Vascular disorders of the kidney Flashcards
List the vascular disorders
Arterial:
- Renal Artery Stenosis - the most frequent one
- Cholesterol embolisation
- Vasculitis
Capillary:
Thrombotic microangiopathies
- HUS, Hemolytic uremic syndrome
- TTP, Thrombotic thrombocytopenic purpura
Veins:
- Renal vein thrombosis
Mechanisms of renal artery stenosis
65% - Atherosclerosis, age related
35% - Fibromuscular dysplasia
rare causes:
Aortic aneurysm or dissection
External compression, malignancy
Takayasu arteritis
Describe fibromuscular dysplasia
non-atherosclerotic, non-inflammatory blood vessel constriction. (idk wtf its called fibromuscular, it just affects arteries)
Caused by abnormal, non-neoplastic growth of the intima, media, or pararterial tissue of a vessel.
Most commonly occurs in females, under the age of 50.
Occurs distally in the Renal Artery, as opposed to atherosclerotic stenosis, which usually occurs very proximal to the aorta.
Can affect any artery, but most commonly the renal and carotids.
Causes secondary hypertension due to RAAS activation of the kidneys.
Usually affects multiple spots, creating a beaded appearance on the artery, with alternating stenosis and aneurysm.
Unilateral Stenosis,
features,
effects of RAS blockade
Plasma renin activity is high
RAS blockade reduces blood pressure acutely,
Increased lateralization of lab tests (lateralization of Renin expression)
GFR may drop precipitously in stenosed kidney, lowering overall function.
Bilateral Stenosis, RAS blockade
Normal or low plasma renin activity
Blood pressure only drops after volume is reduced,
May lower GFR.
Symptoms and signs suggestive of renal artery stenosis:
- Sudden onset of hypertension and age under 50 years
- Sudden onset of hypertension with diffuse atherosclerosis
- Therapy resistant hypertension
- Abdominal bruit
- Decreasing renal function with unclear cause
- Renal function deteriorated by ACE-Is or ARBs.
- Size difference between kidneys >1cm
- Hypokalemia of unknown origin - excessive RAAS
- Peripheral artery disease
- Atherosclerotic retinopathy
Diagnosing RAS
CT-angiography - contrast contra’d less than 3GFR, hydration if >60.
Duplex ultrasound
MR-Angiography- no contrast if eGFR <30ml/mg
Captopril renography - aka Renal scintigraphy,
pre and post- ACE-I administration
ACE-I will significantly reduce flow to the stenosed kidney in unilateral stenosis.
Renal artery stenosis therapy
Angioplasty and stenting
or Surgical revascularization
Control hypertension: CCBs Diuretics BBs Alpha blockers
Control atherosclerosis risk:
Statins
Antiplatelet drugs
Complications of Revascularisation in renal artery stenosis
Just angioplasty has fewer complications than stenting
Stenting
Results are not great, ‘dubious’ according to lecture
May worsen daibetes
Cholesterol embolisation
Arterial dissection, thrombosis, occlusion
Contrast induced nephropathy
When is surgical revascularization indicated and what are its comlications
indications:
- Aortic aneurism
- Aorto-illiac stenosis
- Multiple stenoses,
- Fibromuscular dysplasia with large aneurysms
Complications
Artery dissection
Acute vascular occlusion
General surgery complications, is a major vascular surgery, significant risk and expense.
If successful in well-selected cases, significant blood flow improvement and 80% survival at 5 years.
Indications for renal revascularization
Sudden, rapidly worsening renal function due to stenosis
Therapy resistant severe HTX
Pulmonary edema and HTX
Cholestrol embolisation, causes
Spontaneously from significant atherosclerosis
After major surgery or endovascular intervention
Immediately or 1-3 days later.
Cholesterol emoblisation, presentation
Multi-organ involvement Livedo Reticularis Blue toe syndrome, necrosis of the extremities Bowel Ischemia and necrosis Acute Kidney Injury Acute pancreatitis
Fever
Nausea
Leg/flank pain
labs
Eosinophiluria
Low complement
Definitive diagnosis by histology, with arterioles containing thrombosed regions with cholesterol clefts or biconvex gaps that are empty due to cholesterol washout on slide preparation.
Cholesterol embolisation treatment
ACE-I’s
Corticosteroids
Statins
do NOT give anticoagulants.
What are the thrombotic microangiopathies,
what are their common features
TTP and HUS
Acute disorders, in
Thrombocyte activation and thrombocytopenia, with impaired micro circulation from small vessel/capillary thrombi formation.
Hemolytic anemia, Generation of Schistocytes Increased LDH, Increased Bicarb Decreased haptoglobin
