(105 days)
The IMPRA ePTFE Arteriovenous Cuffed Graft is indicated for use as a subcutaneous arteriovenous conduit for blood access.
The IMPRA ePTFE Arteriovenous Cuffed Graft is an expanded polytetrafluoroethylene angioaccess graft [i.e., an IMPRA ePTFE Vascular Graft, the predicate device for this 510(k)] with a modified venous end. The venous end is cuffed, facilitating vessel conformity, a uniform suturing surface, and improved flow through the anastomosis. The IMPRA ePTFE Arteriovenous Cuffed Graft is made from the same materials as the predicate device, i.e., polytetrafluoroethylene (PTFE), lubricant used as a manufacturing aid, a blue pigment used in the orientation lines, and the external support PTFE beading. These grafts are supplied in the same product configurations as the predicate device (straight, stepped, CenterFlex, and stepped CenterFlex), and are packaged, labeled, and sterilized in the same manner as the predicate device.
Here's an analysis of the provided text regarding the acceptance criteria and supporting studies for the IMPRA ePTFE Arteriovenous Cuffed Graft:
Important Note: The provided document is a 510(k) summary from 1997 for a medical device (vascular graft). It's crucial to understand that the concepts of "acceptance criteria" and "device performance" in the context of this document are primarily focused on demonstrating substantial equivalence to a predicate device, rather than meeting specific quantifiable performance metrics in a standalone, prospective clinical trial with pre-defined statistical endpoints like many modern AI/ML device submissions. The "performance" described relates to comparative outcomes between the new device and the predicate or observations from a clinical use of a similar design.
1. Table of Acceptance Criteria and Reported Device Performance
Given the nature of the 510(k) submission, the "acceptance criteria" are implied by the demonstration of substantial equivalence to the predicate device, particularly in terms of safety and efficacy (patency and complication rates). The document doesn't explicitly state quantitative acceptance criteria in the way a modern AI device might. Instead, it compares the new device (or its template) to the predicate device or established clinical outcomes.
| Aspect | Acceptance Criteria (Implied for Substantial Equivalence) | Reported Device Performance (IMPRA ePTFE Arteriovenous Cuffed Graft / AVP Graft) |
|---|---|---|
| Physical Performance | Equivalent or superior to predicate device (IMPRA ePTFE Vascular Graft) based on ANSVAAMI VP20-1994 and FDA Draft Guidance. | Device testing indicated suitability for use and substantial equivalence to the predicate device. Specific parameters tested included longitudinal, burst, and suture retention strength, and handling characteristics (needle penetration, suture drag, suture hole bleeding). The cuffed portion had significantly reduced wall thickness but did not compromise strength. Handling characteristics were judged equivalent or superior. |
| Biocompatibility | Non-toxic, biocompatible (per ISO Standard 10993, FDA Blue Book Memorandum #G87-1, #G95-1). | IMPRA ePTFE Vascular Grafts (predicate) confirmed biocompatibility. Additional cytotoxicity testing on IMPRA ePTFE Arteriovenous Cuffed Grafts evoked no cytotoxic responses. |
| Intimal Hyperplasia | Reduced or non-inferior intimal hyperplasia compared to predicate (especially at venous end). | Animal study showed IMPRA ePTFE Arteriovenous Cuffed Grafts had less intimal area and a lower percentage of stenosed area at the venous end (not statistically significant). It also had 50% less average intimal thickness in the toe regions, which was statistically significant. Conclusion: decreased intimal hyperplasia at the venous end. |
| Primary Patency (Clinical) | Non-inferior to conventional grafts (predicate design). | Clinical study (using AVP graft, a template for the new device) showed cumulative primary patencies of 88% at 45 months for AVP grafts vs. 66% at 27 months for conventional prostheses (control). This suggests superiority. |
| Thrombosis Rate (Clinical) | Non-inferior (ideally lower) to conventional grafts. | Overall thrombosis rates were 5.2% for the AVP group and 16% for the conventional (control) group, indicating a lower thrombosis rate for the cuffed design. |
| Complications (Clinical) | Non-inferior complication profile compared to conventional grafts. | Complications (excluding deaths and thrombosis rate) in both groups were comparable. The higher death rate in the AVP group was attributed to patient comorbidities, not the device itself. |
| Safety (Overall) | No new types of safety questions or adverse effects. | Clinical implantation and use of the AVP graft did not adversely affect safety or efficacy. The device's design and manufacturing process do not compromise safety. |
| Effectiveness (Overall) | Adequate performance for indicated use, substantially equivalent to predicate, considering benefits. | Demonstrated suitability for use, decreased intimal hyperplasia (animal model), improved patency and lower thrombosis rates (clinical using AVP template), with no adverse effect on safety. |
2. Sample Sizes Used for the Test Set and Data Provenance
Given this is a physical medical device, not an AI model, the concept of "test set" and "data provenance" (as typically used for AI) requires interpretation:
- Physical Testing: Not explicitly stated as a "sample size" but implies multiple units for various physical tests.
