operative thrombosis rates of open bypass repairs and the relative difference

between the rates of necessity for reintervention between open bypass repairs and endovascular

stent graft repairs. An experimental study that includes a large, random sample alleviates the

stress of confounding variables (Leedy & Ormrod, 2005), and hence should be utilized to draw

firm conclusions in the presence of the confounding variables inherent to a medical study.

Additionally, future researchers should conduct studies that are not limited by patient

confidentiality and lack of access to certain patient records.


References

Antonello, M., Frigatti, P., Battocchio, P., Lepidi, S., Cognolato, D., Dall'Antonia, A., ... Grego, F. (2005). Open repair versus endovascular treatment for asymptomatic popliteal artery aneurysm: Results of a prospective randomized study. Journal of Vascular Surgery, 42(2), 185-193. doi: 10.1016/j.jvs.2005.04.049

Arteriosclerosis. (2014). In Merriam-Webster. Retrieved from http://www.merriam-webster.com/dictionary/arteriosclerosis

Autologous [Def. 1]. (2014). In Merriam-Webster. Retrieved December 1, 2014, fromhttp://www.merriam-webster.com/dictionary/autologous

Cronenwett, J. L., & Johnston, K. W. (2010). Lower extremity aneurysms. In Rutherford's vascular surgery (7th ed., pp. 2110-2127). Philadelphia, PA: Saunders Elsevier.

Curl, M. A., Geraghty, P. J., Merino, O. A., Veeraswamy, R. K., Rubin, B. G., Sanchez, L. A., ... Sicard, G. A. (2007). Mid-term outcomes of endovascular popliteal artery aneurysm repair. Journal of Vascular Surgery, 45(3), 505-510. doi: 10.1016/j.jvs.2006.09.064

DeBakey, M. E. (2013, November 10). Aneurysm. In Encyclopedia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/24387/aneurysm

Distal [Def. 1a]. (2014). In Merriam-Webster Medical Dictionary. Retrieved fromhttp://www.merriam-webster.com/dictionary/distal

Ebaugh, J. L., Morasch, M. D., Matsumura, J. S., Eskandari, M. K., Meadows, W. S., & Pearce, W. H. (2003). Fate of excluded popliteal artery aneurysms. Journal of Vascular Surgery, 37(5), 954-959. doi: 10.1067/mva.2003.258

Endovascular stent graft. (n.d.). Retrieved from http://www.vascularweb.org/vascularhealth/Pages/endovascular-stent-graft.aspx

Hamish, M., Lockwood, A., Cosgrove, C., Walker, A. J., Wilkins, D., & Ashley, S. (2006). Management of popliteal artery aneurysms. ANZ Journal of Surgery, 76(10), 912-915. doi: 10.1111/j.1445-2197.2006.03903.x

Huang, Y., Gloviczki, P., Noel, A. A., Sullivan, T. M., Kalra, M., Gullerud, R. E., ... Bower, T. C. (2007). Early complications and long-term outcome after open surgical treatment of popliteal artery aneurysms: Is exclusion with saphenous vein bypass still the gold standard? Journal of Vascular Surgery, 45(4), 706-715. doi: 10.1016/j.jvs.2006.12.011

Ischemia. (2014). In Merriam-Webster. Retrieved from http://www.merriam-webster.com/medical/ischemia

Kirkpatrick, U. J., Mcwilliams, R. G., Martin, J., Brennan, J. A., Gilling-Smith, G. L., & Harris,


P. L. (2004). Late complications after ligation and bypass for popliteal aneurysm. British Journal of Surgery, 91(2), 174-177. doi: 10.1002/bjs.4426

Knipe, H., & Jones, J. (n.d.). Popliteal artery. Retrieved from http://radiopaedia.org/articles/popliteal-artery

Leedy, P. D., & Ormrod, J. E. (2005). Practical research planning and design (8th ed.). Upper Saddle River, NJ: Pearson.

