Surgical Science, 2012, 3, 473-478
http://dx.doi.org/10.4236/ss.2012.310094 Published Online October 2012 (http://www.SciRP.org/journal/ss)
Operative or Interventional Treatment in Infrainguinal
Bypass Occlusion: Are There Predictive Factors
Affecting Outcome?
T. Betz1, C. Uhl1, M. Steinbauer1, N. Zorger2, I. Töpel1
1Department of Vascular Surgery, Krankenhaus Barmherzige Brüder Regensburg, Regensburg, Germany
2Department of Radiology, Krankenhaus Barmherzige Brüder Regensburg, Regensburg, Germany
Received August 16, 2012; revised September 29, 2012; accepted October 10, 2012
ABSTRACT
Purpose: To evaluate outcome of interventional and surgical treatment in infrainguinal bypass occlusion and to identify
predictive factors affecting therapeutic success. Material and Methods: Over a period of three years 96 patients with
infrainguinal bypass occlusion were included in this retrospective study. 52 patients were treated by catheter-directed
thrombolysis and 44 patients by reconstructive vascular surgery. Results: 41 grafts could be reopened in thrombolytic
group (78.8%), thrombolysis failed in 11 cases (21.2%). 34 grafts were treated successfully by reconstructive vascular
surgery (77.3%), 10 grafts couldn’t be reopened or reoccluded within 30 days after surgical therapy. After a median
observation time of 14.7 months 30 of 48 (62.5%) bypass grafts treated with intraarterial thrombolysis and 19 of 27
(70.4%) grafts treated with thrombectomy were overall patent. Limb salvage was 81.3% in thrombolytic group and
88.8% in surgery group . No predictive factors affecting outcome could be identified in both groups excep t the localiza-
tion of the occluded graft (above/below knee). Conclusion: Infrainguinal bypass occlusion is a serious and challenging
complication in vascular surgery. Our study showed similar results for both therapeutic strategies. Despite our data was
retrospective with a small number of patients the localization of the occluded graft as predictive pre-therapeutic factor
was significant in thrombolytic and surgery group. Based on these scientific findings we established a guideline for
choice of therapeutic treatment in our institution after searching curren t literature.
Keywords: Thrombolytic Therapy; Bypass Occlusion; Percutaneous Intervention; Bypass Thrombectomy
1. Introduction
Long-term patency rates of infrainguinal bypass grafts
are—depending on the localization of the graft and the
graft material—satisfying. But critical limb ischemia due
to acute bypass occlusion remains a challenging and se-
rious problem, which threatens both, the patients limb
and life [1].
Two therapeutic strategies—surgical revascularization
or catheter directed intraarterial thrombolysis—are well
established today with similar amputation and mortality
rates [2]. If thrombolysis is successful it is a non-invasive
procedure to restore bypass flow. Not only the bypass
graft, but also outflow and collateral vessels are reopened.
The causative lesion is unmasked and can be treated by
angioplasty or stent placement. If surgical intervention is
still necessary, it can be performed on a well-prepared
patient on an elective basis [3]. Sometimes choice of
therapeutic treatment seems to be difficult. Thus several
factors predicting outcome must be considered by the
clinician.
2. Material and Methods
2.1. Baseline Characteristics
Using the database of our institution we identified 96
patients with infrainguinal bypass occlusion treated in
our department of vascular surgery between June 2008
and August 2011. During this period 52 patients under-
went intraarterial catheter directed thrombolysis. Patients
with an acute graft occlusion (symptoms less than 14
days) and a threatened or viable limb as defined by the
guidelines for acute lower extremity ischemia were in-
cluded. Baseline characteristics and clin ical conditions of
these patients are listed in Table 1.
44 patients with severe ischemic limbs with sensory
loss and muscle weakness were considered unsuitable for
thrombolysis and treated by reconstructive vascular sur-
gery; patients with absolute contraindications for intra-
arterial thrombolysis, too. Before starting thrombolysis a
duplex ultrasound of the ipsilateral and contralateral iliac
and femoral vessels was performed to show any vessel
stenosis affecting puncture.