- Preclinical Testing - Animal Study:
- Sample Size: Numbers of grafts implanted are not explicitly stated, but it involved multiple IMPRA ePTFE Vascular Grafts and IMPRA ePTFE Arteriovenous Cuffed Grafts in an established sheep model. The context suggests a sufficient number for morphometric analysis and statistical comparison.
- Data Provenance: Prospective animal study (sheep model).
- Clinical Testing:
- Sample Size:
- AVP Group (template device for new device): 174 grafts
- Conventional Group (control): 50 grafts
- Data Provenance: Prospective clinical study, conducted at Charite Hospital, Berlin, Germany.
- Sample Size:
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
Again, for a physical device, "ground truth" is established differently than for AI.
- Physical Testing: The "ground truth" is objective measurement against established standards (ANSVAAMI VP20 - 1994, 1993 FDA Draft Guidance). No individual experts "establish ground truth" in the AI sense here.
- Preclinical Testing - Animal Study:
- Experts: Not explicitly stated how many pathologists or researchers evaluated the explanted grafts.
- Qualifications: Implied to be qualified researchers/pathologists capable of morphometric analysis and histological characterization.
- Clinical Testing:
- Experts: Dr. Hans Scholz, Chief of Vascular Surgery, Queen Elisabeth Hospital, Berlin, designed and conducted the study. He is the inventor of the AVP graft.
- Qualifications: Chief of Vascular Surgery, inventor of the AVP, conducted procedures at Charite Hospital, Berlin. This implies significant surgical and clinical expertise.
4. Adjudication Method for the Test Set
- Adjudication Method: Not applicable in the AI sense of resolving disagreements among multiple human annotators.
- Physical/Preclinical: Objective measurements and expert interpretation by implied qualified personnel.
- Clinical: Clinical outcomes were observed and documented by the study investigator. No mention of an independent adjudication committee for clinical events is made, which is common for single-center, investigator-initiated studies from this era.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- MRMC Study: No, an MRMC comparative effectiveness study was not done. This type of study is typically used for diagnostic devices (especially imaging) where multiple readers interpret cases with and without AI assistance to measure human performance improvement. This device is a vascular graft, not a diagnostic tool.
6. Standalone (Algorithm Only) Performance Study
- Standalone Study: No. This device is a physical vascular graft, not an AI algorithm. Therefore, the concept of "standalone performance" for an algorithm doesn't apply. Its performance is assessed through its physical properties and clinical outcomes when implanted.
7. Type of Ground Truth Used
- Physical Testing: Objective measurements against industry standards and guidance documents.
- Preclinical Testing (Animal Study): Histological analysis and morphometric measurements of explanted grafts and vessels.
- Clinical Testing:
- Outcomes Data: Primary patency, thrombosis rates, complication rates, and survival data from patients receiving the grafts. This is considered robust clinical ground truth.
8. Sample Size for the Training Set
Again, in the context of this physical device, there isn't a "training set" in the machine learning sense. The device's design and manufacturing processes are developed based on engineering principles, material science, and prior experience with predicate devices or templates.
- The AVP graft, which served as a "template," was informed by the inventor's experience and data. The IMPRA ePTFE Arteriovenous Cuffed Graft was developed using the AVP as a template, meaning the knowledge and design of the AVP (including its clinical results) guided the development of the new device. So, the 174 AVP cases could retrospectively be seen as informing the development of the final IMPRA ePTFE Arteriovenous Cuffed Graft.
9. How the Ground Truth for the Training Set Was Established
As there's no "training set" in the AI sense:
- The "ground truth" that informed the design of the IMPRA ePTFE Arteriovenous Cuffed Graft was the experience and data from the AVP graft. This included:
- Data from the inventor (Dr. Scholz) regarding cuff angle, length, and width.