Ligation [Def. 1a]. (2014). In Merriam-Webster. Retrieved from http://www.merriam-webster.com/medical/ligation?show=0&t=1410394972

Lovegrove, R. E., Javid, M., Magee, T. R., & Galland, R. B. (2008). Endovascular and open approaches to non-thrombosed popliteal aneurysm repair: A meta-analysis. European Journal of Vascular and Endovascular Surgery, 36(1), 96-100. doi: 10.1016/j.ejvs.2008.02.002

Medial [Def. 2b]. (2014). In Merriam-Webster. Retrieved December 1, 2014, fromhttp://www.merriam-webster.com/dictionary/medial

Mohan, I., Bray, P., Harris, J., May, J., Stephen, M., Bray, A., & White, G. (2006). Endovascular popliteal aneurysm repair: Are the results comparable to open surgery? European Journal of Vascular and Endovascular Surgery, 32(2), 149-154. doi: 10.1016/j.ejvs.2006.01.009

Morbidity. (2014). In Merriam-Webster. Retrieved from http://www.merriam-webster.com/medical/morbidity

Patency. (2014). In Merriam-Webster. Retrieved from http://www.merriam-webster.com/medical/patency

Physicians oaths. (n.d.). Retrieved from http://www.aapsonline.org/ethics/oaths.htm

Posterior [Def. 2b]. (2014). In Merriam-Webster. Retrieved December 1, 2014, fromhttp://www.merriam-webster.com/dictionary/posterior

Rosenthal, D., Matsuura, J. H., Clark, M. D., Kirby, L. B., & Knoepp, L. F. (2000). Popliteal artery aneurysms: Is endovascular reconstruction durable? Journal of Endovascular Therapy, 7(5), 394-398. doi: 10.1583/1545-1550(2000)0072.0.CO;2

Siauw, R., Koh, E. H., & Walker, S. R. (2006). Endovascular repair of popliteal artery aneurysms: Techniques, current evidence and recent experience. ANZ Journal of Surgery, 76(6), 505-511. doi: 10.1111/j.1445-2197.2006.03745.x

Stenosis. (2014). In Merriam-Webster. Retrieved from http://www.merriam-webster.com/medical/stenosis


Taurino, M., Filippi, F., Ficarelli, R., Fantozzi, C., Dito, R., Brancadoro, D., & Rizzo, L. (2013). Different approaches in popliteal artery aneurysm management. European Surgery, 45(4), 221-226. doi: 10.1007/s10353-013-0221-0

Thrombosis. (2014). In Merriam-Webster. Retrieved from http://www.merriam-webster.com/medical/thrombosis

Tielliu, I. F., Zeebregts, C. J., Vourliotakis, G., Bekkema, F., Van den Dungen, J. A., Prins, T. R., & Verhoeven, E. L. (2010). Stent fractures in the Hemobahn/viabahn stent graft after endovascular popliteal aneurysm repair. Journal of Vascular Surgery, 51(6), 1413-1418. doi: 10.1016/j.jvs.2009.12.071

What Is an Aneurysm? (2011, April 1). Retrieved from http://www.nhlbi.nih.gov/health/health-topics/topics/arm/

Yin, R. K. (2003). Case study research: Design and methods (3rd ed.). Thousand Oaks, CA: Sage.


Appendix A: All Collected Data

Table 1

Post-Operative Complication Information from Vascular Surgical AssociatesOpen Bypass Repairs Dating from January 2010 through December 2012Case number Infection Endoleaks Stenosis Thrombosis Reintervention

1 - - - - -2 - - - + +3 - - - - -4 - - - - -5 - - + - -6 - - - - -7 - - + - +8 - - - - -9 - - - + +10 + - - + -

Note. A dash mark (-) denotes the repair did not result in the post-operative complication. A plus sign (+) denotes the repair resulted in the post-operative complication.

Table 2

Post-Operative Complication Information from Vascular Surgical AssociatesEndovascular Stent Graft Repairs Dating from January 2010 through December 2012Case number Infection Endoleaks Stenosis Thrombosis Reintervention

11 - - + - -12 - - - + -13 - - - - -14 + + - - -15 - - - - -16 - - - - -17 - - - + +18 - - - + +19 - - - + -20 - - - - -21 - - - - -22 - + - + -23 - - + - -

Note. A dash mark (-) denotes the repair did not result in the post-operative complication. A plus sign (+) denotes the repair resulted in the post-operative complication.

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