A lesion in a heart artery refers to a localized area of damage or abnormal tissue within one of the coronary arteries. These vessels deliver oxygen-rich blood to the heart muscle. The abnormality is typically an atherosclerotic plaque, a build-up of material that obstructs the artery’s inner channel. This condition, known as Coronary Artery Disease (CAD), is the most common form of heart disease and is directly linked to the presence of these arterial lesions.
How Lesions Form in Arteries
The process that creates these lesions is called atherosclerosis, which begins when the inner lining of the artery, the endothelium, becomes damaged. This damage is often initiated by factors such as high blood pressure, elevated cholesterol levels, or smoking. Once the endothelial barrier is compromised, low-density lipoprotein (LDL) cholesterol particles infiltrate and accumulate within the artery wall.
The immune system responds by sending white blood cells, which transform into macrophages and engulf the trapped LDL, creating “foam cells.” This accumulation forms a fatty streak, the earliest stage of the lesion. Chronic inflammation drives the growth of this deposit, which eventually matures into a complex atherosclerotic plaque.
Plaques are categorized into two types. A stable plaque has a thick, firm fibrous cap covering a small lipid core; it grows slowly, gradually narrowing the artery. Conversely, a vulnerable or unstable plaque is highly inflammatory, possessing a large, soft lipid core and a thin fibrous cap. This thin cap is susceptible to rupture, posing a significant immediate risk.
The Immediate Health Consequences
The primary health consequence of an arterial lesion stems from restricted blood flow, which starves the heart muscle of oxygen, a condition called ischemia. When oxygen demand increases, such as during physical exertion, a stable lesion that significantly narrows the artery can cause chest pain known as stable angina. This discomfort typically resolves with rest or medication.
A vulnerable plaque rupture exposes the highly thrombogenic contents of its lipid core to the bloodstream. The body attempts to repair this disruption by forming a blood clot (thrombus) at the site. This sudden clot formation can completely block the coronary artery, leading to an acute myocardial infarction, commonly called a heart attack.
This acute event requires immediate medical intervention to restore blood flow and minimize permanent damage to the heart muscle. Even slow-growing stable lesions can lead to long-term complications, including heart failure, by weakening the heart’s pumping ability.
Detecting and Measuring the Blockage
Healthcare professionals use several methods to assess coronary artery lesions, starting with non-invasive tests.
Non-Invasive Tests
A coronary computed tomography (CT) angiography is a non-invasive imaging test. A contrast dye is injected, allowing the CT scanner to visualize the arteries and detect plaque buildup. This test also provides a calcium score, which quantifies the amount of calcified plaque present, indicating the overall burden of atherosclerosis.
Other non-invasive methods include:
- An electrocardiogram (ECG) measures the heart’s electrical activity and can detect signs of heart muscle damage.
- Stress testing, using exercise or pharmaceutical stimulation, assesses blood flow by looking for signs of ischemia when the heart is working harder.
Invasive Angiography
The most definitive method for assessment is the invasive coronary angiography. During this procedure, a catheter is threaded through a blood vessel, usually in the wrist or groin, up to the coronary arteries. A contrast dye is injected, and X-ray images are taken, outlining any stenosis caused by the lesion. Specialized tools like fractional flow reserve (FFR) can be used to measure the physiological significance of a moderate blockage, determining if it requires treatment.
Addressing the Lesion
Treatment for a significant coronary lesion involves medical and procedural strategies focused on restoring blood flow and preventing future cardiac events. Medical management uses medications such as statins to lower cholesterol and stabilize existing plaques, making them less prone to rupture. Antiplatelet agents and blood pressure medications are also used to prevent clot formation and reduce the heart’s workload.
Percutaneous Coronary Intervention (PCI)
For lesions causing significant narrowing, a procedure called Percutaneous Coronary Intervention (PCI), or angioplasty, is often performed. This involves guiding a balloon-tipped catheter to the blockage site and inflating the balloon to compress the plaque against the artery wall. A stent, a small mesh tube, is then deployed to keep the artery open and maintain blood flow.
Coronary Artery Bypass Grafting (CABG)
If lesions are numerous, complex, or located in a particularly important vessel (such as the left main coronary artery), Coronary Artery Bypass Grafting (CABG) may be the preferred treatment. This procedure involves taking a healthy blood vessel from another part of the body (like the leg or chest) and grafting it to the heart to create a new path for blood flow around the blocked artery. The choice between PCI and CABG is based on the complexity of the lesion, the number of affected vessels, and the patient’s overall health profile.