Atherosclerotic Disease

Pathophysiology & Risks - Genesis of Plaque

• Endothelial Injury/Dysfunction: Initial step. ↑Permeability, leukocyte adhesion. Triggers: HTN, smoking, hyperglycemia.
• Lipid Infiltration & Modification: LDL enters intima, undergoes oxidation (oxLDL).

  ⭐ Oxidized LDL is a key chemoattractant for macrophages in plaque formation.

• Inflammation & Foam Cell Formation:
  • Monocytes → macrophages; engulf oxLDL → foam cells (fatty streaks).
• Plaque Maturation:
  • Smooth muscle cell (SMC) migration, proliferation.
  • SMCs synthesize ECM (collagen) → fibrous cap.
  • Central necrotic core (lipids, debris) forms.
• Key Risk Factors:
  • Non-Modifiable: Age, male, genetics.
  • Modifiable: Dyslipidemia (↑LDL, ↓HDL), HTN (>130/80 mmHg), smoking, Diabetes (HbA1c >6.5%), obesity (BMI >30), ↑hs-CRP.

Clinical Manifestations - Arterial Distress Signals

Diagnosis - Unmasking the Culprit

Key diagnostic steps include:

• Ankle-Brachial Index (ABI): Key non-invasive test. $ABI = \frac{Highest,Ankle,Systolic,Pressure}{Highest,Brachial,Systolic,Pressure}$
  • Normal: 0.9-1.3
  • PAD: <0.9 (Mild-Mod: 0.41-0.89, Severe: ≤0.4)
  • Calcified vessels (e.g., in DM): >1.3

Start["🩺 Suspected PAD
• Arterial disease• Leg pain symptoms"]

Assess["📋 Clinical Eval
• History and Exam• Pulse palpation"]

ABI["🔬 Initial ABI
• Brachial index• Doppler pressure"]

DUS["🔬 Duplex US
• Localize lesion• Assess severity"]

Exer["🔬 Exercise/TBI
• Post-stress ABI• Toe Brachial Index"]

CTAMRA["💊 CTA or MRA
• Pre-intervention• Vascular mapping"]

Start --> Assess Assess --> ABI ABI -->|ABI < 0.9| DUS ABI -->|Normal+Symptom| Exer DUS --> CTAMRA

style Start fill:#F7F5FD, stroke:#F0EDFA, stroke-width:1.5px, rx:12, ry:12, color:#6B21A8 style Assess fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E style ABI fill:#FFF7ED, stroke:#FFEED5, stroke-width:1.5px, rx:12, ry:12, color:#C2410C style DUS fill:#FFF7ED, stroke:#FFEED5, stroke-width:1.5px, rx:12, ry:12, color:#C2410C style Exer fill:#FFF7ED, stroke:#FFEED5, stroke-width:1.5px, rx:12, ry:12, color:#C2410C style CTAMRA fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534

> ⭐ Digital Subtraction Angiography (DSA) remains the gold standard for arterial imaging but is invasive.