C
opyright © 2012 SciRes. SS

T. BETZ ET AL. 474
Table 1. Baseline characteristics of Patients with infrainguinal bypass occlusion.
Baseline characteristics n Percentage
Age (mean) 69
Gender (M/F) 68/28 70.8%/29.2%
Medical comorbidities
Smoking history 32 33.3%
Coronary arter y disease 66 68.7%
Hypertension 85 88.5%
Diabetes mellitus 42 43.7%
Hypercholesterolemia 77 80.2%
Prethrombosis antiplatelet therapy
Aspirin only 62 64.6%
Clopidogrel only 1 0.01%
Combination of asp irin and clopidogrel 3 0.03%
Warfarin/coumarin 26 27.1%
Combination of coumarin and aspirin 4 0.04%
Symptoms at admission (Fontaine classification)
Stadium IIb 14 14.6%
Stadium III 58 60.4%
Stadium IV 24 25%
Bypass characteristics
Above-knee femoropopliteal bypass 51 53.1%
Below-knee femoropopliteal bypass 15 15.6%
Infrapopliteal bypass 30 31.3%
Venous 19 19.8%
PTFE 69 71.9%
Composite 8 8.3%
2.2. Technique
After percutaneous puncture of the contralateral femoral
artery and introduction of an arterial sheath a diagnostic
angiography was performed in crossover technique. The
occluded graft was passed by a guide wire and a multi-
side hole catheter was placed into the clot after guide
wire transversal test. If the bypass origin couldn’t be
found or the occluded graft could’nt be passed the pro-
cedure was aborted.
Standard thrombolysis protocol consisted of a bolus of
urokinase (250,000 IE) and then a continous overnight
infusion (100,000/h) under close surveillance in the inter-
mediate care unit. Simultaneously unfractionated heparin in
low dose was applicated over the arterial sheath (15,000 -
25,000 IU/24 h). After 24 hours a control an giog raph was
performed. Successful lysis was defined as restoration
of antegrade blood flow and complete clot lysis (>90%
volume). Any causative lesions demasked by thromboly-
sis were treated with immediate PTA or surgical revision
within a few days. In case of surgical treatment graft
thrombectomy with intraoperative angiography was per-
formed. Causative lesions (e.g. anastomotic stenosis)
were treated by adjunctive therapy (patch. intraoperative
angioplasty. new bypass graft). After successful therapy
unfractionated heparin was administered for 48 h intra-
venously aiming a partial thromboplastin time of 60 - 80 s.
Patients achieved a duplex ultrasound for documenting
graft patency prior to discharge.
3. Results
During this period 96 pat i e nt s (68 m al e s, 28 fem a les, mean
age 69, range 53 - 86 years) with infrainguinal graft

T. BETZ ET AL. 475
occlusion underwent therapy. 14 patients presented with
claudication (14.6%). 58 patients with limb-threatening
ischemia and rest pain (60.4%) and 24 patients with a
gangrene or necrosis at the foot (25%). 51 above-knee
femoropopliteal bypasses (53.1%), 15 below-knee femo-
ropopliteal bypasses (15.6%) and 30 infrapopliteal by-
passes (31.3%) were treated by thrombolysis or surgery.
There were 19 vein grafts (19.8%), 69 PTFE grafts (71.9%)
and 8 composite grafts (8.3%).
41 grafts could be reopened by thrombolysis (78.8%).
