Prospective Evaluation of Plasma-TFE and Expanded PTFE Grafts for Routine and Early Use as Vascular Access During Hemodialysis

A

THOMAS S. HELLING, M.D., PAUL W. NELSON, M.D., and LINDA SHELTON, R.N.

The use of prosthetic grafts as vascular access for chronic hemodialysis is frequently necessary in patients with end-stage renal disease. Most commonly, expanded polytetrafluoroethylene (ePTFE) has been employed because of ease of handling, tissue inertness, and acceptable long-term patency. Delay in use to allow for tissue ingrowth, however, has often required placement of temporary access devices. The authors have undertaken evaluation of a new material, plasma polymerized woven dacron Plasma-TFE, in a prospective randomized trial (Plasma-TFE VA) to compare clinical behavior against e-PTFE grafts, and we have used the Plasma-TFE grafts in an additional group of patients (Plasma-TFE AVA) as early access (within 1 week of implantation). Twenty-one Plasma-TFE grafts were implanted in 19 patients and 19 e-PTFE grafts were implanted in 17 patients in a prospective randomized fashion. Additionally, 31 PlasmaTFE grafts were implanted in 31 nonrandomized patients for early access. Primary patency rates in Plasma-TFE VA and ePTFE grafts were equivalent at 12 months (0.471 and 0.556). When Plasma-TFE AVA primary patency was included (0.621), comparisons were not statistically significant (p = 0.50). Similarly, secondary patency rates among the three groups did not differ (cumulative proportion patent at 12 months: Plasma-TFE VA 0.403, e-PTFE 0.658, Plasma-TFE AVA 0.510). In considering after-revision patency after graft thrombosis, however, the Plasma-TFE grafts (both VA and AVA) performed significantly more poorly (p = 0.027) than e-PTFE grafts. Incidence of graft infection, wound infection, arm edema, hematoma from use, and occurrence of distal limb ischemia between Plasma-TFE (VA and AVA) and e-PTFE did not differ statistically. The authors conclude that Plasma-TFE compares favorably to e-PTFE with respect to primary and secondary patency and nonthrombotic complications, even with early use. Plasma-TFE does not perform as well as e-PTFE, however, after graft thrombosis.

F a OR PATIENTS ON chronic hemodialysis, maintenance of suitable vascular access is a continuing

problem. Creation of the classic forearm arteriovenous fistula as described by Brescia and co-workers,' although durable, has limited clinical applicability, par-

Address reprint requests to Thomas S. Helling, M.D., 4320 Wornall Road, Suite 308, Kansas City, MO 641 1 1. Accepted for publication January 28, 1992.

596

From the Department of Surgery, University of Missouri, Kansas City School of Medicine Kansas City, Missouri

ticularly in the elderly or in patients requiring urgent dialysis. In those patients synthetic implantable conduits, most notably expanded polytetrafluoroethylene (e-PTFE), have been used successfully.24 Implantation of e-PTFE, however, generally requires 10 to 14 days of maturation before cannulation can occur. With the advent of percutaneous subclavian hemodialysis catheters,S17 immediate dialysis could be accomplished, allowing time for development of forearm arteriovenous fistulas or maturation of e-PTFE grafts. Use of subclavian catheters may, however, result in subclavian vein stenosis, occurring in as many as 50% of patients, and may produce clinically significant venous hypertension should arteriovenous access be placed distal to the stenotic lesion.8-'0 Development of plasma polymerization techniques to alter intimal surfaces of prosthetic grafts and reduce thrombogenicity while maintaining a stable neointima" has led to interest in the use of these grafts for vascular access in hopes of reducing late thrombotic complications encountered with e-PTFE grafts.'2 Plasma polymerization of microfilament polyethylene terephthalate fibers in a woven configuration has resulted in the commercially available Plasma-TFE graft (Medtronic Inc., Minneapolis, MN). To determine the clinical usefulness of Plasma-TFE grafts for vascular access in chronic hemodialysis, we embarked on a prospective randomized trial comparing Plasma-TFE and e-PTFE grafts. Although, initially our objectives were comparison of primary and secondary patency as well as complications, the discovery that PlasmaTFE grafts could be used early (within 1 week) after implantation prompted the inclusion of a third arm, earlyaccess Plasma-TFE, to determine if early use had any effect on subsequent graft patency.

Vol. 2 16.- No. 5

VASCULAR ACCESS GRAFTS

597

TABLE 2. Comorbid Factors

Clinical Material

February 1988 and August 1989,

Between

grafts

TEE

grafts were inserted in 17 patients (e-PTEE prospective randomized fashion. Between April

and 18 e-PTEE

VA) in

a

May 1990,

1989 and

(Plasma-TEE AVA)

not

an

additional 31 Plasma-TEE

were

purpose of

expressed

grafts implanted in 31 patients for the

early

These 31

access.

patients

were

part of the prospective randomized study. Random-

ization cause

results with

units

frequent

early

grafts

in e-PTEE VA

access

historically unacceptable

were

perigraft

hematoma

thrombosis. The randomized

consent was obtained

according

and

in

subsequent

of the study

arm

and

graft

was

18 4 0 4

28 5 0 9

NS NS NS NS

3

3

5

NS

4

7

4

NS

respect to age, gender, and creation of previous fistulae on

ap-

follow-up for the ( 16

for each patient.

to 1 7

rates were calculated

to standards outlined

addition, patency

graft revision were also calcuComplications examined consisted of graft infec-

patients followed

VA group

at least

(all 18 followed

year). Comorbid factors

at least

examined in Table 2. No

at least

among the three groups

Figure

depicts primary patency no

rates

rates used the Mantel-

Cox test. Chi square

Significance

analysis was used to detect intergroup patient demographics and complications.

was

determined at p