An electrocardiogram, commonly known as an EKG or ECG, is a widely used, non-invasive diagnostic tool that assesses heart health. This test measures the electrical activity of the heart, providing a visual representation of its rhythm and function. It is often an initial evaluation when heart concerns arise, quickly capturing the heart’s electrical signals.
Understanding How EKGs Detect Issues
An EKG records the electrical signals generated by the heart. These electrical impulses control the contraction and relaxation of the heart muscle, orchestrating blood pumping throughout the body. Electrodes are placed on the skin, typically on the chest, arms, and legs, to capture these signals.
The recorded activity translates into a wavy line graph for interpretation. This graph displays distinct patterns, including waves, segments, and intervals, representing different phases of the heart’s electrical cycle. Deviations from a typical pattern in timing, shape, or amplitude can indicate underlying issues with the heart’s function or structure. By analyzing these electrical signatures, an EKG provides insights into how efficiently the heart is working.
Key Heart Conditions Identified by an EKG
The EKG identifies various heart conditions by revealing specific changes in electrical activity.
Arrhythmias
An EKG detects heart rhythm abnormalities, known as arrhythmias. These include a heart beating too fast (tachycardia), too slow (bradycardia), or with an irregular rhythm, such as atrial fibrillation or premature beats. An EKG shows if the heart’s electrical impulses travel along normal pathways and if timing between beats is consistent.
Heart Attacks
EKGs diagnose heart attacks (myocardial infarctions). The test shows evidence of current or past heart attacks through changes in electrical patterns caused by damaged heart muscle. Specific findings like ST segment elevation, ST segment depression, or Q waves indicate areas of heart muscle injury.
Heart Muscle Issues and Ischemia
The EKG offers clues about heart muscle issues, such as an enlarged heart (ventricular hypertrophy). Thickened heart muscle generates larger electrical signals. This appears as increased voltage in EKG leads, indicating the heart works harder to pump blood. It also shows signs of reduced blood flow (ischemia), which often precedes a heart attack. Ischemia may manifest as ST segment depression or T wave changes.
Electrolyte Imbalances
Electrolyte imbalances affect the heart’s electrical stability and appear on an EKG. Imbalances in minerals like potassium, calcium, and magnesium alter heart cell electrical properties, changing rhythm and EKG patterns. For instance, high potassium levels might cause peaked T waves, while low potassium can lead to flattened T waves or prominent U waves. These alterations underscore the interconnectedness of body chemistry and heart function.
What an EKG Does Not Directly Detect
An EKG has limitations and does not directly detect all heart conditions. It cannot directly visualize artery blockages, like those in coronary artery disease (CAD), unless they cause reduced blood flow (ischemia) or a heart attack. While an EKG may suggest a problem, other tests like stress tests or angiography are needed to assess arterial blockages directly.
The EKG does not detect all structural heart problems, such as valve issues or congenital heart defects, unless they significantly impact electrical activity. A valve problem might only appear on an EKG if it causes heart chambers to enlarge, leading to electrical changes. More detailed imaging tests, like echocardiograms, are required to assess the heart’s physical structure and valve function.
A normal EKG does not always rule out heart disease. Some heart conditions may not manifest electrically during the test, especially if intermittent or asymptomatic. An EKG is one piece of a broader diagnostic assessment. Healthcare professionals combine EKG results with medical history, physical examination, and other tests for a complete understanding of heart health.