In 15 cases intraarterial thrombolysis was successful
without adjunctive therapy (36.6%). In 26 cases flow
limiting lesions—hämodynamically significant stenosis
or residual thrombus were unmasked (63.4 %): 9 lesions
were treated by surgery (21.9%) and 17 by angioplasty
(41.5%). Thrombolysis failed in 11 cases (21.2%). Of
these 3 patients declined any further therapy. 1 patient
received a bypass thrombectomy. 5 patients a new bypass
graft and 2 patients a major amputation due to persistent
limb threatening ischemia. In these 2 cases any surgical
revascularization was not possible. Thrombolysis related
complications were seen in 8 cases (15.4%). 3 patients
developed an acute renal failure (5.8%) immediately af-
ter thrombolysis. one patient had a major groin hema-
toma (1.9%) and required blood transfusion and one de-
veloped a wound infection at the puncture site and needed
antibiotic treatment (1.9%); one was operated on a false
aneurysma after thrombolysis (1.9%). Mortality was 5.8%.
Two patients died a few days after thrombolysis propably
due to myocardial infarction (no post mortem examina-
tion was perform e d) .
34 from 44 grafts were treated successfully by surgery
(77.3%). Thrombectomy alone was sufficient in 6 cases
(17.6%). In 28 cases (82.4%) underlying causative le-
sions. e.g. anastomotic stenosis were unmasked and
treated by patch (proximal or distal anastomosis) (20.5%)
or angioplasty alone (20.5%) or patch in combination
with an angioplasty (8.8%). In case of persistent occlu-
sion blood flow was restored by jump bypass or new
bypass graft (32.3%). 2 bypass grafts couldn’t be re-
opened. Reocclusion occurred in 6 cases in the first 30
days. 2 patients died a few days after thrombectomy; one
due to acute myocardial infarction and one due to persis-
tent limb ischemia with progredient ischemia and pallia-
tive therapy. After a median observation time of 14.7
months (1 - 56 months) 4 further patients in thrombolysis
group and 5 patients in thrombectomy group were de-
ceased. 30 of 48 (62.5%) bypass grafts treated with in-
traarterial thrombolysis overall were patent. Primary pate-
ncy in thrombolytic group was 46.7%. 16 patients (53.3%)
needed a reintervention. 12 patients received surgical
treatment due to reocclusion (6 new bypass grafts, 2 jump
bypasses, 4 patches) and 9 patients a major amputation. 4
patients needed a percutaneous transluminal angioplasty.
3 patients were spoiled at time of assessment. Overall
Limb salvage was 81.3%. After median observation time
19 of 27 (70.4%) grafts were overall paten t in thrombec-
tomy group. Primary patency was 33.3%. 10 patients
needed reintervention (37.4%). 5 further patients were
deceased at time of assessment. 2 were spoiled. Overall
limb salvage was 88.8%. Altogether 11 from 96 patients
(11.5%) received a major amputation. 13 patients were
deceased (13%) and 5 patients were lost to follow-up at
time of assessment.
To evaluate an association between patient demogra-
phics and comorbid conditions on thrombolytic or surgi-
cal success we performed a Chi-Test with our data (Ta-
bles 2 and 3). Statistical analysis detected a significant
association between failed or successful thrombolysis and
thrombectomy and graft localization above or below-knee.
4. Discussion
Acute infrainguinal bypass occlusion is a serious com-
plication in vascular surgery. Several studies had been
performed to end ongoing debate when to choose throm-
bolysis and when to choose surgery in case of acute limb
ischemia. Most studies are retrospective with a small and
heterogenous number of patients. Only three large pro-
spective randomized studies had been performed in the
mid-nineties which confirmed that thrombolysis is an
alternative to surgical therapy with similar amputation
and mortality rates [4,5]. However choice of treatment
often seems to be difficult in daily routine.
Despite our data was retrospective with a small num-
ber of patients our study showed that the localization of
the occluded graft as predictive pretherapeutic factor was
significant in thrombolytic and surgery group. It seems
reasonable that therapeutic success depends on the local-
ization of the occluded graft. The better “outflow-sec-
tion”, the better the outcome. Below knee grafts had
poorer outflow v essels. normally. From our experience it
is reasonable to treat “simple” above-knee grafts by sur-
gery. More complex tibial or pedal reconstructions or
patients who had already been operated should be treated
by intraarterial catheter directed thrombolysis. Other
predictive factors like gender, age, preexisting diseases,
antiplatelet therapy and graft material were not signifi-
cant [6]. So we searched literature after additional pre-
dictive factors affecting therapeutic outcome.
