Hypertensive Vascular Disease

Introduction & Pathogenesis - Pressure Problems

• Hypertension (HTN): Sustained elevation of systemic arterial blood pressure; a major risk factor for cardiovascular, cerebrovascular, and renal disease.
• Classification (ACC/AHA 2017 Guidelines):
  • Normal: <120/80 mmHg
  • Elevated: 120-129/<80 mmHg
  • Stage 1 HTN: 130-139/80-89 mmHg
  • Stage 2 HTN: ≥140/90 mmHg

    ⭐ Essential hypertension, accounting for 90-95% of cases, is idiopathic with multiple contributing genetic and environmental factors.

• Pathogenesis - "Pressure Problems":
  • Chronic ↑BP → Sustained hemodynamic stress on arterial walls.
  • Endothelial injury & dysfunction:
    • ↑ Permeability to plasma proteins (e.g., LDL, fibrinogen).
    • ↓ Vasodilators (e.g., Nitric Oxide), ↑ Vasoconstrictors (e.g., Endothelin-1).
  • Vascular remodeling (maladaptive changes):
    • Smooth muscle cell (SMC) proliferation, hypertrophy, & migration.
    • ↑ Extracellular matrix (ECM) deposition (e.g., collagen, fibronectin).
    • Results in arterial wall thickening, luminal narrowing, and increased vascular stiffness.

Vessel Morphology - Morphologic Mayhem

Hypertension inflicts structural damage primarily on arterioles (arteriolosclerosis) and arteries.

• Arteriolosclerosis: Two main forms:

  Feature	Hyaline Arteriolosclerosis	Hyperplastic Arteriolosclerosis
  Associated HTN	Benign hypertension, Diabetes Mellitus, aging	Severe/Malignant hypertension (e.g., DBP > 120 mmHg)
  Pathogenesis	Chronic stress → endothelial injury, plasma protein leakage (hyalinosis), ↑SMC matrix.	Severe ↑BP → endothelial injury, SMC proliferation, reduplicated BM.
  Microscopy	Homogeneous, pink, glassy hyaline thickening of arteriolar wall; luminal narrowing.	"Onion-skin" concentric, laminated thickening; luminal narrowing/obliteration. Fibrinoid necrosis (necrotizing arteriolitis) may occur.
  Key Sites/Effects	Kidney (benign nephrosclerosis), spleen.	Kidney (malignant nephrosclerosis → "flea-bitten kidney"), retina.

⭐ Hyperplastic arteriolosclerosis, characterized by 'onion-skin' thickening of arteriolar walls, is a hallmark of severe or malignant hypertension.

• Larger Arteries (e.g., aorta, cerebral, coronary, renal arteries):
  • Accelerated atherosclerosis, leading to complications like MI, stroke.
  • Increased risk of aortic dissection and cerebrovascular hemorrhage (e.g., Charcot-Bouchard microaneurysms).

Target Organ Damage - Systemic Strike

• Heart:
  • Left Ventricular Hypertrophy (LVH): concentric, from chronic pressure overload.
  • Accelerated Coronary Artery Disease (CAD).
  • ↑ Risk: Ischemic Heart Disease (IHD), Congestive Heart Failure (CHF), arrhythmias, sudden cardiac death.
  • Aortic dissection.
• Brain:
  • Lacunar infarcts: small lesions (basal ganglia, thalamus, pons) from hyaline arteriolosclerosis of deep penetrating arteries.
  • Hypertensive encephalopathy: sudden, severe BP ↑; headache, confusion, convulsions.
  • Intracerebral hemorrhage:

    ⭐ Charcot-Bouchard microaneurysms (lenticulostriate vessels in basal ganglia, thalamus, pons, cerebellum) rupture.

• Kidneys (Nephrosclerosis):
  • Benign Nephrosclerosis: Hyaline arteriolosclerosis → glomerular ischemia, glomerulosclerosis, tubular atrophy → granular contracted kidneys.
  • Malignant Nephrosclerosis (Accelerated HTN): Fibrinoid necrosis, hyperplastic "onion-skin" arteriolosclerosis → "flea-bitten" kidney, Acute Renal Failure (ARF).
• Retina (Hypertensive Retinopathy):
  • Arteriolar narrowing, copper/silver wiring.
  • Arteriovenous (AV) nicking.
  • Hemorrhages (flame, dot-blot), cotton-wool spots (nerve fiber infarcts).
  • Grade IV: Papilledema.

High‑Yield Points - ⚡ Biggest Takeaways

• Benign hypertension causes hyaline arteriolosclerosis (homogenous, glassy pink arteriolar wall thickening).
• Malignant hypertension: hyperplastic arteriolosclerosis ("onion-skinning" of arterioles) and fibrinoid necrosis.
• Kidneys: Benign nephrosclerosis (shrunken, granular surface); Malignant nephrosclerosis ("flea-bitten kidney" with petechiae, fibrinoid necrosis).
• Major risk for atherosclerosis, aortic dissection, cerebrovascular accidents (especially lacunar infarcts), and left ventricular hypertrophy (LVH).
• Essential (primary) hypertension (90-95%) is idiopathic; secondary hypertension has identifiable causes (e.g., renal, endocrine).