Recombinant tissue plasminogen activator to declot dialysis fistulas

JOURNAL OF NEPHROLOGY Vol. 10 no. 2 - 1997 / pp 107-110
 
Clinical investigation
Recombinant Tissue Plasminogen Activator To Declot Dialysis Fistulas
Yousef Boobes 1, Haitham Al Hassan 3, Peter Neglen 3, Kais Obeid 1, Necolas
Denour 2
1Department of Nephrology, 2Department of Radiology, Tawam Hospital,
3Department of Surgery, FMHS, UAE University, Al Ain - United Arab Emirates

ABSTRACT: Background. Thrombosis is the most common complication of
hemodialysis access. Few reports are available concerning the use of
recombinant tissue plasminogen activator (rt-PA) to declot an arterio-
venous (A-V) access. This report describes the use of rt-PA for this
purpose in 17 A-V accesses.
Methods. The rt-PA was infused manually using a small catheter directly
into the A-V access in 10-mg doses at 1-2 hour intervals, to a maximum dose
of 40 mg. The procedure was followed by angiography, through the same
catheter.
Results. One fistula could not be cannulated, and in three the lysis of the
clot failed. The other 13 cases (3 fistulas, and 10 grafts 81%) had
successful lysis with return of bruit and thrill. Most patients had
dialysis the next day using the declotted A-V access. Angiogram detected
stenosis in six patients and surgical revision was done 1-8 days after the
treatment. In the other seven patients no organic lesions were found, and
six of them have a functioning A-V access 50-395 days after the lysis. Only
10-20 mg of rt-PA was needed in 60% of the cases. No major complication
occurred; minor local bleeding was noted in five patients (5/16, 31%).
Conclusion. rt-PA can be considered safe, effective, and fast for
declotting thrombosed arteriovenous fistulas.
KEY WORDS: Hemodialysis, rt-PA, Thrombolysis, Vascular access
 
Introduction
The use of endogenous fistulae and synthetic vascular prostheses has
facilitated repeated and routine vascular access for hemodialysis. However,
thrombosis of the access is still a major problem and substantially
contributes to the morbidity and hospitalization of patients with end-stage
renal disease (1). The most common treatment of clotted arterio-venous
access is still surgical thrombectomy in most centers. However, the outcome
of percutaneous thrombolysis has improved from early poor lysis with
streptokinase (2) to recent excellent results with urokinase (3-7).
There are few reports on the use of recombinant tissue plasminogen
activator (rt-PA) for this purpose (7-9). In most studies, the procedure
was done by interventional radiologists in X-ray departments. In the
present study, the procedure was done in the dialysis unit, or in the
admission ward. The aim of this study was to assess the efficacy and safety
of declotting A-V fistulas with rt-PA in the dialysis unit.
 
Patients and methods
Between September 1994 and April 1996, 17 occluded arteriovenous fistulas
in 13 consecutive patients were included in the study. Patients with an
angioaccess 120 mmHg,
history of hemorrhagic stroke, or history of spinal or head trauma within
the preceding three months were excluded.
Median age was 45 years (range 15-72) and the male:female ratio was 4:9. In
all patients the duration of thrombosis was less than 48 hours. The
occluded angioaccesses included six autogenous veins (four at the wrist and
two at the elbow) and 11 graft fistulas (seven brachial-axillary, one
straight and three loop forearm PTFE fistulas).
The thrombolysis was always performed in the dialysis unit. After local
infiltration of 1% lidocaine in the skin, a needle was introduced, usually
close to the arterial anastomosis, pointing antegradely. Proper placement
of the needle within the lumen of the access was confirmed by distention of
the access with a few ml of 0.9% NaCl. A flexible guidewire was then
introduced and an easy passage confirmed the correct position of the
needle. An end-hole catheter size 6Fr was introduced over the guidewire and
placed within the clotted fistula.
rt-PA was manually infused directly into the angioaccess in 10-mg doses at
1-2 hour intervals until a maximum dose of 40 mg was reached or the
thrombus was lysed. Successful lysis was judged as establishment of patency
with bruit and thrill. During the rt-PA infusion a pressure was applied on
the venous side and maintained 5 min after the end of injection to optimize
the contact time between rt-PA and the thrombus. During the procedure the
patient was kept under close observation for any complication.
After successful lysis a fistulogram was performed. Contrast dye was
injected through the same catheter used for lysis to detect any organic
lesion. The arterial inflow channel was assessed by occlusion of the venous
outflow during injection, forcing the dye retrogradely. After the procedure
the patient was admitted for further observation.

Results
The procedure was unsuccessful in four cases, one with graft and three with
autogenous vein fistulas. In one patient the native fistula could not be
cannulated and in three the thrombus failed to lyse despite infusion of the
full dose of rt-PA (40 mg). For two of these fistulas an organic stenosis
was found at exploration and surgical revision was done. The third patient
was not compliant and refused any further procedure (Tab. I).
 
