(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.
§ 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.”