1. Heart Disease Slideshow Pictures
2. Medical Illustrations of the Heart Image Collection
3. Take the Heart Disease Quiz!

Medical Author:

Daniel Lee Kulick, MD, FACC, FSCAI

Daniel Lee Kulick, MD, FACC, FSCAI

Dr. Kulick received his undergraduate and medical degrees from the University of Southern California, School of Medicine. He performed his residency in internal medicine at the Harbor-University of California Los Angeles Medical Center and a fellowship in the section of cardiology at the Los Angeles County-University of Southern California Medical Center. He is board certified in Internal Medicine and Cardiology.

View Full Profile

Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

View Full Profile

In this Article

• What is an electrocardiogram (ECG, EKG)?
• How is an ECG (EKG) performed?
• What is measured or can be detected on the ECG (EKG)?
• When is an ECG (EKG) performed?
• What conditions may be diagnosed with an ECG (EKG)?
• What are the limitations of the ECG (EKG)?
• Patient Comments: Electrocardiogram (ECG or EKG) - Results
• Electrocardiogram (ECG or EKG) Index

What are the limitations of the ECG (EKG)?

1. The EKG is a static picture and may not reflect severe underlying heart problems at a time when the patient is not having any symptoms. The most common example of this is in a patient with a history of intermittent chest pain due to severe underlying coronary artery disease. This patient may have an entirely normal EKG at a time when he or she is not experiencing any symptoms. In such instances, the EKG as recorded during an exercise stress test may reflect an underlying abnormality while the EKG taken at rest may be normal.
2. Many abnormal patterns on an EKG may be non-specific, meaning that they may be observed with a variety of different conditions. They may even be a normal variant and not reflect any abnormality at all. These conditions can often be sorted out by a physician with a detailed examination, and occasionally other cardiac tests (for example, echocardiogram, exercise stress test).
3. In some instances, the EKG may be entirely normal despite the presence of an underlying cardiac condition that normally would be reflected in the EKG. The reasons for this are largely unknown, but it is important to remember that a normal EKG does not necessarily preclude the possibility of underlying heart disease. Furthermore, a patient with heart symptoms can frequently require additional evaluation and testing.