Dr. McDonnell is with Radiology Associates in
Corpus Christi, TX.
The rapid development of new
percutaneous techniques for the treatment of peripheral vascular
disease continues to expand the role of the interventional
radiologist. The advent of balloon-expandable and self-expanding
stents and the development of percutaneously placed stent-grafts
has altered the more classical, primarily surgical treatment
modalities and will continue to do so. The role of angioplasty
(PTA), the utilization of directional atherectomy devices, and the
use of stents and stent -grafts will herein be reviewed in regard
to their utilization for the treatment of peripheral vascular
disease in the femoral and popliteal arteries.
Angioplasty of occlusive lesions within the femoral and
popliteal arteries often is utilized when patients present with
life-style limiting claudication, rest pain, or now-healing lower
extremity ulcers, and also is used as an adjunct to increase blood
flow, aiding in healing of wounds following surgery (primarily from
amputations). Factors that influence the initial angioplasty
outcome and the patency rate at follow-up exam include certain
lesion characteristics and the quality of the distal run-off
Positive predictors of initial and long-term patency include
short, segmental lesions (of less than 3 cm) which do not involve
the superficial femoral artery (SFA) origin or the popliteal
trifurcation; the presence of at least two run-off vessels;
performing the procedure for claudication symptoms rather than rest
pain or limb salvage; and a good immediate angiographic result with
palpable distal pulses.
Negative predictors of continued patency include those procedures
performed for limb salvage, one or no distal run-off vessels, or
the presence of long segmental stenoses or calcified eccentric
lesions, as well as diffuse cardiovascular disease (i.e. diabetes).
Suboptimal results related to technical factors, such as residual
thrombotic material, residual stenosis greater than 30%, and focal
dissection after angioplasty, also can adversely affect the
The initial success of angioplasty of short segmental lesions
of less than 2 cm with two vessel run-off is approximately 83 to
98%. The one-year primary patency rate is reported to be between 60
and 80%; however, this falls dramatically at 5 years, with patency
rates of 40 to 60%.
Similar results are seen in lesions treated with surgical bypass
procedures, where there is an initial success rate of approximately
100% and a 5-year patency rate
of between 50 and 70%.
Additionally, the utilization of balloon angioplasty in longer
stenoses or occlusions yields significantly lower primary and
secondary patency results.
Procedural complications related to percutaneous balloon
angioplasty occur in approximately 5 to 10% of cases.
These are most commonly groin related (hematomas); however,
dissections related to guidewire manipulations, vessel
perforations, distal embolization, pseudoaneursyms, and acute
thrombosis are recognized complications. Meticulous attention to
detail and operator experience in performing these procedures
should reduce the complication rate.
Within the armamentarium for treatment of infrainguinal
stenosis or occlusions are the peripheral atherectomy devices, the
most commonly utilized device being the Simpson Atherocath
(Mallinckrodt Med. STZ, MO). Atherectomy devices mechanically
remove plaque from the wall of diseased vessels, in either an
extirpative or ablative fashion.
Indications for the use of these devices include focal, eccentric,
or calcified plaque that fails to respond to balloon angioplasty;
post-angioplasty flow-limiting intimal flaps; intimal hyperplasia
in graft anastomoses that fails to respond
to balloon angioplasty (including dialysis fistulas); hyperplasia
and for "valvectomy" in "in-situ" venous grafts that fail balloon
Atherectomy at anastomoses have been particularly successful,
yielding an initial 100% technical success rate and a 2- to
3-year patency rate of 79%.
Utilization of an atherectomy device requires an antegrade
access and placement through a vascular sheath. The Simpson
Atherocath is designed with either a fixed tip guidewire or can be
placed over an .018" wire. As with angioplasty, appropriate
location within the lesion is essential. At the appropriate
position, the support balloon is inflated to oppose the cutting
chamber against the lesion. The rotating blade is then advanced
through the cutting chamber. The debris is collected in the cutting
chamber, and the catheter can then be rotated for additional
Disadvantages of this device include the need for antegrade
access, which can be difficult in obese patients and may preclude
its use in treatment of nearby common femoral and proximal SFA
High cost, prolonged procedure time, and larger arterotomy sites
cause a relatively high incidence of complications. Most of these
complications are groin related (hematomas); however, they may
include pseudoaneursyms, distal embolizations, vessel dissection,
and acute thrombosis.
In regard to initial and long-term patency rates for focal,
segmentally treated SFA and popliteal lesions, numerous studies
have demonstrated that atherectomy does not result in better
long-term patency than does balloon angioplasty. As an example,
Vroegindeweij et al demonstrated that atherectomy does
not provide clinical or hemodynamic improvement in comparison with
angioplasty at 2- or 3-year follow-up (at 2 years: 52% vs 87%, at 3
years: 34% vs 56%). In addition, they compared angioplasty with
atherectomy in a prospective trial and concluded similar
angiographic and clinical results.
From the above, it is apparent that atherectomy should not replace
balloon angioplasty in infrainguinal stenosis.
The advent of balloon-expandable stents and the widespread use
of these devices in the iliac arteries for the treatment of
stenosis and occlusion is well documented; however, their use in
the femoral and popliteal system has been less successful. Primary
and secondary patency rates vary widely from study to study, and
there are many additional factors which contribute to the initial
success of the procedure.
The primary treatment of isolated segmental stenosis within
the superficial femoral and the popliteal arteries continues to be
percutaneous transluminal angioplasty. The use of stents within
these vessels often is performed to improve the immediate results
of PTA, in particular to prevent immediate technical failures.
