What is intravascular ultrasound?
Intravascular ultrasound, or IVUS, is a way of looking at a coronary artery from the inside. A very fine catheter with a tiny ultrasound probe at its tip is passed into the artery during an angiogram, and it produces a detailed cross-sectional picture of the vessel wall, rather like a slice through a garden hose. Where an ordinary angiogram shows only the shadow of the channel through which blood flows, IVUS shows how thick the wall is, how much fatty and calcium build-up there is, and the true size of the artery.
Why is it done?
Your cardiologist uses IVUS to make better decisions. It helps to judge whether a narrowing really needs treatment, to choose the correct size and length of stent, to confirm that a stent has expanded fully and is pressed properly against the wall, and to find the cause if a previously treated artery gives trouble again. It can also show a tear in the artery wall or an unusual cause of narrowing that the angiogram cannot explain. Using IVUS has been shown to improve the long-term results of stenting.
What happens on the day?
IVUS is not a separate appointment; it is done as part of your angiogram or stent procedure in the catheterisation laboratory. You are awake but relaxed, and the wrist or groin is numbed with local anaesthetic. Once the catheter is in position in the heart, the ultrasound catheter is advanced over a fine wire into the artery and then slowly withdrawn while it records images. This adds only a few minutes to the procedure, and you should feel nothing extra, because there are no nerves inside the artery. Additional contrast dye is not usually needed for the imaging itself.
What to expect afterwards
Recovery is exactly the same as for an angiogram or stent procedure. If the wrist was used a compression band is left on for a few hours; if the groin was used you lie flat for a while. Your cardiologist will explain what the images showed and what treatment they support. There is no additional aftercare, no extra medication and no restriction that comes from the IVUS itself.
Possible complications
IVUS is safe and adds very little risk to the angiogram it forms part of. Passing an extra catheter can briefly reduce blood flow in the artery and cause a few seconds of chest discomfort or a change in the heart rhythm, which settles as soon as the catheter is removed. Very rarely the artery wall is torn or the vessel goes into spasm, or a small clot forms; these are treated straight away in the laboratory, usually with medication or a stent. The main risks of the day remain those of the angiogram itself, which your cardiologist will discuss with you.
This information does not replace a consultation. Please discuss your own risks and options with your cardiologist.