IVUS (Intravascular Ultrasound) is an advanced imaging method performed using ultrasound waves from inside the coronary arteries.
What is IVUS?#
IVUS (Intravascular Ultrasound) is 360° imaging of the vessel wall and lumen by placing a miniaturized ultrasound transducer inside the coronary artery.
Key Features:
- High resolution: 100-150 microns
- Penetration depth: 4-8 mm
- Imaging angle: 360°
- Catheter size: 2.6-3.2 Fr
IVUS vs Angiography#
| Feature | Angiography | IVUS |
|---|---|---|
| Imaging | Silhouette (2D) | Cross-sectional (3D) |
| Vessel wall | Invisible | Visible |
| Plaque analysis | Limited | Detailed |
| Lumen measurement | Relative | Absolute |
| Remodeling | Not observable | Observable |
| Stent assessment | Limited | Comprehensive |
IVUS Indications#
Diagnostic Use#
1. Ambiguous Angiographic Findings:
- Moderate stenosis (40-70%)
- Foreshortening/overlap lesions
- Calcified lesions
2. Left Main Coronary Disease:
- Critical location
- Treatment decision support
- Ostial lesions
3. Plaque Characterization:
- Stable vs Vulnerable plaque
- Lipid-rich plaque detection
- Fibrous cap thickness
Interventional Use#
1. Stent Optimization:
- Optimal stent selection
- Adequate expansion control
- Edge dissection detection
- Malapposition control
2. Complex Interventions:
- Bifurcation lesions
- CTO (Chronic Total Occlusion)
- Diffuse disease
- Left main stenting
3. Stent Complications:
- In-stent restenosis assessment
- Stent thrombosis cause investigation
- Neoatherosclerosis detection
IVUS Technologies#
Mechanical (Rotating) IVUS#
- Single element transducer
- Mechanical rotation
- High image quality
- 40-45 MHz frequency
Electronic (Phased-Array) IVUS#
- Multiple element array
- Electronic rotation
- Thinner catheter
- 20 MHz frequency
Virtual Histology (VH-IVUS)#
Color-coded display of plaque components:
- Green: Fibrous tissue
- Yellow-Green: Fibro-fatty
- White: Dense calcium
- Red: Necrotic core
IVUS Procedure Process#
Preparation#
- Standard angiography access
- Anticoagulation (heparin)
- Intracoronary nitroglycerin
Procedure Steps#
- Coronary wire placement: Distal to lesion
- IVUS catheter advancement: Over wire
- Automatic pullback: 0.5-1 mm/sec
- Image recording: Throughout segment
- Measurements: Lumen, vessel, plaque
IVUS Measurements#
Basic Parameters:
- MLA (Minimum Lumen Area): Narrowest lumen area
- EEM (External Elastic Membrane): Outer elastic membrane
- Plaque Burden: (EEM - Lumen) / EEM × 100
- Stent Area: Within stent boundaries
Critical Values:
| Parameter | Critical Threshold |
|---|---|
| Left main MLA | <6 mm² |
| Proximal LAD MLA | <4 mm² |
| Other segments MLA | <4 mm² |
| Optimal stent expansion | >80% reference |
IVUS-Guided Stenting#
Pre-PCI Assessment#
- True lesion length
- Reference vessel size
- Plaque character
- Calcification degree
Stent Selection#
Based on IVUS measurements:
- Stent diameter: According to distal reference vessel diameter
- Stent length: Lesion length + 2-4 mm
Post-PCI Control#
Optimal Stenting Criteria:
- Adequate expansion: MSA ≥ 80% reference
- Complete apposition: No malapposition
- No edge dissection: Longitudinal dissection check
- No geographic miss: All plaque covered
Clinical Benefits of IVUS#
Evidence-Based Data#
IVUS-XPL Study:
- IVUS guidance vs Angiography
- 1-year MACE: 2.9% vs 5.8%
- 50% relative risk reduction
ADAPT-DES Study:
- Stent thrombosis risk reduction
- Importance of optimal expansion
Clinical Advantages#
- Better stent outcomes
- Reduced restenosis
- Lower stent thrombosis risk
- Optimal treatment decision
IVUS Complications#
Rare Complications (<1%)#
- Coronary spasm
- Dissection (catheter-induced)
- Air embolism
- Transient ischemia
Precautions#
- Adequate anticoagulation
- Intracoronary nitroglycerin
- Careful catheter manipulation
IVUS vs OCT#
| Feature | IVUS | OCT |
|---|---|---|
| Penetration | 4-8 mm | 1-2 mm |
| Resolution | 100-150 μm | 10-20 μm |
| Blood clearance | Not required | Required |
| Calcium measurement | Good | Excellent |
| Lipid plaque | With VH | Direct |
| Stent strut | Limited | Detailed |
Frequently Asked Questions#
What is IVUS?
How is IVUS different from angiography?
When is IVUS performed?
Is the IVUS procedure painful?
Is IVUS safe?
Appointment and Contact#
To schedule an appointment for IVUS-guided coronary evaluation and stenting:
📍 Eurasia Hospital - Beştelsiz Mah. 101. Sokak No:107, Zeytinburnu, Istanbul
📞 Phone: +90 212 665 50 50 (Ext: 4012)
This content has been prepared by Assoc. Prof. Habib Çil for general informational purposes. Please consult a cardiology specialist for definitive diagnosis and treatment.
Related Coronary Imaging Services#
Other services related to IVUS:
- Coronary Angiography - Diagnostic coronary imaging
- FFR (Pressure Wire) - Fractional flow reserve
- Coronary Stenting - Vessel opening procedure
- Bifurcation Intervention - Branching site treatment
- CTO Intervention - Chronic total occlusion opening