Vascular Diseases of the Kidney

Vascular Diseases of the Kidney

Vascular Diseases of the Kidney

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Hypertensive Nephropathy - Pressure Problems

  • Benign Nephrosclerosis: Chronic, mild-moderate hypertension.

    • Pathology: Hyaline arteriolosclerosis (thickened arteriolar walls, narrowed lumen).

    • Gross: Symmetrically atrophic kidneys, finely granular cortical surface ('granular contracted kidneys').

    • Clinical: Slow, progressive renal insufficiency.

  • Malignant (Accelerated) Nephrosclerosis: Severe, rapidly rising BP (often >180/120 mmHg).

    • Pathology:

      • Fibrinoid necrosis of arterioles (smudgy, eosinophilic deposits).
      • Hyperplastic arteriolosclerosis ('onion-skinning' due to concentric smooth muscle cell proliferation & collagen deposition).
    • Gross: Normal size or slightly enlarged kidneys; petechial hemorrhages on cortical surface ('flea-bitten' kidney).

    • Clinical: Acute renal failure, papilledema, hypertensive encephalopathy, headaches, visual disturbances.

⭐ 'Onion-skin' appearance of arterioles is pathognomonic for malignant hypertension.

📌 Mnemonic: Benign = Boringly slow, hyaline. Malignant = Madly fast, fibrinoid & onion skinning, Many petechiae (flea-bitten).

Renal Artery Stenosis - Pipe Dreams

  • Causes
    • Atherosclerosis: Most common; elderly males, ostial.
    • Fibromuscular Dysplasia (FMD): Young females; 'string of beads'. 📌 FMD - 'Females, Medial, Dysplasia'.
  • Pathophysiology: ↓ Renal Perfusion → RAAS activation → Renovascular HTN.
  • Clinical Features
    • Refractory HTN (>70% stenosis).
    • Abdominal bruit.
    • Flash pulmonary edema.
    • AKI on ACEi/ARB.
  • Diagnosis
    • Doppler US: Initial.
    • CTA / MRA.
    • DSA: Gold standard.

Renal artery fibromuscular dysplasia "string of beads" Renal artery angiogram: Normal vs. fibromuscular dysplasia

⭐ Unexplained hypokalemia can be a clue for Renal Artery Stenosis due to secondary hyperaldosteronism.

Thrombotic Microangiopathies - Clot Chaos

  • Pathophysiology: Endothelial injury → platelet activation → microvascular thrombi.
  • Hallmarks: Microangiopathic Hemolytic Anemia (MAHA), thrombocytopenia, organ damage (kidney, CNS).
FeatureHemolytic Uremic Syndrome (HUS)Thrombotic Thrombocytopenic Purpura (TTP)
EtiologyTypical (D+): Shiga toxin (E.coli O157:H7)Acquired: Anti-ADAMTS13 Abs
Atypical (D-): Complement dysregulationHereditary: ADAMTS13 mutations. Activity <10%
Key FeaturesPredominant acute renal failure (children)Predominant neurological symptoms, fever (adults)
Lab FindingsMAHA, thrombocytopenia, schistocytes, ↑ creatinineMAHA, thrombocytopenia, schistocytes, severe ADAMTS13 deficiency
Organ Inv.Kidney (severe) >> CNSCNS (prominent), Kidney (milder)

Peripheral blood smear with schistocytes Fibrin thrombi at vascular pole in kidney biopsy

⭐ Presence of schistocytes on peripheral blood smear is a hallmark of thrombotic microangiopathies.

Emboli & Infarcts - Vascular Blockades

  • Atheroembolic Renal Disease (AERD):
    • Cause: Cholesterol crystal emboli, typically after invasive arterial procedures (e.g., angiography).
    • Clinical: Subacute renal failure (↑creatinine), eosinophilia, livedo reticularis, purple toes, ↓complement.
    • Patho: Biconvex, needle-shaped cholesterol crystal clefts in small renal vessels. Cholesterol crystal clefts in renal arteriole
  • Renal Infarction:
    • Etiology: Thromboembolism (e.g., AF, endocarditis, mural thrombi); also trauma, vasculitis (PAN).
    • Gross: Wedge-shaped pale cortical necrosis. Old infarcts: shrunken, fibrotic. Gross image of wedge-shaped renal infarct
    • Features: Acute flank pain, hematuria, fever, nausea, markedly ↑LDH.

⭐ Atheroembolic renal disease often presents with a subacute rise in creatinine, eosinophilia, and low complement levels after an invasive vascular procedure.

High‑Yield Points - ⚡ Biggest Takeaways

  • Renal Artery Stenosis (RAS): Key cause of secondary HTN; atherosclerosis (elderly), fibromuscular dysplasia (young women).
  • Malignant Hypertension: Fibrinoid necrosis, hyperplastic arteriolosclerosis ("onion-skin"), "flea-bitten" kidney. Benign: hyaline arteriolosclerosis.
  • Thrombotic Microangiopathies (TMAs): HUS (Shiga toxin, child, renal failure) vs. TTP (ADAMTS13, adult, neuro).
  • Renal Infarcts: Wedge-shaped cortical necrosis, usually embolic.
  • Atheroembolic Disease: Cholesterol crystals post-procedure; eosinophilia, livedo reticularis.
  • Scleroderma Renal Crisis: Abrupt severe HTN & AKI.
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_____ is a uncapsulated renal hamartoma comprised of blood vessels, smooth muscle, and adipose tissue

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_____ is a uncapsulated renal hamartoma comprised of blood vessels, smooth muscle, and adipose tissue

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