Ultrasound Evaluation for Baxter VASCU-GUARD Vascular Patches Post-Endarterectomy and Complications Assessment
Conditions: Carotid Endarterectomy (CEA) Surgical Patients
Sponsor: The Methodist Hospital Research Institute

PROTOCOL TITLE: Ultrasound Evaluation for Baxter VASCU-GUARD Vascular Patches 
Post-Endarterectomy and Complications Assessment
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PROTOCOL TITLE:
Ultrasound Evaluation for Baxter VASCU-GUARD Vascular Patches Post-Endarterectomy 
and Complications Assessment
PRINCIPAL INVESTIGATOR 
Maham Rahimi, MD / Houston Methodist Hospital-TMC / MDHVC-Cardiovascular Surgery
CO-INVESTIGATORS/ COLLABORATORS:
Zsolt Garami, MD/ Houston Methodist Hospital-TMC / MDHVC-Cardiovascular Surgery 
Diana Husvethova, MD/ Houston Methodist Hospital-TMC / MDHVC-Cardiovascular 
Surgery
SPONSOR / FUNDING AGENCY 
 Investigator-Initiated Protocol - Funding source for project currently Baxter International
VERSION NUMBER/DATE 
Version 1 – Initial Submission
REVISION HISTORY
N/A
Revision #
Version Date
Summary of Changes
Consent Change
(Yes/No)

PROTOCOL TITLE: Ultrasound Evaluation for Baxter VASCU-GUARD Vascular Patches 
Post-Endarterectomy and Complications Assessment
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1. Study Summary 
Peripheral Arterial Disease (PAD) refers to disorders characterized by progressive stenosis and 
altered structure and function of non-coronary arteries that supply the brain, visceral organs, 
and limbs. PAD is most commonly caused by atherosclerosis and plaque buildup. 
Endarterectomy is a surgical intervention intended to address the narrowing or blockage of 
arteries caused by plaque buildup. Its goal is to enhance blood flow in affected areas and relieve 
associated symptoms. Various types of vascular patches are used during endarterectomies to 
reinforce vessel walls, repair arterial defects, reduce the risk of restenosis, and improve patient 
outcomes. 
Postoperative surveillance, particularly through non-invasive ultrasound imaging, is essential for 
monitoring vascular patches' integrity and identifying potential complications. Ultrasound 
provides high-resolution visualization, enabling clinicians to detect abnormalities such as leaks or 
thrombosis early on. The non-invasive nature of ultrasound minimizes patient discomfort and 
allows for timely intervention, ultimately optimizing patient outcomes following vascular 
procedures.
VASCU-GUARD vascular patches by Baxter International Inc. are commonly used in the operating 
room. In November 2022, a package change has been made in the USA. Previously, each VASCU-
GUARD patch was chemically sterilized and packaged in a jar filled with sterile, non-pyrogenic 
water containing propylene oxide. With the implementation of the new packaging, the patch is 
terminally sterilized via gamma irradiation and comes in a double-pouch system (where the 
contents of the outer pouch are sterile). The inner pouch maintains the bovine pericardium 
patch’s moisture while packaged, and it doesn’t contain any water or solution. 
VASCU-GUARD vascular patches with the new packaging have been available at the Houston 
Methodist Hospital since January 2023. This study is a retrospective chart review, aiming to 
compare the performance of Baxter VASCU-GUARD vascular patches implemented during 
carotid endarterectomies (CEA) prior to January 2023 and after January 2023. This study is one 
of a kind, as no other comparative retrospective chart review on the performance of VASCU-
GUARD vascular patches from the old and new packaging has been published yet. 
The project will contribute to the scientific knowledge about long-term outcomes associated 
with the use of patch material during endarterectomies.
2. Purpose of the Study / Objectives 

