An electrocardiogram (EKG) is a non-invasive test that assesses heart health. While an EKG provides valuable insights into heart function, it does not directly visualize blockages in the heart’s arteries. This test primarily evaluates the heart’s electrical signals, offering an indirect view of its condition.
Understanding the EKG
An EKG measures the electrical activity generated by the heart. Small electrodes are placed on the skin, detecting impulses recorded as waves on a graph, representing the heart’s rhythm and rate.
This recording provides a snapshot of the heart’s electrical performance, allowing professionals to observe signal timing and strength. The EKG focuses on the heart’s electrical pathways and how they coordinate muscle contractions.
What an EKG Can Reveal About Your Heart
An EKG can reveal several aspects of heart health by interpreting electrical patterns. It effectively detects arrhythmias, which are irregular heartbeats. The test can also show evidence of a past or ongoing heart attack (myocardial infarction). Specific EKG waveform changes, such as ST-segment elevation or T-wave inversions, can indicate heart muscle damage.
An EKG can also provide clues about heart muscle strain or thickening (hypertrophy). This occurs when the heart works harder, leading to chamber enlargement. The test can also identify certain electrolyte imbalances that disrupt the heart’s electrical stability. These findings are indirect indicators of heart health and function, not direct visualizations of blockages.
Why EKGs Don’t Directly Show Blockages
An EKG does not directly show blockages because it measures electrical activity, not the physical structure of arteries. Coronary artery blockages are typically caused by plaque buildup (atherosclerosis), which physically narrows blood vessels. An EKG cannot visualize this physical narrowing or the plaque itself. It’s like a traffic sensor detecting a slowdown; it knows traffic is impeded but not the specific cause.
While an EKG cannot directly image a blockage, it can detect the effects of a severe blockage, especially if it leads to insufficient blood flow to the heart muscle. For example, during a heart attack caused by a complete blockage, the lack of oxygen to heart tissue alters its electrical signals. These changes are what the EKG picks up, indicating damage from reduced blood supply. Therefore, the EKG reveals the consequence of a blockage rather than the blockage itself.
How Healthcare Professionals Detect Heart Blockages
Since EKGs do not directly show blockages, healthcare professionals use other specialized tests to diagnose coronary artery disease. Stress tests, which can be exercise-induced or pharmacological, evaluate heart performance under exertion. During these tests, an EKG is monitored while the heart is stressed, helping identify blood flow issues that may only become apparent when the heart works harder.
Coronary angiography (cardiac catheterization) is the gold standard for directly visualizing blockages. This invasive procedure involves inserting a thin tube into a blood vessel and guiding it to the heart’s arteries. A special dye is injected, making arteries visible on X-ray images, allowing doctors to see the exact location and severity of any blockages.
Non-invasive options include CT angiography (CTA), which uses X-rays and contrast dye for detailed images of the heart and its blood vessels. Echocardiograms use sound waves to produce images of the heart’s structure and function, can assess pumping ability and valve issues, and can show indirect signs of blockages. Blood tests, measuring cholesterol levels or inflammatory markers like C-reactive protein, also help assess an individual’s risk for developing blockages.