Vascular diseases of kidneys Flashcards
What are the 3 types of large vessel disease?
- ACUTE RENAL ARTERY OCCLUSION/INFARCT
- RENAL ARTERY STENOSIS/ISCHAEMIA
- RENAL VEIN THROMBOSIS
Why is it important to detect acute renal artery occlusion/infarct?
• important, potentially reversible cause of renal failure
Causes of acute renal artery occlusion/infarct
- abdominal trauma, surgery, embolism, vasculitis, extra-renal compression, hypercoagulable state, aortic dissection
- kidney transplant more vulnerable
Px of acute renal artery occlusion/infarct
(depend on presence of collateral circulation)
• fever, nausea, vomiting, flank pain
• leukocytosis, elevated AST, ALP
• marked elevated LDH (LDH >4 times upper limit of normal with minimal elevations in AST/ALT strongly suggestive)
• acute onset hypertension (activation of RAAS) or sudden worsening of long-standing hypertension
• renal dysfunction, i.e. elevated Cr (if bilateral, or solitary functioning kidney)
Ix of acute renal artery occlusion/infarct
- renal arteriography (more reliable but risk of atheroembolic renal disease)
- contrast-enhanced CT or magnetic resonance angiography, duplex Doppler studies (operator dependent)
Rx of acute renal artery occlusion/infarct
- anticoagulation, thrombolysis, percutaneous angioplasty or clot extraction, surgical thrombectomy
- medical therapy in the long-term to reduce risk (e.g. antihypertensives)
Define renal artery stenosis/ischaemia
chronic renal impairment secondary to hemodynamically significant renal artery stenosis or microvascular disease
• significant cause of ESRD: 15% in patients over 50 yr old (higher prevalence if significant vascular disease)
Causes of renal artery stenosis/ischaemia
• usually associated with large vessel disease elsewhere
• causes of renal artery stenosis:
○ atherosclerotic plaques (90%): proximal 1/3 renal artery, usually males >55 yr, smokers
○ electrolytes, osmolality (gently rehydrate when needed, i.e. CHF)
○ fibromuscular dysplasia (10%): distal 2/3 renal artery or segmental branches, usually young females (typical onset
Px of renal artery stenosis/ischaemia
- severe/refractory HTN and/or hypertensive crises, with negative family history of HTN
- asymmetric renal size
- epigastric or flank bruits
- spontaneous hypokalemia (renin activation in under-perfused kidney)
- increasing Cr with ACEI/ARB
- flash pulmonary edema with normal LV function
Ix of renal artery stenosis/ischaemia
- must establish presence of renal artery stenosis and prove it is responsible for renal dysfunction
- duplex Doppler U/S (kidney size, blood flow): good screening test (operator dependent)
- digital subtraction angiography (risk of contrast nephropathy)
- CT or MR angiography (effective noninvasive tests to establish presence of stenosis, for MR avoid gadolinium contrast if eGFR
Rx of renal artery stenosis/ischaemia
• surgical: percutaneous angioplasty ± stent, surgical revascularization, occasionally surgical bypass
• medical: BP lowering medications (ACEI is drug of choice if unilateral renal artery disease but
contraindicated if bilateral renal artery disease)
• little or no benefit if therapy is late i.e. kidney is already shrunken (however, therapy can be
considered to save the opposite kidney if normal)
Risk Factors of renal artery stenosis/ischaemia
- > 50 yr old
- smoking
- other atherosclerotic disease (dyslipidemia, diabetes, diffuse atherosclerosis)
Causes of renal vein thrombosis
• hypercoagulable states (e.g. nephrotic syndrome, especially membranous), ECF volume
depletion, extrinsic compression of renal vein, significant trauma, malignancy (e.g. RCC), sickle cell disease
• clinical presentation determined by rapidity of occlusion and formation of collateral circulation
Px of renal vein thrombosis
- acute: nausea/vomiting, flank pain, hematuria, elevated plasma LDH, ± rise in Cr, sudden rise in proteinuria
- chronic: PE (typical first presenting symptom), increasing proteinuria and/or tubule dysfunction
Ix of renal vein thrombosis
• renal venography (gold standard), CT or MR angiography, duplex Doppler U/S
Rx of renal vein thrombosis
- thrombolytic therapy ± percutaneous thrombectomy for acute RVT
- anticoagulation with heparin then warfarin (1 yr or indefinitely, depending on risk factors)
What are the 4 types of small vessel disease of kidney?
- HYPERTENSIVE NEPHROSCLEROSIS
- ATHEROEMBOLIC RENAL DISEASE
- THROMBOTIC MICROANGIOPATHY
- CALCINEURIN INHIBITOR NEPHROPATHY
Definition of atheroembolic renal disease
progressive renal insufficiency due to embolic obstruction of small and medium-sized renal vessels by atheromatous emboli
Causes of atheroembolic renal disease
spontaneous or after renal artery manipulation (surgery, angiography, percutaneous angioplasty)
anticoagulants and thrombolytics interfere with ulcerated plaque healing and can worsen disease
Ix of atheroembolic renal disease
- eosinophilia, eosinophiluria and hypocomplementia
- renal biopsy: needle-shaped cholesterol clefts (due to tissue-processing artifacts) with surrounding tissue reaction in small/medium-sized vessels
Rx of atheroembolic renal disease
no effective treatment; avoid angiographic and surgical procedures in patients with diffuse atherosclerosis, medical therapy for concomitant cardiovascular disease
Prognosis of atheroembolic renal disease
poor overall, at least a third will develop ESRD
Causes of thrombotic microangiopathy
etiologies include the spectrum of TTP-HUS, DIC, severe preeclampsia
Renal involvement of thrombotic microangiopathy & its characterisation
- renal involvement more common in HUS than TTP
* renal involvement characterized by fibrin thrombi in glomerular capillary loops ± arterioles
