IMPRA CARBOFLO EPTFE VASCULAR GRAFT

K962639 · Impra, Inc. · DSY · Oct 3, 1996 · Cardiovascular

Device Facts

• Record ID: K962639
• Device Name: IMPRA CARBOFLO EPTFE VASCULAR GRAFT
• Applicant: Impra, Inc.
• Product Code: DSY · Cardiovascular
• Decision Date: Oct 3, 1996
• Decision: SESP
• Submission Type: Traditional
• Regulation: 21 CFR 870.3450
• Device Class: Class 2
• Attributes: Therapeutic

Intended Use

IMPRA Carboflo™ ePTFE Vascular Grafts are intended for use in peripheral vascular applications to replace or bypass diseased or occluded blood vessels.

Device Story

IMPRA Carboflo™ ePTFE Vascular Graft is a synthetic vascular prosthesis; constructed from expanded polytetrafluoroethylene (ePTFE) with USP grade activated charcoal particles impregnated into the luminal wall (approx. 20-25% of wall thickness). Carbon integration occurs during a singular extrusion process, creating a monolithic structure. Device is used by vascular surgeons in clinical settings to replace or bypass occluded peripheral vessels. Carbon inclusion aims to reduce surface thrombogenicity and platelet accumulation compared to standard ePTFE grafts. Clinical performance is evaluated via patency rates and adverse event monitoring. The device is supplied in various configurations, sterilized, and handled similarly to standard ePTFE grafts.

Clinical Evidence

Multi-center, prospective, randomized clinical trial (n=160; 81 Carboflo, 79 Standard) comparing patency in lower extremity vascular disease over 24 months. Primary patency: 36.8% (Carboflo) vs 27.7% (Standard). Secondary patency: 42.7% (Carboflo) vs 32.3% (Standard). Differences were not statistically significant (p=0.05). Adverse events, including thrombosis, infection, and amputation, were comparable between groups. Pre-clinical animal studies (dogs/rabbits) showed significantly higher thrombus-free surface area and reduced platelet accumulation for Carboflo grafts.

Technological Characteristics

Material: ePTFE with USP grade activated charcoal (<1% total weight). Construction: Monolithic extruded wall with carbon-impregnated luminal layer. Form factor: Tubular vascular graft with external PTFE beading. Sterilization: Same as predicate. Connectivity: N/A. Software: None.

Indications for Use

Indicated for patients with peripheral vascular disease requiring replacement or bypass of diseased or occluded blood vessels.

Regulatory Classification

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.

Special Controls

*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.”

Predicate Devices

• IMPRA ePTFE Vascular Graft

Submission Summary (Full Text)

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K962639

# Summary of Safety and Effectiveness for IMPRA Carboflo™ ePTFE Vascular Graft

## SUBMITTER

Rajagopal R. Kowligi, Ph.D
Senior Clinical Research Specialist
IMPRA, Inc.
1625 West Third Street
Tempe, AZ 85281

OCT - 3 1996

## DATE SUMMARY WAS PREPARED

June 18, 1996

## NAME OF THE DEVICE

IMPRA Carboflo™ ePTFE Vascular Graft

## IDENTIFICATION OF PREDICATE DEVICE

IMPRA ePTFE Vascular Graft

## DESCRIPTION OF THE DEVICE

IMPRA Carboflo™ ePTFE Vascular Grafts are made primarily of expanded polytetrafluoroethylene (ePTFE) using the same manufacturing procedures that are used to manufacture IMPRA ePTFE Vascular Grafts, the devices to which substantial equivalence is claimed. The region of the graft wall adjacent to the lumen, approximately 20-25% of the total wall thickness, is uniformly impregnated with Carbon particles along the entire length of the graft. The carbon impregnated region is formed integral to the outer region of the wall by mixing the PTFE resin mixed with carbon particles, with the non-carbon containing PTFE resin during a singular extrusion process, which results in a monolithic graft wall. The carbon used in the device is USP grade activated charcoal. All other components of the Carboflo graft, namely PTFE, lubricant used as a manufacturing aid, blue pigment incorporated in the orientation lines, and the external support PTFE beading are the same as those used in the manufacture of the predicate devices. These grafts are supplied in the same product configurations as the predicate device, and are packaged, labeled, and sterilized in the same manner as the predicate devices.

