Post-Surgical Cardiovascular Imaging

CABG Imaging - Grafting Goods

• Graft Types:
  • Arterial: LIMA (to LAD = workhorse), RIMA.
  • Venous: SVG (Saphenous Vein Graft).
  • Radial Artery.
• CTA (Coronary CT Angiography):
  • Primary non-invasive tool.
  • Assesses: Patency, stenosis (>50% significant), occlusion, aneurysm.
  • Optimal timing: 1-6 months post-op (baseline), then as needed.
• DSA (Digital Subtraction Angiography):
  • Gold standard for diagnosis/intervention.
  • Use if CTA inconclusive or intervention planned.
• Key CTA Checks:
  • Graft origin, course, anastomosis, run-off.
  • Competitive flow from native vessels.
  • Stenosis: Proximal/distal anastomosis, body.

⭐ Patency: LIMA to LAD > Radial Artery > SVG. LIMA to LAD is gold standard graft. 📌 Mnemonic: LIMA Lasts, SVG Sags (Saphenous Vein Grafts sag/stenose earlier).

Prosthetic Valve Imaging - Valve Vibes

• Valve Types:
  • Mechanical: Durable (e.g., bileaflet). Lifelong anticoagulation.
  • Bioprosthetic (Tissue): Porcine, bovine. Risk of Structural Valve Deterioration (SVD).
• Key Imaging:
  • Echocardiography (TTE/TEE): Initial & follow-up. Assesses gradients, regurgitation.
  • CT Angiography (CTA): Anatomy, Paravalvular Leak (PVL), thrombus, pannus.
  • Fluoroscopy: Mechanical valve leaflet motion.
• Complications (📌 Mnemonic: "VALVES"):
  • Valve thrombosis/pannus
  • Abscess (Endocarditis)
  • Leak (Paravalvular)
  • Vegetations (Endocarditis)
  • Embolism
  • Structural failure/Dehiscence
• Thrombus vs. Pannus (CT):

  Feature	Thrombus	Pannus
  Attenuation	Low (<90 HU)	Higher (soft tissue)
  Onset	Acute/Subacute	Chronic

⭐ Cine fluoroscopy is excellent for assessing mechanical valve disc mobility; Cine MRI is a radiation-free alternative.

Aortic Repair Imaging - Aorta Alerts

• Primary Goal: Detect complications post EVAR/TEVAR (Endovascular/Thoracic Endovascular Aortic Repair).
• Key Complications:
  • Endoleaks (most common, see flowchart)
  • Graft infection, migration, kinking
  • Pseudoaneurysm at anastomoses
  • Graft limb stenosis/occlusion
  • Aortoenteric fistula (rare, catastrophic)
• Imaging: CTA is gold standard. Monitor aneurysm sac diameter: stability or shrinkage indicates success. Sac expansion >5mm is concerning for endoleak or endotension.
• Surveillance: Lifelong imaging (CTA/MRA/US) crucial. Typically at 1, 6, 12 months, then annually if stable.

⭐ Type II endoleak is the most common type following EVAR, often from lumbar arteries or IMA. Many are managed conservatively if aneurysm sac is stable/shrinking.

Post-Op Complications - Sternal Scares & More

• Sternal Dehiscence & Instability:
  • Clinical: Sternal pain, clicking, palpable gap, instability.
  • CXR: Wire fracture/migration, sternal separation > 2-3 mm.
  • CT: Defines extent, associated collections, early osteomyelitis.
• Sternal Wound Infection & Mediastinitis:
  • Spectrum: Superficial cellulitis to deep mediastinitis.
  • Mediastinitis: Fever, sepsis, chest pain, purulent discharge.
  • Risk factors: Diabetes, obesity, smoking, prolonged bypass.
  • CT (gold standard):
    • Retrosternal fluid collections, abscess formation.
    • Peristernal soft tissue stranding, edema, enhancement.
    • Gas bubbles, air-fluid levels (ominous).
    • Sternal osteomyelitis (erosion, sequestrum, involucrum).

  ⭐ CT signs of mediastinitis include retrosternal fluid collections, soft tissue stranding, and gas bubbles.

• Other common issues: Post-op hematoma, seroma, hypertrophic scarring, keloid formation.

High‑Yield Points - ⚡ Biggest Takeaways

• CABG: CTA for graft patency, sternal dehiscence, and mediastinitis.
• Prosthetic Valves: Echo (TTE/TEE) for leaks, thrombus, vegetations; CT for pannus/structure.
• Aortic Grafts (EVAR/TEVAR): CTA is crucial for endoleaks, infection, and pseudoaneurysms.
• Device Leads: CXR for position/fracture; CT/Echo for perforation, thrombosis.
• LVADs: Echo/CT for pump thrombosis, outflow graft issues, and device infection.
• Sternal Complications: CT is best for early detection of dehiscence or mediastinitis.