1. Diagnostic Medical Sonography Program Vascular Technology
Holdorf
LECTURES 3 & 4 PART 2
Arterial Testing
Signs, Symptoms, and Disease Mechanisms

2. Doppler Waveform Analysis

4. CAPABILITES
Help confirm diagnosis / approximate location of arterial occlusive disease
Indicate severity of the occlusive process
Combined with Doppler segmental pressures
LIMITATIONS
Patients with casts or extensive bandages
Waveforms may be affected by ambient temperature
Uncompensated congestive heart failure may result in dampened waveforms
Unable to discriminate stenosis from occlusion
Technically dependent test

5. The patient’s hip is externally rotated, knee slightly bent.
PATIENT POSITIONING
Supine with the extremities at the same level as the heart. To decrease influence of hydrostatic pressure.
The patient’s hip is externally rotated, knee slightly bent.
Other positions: Rt/Lt lateral decubitus positon, or prone
PHYSICAL PRINCIPLES
The DOPPLER effect:
When a wave is reflected from a moving target, the frequency of the wave received is different (Doppler shift) from that of the transmitted wave
This effect occurs with relative motion between the source and the receiver of the sound
Blood is moving target: Transducer is stationary source

6. Continuous-wave (CW) Doppler is utilized
The reflected frequency is higher/lower than the transmitted frequency, defending on the direction of flow
Types of Doppler Velocimetry:
Analog: Employs a zero crossing frequency meter, to display the signals graphically on a strip chart recorder. Paper speed = 25mm/sec.
Zero Crossing Frequency Meter
Circuitry counts each time the input signal crosses through zero (the baseline) within a time span
High frequency waves have may oscillations; low frequency waves have few
Direction of blood flow varies during the cardiac cycle
Machine estimates frequencies present in reflected signal and displays them.

7. Has acceptable accuracy
Drawbacks include: noise, less sensitivity, high velocities are underestimated, low velocities are overstated
Most equipment does a self calibration when the system is activated.

8. Zero Crossing Frequency Meter: Analog Doppler

9. Spectral analysis: Individual frequencies displayed by Fast Fourier Transform (FFT) method
More commonly used during duplex evaluation
Time displayed on the horizontal axis (X), frequency shifts displayed on the vertical axis (Y)
Free of many of the analog recording drawbacks.

10. Spectral analysis

11. Technique Acoustic Gel applied: 8 – 10 MHz Doppler probe utilize
Upper extremities: Doppler velocity wave forms record from the following bilaterally:
Subclavian
Axillary (axilla)
Brachial (at elbow –antecubital fossa
Radial (thumb side, at wrist)
Ulnar (5th finger side, at wrist

12. Lower extremities
Doppler velocity wave forms recorded from the following arteries bilaterally:
Common Femoral CFA
Superficial Femoral SFA
Popliteal PopA
Posterior tibial PTA Medial Malleolus
Dorsalis Pedis DPA Top of foot
Peroneal (if necessary Location: Lateral Malleolus

13. POTENTIAL SOURCES OF TECHNICAL ERROR
The audible AND wave form qualities are observed, documented, and combined with Doppler segmental pressures:
POTENTIAL SOURCES OF TECHNICAL ERROR
Improper probe position
Inadvertent probe motion
Incorrect angle of incidence
Inadequate amount of gel
Excessive pressure on the probe tip
Insufficient period of rest before testing (For patient)

14. Interpretation - Qualitative

15. Normal Signals
Triphasic
Rapid upslope
Sharp peak
Rapid downstroke
Flow reversal
Resumption of forward flow
Example: UE, LE arteries

16. Triphasic signal

19. Biphasic Rapid upslope Sharp peak Fairly rapid downstroke
Flow Reversal
No resumption of forward flow
Also considered normal in some patients

20. Biphasic signal