Extensive bench testing and microscopic analysis has shown that the carbon

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particles are an integral part of the wall and cannot be separated. The amount of carbon incorporated in each Carboflo vascular graft is less than 1% of the total weight of the graft.

## INTENDED USE

IMPRA Carboflo™ ePTFE Vascular Grafts are intended for use in peripheral vascular applications to replace or bypass diseased or occluded blood vessels.

## COMPARISON OF THE DEVICE CHARACTERISTICS TO THE PREDICATE

Physical properties of the Carboflo vascular grafts were compared to the values for Standard IMPRA ePTFE vascular grafts, using methods recommended by the AAMI Vascular Graft Standard or the FDA Guidance Document on Vascular Prostheses. Testing of a variety of product types shows that the addition of carbon particles into the graft wall did not affect the physical properties of the Carboflo grafts. Both the new device and predicate device undergo the same testing and evaluation procedures. The acceptance criteria for both the new device and predicate devices are the same.

## NON-CLINICAL TESTING

Carbon containing surfaces in medical devices, e.g. Heart valves, have been shown to impart anti-thrombogenic properties¹. Short-term pre-clinical studies have been conducted with IMPRA Carboflo™ ePTFE Vascular Grafts to determine the performance of carbon containing blood contact surface. Animal studies comparing the Carboflo grafts with Standard IMPRA ePTFE grafts have shown that the inside surfaces of the Carboflo grafts have a significantly higher Thrombus Free Surface Area after 3 months². Patencies of both Carboflo and Standard grafts were similar. Short-term animal studies in dogs and rabbits have shown that the Carboflo inside surfaces have reduced platelet accumulation when compared to Standard ePTFE vascular grafts, suggesting that the addition of carbon particles reduces the thrombogenicity of the surface³.

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¹ References on file
² Data on file
³ References on file

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CLINICAL INFORMATION

A multi-center, prospective, randomized clinical trial comparing IMPRA Carboflo™ ePTFE Vascular Grafts to commercially available ePTFE Vascular Grafts, was performed in France between 1990-1994. The purpose of the investigation was to compare the patencies of both IMPRA Carboflo ePTFE Vascular Grafts and Standard ePTFE Vascular Grafts. A total of 81 patients received Carboflo grafts and 79 received Standard ePTFE grafts. All grafts were implanted to treat lower extremity vascular disease. Of the 160 grafts, only 5 grafts (3 Carboflo, 2 Standard) were considered to be Above-Knee, and the remaining grafts were all Below-Knee.

73% of the distal anastomoses were direct graft to vessel, with the following types comprising the other anastomoses: venous patch (16%), distal arterio-venous fistula (5.8%), or interpositional vein cuff graft (5.2%). All implanted grafts were followed for at least 24 months, or until failure, lost to follow-up, or death of patient. Adverse events were recorded and documented on Case Report Forms (CRF).

## Analysis

PRIMARY PATENCY was defined as the time between implant date and date of follow-up when the graft was patent, prior to the first intervention to correct complications. Interventions included immediate re-operations to correct any complication post implantation. SECONDARY PATENCY was defined as the time between implant date and date on which the graft is no longer patent or useful, after a series of interventions. Conventional life-tables were then constructed to determine the Cumulative Primary and Secondary Patencies. At the end of the 2 yr follow-up, patencies were as follows:

Cumulative Primary Patency for Carboflo grafts was 36.8% compared to 27.7% for Standard grafts at the end of 24 months.

Cumulative Secondary Patency for Carboflo grafts was 42.7% compared to 32.3% for Standard grafts.

These results are not statistically significantly different at p = 0.05.

