What is IVUS?
Endovascular ultrasonography or intravascular echocardiography are other names for intravascular ultrasound or IVUS. It produces images of the interior of blood vessels using sound waves(ultrasound) in the 10 to 40 MHz range produced by a transducer or probe. A unique catheter with a tiny ultrasonic transducer on one end is used for IVUS. To reach the desired place, the clinician threads the catheter through an artery or vein. After arriving, the transducer produces sound waves to create images of the blood vessels and aid in the evaluation of various problems. With the help of IVUS, transcatheter coronary procedures can be guided by defining the distribution and form of the plaque.
What are the types of IVUS?
Mechanical and phased array IVUS catheters are the two varieties currently in use.The most popular IVUS catheter makes use of a single mechanical transducer positioned at the tip that spins swiftly to show the whole vessel in cross-section. The mechanical transducer benefits from a straightforward design, less complex technology, and a higher output signal-to-power ratio. With modern 40 MHZ transducers, an overall resolution of 100 to 150 micrometres generally results in higher image quality. Higher frequency and/or dual transducers are used in second-generation “HD” or high-density transducers to produce images with better resolution. However, the therapeutic use of higher frequency transducers is constrained by their inferior blood penetration and greater blood reflection.
Multiple transducer elements are permanently positioned around the catheter tip in phased array catheters. The sectors from which each element sends and receives ultrasonography are combined to provide a cross-sectional image of the vessel. However, phase array catheters have poor image quality and need complicated programming. Nevertheless, during the past few years, phased array images have advanced significantly and are now producing images that are on par with those from mechanical transducers thanks to the development of faster processors, better software, and additional components attached to the catheter tip.
Combination IVUS-NIR (Near Infrared spectroscopy) catheters enhance the imaging benefits of IVUS by enabling NIR to distinguish between different tissue types, such as lipid-rich plaque.
Clinical Applications
Optimal stent placement, determining the severity of intermediate coronary stenoses detected on coronary angiography, and identifying cardiac allograft vasculopathy are some of the pivotalclinical applications of IVUS.
IVUS can be used to evaluate any artery in the body. It is especially helpful for imaging coronary arteries and the peripheral arteries of the legs. IVUS is frequently combined with catheter angiography by medical professionals to assist identify the peripheral vascular disease (PVD). The best way to diagnose PVD is by IVUS, which is also helpful for determining the size of the stents needed to keep the artery open.Additionally, IVUS is employed to evaluate abdominal aortic aneurysms before, during, and following procedures to repair the vessel.
Benefits and Risks
There are plenty of benefits of IVUS including:
- no exposure to radiation
- showing the presence and amount of plaque in arteries
- measuring the degree to which the vessel has narrowed from plaque
- providing information about the composition of the plaque
- detection of restenosis
- more accurate stent placement and reduced incidence of stent thrombosis in arteries and veins
- finding stenosis or narrowing which is not well seen with angiography
- finding areas of vein external compression, which may be predisposed to blood clots
There are risks involved with any treatment that inserts a catheter inside a blood vessel. These risks include infection, bleeding or bruising at the puncture site, and damage to the blood vessel. To lessen these dangers, appropriate measures will be taken. Other risks are arrhythmias, thrombosis, and allergy to medications used during the procedure. The occurrence of myocardial infarction, stroke or pulmonary embolism is very rare.
Conclusion
The importance of IVUS can be simply understood by the two main clinical uses of IVUS: to direct coronary procedures and to clarify murky or uncertain radiological angiography. Therefore, this imaging modality would continue to evolve opening doorways to revolutionize vascular imaging further.
References
- Intravascular ultrasound, optical coherence tomography, and angioscopy of coronary circulation – UpToDate. Accessed September 18, 2022. https://www.uptodate.com/contents/intravascular-ultrasound-optical-coherence-tomography-and-angioscopy-of-coronary-circulationsearch=IVUS&source=search_result&selectedTitle=1~89&usage_type=default&display_rank=1
- Intravascular Ultrasound. Accessed September 18, 2022. https://www.radiologyinfo.org/en/info/ultrasound-intravascular
