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RENAL ARTERY DOPPLER

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Patients with abdominal aortic dissection. Evaluation of renal transplant. Audible Bruit Patients with AAA Relationship: Renal Artery Stenosis causes hypertension. – PowerPoint PPT presentation

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Title: RENAL ARTERY DOPPLER


1
RENAL ARTERY DOPPLER
2
Objectives
  • Upon completion of the presentation
  • the viewer should be able to
  • Identify a normal renal artery signal.
  • Describe Tardus-Parvus, RAR and Acceleration
    index.
  • List causes for hypertension
  • Outline a normal Renal Doppler exam

3
Table of Contents
  • Indications for a Renal Doppler Exam
  • Renal Artery Stenosis
  • Hypertension
  • Anatomy Variants
  • Diagnostic Criteria
  • Doppler waveform
  • Exam Protocol
  • Case Examples

4
Clinical Indications for Doppler
  • Evaluate a hypertensive patient for renal artery
    stenosis (RAS).
  • Hypertensive patients not controlled with medical
    treatment.
  • Patients with abdominal aortic dissection.
  • Evaluation of renal transplant.
  • Audible Bruit
  • Patients with AAA

5
Renal Artery StenosisCauses
  • Atherosclerosis Plaque deposits cause
    narrowing/blockage.
  • Affects men gt women
  • Typically effects age gt40 years
  • Involves proximal aspect renal artery
  • Fibromuscular Fibrous tissue growth in arterial
    walls.
  • Affects women gt men ( approx.. 4 1).
  • Typically affects ages lt 50 years
  • Involves mid to distal aspects of renal artery
  • Acute Traumatic injury causing obstruction.

6
Hypertension and RAS
  • Relationship
  • Renal Artery Stenosis causes hypertension.
  • Hypertension is the symptom that indicates RAS
    Doppler needed

7
Hypertension and RAS
Adrenal Gland
Kidney
8
Hypertension and RAS
  • RAS
  • Increased PR
  • Decrease renal blood flow
  • Production of rennin

9
Hypertension and RAS
  • Rennin converts angiotensinogen to angiotensin.
  • Angiotensin is a potent vasonstrictor.

10
Hypertension and RAS
  • Angiotensin also acts on the adrenal cortex to
    produce aldosterone.
  • Aldosterone causes the kidney to absorbed more
    sodium and water.

11
Hypertension and RAS
  • This leads to increased in blood volume and also
    the BP.

12
Renal Artery Stenosis
  • Anatomy Variants
  • Diagnostic Criteria
  • Doppler waveform
  • Exam Protocol
  • Case Examples

13
Renal Anatomy
  • Kidneys
  • Vessels
  • Accessory Vessels
  • Doppler Waveform

14
Normal Anatomy of the Kidneys
  • Size 9-11cm
  • Difference between Lt. Rt. Renal Length lt 2 cm

15
Normal Anatomy of the Kidneys
16
Normal Anatomy of the Kidneys
17
Celiac Axis
Rt Renal Artery
Lt Renal Artery
Superior Mesenteric Artery
Aorta
18
Segmental arteries
Interlobar arteries
Main Renal artery
Arcuate arteries
19
Normal Right and Left Renal Artery
Coronal View
Transverse
20
Normal Right Renal Artery
Transverse
21
Normal Left Renal Artery
Transverse
22
Renal Artery Stenosis
  • Normal Variants Accessory Vessels

23
Normal Variants of Renal Arteries
  • Most common anatomy is single right and left
    renal artery (approx. 55 population)

24
Normal Variants of Renal Arteries
  • Second most common an is accessory renal artery
    branching off a main renal artery (14)

25
Accessory Renal Arteries
  • Branch off a main renal artery or aorta.
  • Supply small portions of the renal parenchyma.
  • Can be
  • 1) single or multiple
  • 2) unilateral or bilateral

26
Accessory Renal Arteries
27
Accessory Renal Arteries
  • Can extend to upper, mid,or lower poles of
    kidney.
  • Stenosis in an accessory can result in
    hypertension.
  • Best evaluated in coronal plane with color
    Doppler.

28
Accessory Renal Arteries
Two Left Renal Arteries
29
The Normal Renal Waveform
  • Low resistant waveform.
  • Rapid and steep upstroke during systole.
  • Dicrotic notch.
  • Low resistant runoff during diastole.

30
The Normal Renal Waveform
31
RAS Exam
  • Diagnostic Criteria
  • Protocol
  • Example of normal Exam

32
Diagnostic Criteria
  • Color Doppler non-visualization
  • Peak Systolic Velocity
  • RAR
  • Acceleration time
  • Acceleration Index
  • End Diastolic Ratios
  • Tardus Parvus

33
Diagnostic Criteria
34
Peak Systolic Velocity
  • Normal gt1.8 m/sec
  • Low grade(1-59)gt1.8 m/sec
  • No post-stenotic disturbance
  • High grade(60-99)gt1.8 m/sec
  • Post-stenotic turbulence
  • Total occlusion - no flow

35
Peak Systolic Velocity
36
Remember all angles MUST be 60 degrees or less!
Peak Systolic Velocity
37
Renal-Aortic Ratio
  • RAR PSV renal artery
  • PSV aorta

