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Doppler ultrasound in renal patients

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Doppler uses in renal patients.

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Doppler ultrasound in renal patients

  1. 1. Doppler Ultrasound in renal patients The essentials Dr/Ahmed Bahnassy Consultant Radiologist MBCHB-MSc-FRCR(UK)
  2. 2. Aim of the lecture • highlighting the essential role of doppler in renal ultrasound examination. • illustrating the role of doppler in renal transplant evaluation. • expaining the role of doppler in renal failure patients as pre-operative planning to AV fistula for dialysis and monitoring its function and complications.
  3. 3. Anterior approach
  4. 4. Oblique approach
  5. 5. Transverse B-mode view of the abdominal aorta and right renal artery from an anterior approach. The ultrasound probe is oriented at midline and the Doppler cursor placed in the proximal right renal artery. The angle of incidence of the Doppler beam to the flow is unacceptable at approximately 89 degrees. By moving the probe to the left of midline and angling toward the patient’s right, an acceptable Doppler angle of 60 degrees is achieved
  6. 6. Flank approach
  7. 7. The Doppler sample volume is placed within the proximal right renal artery. In this view, an acceptable Doppler angle of 60 degrees or less is easily obtained.
  8. 8. values
  9. 9. Normal
  10. 10. Methods of evaluation of RA • Direct visualization • with Doppler • throughout the Main • renal artery and all • accessory renal • arteries • • Indirect Evaluation • – Doppler of the • segmental/interlobar • renal arteries at the • upper, mid and lower • renal poles • The most reliable approach combines the two methods.
  11. 11. Criteria for Renal Artery Stenosis Direct Evaluation • Velocities greater than 200 cm/sec have been shown to indicate a >60% RAS. • Post-stenotic turbulence must be documented beyond any focal velocity increase to confirm stenosis. • Bruits seen in Color Doppler or in the spectral waveform can also increase diagnostic confidence and aid in localization of a stenosis. • The RAR is calculated by dividing the highest peak systolic velocity in the renal artery by the normal aortic velocity. An RAR greater than 3.5 is considered abnormal. The use of the RAR instead of the absolute PSV value is preferable since hypertension itself can cause increased PSV velocities in all the vessels in hypertensive patients
  12. 12. Image A is a color Doppler image of a stenotic right renal artery origin. A color bruit is seen in the tissue surrounding the area of the post stenotic turbulence. The presence of the bruit can help to identify the location of the stenosis and increase diagnostic confidence.
  13. 13. A Doppler reading(B) obtained near the renal artery origin shows velocities over 600 cm/s in systole and over 300 cm/s in diastole consistent with a high grade stenosis.
  14. 14. Image C shows a spectral waveform obtained in the area of poststenotic turbulence just beyond the maximal area of stenosis. The velocity is lower at 317 cm/s and the waveform profile is irregular due to the turbulent flow.
  15. 15. Tardus–parvus waveform in a patient with RA stenosis. Note the delayed and dampened upstroke yielding a rounded appearance to the waveform.
  16. 16. The ESP is detected on each waveform. • In some cases, the ESP is the highest peak, but in others, the highest peak occurs later in systole. • The AT is always measured to the first systolic peak, which is the ESP in normal waveforms. Since the ESP is absent on abnormal waveforms, the AT is measured from the beginning of systole to the systolic peak. These waveforms are termed tardus parvus due to the delayed systolic acceleration
  17. 17. Fibromuscular dysplasia
  18. 18. FMD
  19. 19. Atheromatous plaque
  20. 20. Atheromatous stenosis
  21. 21. Alliasing effect
  22. 22. Severe stenosis criteria
