A 72-year-old hypertensive man with chronic back pain presents to the emergency department with acute, tearing chest pain radiating to the back, accompanied by sudden onset of left leg weakness and sensory loss below the knee. Blood pressure is 185/110 mmHg, heart rate 105/min. Femoral pulses are diminished on the left. CT angiography shows a Type B aortic dissection with extension into the left iliac artery and compression of the left L4 nerve root. Which of the following is the most appropriate next step?

Explanation

## Clinical Presentation and Classification **Key Point:** Type B aortic dissection (distal to the left subclavian artery) without signs of rupture, organ malperfusion, or uncontrolled hypertension is managed **medically first** with aggressive blood pressure control, followed by imaging surveillance. Surgery is reserved for complications. ## Pathophysiology of Aortic Dissection Aortic dissection occurs when a tear in the intima allows blood to enter the media, creating a false lumen. Type B dissection involves the descending thoracic aorta and may extend into the abdominal aorta and iliac vessels. **High-Yield:** The neurological deficit (left leg weakness and sensory loss) in this case is secondary to **aortic compression of the L4 nerve root**, not primary nerve injury. This is a consequence of the dissection anatomy, not an indication for immediate surgical decompression. ## Indications for Medical vs. Surgical Management | Indication | Type B Dissection Management | |------------|------------------------------| | **Uncomplicated (no rupture, no malperfusion)** | Medical: BP control, beta-blockers, vasodilators | | **Complicated (rupture, malperfusion, expanding)** | Urgent endovascular or open repair | | **Uncontrolled hypertension despite medical therapy** | Escalate to intervention | | **Aortic diameter >6 cm or rapid expansion** | Consider elective intervention | ## Management Algorithm for Type B Dissection ```mermaid flowchart TD A[Type B Aortic Dissection]:::outcome --> B{Complicated?}:::decision B -->|Rupture/Malperfusion/Expansion| C[Urgent endovascular or open repair]:::urgent B -->|Uncomplicated| D[Aggressive medical management]:::action D --> E[Beta-blockers + vasodilators]:::action E --> F[Target SBP 100-120 mmHg, HR 60 bpm]:::action F --> G[Serial imaging: CTA at 1 week, 1 month, 3 months]:::action G --> H{Complications develop?}:::decision H -->|Yes| I[Endovascular or open repair]:::urgent H -->|No| J[Continue surveillance]:::action ``` **Clinical Pearl:** The neurological deficit (nerve root compression) is **not an independent indication for surgery**. It may improve with resolution of aortic swelling and dissection stabilization. Nerve decompression alone would not address the underlying aortic pathology and carries high morbidity. **Warning:** Do NOT perform lumbar decompression for aortic dissection-related nerve compression. The nerve is compressed by the dissected aorta itself; decompressing the nerve without treating the aorta is futile and delays definitive care. ## Why Medical Management is Correct Here **Key Point:** This patient has an **uncomplicated Type B dissection** (no rupture, no acute malperfusion—the leg weakness is from nerve compression, not limb ischaemia). First-line management is aggressive blood pressure control with target SBP 100–120 mmHg and heart rate 60 bpm to reduce aortic shear stress and prevent propagation. **High-Yield:** Endovascular stent graft is reserved for **complicated Type B dissection** (rupture, expanding dissection, malperfusion). This patient's dissection is stable and uncomplicated; early intervention increases morbidity without proven benefit. [cite:Harrison 21e Ch 297]