The echocardiogram (echo) is a common diagnostic test that uses ultrasound technology to assess the heart’s structure and function. While it provides extensive information about the heart’s performance, the test cannot directly image plaque blockages within the small coronary arteries. The primary purpose of an echocardiogram is to visualize the effects of disease on the heart muscle, chambers, and valves, not to serve as a direct plumbing inspection of the coronary blood vessels. Understanding what this test does and does not show is important for clarity on heart health.
Defining the Echocardiogram
An echocardiogram is an ultrasound of the heart that uses high-frequency sound waves to create real-time, moving pictures. A technician applies a gel to the chest and uses a handheld transducer, which sends sound waves through the body and captures the echoes that bounce back off the heart structures. A computer then translates these echoes into images that show the heart’s size, shape, and motion. This process is non-invasive and painless, making it a safe procedure for evaluating cardiac health.
The most common type is the Transthoracic Echocardiogram (TTE), where the transducer is placed directly on the chest wall. If a clearer image is required, a Transesophageal Echocardiogram (TEE) may be used. The TEE involves inserting a thin tube with a tiny transducer down the throat into the esophagus, which sits directly behind the heart, allowing for superior image quality by bypassing the ribs and lungs. Doppler technology is often incorporated to measure the speed and direction of blood flow through the heart’s chambers and vessels.
Core Information Provided by the Echo
The echocardiogram examines the mechanical performance and structural integrity of the heart. It allows healthcare providers to assess the size and volume of the heart’s four chambers, noting enlargement or abnormal thickening of the walls. Changes in heart size can often indicate conditions like high blood pressure or other diseases that place strain on the heart muscle.
The test provides detailed information about the function of the heart valves, which control blood flow within the heart. It can diagnose problems such as stenosis, which is a narrowing of a valve, or regurgitation, which is when a valve leaks, allowing blood to flow backward. The Doppler feature is particularly helpful here, visualizing turbulent or irregular blood flow patterns that suggest a valve issue.
A measurement provided by the echo is the heart’s pumping strength, quantified as the Ejection Fraction (EF). The EF is the percentage of blood pumped out of the left ventricle with each beat, and a reduced fraction is a key indicator of heart failure or general muscle weakness. By observing the movement of the heart muscle, the echo helps define the heart’s capacity to meet the body’s circulatory needs.
How Echocardiography Identifies Damage
While the echo does not directly visualize blockages, it shows the consequences of a blocked artery on the heart muscle. Coronary artery disease restricts blood flow, leading to a lack of oxygen (ischemia) in the affected heart muscle tissue. This damage manifests on the echocardiogram as a Wall Motion Abnormality, where a section of the heart muscle moves weakly or stops moving entirely.
These abnormalities are categorized based on the severity of movement, ranging from hypokinesis (reduced movement) to akinesis (no movement). The location of the abnormal motion often correlates directly with the specific coronary artery that is narrowed or blocked. The test is used to identify damage from a past heart attack or to assess risk in a patient presenting with symptoms like chest pain.
A Stress Echocardiogram evaluates the heart under strain. The patient either exercises on a treadmill or is given medication that mimics the effects of exercise by increasing the heart rate. Images are taken before and immediately after the stress is induced; if an area of the heart muscle that moved normally at rest suddenly develops a wall motion abnormality under stress, it suggests a significant underlying blockage is preventing adequate blood flow when demand increases.
Direct Imaging of Coronary Artery Disease
For a diagnosis that visualizes the extent and location of plaque blockages, other specialized tests are necessary. The standard test for seeing inside the coronary arteries is Coronary Angiography, also known as cardiac catheterization. This invasive test involves inserting a catheter into a blood vessel in the arm or groin and guiding it to the coronary arteries.
A contrast dye is injected, which makes the arteries visible under X-ray imaging, allowing the healthcare provider to see any narrowing or obstruction. This technique provides the clearest picture of the arterial “plumbing” and is often used to guide immediate treatment, such as placing a stent.
A non-invasive alternative is Coronary CT Angiography (CT scan). This test uses a computed tomography scanner to take detailed three-dimensional images of the heart and blood vessels after a contrast dye is injected intravenously. It is accurate for detecting plaque buildup and narrowing in the coronary arteries, offering a detailed assessment without the need for a catheter.