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Post-Endarterectomy and Complications Assessment
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Primarily focusing on the implementation of VASCU-GUARD vascular patches in carotid 
endarterectomies (CEA), the study aims to identify VASCU-GUARD patches with old (before 
January 2023) and new (after January 2023) packaging and compare the results of standard-of-
care exams between the two groups.
The objectives of this study include:
Ultrasound evaluation of Baxter VASCU-GUARD vascular patches:
Retrospective review of ultrasound recordings and ultrasound reports at one-month, 3-months, 
6-months and 1-year follow-up after endarterectomy – if available, to evaluate patch patency, 
morphology, integrity, complications, and blood flow dynamics.
Complications assessment:
Analyze complications linked with Baxter Vascular Patches (VASCU-GUARD), including but not 
limited to thrombosis, stroke, dissection, restenosis, infection, fluid collection, pseudoaneurysm 
formation, fraying or irregularities in patch material.
Correlation with Clinical Outcomes:
Recognize correlations between ultrasound findings and clinical outcomes. This correlation will 
complement the understanding of how ultrasound monitoring can predict and influence patient 
prognosis.  
3. Background
Peripheral artery disease (PAD) results in the buildup of plaque in the arteries, leading to a 
disruption of blood flow to the head, organs, and limbs. In the US, it affects approximately 8.5 
million people, predominantly those over the age of 40, and contributes significantly to 
healthcare costs, amounting to tens of billions of dollars annually.
Endarterectomy is a surgical procedure, during which atherosclerotic plaque from the inner 
lining of arteries is removed. The objective of endarterectomies is to improve blood flow in 
affected territories and to alleviate symptoms. The use of vascular patches in these interventions 
has become standard practice to reinforce vessel walls, repair arterial defects, reduce the risk of 
restenosis, and improve patient outcomes. Postoperative surveillance, especially through 
ultrasound imaging, plays a pivotal role in monitoring the efficacy of these vascular patches and 
identifying potential complications. 
VASCU-GUARD vascular patches by Baxter International Inc. are commonly used in the operating 
room. In November 2022, a packaging change was made in the USA. Before November 2022, 
each VASCU-GUARD patch was chemically sterilized and packaged in a jar filled with sterile, non-
pyrogenic water containing propylene oxide. With the new packaging, the patch is terminally 

PROTOCOL TITLE: Ultrasound Evaluation for Baxter VASCU-GUARD Vascular Patches 
Post-Endarterectomy and Complications Assessment
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sterilized via gamma irradiation and comes in a double-pouch system (where the contents of the 
outer pouch are sterile). The inner pouch maintains the bovine pericardium patch’s moisture 
while packaged, and it doesn’t contain any water or solution. 
VASCU-GUARD vascular patches with the new packaging have been available at the Houston 
Methodist Hospital since January 2023. This study is a retrospective chart review aimed at 
comparing the performance of Baxter VASCU-GUARD vascular patches used in carotid 
endarterectomies (CEA) prior to January 2023 and after January 2023. This study is one of a kind, 
as no other comparative retrospective chart review on the performance of VASCU-GUARD 
vascular patches from the old and new packaging has been published yet. 
Ultrasound provides high-resolution visualization, enabling clinicians to detect abnormalities 
such as leaks or thrombosis early on. The non-invasive nature of ultrasound minimizes patient 
discomfort and allows for timely intervention, ultimately optimizing patient outcomes following 
vascular procedures.
Figure 1. Ultrasound showing pseudoaneurysm formation directly from the patch material. Left – 
true lumen is measured with yellow crosses. Right – “Pepsi sign” on color Doppler in the context 
of bidirectional flow from a pseudoaneurysm.

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Post-Endarterectomy and Complications Assessment
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Figure 2. Ultrasound showing irregularities in the patch material due to infection.
4. Study Design
This study is a retrospective chart review. The data is collected from January the 1st 2022 till April 
the 30th 2024. 
Medical Records Review
Baseline information, operative information, and outcomes will be determined via retrospective 
review of medical records. Data obtained via medical record review will include demographic 
information (age, gender, ethnicity), baseline clinical information (medical co-morbidities, 
medications, history of underlying cause of peripheral artery disease, etc.) data on the operation 
(date of operation/procedure, discharge date, surgeons name, anatomical site, campus where 
the surgery was performed, type of anesthesia, intraoperative blood pressures, estimated blood 
loss, intraoperative complications, etc.), results of standard-of-care exams.
Data Processing Procedure
The data collectors will complete the data forms and review all items for accuracy.  All 
information will be entered into an electronic excel database created for the study.
Statistical Analysis
A retrospective chart review will be conducted on a maximum of 500 patients. Analyzing data 
from 500 patients will provide a robust baseline to conduct a study of differences, similarities, 
and trends among the patients. All information will be entered into an electronic excel database 
created for the study and analyzed in STATA statistical program. All subjects meeting eligibility 
criteria will be enrolled.
The data will be abstracted from Houston Methodist Hospital electronic medical records, 
DigiView and from the MCVSA office charts by the PI and trained members of his research staff. 
The required information will be transferred from electronic medical records by the research 
staff to the study specific electronic Excel data collection forms. 