  23. 23. Absent pic
  24. 24. Stenosis grading
  25. 25. Renal artery dissection
  26. 26. Renal artery dissection
  27. 27. AVM
  28. 28. AVM
  29. 29. AVF
  30. 30. AVF
  31. 31. Aneurysm
  32. 32. Nutcracker
  33. 33. Renal mass
  34. 34. Normal variants
  35. 35. Nephropathies
  36. 36. Lithiasis
  37. 37. twinkle artefact
  38. 38. Hydronephrosis
  39. 39. Renal vein evaluation
  40. 40. Renal vein thrombosis
  41. 41. Renal transplant evaluation
  42. 42. Rejection The edema leads to increased vascluar resistance and elevation of the resistive index. However, the finding of increased resistive index is a non-specific finding which can also be seen in the setting of infection, acute tubular necrosis, perioperative ischemia, hydronephrosis and extrinsic compression
  43. 43. ATN
  44. 44. Infarction
  45. 45. RAS
  46. 46. Renal vein anastomotic stenosis
  47. 47. RV thrombosis • Venous thrombosis can occur secondary to infection, severe rejection or technical problems with the anastomosis. • The diagnostic ultrasound findings include absence of flow on Power color and spectral Doppler analysis. • Venous thrombosis results in a high-resistance vascular circuit and can result in subsequent reversal of diastolic flow in the arterial waveform; • however, reversed diastolic flow is a nonspecific finding which can be seen in severe rejection, severe pyelonephritis, drug toxicity and extrinsic compression.
  48. 48. RV thrombosis
  49. 49. AV fistula
  50. 50. AV shunt evaluation
  51. 51. Changes after fistula
  52. 52. • Preoperative color Doppler ultrasound criteria • for good AVF outcome : • Arterial luminal diameter • - >1.6 mm (internal diameter) • Venous luminal diameter • - >2.0 mm / 3mm (without use of a tourniquet) • Arterial resistance index • - <0.7 ( at reactive hyperemia) fist test
  53. 53. Preoperative colour Doppler ultrasound of the radial artery, showing a change from triphasic high-resistance to biphasic low-resistance Doppler waveform at reactive hyperaemia.
  54. 54. mapping
  55. 55. Post operative assesment Good mature draining vein Diameter > 6mm Depth < 6mm No branches
  56. 56. • Assessment of blood volume • flow of the shunt: • Access volume flow / adequacy / • function : •  Normal ………… around….. 500 ml / m •  Malfunction … …..below…... 250 ml / m •  Above …………………………… 1000 ml /m • forearm-arm •  Risk of cardiac failure / hand ischemia ?
  57. 57. • Places of volume assessment •  Inflow / feeding •  Outflow / draining •  Access assessment AVF : • GRAFT : along the graft
  58. 58. Feeding artery
  59. 59. Shunt High flow velocity in shunt more than 250 cm/sec & characteristic low resistive flow
  60. 60. High flow fistula [ near 1000 ml / min ] showing proximal and distal flow in opposite direction .
  61. 61. Complications:1.stenosis
  62. 62. Graft stenosis
  63. 63. Venous stenosis-intimal hyperplasia
  64. 64. Arterial stenosis Significant stenosis at the anastomosis, with an elevated peak systolic velocity of 696 cm/s Venous stenosis, with an elevated peak systolic velocity of 662 cm/s
  65. 65. Significant anastomotic stenosis
  66. 66. 2.Thrombosis
  67. 67. changing arterial waveform dt fistula thrombosis
  68. 68. 3.Haematoma
  69. 69. Post operative haematoma
  70. 70. 4.Aneurysm
  71. 71. True venous aneurysm
  72. 72. 5.Steal syndrome • Clinical condition caused by arterial • insufficiency distal to a hemodialysis access • • Usually associated with reversal of distal flow • • Incidence around 3-5% • • Can progress to irreversible neuropathy , loss • of function (claw hand), gangrene, digit loss, • limb loss
  73. 73. Hand pain • Diminished/altered sensation • Pale, cold hand • Diminished/absent pulses • Weakness • Ischemic monomelic neuropathy
  74. 74. Haemodynamics
  75. 75. Reversed flow
  76. 76. Diagnosis Proximal Distal
  77. 77. 6.pseudoaneurysm risk of rupture
  78. 78. 7.poor outflow good outflow poor outflow

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