Name "Sex "Age (year) "Fistula type "Dose (mg) "Lysis "Lysis time (min)
"Angiogram "Surgery "Patency* (days) "Complication " "ASZ "F "40 "BA-graft
"20 "Yes "120 "No stenosis "No "50 "Local bleed " "HD "F "38 "ST. graft "20
"Yes "60 "No stenosis "No "434 "No " "ASZ "F "40 "BA-graft "10 "Yes "60
"Venous stenosis "Yes "-- "No " "ASZ "F "40 "BA-graft "20 "Yes "~60 "Venous
stenosis "Yes "-- "Local bleed " "MBB "F "65 "Loop graft "30 "Yes "240
"Venous stenosis "Yes "-- "No " "KMI "F "19 "BA-graft "20 "Yes "70 "Venous
stenosis "Yes "-- "Local bleed " "MG "F "45 "Loop graft "35 "Yes "95 "No
stenosis "Yes "3 "Local bleed " "KB "M "60 "BA-graft "20 "Yes "125 "Venous
stenosis "Yes "-- "Local bleed " "ASS "M "46 "Autogenous "30 "No "240
"Arterial stenosis "Yes "-- "No " "JES "F "15 "Autogenous "10 "Yes "120 "No
stenosis "No "560 "No " "MAJ "F "23 "Autogenous "20 "Yes "70 "No stenosis
"No "511 "No " "MTK "M "72 "Autogenous "30 "Yes "170 "No stenosis "No "196
"No " "SS "F "62 "Autogenous "40 "No "240 "-- "-- "-- "No " "KA "M "48 "BA-
graft "40 "No "300 "Venous stenosis "Yes "-- "No " "MG "F "45 "Loop graft
"30 "Yes "150 "No stenosis "Yes "-- "Local bleed " "KA "M "48 "BA-graft "25
"Yes "150 "Venous stenosis "No ">60 "No " "F = female; M = male; BA =
brachial=axillary; St. straight forearm. * Patency of the vascular access
if no surgery
Table I - Patients receiving rt-PA and results of treatment
The remaining 13 accesses had successful lysis with return of bruit and
thrill, giving a success rate of 81% (13/16). Figure 1 shows consecutive
fistulograms of lysis in an occluded graft.
 
a
 
b
 
c
 
Fig. 1 - Three consecutive fistulograms before (A), and after 20 mg (B) and
30 mg (C) of rt-PA, showing progressive lysis of the thrombus. 
In two instances lysis was already adequate after only 10 mg rt-PA, seven
needed 20 mg, three 30 mg and one 35 mg. Thus in nine of the 13 cases (69%)
only 10-20 mg of rt-PA was required. Lysis time was 60-240 min (median
120). Minor local bleeding at previous dialysis puncture sites was noted in
five patients (31%), which was easily controlled by direct application of
pressure. No embolism or other major systemic complication occurred.
Angiogram found organic stenosis in six fistulas in the venous outflow
tract and surgical revision was done 1-8 days after the treatment. In the
remaining seven fistulas no organic lesion was found, and six of these were
functioning 50-395 days later. One fistula clotted two days after lysis and
surgical thrombectoy was necessary.
Hemodialysis was done the same or the next day using the declotted vascular
access. No hemorrhagic complication was encountered during or after
dialysis.

Discussion
There have been several attempts at thrombolysis of occluded dialysis
vascular access in the last 20 years. However, initial reports were
discouraging. The major disadvantages were prolonged infusion time, a high
incidence of bleeding complications, arterial and venous embolization and a
low success rate, mainly with streptokinase (1, 10). Subsequent reports,
particularly with urokinase, were more encouraging (2-7).
Reports of the use of rt-PA have now been published. Ahmed et al (8)
achieved successful thrombolysis in 10/15 (67%) using 20-30 mg of rt-PA.
Anderiani et al (9) reported complete thrombolysis in 71% of 42 fistulas,
with continuous infusion of an average of 21 mg rt-PA. In both studies, the
main complication was local bleeding through fresh puncture sites. No
systemic major complication was observed. In our study the success rate of
lysis, and type and rate of complications are comparable. Roberts et al (7)
reviewed 202 clotted AV-grafts treated by infusion of urokinase (180) or rt-
PA (22) using the pulsed spray technique through two catheters with
multiple side holes. This technique was highly successful with a high lysis
rate (99%) during a short infusion time (mean 40 min) using a small dose of
rt-PA (6.9 mg).
The absence of systemic and the low incidence of minor complications using
rt-PA is a major improvement over the more frequent and severe
complications seen with streptokinase and, to a lesser extent, with
urokinase (3-5, 10). The immediate safe use of the declotted fistula
obviates any temporary used for central catheters, a procedure associated
with both immediate and delayed complications (11-13).
In the present study, the procedure was done mainly in the dialysis unit,
immediately after establishing the diagnosis. Doing the procedures in an X-
ray department by an interventional radiologist calls for easy availability
of these facilities, and it usually takes time to prepare and coordinate
for the procedure. The incidence of complications in this study is
comparable to those in the literature.
The most common cause of clotting of an arteriovenous fistula is
hemodynamically significant stenosis, usually in the venous outflow tract.
In seven of our patients (54%) angiography revealed no organic stenosis in
this study. This rate of normal fistulograms is substantially higher than
described in other reports. Roberts et al (7) found only 3% normal
angiograms and Schilling et al (4) reported 27% negative results. The
reason is not obvious. It may be partially explained by a different cohort
of patients. In our group many comply poorly with treatment, which results
in excessive fluid retention between sessions. This requires a high
ultafiltration rate during dialysis, which often causes major fluctuations
in the plasma viscosity and sometimes post-dialysis hypotension. High
viscosity in combination with low perfusion pressure may lead to a fistula
clotting without any organic stenosis.
In conclusion, this study shows that rt-PA can safely be infused to achieve
rapid thrombolysis of clotted arteriovenous fistulas, with high efficacy.
This was especially advantageous in this caselist, where there was less
underlying stenosis of the fistulas. Percutaneous lysis prevented
unneccessary surgery and central catheters were not needed. A fistulogram
or maybe duplex Doppler investigation is important after complete lysis to
check for any organic lesion.

Reprint requests to: Yousef Boobes, MD, PO Box 15258, Tawam Hospital, Al
Ain, Abu Dhabi - United Arab Emirates
 
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Received: January 16, 1977; Accepted: February 01, 1997
 

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