DEVICE SAFETY was demonstrated by determining adverse events for both Carboflo and Standard grafts. Complications were counted as they were encountered and added up at the end of the study period for each patient. The results are tabulated below:

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COMPLICATIONS: CARBOFLO VS. STANDARD

| Adverse event | Device Type | |
| --- | --- | --- |
| | Standard | Carboflo |
| No. At Start | 79 | 81 |
| No. LFU @2yrs * | 7 | 17 |
| No. Patent @2yrs | 17 | 16 |
| No. Immed. Redos | 6 | 12 |
| No. Failed @2yrs | 52 | 43 |
| Thrombosis | 34 | 26 |
| False aneurysm | 1 | 1 |
| Infection | 5 | 4 |
| Other adverse events | 2 | 3 |
| Amputation | 26 | 28 |
| Deaths | 16 | 13 |

* LFU = Lost to follow-up

It is important to note that no new type of complications were identified with Carboflo grafts.

RISK FACTORS in patients with Carboflo and Standard ePTFE Vascular Grafts were similar (p &gt; 0.05), except for Smoking. There were a higher number of patients who were smokers, in the Carboflo group (p&lt;0.05). The risk factors for the patients in this study were then compared to the risk factors for patients in USA who had treatment for peripheral vascular disease (information was summarized from published literature). Risk factors were comparable for both groups (p&gt;0.05), except for Smoking. There were a higher number of patients who were smokers, in the US (p&lt;0.05).

CONCLUSION

IMPRA ePTFE Carboflo Vascular Grafts are substantially equivalent to the currently marketed IMPRA ePTFE Vascular Grafts.

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# References

Topic: Carbon containing surfaces- biocompatibility, performance

1. Gott, V. L.; et al.: "The anticlot properties of graphite coatings on artificial heart valves." *Carbon*, 1:378, 1964.
2. Haubold, A. D.; et al.: "Carbon in medical devices." *Biocompatibility of Clinical Implant Materials*, Vol. II, edited by D. F. Williams, p. 3, 1983.
3. Olcott, E. L.: "Pyrolytic biocarbon materials." *Journal of Biomedical Research Symposium*, No. 5 (Part 1), 209, 1974.
4. Adams, D.; et al.: "Carbon fiber-reinforced carbon as a potential implant material." *Journal of Biomedical Material Research*, 12:35, 1978.
5. Homsy, C. A.: "Biocompatibility of perfluorinated polymers and composites of these polymers." *Biocompatibility of Clinical Implant Materials*, Vol II, edited by D. F. Williams, p. 59, 1981.
6. Lipsig, L. J.; et al.: "Clinical experience with transcutaneous vascular access." *Dialysis and Transplantation*, 13(12):786, December 1984.
7. Gott, V. L.; et al.: "Heparin bonding on colloidal graphite surfaces." *Science*, 142:1297, April 1963.
8. Whiffen, J. D.; et al.: "Heparin application to graphite coated intravascular prostheses." *Surgery*, 56(2):404, August 1964.
9. Gott, V. L.; et al.: "Techniques of applying a graphite-benzalkonium-heparin coating to various plastics and metals." *Transactions American Society of Artificial Internal Organs*, 10:213, 1964.
10. Haubold, A. D.; et al.: "Ultra-low temperature isotropically (ULTI) deposited carbon (Biolyte): a promising new flexible blood interface material." *Cardiovascular Diseases*, 4(4):369, 1977.
11. Sharp, W. V.; et al.: "Pyrolytic carbon-coated grafts." *Graft Materials in Vascular Surgery*, edited by H. Pardik, p. 203, 1978.
12. Sharp, W. V.: "Present Status of carbon grafts." *Vascular Grafting: Clinical Applications of Techniques*, edited by J. Wright, p. 326, 1983.

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13. Debski, R.; et al.: "Polytetrafluoroethylene grafts coated with ULTI carbon." Transactions American Society of Artificial Internal Organs, 28:456, 1982.

14. Sharp, W. V.; et al.: "A bioelectric polyurethane elastomer for intravascular replacement." Transactions American Society of Artificial Internal Organs, 12:179, 1966.