Despite the initial high rate of technical success with stents,
results have been discouraging regarding long-term patency
(restenosis remains a significant problem).
Nevertheless, stenting of the femoropopliteal vessels is performed
by some interventionalists for residual stenosis after angioplasty,
in acute occlusion or thrombosis, post PTA flow-limiting
dissections, in calcified lesions not responsive to angioplasty,
and in those cases where stenting of an obstructing lesion may
increase inflow in an attempt at limb salvage.
Regarding the initial and long-term success of stent
placement, publicized results have been inconsistent and, at times,
conflicting. However, it is apparent that focal stenosis (of less
than 4 cm) treated with short stents demonstrated longer primary
and secondary patency than longer lesions (the 2-year primary
patency rate for stents of less than 4 cm is approximately 60%,
while it is approximately 30% for longer lesions).
Also, stenotic lesions have demonstrated better primary and
secondary patency than lesions of an occlusive nature (the 2-year
patency for stenosis is approximately 73% vs 33% for occlusions).
In regard to the efficacy of primary stenting of lesions within the
SFA and popliteal vessels versus angioplasty, it is apparent that
stent placement does not improve the clinical or hemodynamic
As an example, a prospective study of primary stenting versus
balloon angioplasty demonstrated that the primary patency rate at 1
year was slightly less for the stented group (approximately 63% for
the stented group and 74% for the angioplasty group).
As described above, there are certain factors which influence
the patency of stented infrainguinal vessels. These include the
length of the stenosis, whether the area stented is a stenosis or
an occlusion, the number of stents utilized (use of a greater
number of stents has a much lower primary patency), and the
existence of comorbid processes, such as diabetes mellitus and
diffuse peripheral vascular disease.
As with angioplasty, the presence of two vessel runoff greatly
influences the primary patency rate. Smoking negatively influences
the outcome of the procedure, as does small vessel diameter.
Additionally, the placement of stents across joints is often
associated with a poor result secondary to compression.
The incidence of complications with PTA and stent placement is
relatively low and there is a high initial success rate. Groin
complications are the most common and include hematomas and
pseudoaneurysms. Acute thrombosis, pain, sepsis, vessel rupture,
and stent compression also are recognized complications.
Dissections may occur and may require stent placement if they are
The most recent tool under investigation for treatment of
infrainguinal occlusive disease is the stent graft. As of this
date, stent grafts have been utilized primarily in the aorta and
iliac vessels; however, this has been expanded to the infrainguinal
region for the treatment of claudication and limb threatening
These conduits have been utilized in long segmental occlusive
disease, complex lesions unlikely to be successfully treated with
other endovascular techniques, for the exclusion of aneurysms, and
as an alternative to uncovered stents for failure of primary
A variety of devices are under investigation, but most utilize a
self-expanding metallic stent covered with a synthetic graft
material. It is postulated that lining the stent with a synthetic
graft material reduces the incidence of restenosis and excludes
thrombus and/or plaque from the lumen.
Numerous studies are now being performed to evaluate the
patency rate of covered versus non-covered stents. The initial
results of patency have varied; however, this technique of
percutaneous endovascular repair appears feasible.
In a study of endovascular grafting of SFA stenosis,
occlusions, complex lesions, and angioplasty failures, the initial
success rate was nearly 100%, with a primary patency of 72% and a
secondary patency of nearly 84%.
The mean length of these lesions was approximately 20 cm. In
another study, the stent graft system was used in patients with
similar or shorter lesions and demonstrated 6-month to 1-year
primary patencies ranging from 59 to 70%, with secondary patencies
from 70 to 85%. In each study, the initial technical success rate
was nearly 100%.
As attested to by the above, the stent graft system is technically
highly successful; however, additional clinical trials are
necessary to evaluate their clinical utility.
The incidence of complications occurring during stent graft
placement within the femoral and popliteal system is relatively
high. However, refinement of the techniques and continued user
experience will undoubtedly reduce their occurrence. The most
common complications are hematomas and pseudoaneurysms. Technical
problems occasionally require conversion to a femoral bypass
procedure. Distal embolization, acute graft occlusion/
thrombosis requiring lytic therapy, perigraft leak, and distal
dissections related to guidewire manipulations also occur
infrequently. The operative mortality is low.
The percutaneous treatment of vascular disease has expanded
the role of the interventional radiologist. The utilization of
percutaneous transluminal angioplasty in short focal lesions of the
superficial femoral arteries has both short- and long-term patency
rates approaching those of classical surgical bypass procedures.
Atherectomy devices, of which there are many, have slightly lower
primary patencies and have a higher incidence of complications.
Therefore, it should not replace angioplasty as the initial
percutaneous treatment modality for infrainguinal lesions.
Atherectomy is, however, effective in the treatment of graft
intimal hyperplasia and eccentric calcified stenosis when balloon
angioplasty has failed, or for treating post-angioplasty dissection
Primary stenting of SFA lesions does not improve the clinical
or hemodynamic outcome in comparison with balloon angioplasty,
and probably results in a slightly lower primary and secondary
However, stents are effective in the treatment of suboptimal
angioplasty results, including residual stenosis, flow-limiting
dissections, and calcified lesions that fail to respond to balloon
Finally, the use of covered stents for a variety of SFA lesions is
an attractive idea with the potential to further expand
endovascular therapy. Early results attest to its feasibility;
however, additional clinical trials are necessary to define its
role in the percutaneous management of femoral lesions.