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Post-Endarterectomy and Complications Assessment
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Permission to review medical records will be obtained from the Houston Methodist Hospital 
Research Institute (TMHRI) Human Subjects Committee via a HIPAA Waiver of Authorization and 
Waiver of Consent. 
Data to be collected:

Age at surgery, sex, race

Preoperative risk factors: HTN, DM, TIA, CAD, HLD, previous strokes, previous 
thromboembolic events, previous surgeries

Intraoperative data: Type of patch material used, intraoperative complications (if any), 
MAP, Heart rate, Medications given, Estimated blood loss, Intraoperative antibiotics 
given, Intraoperative antiplatelet/anticoagulation medication given

Postoperative outcomes: Stroke/TIA, Postop ICU time, mortality (up to 30 days)

Follow up neurological evaluation, any symptoms reported by the patient

Imaging: MRI/CT, MRA, CTA, TCD, vascular duplex ultrasound
Postoperative ultrasound follow-up: 

ultrasound assessment of the vascular patch: patch patency, morphology, integrity, 
complications, and blood flow dynamics.

detection of complication: thrombosis, dissection, restenosis, infection, fluid collection, 
pseudoaneurysm formation, fraying or irregularities in patch material

repeat ultrasound assessment: morphological changes in the vascular patch, evolution of 
blood flow dynamics, signs of restenosis or complications

Data obtained from duplex ultrasound: wall thickness, presence of plaque, lumen 
diameter, peak systolic velocity (PSV), end-diastolic velocity (EDV), mean flow velocity 
(MFV), pulsatility index (PI), direction of blood flow, velocities, degree of stenosis
5. Study Intervention 
N/A. Retrospective chart review of standard-of-care exams.
6. Drugs, Biologics, Devices 
N/A
7. Collaborative / Multi-site Research
N/A – Investigator Initiated Project

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8. Data Privacy / Confidentiality 
Required for all protocol types including Sponsored trials.  Provide local information. 
The data will be abstracted from Houston Methodist Hospital electronic medical records by the 
PI and trained members of his research staff.  The required information will be transferred from 
electronic medical records by the research staff to the study specific data collection forms.
Study data will be registered into an electronic, password protected database located on the 
TMHS server accessible only by the research team, applicable regulatory personnel and 
authorities.
Documents requiring an investigator's signature, should any be created, will be promptly signed, 
and dated in real-time. In accordance with departmental policies, research-specific documents 
will be retained on-site for 6 years post-study closure. 
No images, video recordings, or photographs of patients will be requested for this study. Study 
will remain minimal risk with provisions to limit the risk of loss of confidentiality, outlined in 
section 17. Minimal PHI identifiers will be utilized to build the cohort. Identifies will not be 
utilized for cohort analysis. Sufficient security and data privacy measures will be implemented in 
terms of data collection, processing, storing, and maintaining the database as per the 
institutional policies and the regulations of the Health Insurance Portability and Accountability 
Act of 1996 (HIPAA). Study site/investigators will not disclose any proprietary information or 
confidential data.
As applicable, the IRB, FDA, or other relevant health authorities will have the right to review 
study data at any point in time. 
Identifier (or parts of) 
Recorded 
Disclosed Comment
Names
Yes
No
This information will be 
gathered for the chart review 
and will not be provided or 
shared with anyone not part of 
the research team or outside 
of the institution. Only for the 
purpose for screening patients 
of inclusion in cohort.
All elements of dates (except year) for 
dates directly related to an individual, 
including birth date, admission date, 
discharge date, date of death; and all 
Yes
No
This information will be 
gathered for the chart review 
and will not be provided or 
shared with anyone not part of 
the research team or outside 

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Post-Endarterectomy and Complications Assessment
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ages over 89 and elements of dates 
(including year) indicative of such age
of the institution. Only for the 
purpose for screening patients 
of inclusion in cohort.
Medical record numbers
Yes
No
This information will be 
gathered for the chart review 
and will not be provided or 
shared with anyone not part of 
the research team or outside 
of the institution. Only for the 
purpose for screening patients 
of inclusion in cohort.
9. Data and Specimen Banking 
De-identified data pertaining to this investigation will be maintained in encrypted, Houston 
Methodist provided computers. Only IRB approved study personnel on this study will have 
access to the study information.
10.
Study Population 
The study population is patients undergoing carotid endarterectomy (CEA) with the use of Baxter 
VASCU-GUARD vascular patches in all campuses of the Houston Methodist Hospital.
Inclusion criteria:

Patients aged 18 years and above.

