Nonimaging Physiologic Tests

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Nonimaging Physiologic Tests

• Assessment of Lower Extremity Arterial Disease
• Part II

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Stress Testing
Exercise and Reactive Hyperemia Vasodilatation
of PRV Increased Blood flow
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Stress Testing
Limb with Normal Limb with
Occlusion No Decrease in ASP
Decrease in ASP
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Stress Testing

1. Exercise
2. Reactive hyperemia

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Exercise

• Standard Treadmill exercise 2 mph at 12 grade
  for
• 5 minutes or until symptoms occur.
• Record the walking time and nature of symptoms
• Record BSP and ASP before and immediate
  post-exercise
• Evaluate (A) Magnitude of immediate decrease in
  ASP
• (B) Time to recovery to resting pressure.

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Exercise

• Normal Response
• Negative Stress test
• Increase or No Increase in ASP
• Abnormal Response
• Positive Stress test
• Decrease in ASP

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Exercise

• Normal - End Examination
• Abnormal Measure ASP at 1-2 min interval
• up to 10 minutes or until pressure returns
  to
• pre-exercise level.

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Exercise

• Abnormal Response Fall into three groups
• Group 1
• Group 2
• Group 3

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Exercise

• Group 1 - Decrease AP to low or unrecordable
  level
• and return to resting value in 2 to 6
  minutes
• Indicates Single level Stenosis/Occlusion

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Exercise

• Group 2 - Decrease AP to low or unrecordable
  level
• and remains so up to 12 minutes
• Indicates Multiple levels Stenosis/Occlusion

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Exercise

• Group 3 - Decrease AP to low or unrecordable
  level
• and remains so up to 15 minutes
• Indicates Ischemic Rest Pain

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Reactive Hyperemia

• Inflate Pneumatic Cuff at thigh level to
  suprasystolic
• level.
• Record ASP before and after release of cuff.
• Normal response includes a decrease in ASP 17
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• Single-Level - lt 50 decrease in ASP
• Multiple Levels - gt 50 decrease in ASP

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Doppler Signal Waveform Analysis

• Flow Pattern in main arteries of lower limb has 3
  
• components.
• Large forward velocity peak cardiac systole
• Brief phase of flow reversal in early diastole
• Low frequency phase of forward flow in late
• diastole
• TRIPHASIC FLOW PATTERN

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Doppler Flow Pattern

• Distal to the Stenosis - Single forward velocity
  component
• (Monophasic), with lower PSF and flat and rounded
  
• waveform.
• At Stenosis Abnormally high PSF
• Proximal to Stenosis 1. Good Collaterals
  Normal
• 2. No
  Collateral harsh thumping sound

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Doppler Flow Pattern

• Measuring the Pulsatility Index
• Peak to Peak Frequency/ Mean Frequency
• Values
• CFA 6.7
• Pop A 8
• PTA 14.1

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Pulse Volume Recording

• Volume of tissue changes with cardiac cycle.
• Systole AI gt VO Volume increases. -
• Diastole AI decreases and VO predominates
• volume decrease
• Brief period of flow reversal in early diastole
• These volume changes can be measured by
• Plethysmographic Methods.

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Pulse Volume Recording

• Systole - Upward Slope rise rapidly to a
  sharp
• peak.
• Diastole Downward Slope falls more slowly
• bowed towards baseline.
• Flow reversal Dicrotic Notch

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Pulse Volume Recording

• Proximal Disease

1. Loss of Dicrotic notch RWA
2. Slower systolic rise
3. Delayed Peak
4. Flat and rounded shape
5. Downward slope is bowed away from baseline

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Pulse Volume Recording

• Factors Affecting the PVR waveforms
• Edema reduce the amplitude
• Obesity and well-developed muscle reduce
• amplitude and loss of reflected waves.
• 3. Patient positioning
• 4. Well developed Collateral high amplitude

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Pulse Volume Recording
Valuable when pressure measurements are
artifactually due to medial calcification.
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Sources of Error

• Cuff artifact
• Incompressible vessels
• Hypertension
• Low cardiac output
• Collateral formation

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Goal of Noninvasive Arterial Testing

• Confirm the diagnosis.
• Indicate the location of the lesion.
• Quantify the resulting degree of disability.

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Goal of Noninvasive Arterial Testing

1. Initial Evaluation
2. Follow up Testing
3. Healing of ulcers and amputations (ASP lt 55mm Hg/
   80 mmHg in ND/D)
4. Predicting the results of Arterial Surgery TPI
   of 0.85 or less / API of gt 0.8
5. Predicting the results of Sympathectomy API of
   gt 0.35

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Differential Diagnosis

1. Osteoarthritis
2. Neurospinal Disease Lumbar disk, spinal
   stenosis
3. Nocturnal muscle cramps
4. Peripheral Neuropathy
5. Reflex sympathetic dystrophy
6. Venous thrombosis