- The clinical experience with the AVP graft (174 cases), which demonstrated its safety and efficacy (patency, thrombosis rates). These clinical outcomes were established through direct medical observation, follow-up, and diagnostic procedures for events like thrombosis.
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KQ64877
Section 510(k)
MAR 20 1997
Summary of Safety and Effectiveness Information
Regulatory Authority: Safe Medical Devices Act of 1990, 21 CFR 807.92
Company Name/Contact
| Company: | IMPRA, A Subsidiary of C. R. Bard, Inc1625 West Third StreetTempe, Arizona 85281 |
|---|---|
| Contact: | Kristi M. KistnerManager, Regulatory AffairsTelephone: (602) 894-9515Fax: (602) 966-7062 |
Establishment
Registration Number: 2020394
Device Name
| Trade Name: | IMPRA ePTFE Arteriovenous Cuffed Graft |
|---|---|
| Common Name(s): | Vascular Graft Prosthesis |
| Classification Names/Codes: | Vascular graft prostheses of less than 6 mm diameter |
| (74DYF) |
.
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Substantially Equivalent Device
IMPRA ePTFE Vascular Graft
Device Description
The IMPRA ePTFE Arteriovenous Cuffed Graft is an expanded polytetrafluoroethylene angioaccess graft [i.e., an IMPRA ePTFE Vascular Graft, the predicate device for this 510(k)] with a modified venous end. The venous end is cuffed, facilitating vessel conformity, a uniform suturing surface, and improved flow through the anastomosis.
The IMPRA ePTFE Arteriovenous Cuffed Graft is made from the same materials as the predicate device, i.e., polytetrafluoroethylene (PTFE), lubricant used as a manufacturing aid, a blue pigment used in the orientation lines, and the external support PTFE beading. These grafts are supplied in the same product configurations as the predicate device (straight, stepped, CenterFlex, and stepped CenterFlex), and are packaged, labeled, and sterilized in the same manner as the predicate device.
Indication for Use
The IMPRA ePTFE Arteriovenous Cuffed Graft is indicated for use as a subcutaneous arteriovenous conduit for blood access. The predicate device, the IMPRA ePTFE Vascular Graft, is indicated for use in blood access, bypass, or reconstruction of arterial blood vessels.
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Packaging
The IMPRA ePTFE Arteriovenous Cuffed Graft is packaged in a double tray configuration and placed inside of a box. The trays are made from either PVC or PETG and are sealed with Tyvek lids. After sterilization, the product Directions for Use is applied to the outside of the box and the assembly is shrinkwrapped prior to being released to inventory.
Sterilization/Re-sterilization
The IMPRA ePTFE Arteriovenous Cuffed Graft is sterilized with 100% Ethylene Oxide prior to being placed into inventory for sale. Validation of the sterilization process is performed using the overkill method.
The IMPRA ePTFE Arteriovenous Cuffed Graft is a single use device, intended for single patient use, only. The Directions for Use for both the IMPRA ePTFE Arteriovenous Cuffed Graft and the predicate device, the IMPRA ePTFE Vascular Graft, allow for resterilization of the graft with steam in the event that a package has been inadvertently opened. and the product has not been damaged or contaminated with blood or any foreign material. The resterilization instructions in the Directions for Use have been validated by IMPRA.
Physical Testing
: ..
Device testing was performed on the cuffed portion of the IMPRA ePTFE Arteriovenous Cuffed Graft and compared to the results of testing performed on the IMPRA ePTFE Vascular Graft. The testing was conducted using methods recommended in ANSVAAMI VP20 - 1994:
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Cardiovascular implants - Vascular Prostheses and the 1993 FDA Draft Guidance: Guidance for the Prevaration of Research and Marketing Applications for Vascular Graft Prostheses. The results of all testing indicated that the IMPRA ePTFE Arteriovenous Cuffed Graft is suitable for use as a subcutaneous arteriovenous conduit for blood access and the anticipated conditions of use imposed on the device. The results demonstrated that the IMPRA ePTFE Arteriovenous Cuffed Graft has been adequately designed to perform in a manner substantially equivalent to that of the predicate device.
Preclinical Testing - Animal Study
A short-term animal study (8 weeks) was conducted to compare intimal hyperplasia formation in IMPRA ePTFE Vascular Grafts and IMPRA ePTFE Arteriovenous Cuffed Grafts in an established sheep model. Grafts were evaluated at implant for handling characteristics (needle penetration difficulty, suture drag, and suture hole bleeding). At explant, grafts and adjacent vessels were photographed and prepared for histology to determine thickness of intimal hyperplasia, degree of luminal narrowing and cellular characterization.