Patients undergoing carotid endarterectomy with the use of VASCU-GUARD vascular 
patches.

Follow-up ultrasound assessment available.
Exclusion criteria:

No postoperative ultrasound assessment is available.
11. Screening and Recruitment S R
 Subjects will be retrospectively identified through retrospective review of medical records.
12.
Withdrawal of Subjects

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Post-Endarterectomy and Complications Assessment
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N/A
13.
Provisions to Protect the Privacy Interests of Subjects 
N/A
14.
Risks to Subjects
This research involves no more than minimal risk because it will involve only a retrospective 
review of clinical records. All Confidentiality and Data privacy protocols will be strictly adhered 
to.
15.
Potential Benefits 
Future participants may receive improved care as the outcome data from this study can 
influence current practices. However, no direct benefits to participants are anticipated from this 
research.
16.
Financial and Economic Issues 
Investigator Initiated project – Funding source for project currently Baxter International
17.
Data Safety Plan 
The HMRI SOP’s will be strictly adhered to in terms of data safety. All information will be kept in 
excel spreadsheets on locked computers within Houston Methodist Hospital. Information will 
not be provided outside of the institution. All investigators will be added to the research study 
via MORTI before assisting in the research study.
18.
Waiver of Informed Consent and /or Authorization 
Requesting a waiver of informed consent and HIPAA waiver of authorization. 
We are requesting a waiver of authorization for the conduct of this research study. As this 
project only involves the analysis of secondary data in the patient chart, it is deemed minimal 
risk for participants, and therefore, a waiver of consent can apply. All data being collected are 

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Post-Endarterectomy and Complications Assessment
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part of the standard of care, and thus, a waiver should apply as the data being collected is used 
to understand underlying factors that affect the variables being collected.
Waiver of HIPAA Authorization for Research
Complete this section if you will access identifiable health information in a patient’s electronic health 
record or other record held by Houston Methodist Hospital and you are not obtaining a signed 
authorization from the patient.  This waiver can apply to health information accessed to identify potential 
research participants or for research involving retrospective chart reviews.  
1. Purpose of the Waiver: 
   
   Chart review study – collecting retrospective clinically available data that will not have 
bearing on clinical outcomes.
   
   Partial waiver of authorization to identify, prescreen and contact potential participants.  
   
   Alteration of the requirements for a HIPAA Authorization to remove the signature. *  
   
  Other Please explain Retrospective Study – clinically available data only
* Note if the IRB waives the signature requirement, the participant must receive a copy of the HIPAA 
authorization language.  
2.  Provide protocol-specific responses to the following items that describe why the waiver is 
being requested for the use of PHI in this research.
a. The IRB must find that the use/disclosure of protected health information (PHI) involves no more 
than minimal risk to the privacy of individuals.  Please select the safeguards your team will use to 
meet this requirement. 
 
   Electronic safeguards, such as password protection, data encryption, and institution 
firewall, will be used to protect PHI
 
   Physical safeguards, such as locked cabinets, locked filing room, secure, locked office 
area, will be used to protect PHI
  
  The study team will record only anonymous data or coded data that are linked to the 
participants’ identity through a file that is separate from the data.    
  
   Administrative safeguards such as polices and procedures, staff education on the 
HIPAA Privacy Rule. 
  ☐  Other:      
c. Describe why the research cannot practicably be conducted without the waiver or alteration of 
patient authorization to use PHI in research
  Access to and use of PHI is necessary to obtain information of potential subjects. 
☐  The number of screen failures is anticipated to be high for this research and access to 

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Post-Endarterectomy and Complications Assessment
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the PHI to confirm potential study eligibility will prevent unnecessary contact with 
potential participants. 
  Too many participants will be lost to follow up or will not answer the request for an 
authorization to conduct the record review study.  
  Other:       Retrospective Study – clinically available data only
 
d.  Describe why the research cannot practicably be conducted without access to and use of
    the PHI:
    
  The study team will access the minimum PHI necessary to contact potential participants to 
assess their interest and eligibility. 
    
   The study team will access the minimum PHI necessary to prescreen for eligibility. 
    