Thrombolyis only seems to be successful in a defined
time frame. This is due to the fact that presence of vessel
thrombus causes damage to the vessel endothelium and
longer ischemic intervals (longer than 14 days) are asso-
ciated with more extensive endothelial injury and in-
creasing thrombogenicity [7]. If the clinical symptoms
last longer than 14 days a thrombolytic therapy doesn’t
seem to be reasonable [2,5,8]. Because intravascular clot
is organized and adherent at the graft wall. Age of the

T. BETZ ET AL. 476
Table 2. Association between successful thrombolysis and prethrombolytic factors in 52 patients treated with intraarterial
thrombolysis.
Thrombolytic outcome versus Chi-Test: p-values
Male Female 0.281
<70 years 70 years > 0.859
Claudication Rest pain 0.178
Smoker Non-smoker 1.000
Hypercholesterolemia Normal cholesterol level 0.668
Diabetics Non-diabetics 0.721
Graft localization above knee Below-knee 0.044
Venous graft PTFE graft 0.329
Renal insufficiency Normal renal function 0.331
ASS Phenprocoumon 0.419
Table 3. Association between successful thrombectomy and preoperative factors in 44 patients treated with surgery.
Outcome after Thrombectomy versus Chi-Test: p-values
Male Female 0.557
<70 years 70 years > 0.126
Claudication Rest Pain 0.255
Smoker Non Smoker 0.557
Hypercholesterolemia normal cholesterol level 0.445
Diabetics Non-diabetics 0.601
Graft localization above knee below knee 0.031
Venous graft PTFE graft 0.678
Renal insufficiency Normal renal function 0.968
ASS Phenprocoumon 0.459
bypass graft and the graft material might be relevant for
thrombolytic success. too. Vein grafts longer than one
year in place had better long term patency after throm-
bolysis [9]. Older grafts are better incorporated into the
connective tissue and the nutrient supply depends not on-
ly on the intraluminal blood flow but also on the ingrown
adventitial capillaries. So vessel endothelium compen-
sates “thrombolytic damage” better. However long-term
patency of vein grafts after thrombolysis is poorer than
patency of prosthetic grafts. Thrombotic occlusion causes
sclerosis with thrombotic organization and endothelial
necrosis of the vein graft [10]. Thrombus of a occluded
prosthetic graft is less adhesive and inner surface will be
slower remodeled and obturated by connective tissue.
Based on these scientific findings we developed a guide-
line for choice of thrombolytic treatment in our institu-
tion (Flowchart Table 4) and established a scoring
system to assess thrombolytic success: patients presenting
with limb ischemia due to infrainguinal bypass occlusion
should be first clinically examined to evaluate the clini-
cal category. A duplex ultrasound must be performed to
detect any vessel stenosis above or below the occluded
bypass graft. Patients with sensory loss muscle paralysis
and inaudible Doppler signals (clinical category Ruther-
ford III) shouldn’t be treated by thrombolysis and need
immediate surgical therapy. Exclusion criteria for throm-
bolysis must be checked: patients with absolute contrain-
dications for intraarterial thrombolysis, including severe
uncontrolled hypertension, stroke or transient ischemic
attack within two months, history of internal, gastron-
intestinal bleeding or major surgery within two weeks
must be excluded from thrombolytic therapy [4]. Before
starting thrombolytic therapy prethrombolytic situation
hould be checked (duration of clinical symptoms, age of s

T. BETZ ET AL. 477
Table 4. Guideline for choice of thrombolytic treatment.

T. BETZ ET AL. 478
bypass graft, bypass material, graft localization). A scor-
ing system helps to assess therapeutic outcome (Yes: 1
point, No: 0 point, 4 points thrombolytic success most
likely, with diminishing value high risk for therapy fail-
ure).
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