## Management Approaches - Revascularization Roadmap

*   **Baseline**: Optimal Medical Therapy (OMT) - Aspirin **75-325mg** / Clopidogrel **75mg**, Statins (LDL <**70mg/dL**), BP/DM control.
*   **Peripheral Arterial Disease (PAD)**:
    -   Intermittent Claudication:
        +   Conservative: Exercise, Cilostazol **100mg** BID (📌 CI: Heart Failure).
        +   Revascularization (Endovascular/Surgical) if lifestyle-limiting.
    -   Critical Limb Ischemia (CLI): Urgent Revascularization!

```mermaid
%%{init: {'flowchart': {'htmlLabels': true}}}%%
flowchart TD

Start["<b>⚠️ Critical Ischemia</b><br><span style='display:block; text-align:left; color:#555'>• Rest pain/ulcers</span><span style='display:block; text-align:left; color:#555'>• Gangrene symptoms</span>"]

Assess["<b>📋 Patient Assessment</b><br><span style='display:block; text-align:left; color:#555'>• Lesion evaluation</span><span style='display:block; text-align:left; color:#555'>• Risk stratification</span>"]

Optimize["<b>💊 Optimize Therapy</b><br><span style='display:block; text-align:left; color:#555'>• Medical management</span><span style='display:block; text-align:left; color:#555'>• Risk reduction</span>"]

Revasc["<b>📋 Revascularization</b><br><span style='display:block; text-align:left; color:#555'>• Endo vs Surgical</span><span style='display:block; text-align:left; color:#555'>• Plan strategy</span>"]

Angio["<b>💊 Angioplasty +/- Stent</b><br><span style='display:block; text-align:left; color:#555'>• Minimal invasive</span><span style='display:block; text-align:left; color:#555'>• Endo preference</span>"]

Success1["<b>📋 Success?</b><br><span style='display:block; text-align:left; color:#555'>• Evaluate flow</span><span style='display:block; text-align:left; color:#555'>• Clinical response</span>"]

Bypass["<b>💊 Surgical Bypass</b><br><span style='display:block; text-align:left; color:#555'>• e.g. Fem-Pop</span><span style='display:block; text-align:left; color:#555'>• Open procedure</span>"]

Success2["<b>📋 Success?</b><br><span style='display:block; text-align:left; color:#555'>• Graft patency</span><span style='display:block; text-align:left; color:#555'>• Wound healing</span>"]

Follow["<b>👁️ Follow-up + OMT</b><br><span style='display:block; text-align:left; color:#555'>• Regular monitoring</span><span style='display:block; text-align:left; color:#555'>• Continue therapy</span>"]

Amputate["<b>⚠️ Palliative Care</b><br><span style='display:block; text-align:left; color:#555'>• Consider amputation</span><span style='display:block; text-align:left; color:#555'>• Comfort measures</span>"]

Start --> Assess
Assess --> Optimize
Optimize --> Revasc

Revasc -->|Endo First| Angio
Revasc -->|Complex/Failed| Bypass

Angio --> Success1
Success1 -->|Yes| Follow
Success1 -->|No| Bypass

Bypass --> Success2
Success2 -->|Yes| Follow
Success2 -->|No| Amputate

style Start fill:#FDF4F3, stroke:#FCE6E4, stroke-width:1.5px, rx:12, ry:12, color:#B91C1C
style Assess fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E
style Optimize fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534
style Revasc fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E
style Angio fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534
style Success1 fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E
style Bypass fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534
style Success2 fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E
style Follow fill:#EEFAFF, stroke:#DAF3FF, stroke-width:1.5px, rx:12, ry:12, color:#0369A1
style Amputate fill:#FDF4F3, stroke:#FCE6E4, stroke-width:1.5px, rx:12, ry:12, color:#B91C1C

• Carotid Artery Stenosis:
  • Symptomatic (TIA/Stroke): Carotid Endarterectomy (CEA) for stenosis >70% (NASCET) or >50% (ECST). Carotid Artery Stenting (CAS) for high surgical risk.
  • Asymptomatic: OMT. Consider CEA/CAS if stenosis >60-70% & low peri-operative risk (<3%).

⭐ Cilostazol, a phosphodiesterase III inhibitor, is used for intermittent claudication; it has antiplatelet and vasodilatory effects. Avoid in heart failure.

High‑Yield Points - ⚡ Biggest Takeaways

• Atherosclerosis is a systemic disease; affects multiple arterial beds.
• Key risk factors: smoking, diabetes, hypertension, hyperlipidemia.
• Common sites: abdominal aorta, coronaries, carotids, femoro-popliteal segment.
• Ankle-Brachial Index (ABI) <0.9 diagnoses Peripheral Arterial Disease (PAD); <0.4 indicates Critical Limb Ischemia (CLI).
• CLI (rest pain, ulcer, gangrene) needs urgent revascularization.
• Management: risk factor control, antiplatelets (aspirin, clopidogrel), statins, revascularization.
• Symptomatic carotid stenosis >50-70% often requires carotid endarterectomy (CEA) to prevent stroke.