This document discusses Doppler ultrasonography and the spectral waveforms used to analyze blood flow patterns in vessels. It provides details on: - The Doppler spectrum which represents blood flow velocities over time on a graph with frequency on the vertical axis and time on the horizontal axis. - Characteristics of normal flow patterns seen in major vessels and how they relate to vessel anatomy and organ function. - Abnormal flow patterns seen in pseudoaneurysms and arteriovenous fistulas which involve damage to vessel walls. Specific waveform patterns are described that indicate these conditions.

1. PERIPHERAL VASCULAR
DOPPLER
DR MOHIT GOEL
5 July 2013

2. Each normal major vessel in the human body has a characteristic flow pattern
that is representable in spectral waveforms obtained with Doppler
ultrasonography (US) and that reflects both the anatomic position of the
vessel and the physiologic need of the organ it supplies.
The Doppler spectrum is a time-velocity waveform that represents variation
in intravascular blood flow velocities during the cardiac cycle.

3. Time is represented along the horizontal axis, and frequency shift (velocity) is depicted
along the vertical axis.
The intensity or brightness (also referred to as the gray-scale velocity plot) of the
spectral line represents the number of red blood cells that are reflecting the ultrasound
beam at each velocity. The width of the spectral line represents the range of velocities
within a vessel. The width may vary during the normal cardiac cycle, narrowing during
systole and widening in diastole.
The spectral window is the clear black zone between the spectral line and the baseline.
Widening of the spectral line and filling of the spectral window is called spectral
broadening. Spectral broadening is normally seen in the presence of high flow velocity,
at the branching of a vessel, or in small-diameter vessels.

12. ATA
TPT

31. PSEUDOANEURYSMS
A pseudoaneurysm is a complete rupture through the three walls
of the artery. The intima, media and adventitia are compromised.
In the lower extremity, the escaping blood pools as a well
circumscribed mass and is constrained by the surrounding soft
tissues.
Pseudoaneurysms can develop following penetrating trauma or
arterial catheterization.
The communicating channel between pseudoaneurysm and arterial
lumen is detectable by color Doppler imaging.
Often, a high velocity scale (PRF, peak repetition frequency) is
needed since blood flow velocities are very high.

32. The presence of a "to-and-fro" or "forward-backward" waveform is typically
seen when the Doppler gate is placed over the communicating channel of the
pseudoaneurysm.
The "to" or "forward" component is due to entry of blood into the collection as
the soft tissues expand to accommodate entry of blood within the
pseudoaneurysm cavity. This occurs during systole.
The "fro" or "backward" component is seen during diastole as the blood stored
in the cavity is ejected back into the artery.
This is caused by the stored energy due to
the elasticity of the surrounding soft tissues.
Pseudoaneurysms can have multiple
compartments as well as be solitary .
Blood flow in a pseudoaneurysm cavity
has a tendency to show a swirling pattern.

33. PSEUDOANEURYSMS
Color swirl on CD and “to & fro” sign on pulsed doppler

34. classic to-and-fro waveform of a pseudoaneurysm

37. Arteriovenous fistulas
Arteriovenous fistulas (AVFs) can result when there is puncture of
an artery and vein with a direct communication between the two
injured vessels.
A significant pressure gradient will result in a focal area of
significantly increased velocity at the site of the AVF with flow
directed from the artery to the vein.
Color Doppler imaging of AVFs will often demonstrate a bruit
artifact and/or a thrill may be palpable.

38. Spectral Doppler analysis of the effected artery above the
AVF will demonstrate a mono-phasic continuous waveform
with elevated systolic and diastolic velocities.
Flow in the injured artery distal to the AVF will generally have
normal pulsatility.
Spectral Doppler analysis of the effected vein central to the
AVF will demonstrate “arterialized flow” with pulsations
during systole and a lack of respiratory phasicity.

39. This CDI demonstrates a typical color bruit artifact associated with tissue vibration.

40. Spectral Doppler analysis image of common femoral vein above fistula shows arterialized
flow.

41. A, Color flow Doppler image shows a high-velocity jet (arrow)from the common
femoral artery (A) into the distended common femoral vein (V)

42. B, The arterialtype signals sampled in the common femoral vein are consistent
with a large AV fistula showing an arterialized venous blood flow pattern.

43. THANK YOU