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