The handling assessment indicated that the IMPRA ePTFE Arteriovenous Cuffed Graft performed better, overall, than the IMPRA ePTFE Vascular Graft. The morphometric analysis of cross sections through the venous ends of the grafts showed that IMPRA ePTFE Arteriovenous Cuffed Grafts had less intimal area and a lower percentage of stenosed area at the venous end than did the IMPRA ePTFE Vascular Grafts. However, the differences between groups were not statistically significant. The morphometric analysis of sections though the toe regions of the grafts
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showed that the IMPRA ePTFE Arteriovenous Cuffed Grafts had 50% less average intimal thickness in this region than did the IMPRA ePTFE Vascular Grafts. This difference was statistically significant.
The conclusion of the study was that the results demonstrated that the addition of a distal cuff decreased intimal hyperplasia at the venous end of the graft. This effect could be expected to result in a decreased failure rate and longer graft patency.
Preclinical Testing - Biocomnatibility/Toxicity
IMPRA has completed biocompatibility/toxicity testing on IMPRA ePTFE Vascular Grafts, the predicate device for this 510(k), in accordance with the requirements of ISO Standard 10993, FDA Blue Book Memorandum #G87-1, and Good Laboratory Practices. This testing confirms the biocompatibility of IMPRA ePTFE Vascular Grafts. Additional cytotoxicity testing was conducted on IMPRA ePTFE Arteriovenous Cuffed Grafts (per the guidelines in FDA Blue Book Memorandum #G95-1). The test samples evoked no cytotoxic responses.
Clinical Testing
Clinical testing was performed on a device (AVP) that utilized the same cuffed configuration at the venous anastomosis as the IMPRA ePTFE Arteriovenous Cuffed Graft. The IMPRA ePTFE Arteriovenous Cuffed Graft was developed using the AVP graft as a template. The cuff angle is the same for both devices, and the overall cuff length and width for the IMPRA ePTFE Arteriovenous Cuffed Graft were based on data from the inventor of the AVP.
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The primary differences between the two devices are the construction and the wall thickness. The IMPRA ePTFE Arteriovenous Cuffed Graft is manufactured from one piece of expanded PTFE, using no sutures or additional materials. The AVP is made using two ePTFE pieces, sutured together to form the cuff. The wall thickness of the cuffed portion of the IMPRA ePTFE Arteriovenous Cuffed Graft is less than the wall thickness of the cuffed portion of the AVP. This difference in wall thickness is due to the proprietary manufacturing process utilized in the manufacture of the IMPRA ePTFE Arteriovenous Cuffed Graft and does not compromise the safety of the device.
The clinical study was designed and conducted by Dr. Hans Scholz, Chief of Vascular Surgery, Oueen Elisabeth Hospital. Berlin. Dr. Scholz is the inventor of the AVP. All clinical procedures were performed at the Charite Hospital, Berlin. Between August 1992 to June 1996, 174 AVP grafts constructed from standard 4 mm to 7 mm Stepped IMPRA ePTFE grafts were implanted as straight AV shunts in the upper arm of patients in need of vascular access for hemodialysis. The AVP grafts used in this study were constructed by the investigator intra-operatively. During the same period, fifty (50) conventional 4 mm to 7 mm Stepped IMPRA ePTFE grafts were also implanted in the upper arm in a non-randomized fashion. Patients were entered into this study only if a native A-V fistula could not be constructed in the arm. Patients were excluded only if they had a known hypercoagulability condition, or had arterial hypotension with systolic values below 100 mm Hg.
No anticoagulants were used during this study. Beginning with patient number 101, intra-
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operative application of antibiotics (Tarzobac) was instituted as an infection prophylactic.
Observations were recorded at the time of the operation. Follow-up included immediate postoperative development and continued up to the second year after implantation of the prosthesis. Post-operative observations took place at intervals of six months.
Analysis of the results indicated that patient demographics in both groups were comparable with regard to the gender, age, height, weight, mean blood pressure, and number of previous operations.
Life table analysis indicates that the cumulative primary patencies were 88% at 45 months for AVP grafts and 66% at 27 months for the conventional prostheses (control). The mean duration of shunt function was comparable in both groups.
