4 Vascular disease/CKD Flashcards
What is hypertensive nephrosclerosis?
- chronic kidney disease (scarring!) in a patient with long-standing, poorly controlled HTN
- typically evidence of other end organ damage as well
- proteinuria often present (many filters scarred, so the remaining ones become stressed and “leaky”)
What are the gross morphologic features of hypertensive nephrosclerosis?
- normal to slightly small kidney
- finely granular subcapsular surface
What are the histological findings of hypertensive nephrosclerosis?
- subcapsular glomerular sclerosis
- arteriolar hyaline
- “downstream damage” from glomerular sclerosis:
- tubular atrophy
- interstitial fibrosis
What are the histologic findings in the kidney caused by malignant HTN?
- mucoid intimal thickening (arteries)
- glomerular capillary wrinkling (afferent constriction, kidney trying to protect itself from high pressures)
- glomerular basement membrane duplication (similar to thrombotic microangiopathy)
What causes renovascular HTN?
-
renal artery stenosis from…
- atherosclerosis (in older patients)
- fibromuscular dysplasia (especially in young females)
- trauma, dissection, extrinsic compression/tumor
- decreased blood flow to the kidneys causes secondary HTN
What is the mechanism of renovascular HTN?
- decreased renal blood flow releases renin
- renin converts angiotensinogen to angiotensin I
- ACE converts ang I to ang II
- ang II vasoconstricts and stimulates aldosterone release
- aldosterone increases Na/water reabsorption
When should you suspect renal artery stenosis?
- early or late onset HTN (outside the range of 20-60 yo)
- difficult to control HTN
- abdominal or flank bruit
- renal failure after starting ACE inhibitor
- efferent arteriole dilation unmasks dysfunction
What are the morphologic features of renal artery stenosis caused by atherosclerosis?
- stenosis in the proximal renal artery
- eccentric plaque with intimal fibrosis, cell debris, lipid and foam cells
- medial and adventitial fibrosis
- plaque may hemorrhage/dissect
- calcification may occur
What are the morphologic features of renal artery stenosis caused by FMD?
FMD= fibromuscular dysplasia (intimal, medial, and adventitial forms)
- alternating thinned media and thickened fibromuscular ridges
- forms “string of beads” radiographically
- beading is larger than caliber of artery
- middle to distal artery
What are the arteries commonly affected by FMD?
FMD= fibromuscular dysplasia
- renal artery (60-75%, bilateral 35%)
- cervicocranial arteries (25-30%)
- visceral arteries (9%)
- extremity arteries (5%)
**two vascular beds involved in up to 28%
What are the treatments for renal artery stenosis?
- medical management only (common)
- surgical revascularization (only if severe)
- angioplasty and stenting
What are the morphologic features of a renal cortical infarct?
- renal artery occlusion -> extensive parenchymal infarction
- smaller branch -> wedge-shaped infarct
- pale with hyperemic border
- coagulative necrosis
- hemorrhage and acute inflammation at edge
- fibrotic (later)
Describe atheroembolic disease
- Disruption of atherosclerotic plaques (aka “a kidney heart attack”)
- Can cause acute and subacute renal failure
- Eosinophils can be seen in the blood or urine (may be related to activation of C5a)
- Occurs after procedures that disrupt plaques in the aorta, leading to a shower of cholesterol emboli that lodge in the renal microvasculature
What are the outcomes of atheroembolic disease?
- stabilized or normal renal function in mild, isolated cases
- chronic, progressive deterioration in renal function in subacute cases
- end-stage renal disease in severe cases
- permanent dialysis may be necessary
What is TMA?
TMA= thrombotic microangiopathy
- characterized by thrombosis in capillaries and arterioles
- microangiopathic hemolytic anemia (MAHA)
- thrombocytopenia
- renal failure
- e.g. hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP)
What is the pathogenesis of TMA?
TMA=thrombotic microangiopathy
- endothelial injury and activation
- intravascular thrombosis
- platelet aggregation
- vascular obstruction
- vasoconstriction
- “small blood vessels taking a beating” -> disrupts flow -> increases clotting -> RBCs lyse
What is HUS?
HUS= hemolytic uremic syndrome
- commonly from shiga toxins
- often occurs after intestinal infection with E coli O157:H7
Define chronic kidney disease
- progressive irreversible renal insufficiency that develops over months to years
- may ultimately lead to end-stage renal disease (GFR <10 ml/min)
What are the main causes of chronic kidney disease?
- diabetes (irreversible; “caterpillar on a leaf” analogy)
- hypertension
- glomerulonephritis
- cystic diseases
How is the kidney size affected in chronic kidney disease?
- usually (but not always) reduced kidney size
- may have normal or large kidneys in…
- diabetes
- amyloidosis
- HIV
- cystic kidney disease
What are the 3 main consequences of CKD?
CKD= chronic kidney disease
- anemia
- decreased erythropoietin production (because of decreased function of fibroblasts at the cortico-medullary junction)
- occurs below GFR of 60 ml/min
- hypertension (increased renin)
- secondary hyperparathyroidism
Describe the complications of secondary hyperparathyroidism in CKD
- decreased renal synthesis of 1,25 dihydroxy vitamin D3 and decreased phosphate excretion result in…
- hypocalcemia
- hyperphosphatemia
- renal osteodystrophy
What are some other possible findings in CKD?
- metabolic acidosis
- decreased secretion of ammonium and retention of phosphates/sulfates
- hyperkalemia (K excretion increased via GI)
- inability to maintain sodium and water balance
- coagulopathy- platelet dysfunction
- sensorimotor neuropathy
What are the physical symptoms of CKD?
Physical symptoms of chronic uremia:
- lethargy, fatigue
- day-night sleep reversal
- anorexia, N/V
- pruritus
- restless legs syndrome
- uremic percarditis
How can you slow the progression of CKD?
- control hypertension (ACEi, ARB)
- reduce proteinuria (slows “holes in the filter”; tubules are injured by protein)
- control blood sugar and hyperlipidemia
- smoking cessation
- disease-specific therapy as indicated (anemia, acidosis)
- dietary restrictions
- Na, K, phosphorus, protein?
What is the most common cause of CKD and end-stage renal disease in the US?
diabetes
How do you treat ESRD?
- ESRD= end-stage renal disease
- treat with…
- dialysis
- kidney transplant