  The study team will access the minimal PHI necessary data elements to answer the 
research question.
       *Retrospective Chart Review* PHI only accessed and recorded locally for the purpose of 
screening patients for inclusion in cohort. Patients will consent to SOC procedures and 
surgical consents, which state
3. Identify 
List the identifiers you will record by HMRI research team only, not disclosed. Minimal PHI will be 
accessed
  
   Name
   ☐   Address (all geographic subdivisions smaller than state, including street address, city 
county, and zip code)
  
   All elements (except years) of dates related to an individual (including birthdate, 
admission date, discharge date, date of death, and exact age if over 89)
   ☐   Telephone number 
   ☐   Fax number
   ☐   Email addresses 
   ☐   Social Security Number
   
   Medical record number
   ☐   Health plan beneficiary number
   ☐   Account number
   ☐   Certificate or license number
   ☐   Vehicle identifiers and serial numbers, including license plate numbers
   ☐   Device identifiers and serial numbers
   ☐   Web URL
   ☐   Internet Protocol (IP) Address
   ☐   Finger or voice print
   ☐   Photographic image - Photographic images are not limited to images of the face.
   ☐   Any other characteristic that could uniquely identify the individual

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By submitting this request for waiver of patient authorization, I certify:
(1)
That the identifiers will be destroyed at the earliest opportunity consistent with the conduct 
of the research as defined by federal, state, and/or local laws and regulations.  
(2)The PHI will not be reused or disclosed to any other person or entity, except as required by law, for 
authorized oversight of the research study, or for other research for which the use or disclosure of 
PHI would be permitted.

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19.
References
1. AbuRahma AF, Stone P, Deem S, Dean LS, Keiffer T, Deem E. Proposed duplex velocity criteria 
for carotid restenosis following carotid endarterectomy with patch closure. J Vasc Surg. 
2009;50(2):286-291. doi:10.1016/j.jvs.2009.01.065
2. Jonsson M, Hammar K, Lindberg M, et al. Editor's Choice - Nationwide Outcome Analysis of 
Primary Carotid Endarterectomy in Symptomatic Patients Depending on Closure Technique and 
Patch Type. Eur J Vasc Endovasc Surg. 2023;65(4):467-473. doi:10.1016/j.ejvs.2022.12.033
3. Lazarides MK, Argyriou C, Georgakarakos E, Georgiadis GS. More on the comparison of the 
various carotid endarterectomy patch materials. J Vasc Surg. 2021;74(4):1431-1432. 
doi:10.1016/j.jvs.2021.05.061
4. Liesker DJ, Gareb B, Looman RS, et al. Patch angioplasty during carotid endarterectomy using 
different materials has similar clinical outcomes. J Vasc Surg. 2023;77(2):559-566.e1. 
doi:10.1016/j.jvs.2022.09.027
5. Orrapin S, Benyakorn T, Howard DP, Siribumrungwong B, Rerkasem K. Patches of different 
types for carotid patch angioplasty. Cochrane Database Syst Rev. 2021;2(2):CD000071. Published 
2021 Feb 18. doi:10.1002/14651858.CD000071.pub4
6. Papakostas JC, Avgos S, Arnaoutoglou E, et al. Use of the vascu-guard bovine pericardium 
patch for arteriotomy closure in carotid endarterectomy. Early and long-term results. Ann Vasc 
Surg. 2014;28(5):1213-1218. doi:10.1016/j.avsg.2013.10.021
7. Ren S, Li X, Wen J, Zhang W, Liu P. Systematic review of randomized controlled trials of 
different types of patch materials during carotid endarterectomy. PLoS One. 2013;8(1):e55050. 
doi:10.1371/journal.pone.0055050
8. Seager MJ, Dharmarajah B, Davies EB, Davies AH, Franklin IJ. The use of functional imaging in 
the diagnosis of carotid patch infection. Vascular. 2015;23(5):542-544. 
doi:10.1177/1708538114560605
9. Stone PA, AbuRahma AF, Mousa AY, et al. Prospective randomized trial of ACUSEAL versus 
Vascu-Guard patching in carotid endarterectomy. Ann Vasc Surg. 2014;28(6):1530-1538. 
doi:10.1016/j.avsg.2014.02.017
10. Suroto NS, Rantam FA, Al Fauzi A, Widiyanti P, Turchan A, Pangaribuan V. Selection criteria 
for patch angioplasty material in carotid endarterectomy. Surg Neurol Int. 2022;13:362. 
Published 2022 Aug 19. doi:10.25259/SNI_470_2022