The Vascular Lab and the Angiographic Assessment of PAD

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• The Vascular Lab and the Angiographic Assessment
  of PAD
• John C. Lantis II, MD
• Assistant Professor of Surgery Columbia
• Director of Clinical Research
• St Lukes-Roosevelt Hospital

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The Questions

• Does the patient have enough blood flow to heal
  their wound / or the intervention ?
• Does the patient have PAD, and should I be
  helping them to find coordinated care ?
• Is the patients circulation compromised to the
  point that I am highly concerned about tissue
  loss ?

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The Answers!

• (Obviously) A good physical exam
• Physiologic testing
• Ankle brachial index
• Pulse volume recording
• Duplex/MRI NOVA
• TCPO2 (Transcutaneous Oxygen Tension)
• Anatomic testing
• Duplex
• MRA
• Angiogram
• CTA

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The Ankle Brachial Index

• Measurement of segmental leg pressure compared to
  the highest brachial artery pressure
• Can be done at the bedside
• Requires little equipment
• Helps determine level of disease

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The ankle brachial Index

• Prognostic capabilities
• Forefoot amputations are likely to heal, if the
  ankle pressure is gt 70 mmHg, or if the ABI gt 0.45
• Toe amputations are likely to heal with ankle
  pressures of gt 35 mmHg or toe pressures gt 55 mmHg
  
• Limitations
• Ankle pressures can be artificially inflated in
  patients with diabetes mellitus and ESRD
• Toe pressures are therefore relied upon
• Pressure less than 50 mm Hg and a toe-to-arm
  ratio of less than 0.6 is indicative of ischemic
  arterial disease
• Foot lesions usually heal if toe pressures exceed
  30 mmHG in non-diabetic patients and 55 mmHG in
  diabetic patients
• Ipsilateral ankle to toe pressures can be used to
  assess for obstructive pedal vascular disease
• AVG 0.65 in normals
• AVG 0.23 in patients with rest pain of tissue loss

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Pulse Volume Recordings

• More sensitive and more specific
• Probably the bread and butter physiologic test
• Will give good guidance to the level and severity
  of disease

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Pulse Volume Recordings(with ABI and exercise)

• Treadmill walking test
• Walking at 1.8 mph
• 10 incline
• Uncovers more subtle lesions
• Especially proximal lesions in the iliac and SFA
  vessels
• A fall in the ABI of 0.2 or a recovery to
  baseline pressure that is greater than 1 minute
  is significant

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Categories of Chronic Limb Ischemia

• Clinical Description
• Normal Asymptomatic
• Mild Claudication
• (ABI - lt 0.7)
• Moderate Claudication
• Severe claudication
• Rest Pain
• (ABI - lt 0.4)
• Minor Tissue Loss
• Major Tissue Loss

• Pressure Criteria
• Normal Treadmill test
• Completes test, ankle pressure drops gt 20 mmHg,
  absolute ankle pressure gt 50 mmHg
• Between mild and severe
• Cannot complete treadmill test and ankle pressure
  after exercise lt 50 mm Hg
• Resting ankle pressure lt 60 mmHG or toe pressure
  lt 40 mmHG
• Resting ankle pressure less than 40 mmHg or toe
  pressure less than 30 mmHg
• Same as minor

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Duplex Ultrasound(Combination of B mode imaging
and doppler velocity criteria)

• Doppler waveform analysis of the femoral,
  popliteal and tibial vessels can be carried out
• Waveforms are evaluated similarly to the PVR
  tracings
• More accurate at localizing disease than PVRs
• Very labor intensive

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Transcutaneous Partial pressure of Oxygen

• Transcutaneous oxygen (tcPO2)
• Reflects the metabolic state of the target tissue
• Best for severe ischemia
• Heated Clark electrode (very tech dependent, hard
  to reproduce)
• lt 20 mmHg healing failure
• gt 40 mmHg healing success
• Elevate limb gt 300 /3 min drop gt 15 mmHg
  healing failure

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Other Methods of Assessing Blood Supply

• Laser Doppler Velocimetry
• A relative index of cutaneous blood flow
• With ischemia pulse waves are attenuated, mean
  velocities are decreased
• If mean velocity is gt 40 millivolts (mV) and
  pulse wave amplitude is gt 4 mV associated with
  healing
• NOVA
• Non-invasive Optimal Vessel Analysis (NOVA) a
  non-invasive Magnetic Resonance Imaging (MRI)
  technique
• NOVA provides actual milliliter/minute blood flow
  data using specialized software analysis of
  standard MRI phase contrast imaging
• Investigational

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Back to the Questions.

• Does the patient have enough blood flow to heal
  their wound / or the intervention ? NO
• Does the patient have PAD, and should I be
  helping them to find coordinated care ? YES
• Is the patients circulation compromised to the
  point that I am highly concerned about tissue
  loss ? YES

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Leads to the next two questions

• Where is the patients lesion?
• Segmental Pressures
• Segmental PVRs
• Long leg duplex
• Can I get this patient revascularized?
• What type of lesion?
• How many and where?

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MRA

• Non nephrotoxic contrast
• No arterial puncture
• However, claustrophobia limited
• Sensitivity and specificity to level of disease
  80-85
• Approximately 85 concordance with Angiography

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MRA
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Angiography

• Usually nephrotoxic dye
• Arterial puncture
• Done with sedation (few issues with
  claustrophobia)
• Able to intervene at time of procedure
• With subtraction capabilities probably able to
  see post-occluded vessels as well as MRA

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Angiography
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CT Angiogram

• Approaching MRAs capabilities
• Relatively large nephrotoxic dye load
• No arterial puncture
• Minimal claustrophobia issues
• Distal vessel resolution still machine and center
  dependent

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CT Angiogram
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A day in the life.

• A patient limps in
• No palpable pulse
• Small amount of tissue loss
• ABI/PVRs are obtained
• .Obtain toe NIFs..
• Pt went onto heal..

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Or more likely..

• We have flat line tracings
• Which we follow with a anatomic diagnostic .
• Which leads us to our next speakers