Coronary artery disease (CAD) is a prevalent heart condition where the major blood vessels supplying the heart become narrowed or blocked. This narrowing, often referred to as an arterial blockage, reduces blood flow to the heart muscle. A common treatment approach for significant blockages involves the placement of a stent, a small mesh tube designed to prop the artery open and restore adequate blood flow.
Understanding Arterial Narrowing
Arterial narrowing, or “percent blockage,” refers to the reduction in the inner diameter, or lumen, of an artery. This measurement quantifies the constriction of the vessel’s pathway for blood flow. The primary cause of this narrowing is atherosclerosis, a slow, progressive disease characterized by the buildup of plaque within the artery walls.
Plaque consists of fatty substances, cholesterol, cellular waste products, and calcium. As these deposits accumulate, they harden and stiffen the artery walls, leading to narrowing. This plaque buildup can significantly impede blood flow, potentially causing symptoms like chest pain or shortness of breath.
Diagnostic Assessment
Doctors utilize several methods to accurately determine the extent and significance of an arterial blockage. Coronary angiography is a primary method for visualizing blockages and estimating their percentage. During this procedure, a catheter is inserted into an artery and guided to the heart. A special dye is injected, making blood vessels visible on X-ray images to identify narrowed or blocked areas.
Other tools provide more detailed functional or structural information. Fractional Flow Reserve (FFR) measures pressure differences across a narrowing to determine if it significantly impedes oxygen delivery to the heart muscle. An FFR value below 0.80 indicates a significant lesion that may warrant intervention.
Intravascular Ultrasound (IVUS) uses sound waves from a miniature probe on a catheter to create detailed cross-sectional images from inside the blood vessel. IVUS provides a comprehensive view of plaque volume and vessel wall structure, which angiography cannot fully show. Optical Coherence Tomography (OCT) is another advanced imaging technique that uses near-infrared light to produce extremely high-resolution images of the artery’s inner lining. OCT offers detailed insights into plaque characteristics, such as composition and fibrous cap thickness, helping identify vulnerable plaques.
Factors Guiding Stent Decisions
While the percentage of arterial blockage is an important consideration, it is rarely the sole factor in deciding whether a stent is necessary. For patients with stable angina, causing chest pain during exertion, a blockage of 70% or more is a common threshold for stent consideration to improve blood flow and relieve symptoms. A lower percentage, such as 50%, may warrant intervention if associated with significant symptoms or an acute coronary syndrome, such as a heart attack. During a heart attack, where a clot completely blocks an artery, a stent is immediately needed to restore blood flow and prevent permanent heart damage.
Patient symptoms are important. Stents are used to alleviate symptoms like chest pain, tightness, or shortness of breath that do not improve with medication and lifestyle changes. Blockage location also plays a role; those in major coronary arteries supplying large heart muscle areas are more serious than in smaller branches. Functional significance, often assessed by FFR, determines how much the blockage limits blood flow, guiding treatment for intermediate blockages.
Plaque stability is another consideration, as unstable plaques are prone to rupture and cause acute events. Diagnostic tools like OCT can help identify these vulnerable plaques. Overall patient health, other medical conditions, and individual risk factors are also evaluated. A comprehensive assessment ensures personalized stent decisions for the best outcome.