EVUS to IVUS: a Continuous Spectrum

Jill Sommerset is the director of ultrasound at Advanced Vascular in Portland, OR and Hope Clinical Innovation Center in Houston, TX, and chair of the SVU annual conference. Dr. Fadi Saab is an interventional cardiologist and associate professor at Michigan State University. He begins by introducing what intravascular ultrasound (IVUS) and extravascular ultrasound (EVUS) are. EVUS is looking from the outside in, and can be used to measure vessel width, hemodynamics, and cross chronic total occlusions (CTOs). IVUS is looking from inside a vessel towards the outside of the body, and can be helpful for viewing the extent of arterial disease and discerning the exact plaque anatomy.

Dr. Saab always has a specially trained interventional sonographer involved in the case and in the room for critical limb ischemia (CLI) cases. He values them not only for obtaining access, but also to provide greater safety to the patient. He considers them a core member of the team. He notes the importance of training an ultrasonographer who is good when working under pressure, can interact with multiple personality types, and most importantly, someone willing to learn, be engaged in the case, and willing to put themselves out there in this foreign environment. Jill says it took her around 4 months to feel comfortable working in the cath lab, and for other members of the team to get used to her presence during cases. She describes her work as a dance with the physician. When a wire or catheter is being exchanged, Jill is always scanning and thinking ahead, and she is always ready to check for dissections after balloon angioplasty.

Most arterial cases can benefit from the addition of EVUS. Jill says the only time EVUS is not as helpful is when the CTO cap morphology shows a rock hard plaque that casts shadows on the screen. Dr. Saab says he uses EVUS for crossing CTOs, patient safety, and looking at complications. He usually introduces IVUS after he crosses a lesion to look at plaque in a more granular way and understand it’s anatomy. Jill adds that she uses IVUS to help the physician cross a CTO sometimes, but notes that it is important for the tech to hold the probe still and not move in this scenario. The two end by restating the value that EVUS and IVUS add to the procedure, especially because angiography misses a lot of plaque burden that can be seen with IVUS. They recommend finding ultrasonographers interested in working in the cath lab, and taking the responsibility as physicians to mentor them and make them feel like an invaluable member of the treatment team.