What is it?
Traditional angiography can only look at the coronary arteries in a two-dimensional view (See Figure I). Intravascular ultrasound (IVUS) is a newer technique used in conjunction with traditional two-dimensional angiography. IVUS enables the cardiologist to not only demonstrate how severe the narrowing of the blood vessel is, but also to determine the exact composition of the plaque. The information obtained can aid the physician in determining the best treatment plan.
Why is it performed?
The cardiologist may decide to perform IVUS:
- To determine if a questionable narrowing seen on 2-D angiography is severe enough to cause symptoms or a positive stress test.
- To immediately assess the results of angioplasty and stenting to determine correct deployment of the stent.
- To determine the composition of the plaque after angioplasty to guide further treatment.
- To detect any underlying dissection (tear in the arterial wall) and therefore treat it appropriately.
How is it done?
The procedure is performed in the cardiac catheterization laboratory. The physician must perform (or have looked at) a routine angiogram prior to deciding to perform IVUS. The physician then passes a small catheter (<1mm) over a wire within the blood vessel under X-ray guidance. A small probe at the catheter tip then transmits the ultrasound image to a computer screen. IVUS usually adds no more than 10 minutes to the total procedure time.
Since this procedure is performed with other angiography procedures, the post-procedure care is the same as a cardiac catheterization.