15. Sharp, W. V.: "Bioelectric properties of the vascular system as related to artificial internal organs." Surgery, 61(5):763, May 1967.

16. Sharp, W. V.; et al.: "Electrolour: a new vascular interface." Transactions American Society of Artificial Internal Organs, 14:73, 1968.

17. Taylor, B. C.; et al.: "The importance of the zeta potential, ultrastructure, and electrical conductivity of the in-vivo performance of polyurethane-carbon black vascular prostheses." Transactions American Society of Artificial Internal Organs, 17:22, 1971.

18. Miller, B. G.; et al.: "Electrical conductivity: effect on intravascular performance of foams, velour, flock, and fabric." Transactions American Society of Artificial Internal Organs, 20:91, 1974.

19. Bokros, J. C.; et al.: "Control of structure of carbon for use in bioengineering." Chemistry and Physics of Carbon, Vol. 9, edited by F. L. Walker, Jr., Marcel Dekker, New York, 1973.

20. Baier, R. E.; et al.: "Surface chemical evaluation of thromboresistant materials before and after venous implantation." Transactions American society of Artificial Internal Organs, 16:50, 1970.

21. Sawyer, P. N.; et al.: "Bio-electric phenomena as an etiologic factor in intravascular thrombosis." American Journal of Physiology, 175:103, October 1953.

22. Sawyer, P. N.; et al.: "Relations of abnormal and injury electrical potential differences in intravascular thrombosis." American Journal of Physiology, 175:108, October 1953.

23. Sawyer, P. N.; et al.: "Electric potential differences across the normal aorta and aortic grafts of dogs." American Journal of Physiology, 175:113, October 1953.

24. Goldfarb, D.; et al.: "Graphite-expanded polytetrafluoroethylene: an improved small artery prosthesis." Transactions American Society of Artificial Internal Organs, 23:268, 1977.

25. Schmidt, S. P., Ph. D.; et al.: "In vivo performance of carbon-coated PTFE vascular grafts in a canine model." Presented at the 15th Annual Meeting of the Society for Biomaterials, Lake Buena Vista, Florida, USA, April 28 - May 2, 1989.

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26. Tsuchida, Hiromitsu, M.D., Ph. D.; et al.: "Modified polytetrafluoroethylene: Indium 111-labeled platelet deposition on carbon-lined and high-porosity polytetrafluoroethylene grafts." Journal of Vascular Surgery, 16(4):643-650, October 1992.

27. Babatasi, G.; et al.: "Indium-labelled platelet deposition in carbon-lined modified polytetrafluoroethylene grafts in an experimental model: aortic replacement in rabbits. Effects of heparin and hirudin." Cardiovascular Surgery, September 1994.

28. Bacourt, F.; A.U.R.C. (Group of University hospitals): "Etude Prospective Randomisee Comparative de Protheses PTFE carbone et PTFE standard in Position Sous-articulaire." Presented at the meeting of French Speaking Vascular Society (IX Congress: SCV en langue française, June 16, 1994).

29. Baste, J. C.; et al.: "Etude Prospective Comparative D'Une Protheses PTFE Carbone Versus Prothese Standard Dans Les Abords Vasculaires Pour Hemodialyse Chronique-Resultats A Un An." Presented at the meeting of French Speaking Vascular Society (VIII Congress: SCV en langue française, June 24 - 26, 1993).

30. Bourquelot, P. D.; et al.: "Pontages PTFE-Carbone et PTFE-Standard en Hemodialyse etude Preliminaire a 36 mois - N = 97." Presented at the meeting of French Speaking Vascular Society (VIII Congress: SCV en langue française, June 24 - 26, 1993).

31. Ruehland, D., M.D.: "Use of IMPRA Carbon-Lined PTFE Prostheses: A Preliminary Report." Unpublished, IMPRA ePTFE Carbon-Lined Vascular Graft Design File.

32. Moggi, L. MD, "Reconstructive Surgery: Developments in Grafts", Critical Ischaemia, Vol. 4, no.3, 71-76.