Intravascular Imaging and Physiology in Cardiology: FFR, OCT, and IVUS
Advances in cardiovascular imaging and physiology have transformed the way cardiologists assess and treat coronary artery disease (CAD). Among the most significant innovations are Fractional Flow Reserve (FFR), Optical Coherence Tomography (OCT), and Intravascular Ultrasound (IVUS). Each of these tools provides critical insights into the coronary arteries and aids in tailoring patient-specific treatments. Here’s a closer look at what they offer.
Fractional Flow Reserve (FFR)
FFR is an invasive technique that evaluates the functional impact of coronary artery stenosis. By measuring pressure differences across a narrowed section of a coronary artery during maximal blood flow, FFR assesses whether the stenosis is likely to cause ischemia (reduced blood flow) in the heart muscle. An FFR value of 0.80 or below is generally considered to indicate ischemia, guiding decisions on whether to perform interventions like stenting. FFR has become an essential tool for making evidence-based decisions, allowing cardiologists to better target interventions to lesions that truly affect heart function.
Optical Coherence Tomography (OCT)
OCT is an imaging technique that uses near-infrared light to create high-resolution images of the coronary arteries. Its exceptional detail—up to 10 micrometers—allows cardiologists to visualize the structure of the arterial wall, identify plaque characteristics, and assess stent deployment and apposition. OCT is particularly valuable in cases where detailed assessment of the vessel wall and plaque morphology is essential, such as for detecting thin-cap fibroatheromas or other vulnerable plaque types that can lead to adverse cardiac events. However, OCT has limited penetration depth, making it most effective for superficial imaging.
Intravascular Ultrasound (IVUS)
IVUS employs high-frequency sound waves to create cross-sectional images of the coronary arteries. Unlike OCT, IVUS can penetrate deeper into the vessel wall, making it useful for evaluating plaque burden and vessel remodeling. IVUS is especially advantageous for visualizing calcified or large plaques, assessing complex lesions, and guiding stent placement in challenging cases. IVUS data can also help estimate lesion length and determine appropriate stent sizing, contributing to improved outcomes in interventional procedures.