Intravascular ultrasound

Intravascular ultrasound (IVUS) – a combination of echocardiography and a procedure called cardiac catheterization. IVUS uses sound waves to produce an image of the coronary arteries and to see their condition. The sound waves travel through a tube called a catheter. The catheter is threaded through an artery and into the heart. This test lets doctors look inside your blood vessels.

IVUS is rarely done alone or as a strictly diagnostic procedure. It is usually done at the same time that a percutaneous coronary intervention, such as angioplasty, is being performed.

How does it work?

IVUS uses high-frequency sound waves (also called ultrasound) that can provide a moving picture of the heart. The pictures come from inside the heart rather than through the chest wall. The sound waves are sent with a device called a transducer. The transducer is attached to the end of a catheter, which is threaded through an artery and into the heart. The sound waves bounce off of the walls of the artery and return to the transducer as echoes. The echoes are converted into images on a television monitor to produce a picture of the coronary arteries and other vessels in the body.

Advantages of Intravascular Ultrasound

• IVUS enables a physician to get inside the artery with a camera-like device.
• IVUS can quantify the percentage of narrowing and give insight into the nature of the plaque.
• It also may reveal what in the past has been referred to as “re-stenosis” (a recurrence of the plaque build-up that may have previously been removed).
• There is evidence that this is not a re-stenosis but rather the IVUS’s ability to see build-up that may have been missed during an angiogram and angioplasty.

What to Expect During Intravascular Ultrasound?

IVUS is an invasive procedure and, as such, comes with the risks associated with any invasive procedure.

The entire procedure might take less than an hour or as long as several hours:

• An area around the groin will be shaved and cleaned in preparation for the insertion of a catheter (a thin tube)
• A mild sedative is administered to aid in relaxation
• A local anaesthetic is injected into the catheter site
• The imaging physician directs this catheter, painlessly, through arteries until it reaches the area to be studied
• A guide wire with an ultrasound probe on its tip is inserted into the catheter and guided to the furthest position to be imaged
• Sound waves are emitted from the probe. The probe also receives and returns the echo information, sending images to a computer
• The guide wire is held in place and the probe is slid backwards – usually under steady, smooth, motorized control – sending and receiving ultrasound images along the way.

Results of the Intravascular Ultrasound

The blood vessel wall inner lining, atheromatous disease within the wall, and connective tissues are echogenic (they return echoes making them visible on the monitor). Blood and healthy muscular tissue are echolucent (they return no images, just black spaces on the monitor).

Heavy calcium deposits are very echogenic, which means they reflect sound, and are distinguishable by shadowing. Heavy calcifications are reflected as bright images with shadowing behind it.

Patients need to meet with their physician to discuss their test results and any recommended treatment plans.