Overview Graft surveillance

7/18/2015
Overview
• Graft surveillance
• Veins bypass
• Prosthetic bypass
• Extra-anatomic bypass
• Why extra-anatomic?
• What are the types
• Carotid - carotid
• Carotid - subclavian
• Thoraco - bifemoral
• Axillary - femoral/bifemoral
• Femoral - anterior tibial
• femoral- distal peroneal
Extra-Anatomic Bypass Grafts
Eric Hager, MD
Assistant Professor of Surgery
University of Pittsburgh Medical Center
Graft surveillance
Introduction
• Goal of arterial reconstructions is to
improve arterial blood flow
• Unfortunately, the durability of these
reconstructions is limited, often due to
development of stenosis
• 20-30% of all vein grafts will develop
hemodynamically significant stenosis
within the first year
•
Introduction
• Prospective analyses suggest QOL,
limb salvage in CLI patients depends
Surveillance
programs
on
sustained graft patency
are used to detect failing
grafts and allow
• Revisions
for failing to
grafts
are far
intervention
prevent
more successful than those for
thrombosis
failed grafts
•
•
Chetter IC, Spark JI, Scott DJ, et al. Prospective analysis of quality of life in
patients following ingra-inguinal reconstruction for chronic critical ischaemia.
Br J Surg. 1998; 85:951-5.
Mills JL. Infrainguinal vein graft surveillance: How and when. Semin Vasc
Surg. 2001;14:169-76.
Mills JL, Wixon CL, James DC, et al. The natural history of intermediate and critical
vein graft stenosis: Recommendations for continued surveillance or repair. J Vasc
Surg. 2001; 33:273-80.
Qualities of an ideal surveillance program
• Accurate, precise, and predictive
of impending failure
• Easily accessible
• Noninvasive
• Cost-effective
• Can lead to successful
intervention once problem is
found
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Purpose of Surveillance
• Improve long-term patency
• Detect impending graft failure
• Minimize number of secondary
interventions
• Maximize benefit of secondary
interventions
Duplex Technique
• Patient lying supine
• Repositioning may be necessary
depending on graft location
• 5-10 MHz, flat linear array
transducers are best for
infrainguinal graft imaging
• Minimize cost of care
**Peripheral Vascular Ultrasound: How, Why and When. 2nd Ed. Thrush A, Hartshorne T. Elsevier 2005.
Duplex Technique
• Divide graft into three segments to facilitate
communications (proximal, middle, distal)
• Spectral waveform from region of normal-appearing
graft from each segment, as well as from areas of flow
disturbance
• Analyze the anastomoses, as well as the inflow and
outflow vessels
Duplex Technique
• In-Situ vein graft
• Course superficially in leg
• 10MHz transducer provides best image
• Superficial location may make difficult obtaining good
doppler angle
• Careful not to apply pressure to graft, creating false stenosis
• Distal anastamosis may be deep
• May encounter missed vein branches, resulting in graftvenous fistulas
Duplex Technique
• Ratio calculations (Vr)
Risk Categories
• I: Low risk
• PSV < 180 cm/sec and Vr < 2.0
and
– Graft flow velocity > 45 cm/s and ABI decrease < 0.15
Vr = 335 cm/s / 69 cm/s = 4.8
• Therapy: No intervention or change in surveillance
required
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Risk Categories
• II: Intermediate risk
• PSV 180-300 cm/s or Vr > 2.0
and
• Graft flow velocity > 45 cm/s and ABI
decrease < 0.15
• Therapy: Closely follow with serial duplex
examination and repair only if evidence of
progression
Risk Categories
• IV: Highest risk
• PSV > 300 cm/s or Vr > 3.5
and
• Graft flow velocity <45 cm/s or
water-hammer flow
• Therapy: prompt repair
Risk Categories
• III: High risk
PSV<20 cm/s
• PSV > 300 cm/s or Vr > 3.5
and
• Graft flow velocity > 45 cm/s
and ABI decrease > 0.15
PSV >300cm/s
• Therapy: Repair electively
within 2-3 weeks
Natural history of vein graft stenosis
• With serial duplex US
surveillance:
• Normal – Incidence of graft
thrombosis 3% per year (mean fu
27.5mo)
• Intermediate – 63% progressed to
critical stenoses, 32% resolved or
stabilized, 12% thrombosis per
year
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
92%
12%
3%
NormalThrombosis
IntermediateriskSevere
• Severe – when not repaired, 92%
occlude within 12 months
Mills JL, Wixton CL, Donovan CJ, et al. The natural history of intermediate and critical vein
graft stenosis: Recommendations for continued surveillance or repair. J Vasc Surg.
2001;33:273-280.
Prosthetic Grafts
• Evidence is weak regarding duplex surveillance for
prosthetic bypass grafts
• Failure is usually thrombotic resulting from low
flow, instead of intrinsic lesions
• Has been suggested that best use of duplex in this
setting is to select patients for anticoagulation (lowflow grafts) **
Graft Surveillance
• Operative report should be available
• To review graft type, location, anastomosis site, other
procedures on inflow/outflow (e.g., endarterectomy)
• Prior studies should be available
• Facilitate evaluation for lesion progression
• Role of duplex surveillance not as well defined
** Brumberg RS, Back MR, Armstrong PA, et al. The relative importance of graft surveillance and warfarin
therapy in infrainguinal prosthetic bypass failure. J Vasc Surg. 2007;46:1160-6.
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Extra-anatomic bypass
Extra-anatomic bypass
• Bypass placed in a nonanatomic bed
• Infection
• Non-reconstructable
disease
•
•
•
•
•
•
Axillary-bifemoral bypass
• Performed in patients
sickly patients or those
with a hostile abdomen
• History of abdominal
surgery/radiation
• Inflow – medial axillary
artery
• Tunneled under pec major
and under the skin
• Outflow- one or both
femoral arteries
• Used to re-profuse the
lower extremities and
avoid the abdomen
Thoracic Aorta-bifemoral bypass
Axillary-bifemoral
Thoraco-bifemoral
Fem-fem
Carotid-subclavian
Carotid-carotid
Femoral-AT, Femoral-distal
peroneal
Thoraco-bifemoral
bypass
• Patients that failed Axillary
bifemoral bypass OR are
younger and more robust
(better patency)
• Inflow – Mid thoracic aorta
through thoracotomy
• Tunneled posteior laterally
through diaphragm and
into a subcutaneous tunnel
• Outflow – one or both
femoral arteries
Femoral-femoral
bypass
• Patients with an
occluded common
(external) iliac artery,
inflow can be gained
from the contralateral
femoral artery
• Tunneled in a “lazy C”
configuration in a
subcutaneous manner
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Carotid/carotid or carotid
subclavian bypass
Subclavian to CCA bypass- pre op
• Patients with occluded
proximal SCA who are not
candidates for
endovascular intervention
(proximity to vertebral
artery etc.)
OR
• Patients with long
segment occluded CCA
Subclavian to common carotid – post op
Femoral – anterior tibial
bypass or femoral – distal
peroneal bypass
(fibulectomy)
Thank you!
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