Complications in both groups were comparable except for the number of deaths and the thrombosis rate. The overall thrombosis rates were 5.2% for the AVP group and 16% for the conventional (control) group. There was a 21.8% death rate in the AVP group and a 12% death rate in the conventional group, with the mean time to death in the AVP group longer than the time for the conventional group (23.6 vs. 13.2 months, respectively). The patients that died due to cardiac failure in the AVP group were found to have had significant cardiac and other comorbidities at the time of graft implantation. Comparison of flow rates between selected patients with AVP and conventional grafts at various follow-up times indicated that the AVP graft did not
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increase the flow rates through the shunt. It was concluded that the AVP grafts did not contribute to the deaths of these patients.
The above summary indicates that clinical implantation and use of the AVP graft did not adversely affect the safety (complications) or efficacy (patency) when used as a vascular access graft for hemodialysis. The AVP clinical experience evaluates the performance of the cuffed design and supports the safety of the IMPRA ePTFE Arteriovenous Cuffed Graft.
Equivalence
The IMPRA ePTFE Arteriovenous Cuffed Graft is supplied in the same sizes (internal diameter and usable length) and configurations (Straight, CenterFlex, Stepped, and Stepped CenterFlex grafts in standard wall thickness), and is packaged, and sterilized in the same manner as the IMPRA ePTFE Vascular Graft to which substantial equivalence is claimed. The uncuffed portion of the IMPRA ePTFE Arteriovenous Cuffed Graft is the IMPRA ePTFE Vascular Graft. The IMPRA ePTFE Arteriovenous Cuffed Graft is made by further processing the predicate device to create a flared or cuffed end on the venous end of the graft. The cuffed portion of the IMPRA ePTFE Arteriovenous Cuffed Graft is the only technological characteristic that differentiates this device from the IMPRA ePTFE Vascular Graft.
Functionally, the cuffing processes produce a flared segment on the largest diameter end of the graft. This flared end is referred to as the cuff and has the same configuration (angle, length, and width) on all graft sizes and product types. The cuffing processs do not affect the microporous
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structure of the product, but they do significantly reduce the wall thickness at the cuff. This reduction in wall thickness does not compromise the strength (longitudinal, burst, suture retention) of the IMPRA ePTFE Arteriovenous Cuffed Graft. Also, the handling characteristics (needle penetration, suture drag, suture hole bleeding) of the IMPRA ePTFE Arteriovenous Cuffed Graft were judged to be equivalent or superior to the IMPRA ePTFE Vascular Graft when implanted in eight sheep.
Therefore, it must be concluded that the technological characteristics of this device do not raise any new types of questions of safety or effectiveness. The IMPRA ePTFE Arteriovenous Cuffed Graft has been adequately designed to perform in a manner substantially equivalent to that of the predicate device.
Conclusion
IMPRA ePTFE Arteriovenous Cuffed Grafts and IMPRA ePTFE Vascular Grafts are manufactured in the same ISO 9001:1994 certified facility in Tempe. Arizona. This facility has recently undergone FDA GMP establishment inspections and UK Department of Health inspections. The IMPRA ePTFE Arteriovenous Cuffed Graft utilizes the same validated base graft and secondary processes as the IMPRA ePTFE Vascular Graft. The cuffed portion of the graft is formed with three additional processes after base graft and secondary processes have been completed. These cuffing processes are subject to the same equipment and process qualifications, validations, and quality system requirements as the base graft and secondary processes.
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There are no significant differences in design, material, or performance characteristics between the IMPRA ePTFE Arteriovenous Cuffed Graft and the IMPRA ePTFE Vascular Graft that could adversely affect safety or effectiveness. The IMPRA ePTFE Arteriovenous Cuffed Graft is substantially equivalent to the IMPRA ePTFE Vascular Graft.
ill
§ 870.3450 Vascular graft prosthesis.
(a)
Identification. A vascular graft prosthesis is an implanted device intended to repair, replace, or bypass sections of native or artificial vessels, excluding coronary or cerebral vasculature, and to provide vascular access. It is commonly constructed of materials such as polyethylene terephthalate and polytetrafluoroethylene, and it may be coated with a biological coating, such as albumin or collagen, or a synthetic coating, such as silicone. The graft structure itself is not made of materials of animal origin, including human umbilical cords.(b)
Classification. Class II (special controls). The special control for this device is the FDA guidance document entitled “Guidance Document for Vascular Prostheses 510(k) Submissions.”