38
Renal-Aortic Ratio
  • PSV alone may be inaccurate due to
    difficulty with Doppler angle insonation
  • RAR angle independent
  • Obtain aortic signal 2cm distal to SMA
  • Use highest main renal artery signal

39
Renal-Aortic Ratio
  • Normal lt 3.5
  • Low grade (1-59) lt 3.5
  • High grade (60-99) gt 3.5
  • Total occlusion renal length lt 9cm

40
End Diastolic Ratio
  • Assess both parenchymal vascular resistance and
    disease.
  • Sufficient perfusion gt 0.23
  • Severe parenchymal vascular disease lt 0.23

41
Acceleration Index
?V
AT
?T
AI ?V/ ?T
42
Acceleration Index
  • Acceleration time time for peak systolic
    velocity
  • Acceleration index acceleration slope divided
    change in time
  • lt 3.78 kHz/sec/MHz indicates greater than 50
    stenosis.

43
Acceleration Index
  • To calculate
  • Place the first cursor at the beginning of
    systole.
  • Place the second cursor at the peak of systole.

44
Acceleration Index
45
Acceleration Time
  • Acceleration time gt 0.1 sec indicates greater
    than 50 stenosis.
  • Measure with sweep speed of 100 mm/sec.
  • Normal waveforms have steep systolic upstrokes,
    whereas waveforms distal to a stenosis have a
    more gradual upstroke and dampened systolic peak.

46
Abnormal Doppler Findings
  • Peak systolic velocity ( PSV) in renal artery
    ( proximal, mid, or distal ) gt 180
    cm/sec.
  • Renal Artery / Aorta Ratio ( RAR), gt 3.5.
  • Tardus-Parvus.

47
What is Tardus-Parvus?
  • Tardus delayed early systolic acceleration or
    upstroke
  • Parvus diminished amplitude and rounding
    systolic peak.

48
What is Tardus-Parvus?
Delayed upstroke
49
What is Tardus-Parvus?
Rounded
50
Tardus-Parvus
  • Seen in distal segmental arteries, indicating
    high grade stenosis proximally.
  • Measured using either
  • Acceleration time (normal is less than 70ms)
  • Acceleration Index ( normal is greater than 3/m/s
    square)
  • When present, 100 indicative of RAS, but not
    ALWAYS present in RAS patients

51
Tardus-Parvus
Normal
52
Tardus-Parvus
Abnormal
53
Tardus-Parvus
Normal renal artery notice the steep upstroke
normal acceleration index in this waveform.
54
Tardus-Parvus
Notice the rounded waveform and the blunted
upstroke with tardus-parvus.
55
Renal Artery Protocol
  • Exam Protocol
  • Normal RAS Exam

56
Renal Artery Doppler Scanning
  • Test usually takes 60-90 minutes.With experience
    the time can be reduced.
  • Patient should be fasting (at least 8 hours).
  • Patient should be well hydrated, encourage water
    intake.
  • 4 to 2 MHz transducer

57
Protocol
  • Grey Scale
  • Measure and document kidney size, and any
    abnormalities. (Normal size 9-13 cm.)
  • Rule out mass, stones, hydronephrosis, etc.
  • Start with the abdominal aorta midline and
    obtain and measure Doppler signal. Remember to
    look for plaque (arteriosclerosis).

58
Protocol / Kidneys
  • Abnormalities
  • Hydronephrosis
  • Stones
  • Renal Failure
  • Polycystic Disease

59
Protocol / Kidneys
60
Protocol / Kidneys
61
Protocol / Kidneys
62
Protocol / Kidneys
63
Protocol / Aorta
  • Doppler Midline
  • Beware of Plaque

64
Protocol / Aorta
65
Protocol / Aorta
66
Protocol / Aorta
67
Protocol
  • Doppler and Measure
  • Rt. and Lt. renal arteries, Prox , mid, and
    distal aspects of each and any accessory
    arteries.
  • ALL Doppler angles are 60 degrees or LESS.
  • Segmental arteries (upper, mid, and lower poles)
    of each kidney.
  • Acceleration index of segmental arteries. Look
    for tardus-parvus.

68
A Normal Renal Artery Examination
69
Proximal Right Renal Artery
70
Mid Right Renal Artery
71
Mid Right Renal Artery
  • Transverse view

72
Mid Right Renal Artery
  • Transverse view

73
Distal Right Renal Artery
74
Segmental Renal Artery
75
Segmental with Acceleration Index
76
Angle lt 60
T 60
77
Angle lt 60
T 78
78
Overview of Renal Artery Study
  • Routine US exam of the Kidneys
  • evaluate size and echotexture, r/o pathology
  • Doppler Aorta
  • Measure PSV, for RAR calculation
  • Doppler renal arteries
  • Measure PSV, for RAR calculation

79
Overview of Renal Artery Study
  • Doppler segmental arteries
  • obtain acceleration index
  • look for Tardus-Parvus
  • Calculate RAR
  • RARPSV Renal artery/ PSV Aorta

80
Renal Artery Stenosis Treatment
  • Medically with ACE inhibitors
  • Balloon angioplasty
  • Arterial stent
  • Surgically.
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