Is the Right Atrium Enlarged?
By Ken Grauer, MD, Professor Emeritus in Family Medicine, College of Medicine,
University of Florida
Dr. Grauer is the sole proprietor of KG-EKG Press, and publisher of an ECG pocket brain book.
Scenario: The 12-lead ECG in the Figure was obtained from a 27-year-old man. Does the patient have a large right atrium?
Interpretation: The ECG shows sinus arrhythmia with a "vertical" axis that we estimate to be about +80 degrees (the QRS is much more positive in lead aVF than it is in lead I). There are small, narrow q waves in multiple leads. QRS amplitude is probably not increased given the young age of this adult. The insert highlights the P wave in lead II, which is at least 3 mm tall and pointed. This satisfies criteria for right atrial abnormality (RAA). Otherwise, all findings on this tracing might be normal if this 27-year-old man was asymptomatic with a normal physical exam.
Many clinicians interchange the terms LAA/RAA and LAE/RAE. We prefer the terms "LAA" and "RAA" — where the second letter "A" stands for left and right atrial "abnormality." Given the poor sensitivity and specificity of ECG for assessing atrial dimensions — use of the designations LAA/RAA allows us to acknowledge unusual P wave morphology on ECG that may not necessarily correlate with true anatomic atrial "enlargement." Reasons for abnormal P wave morphology not due to atrial chamber enlargement include atrial conduction defects, increased atrial pressure (as may occur in patients with acute heart failure), and body habitus. For example, it is not uncommon to see peaked inferior P waves in otherwise healthy young adults who have a relatively vertical mean QRS axis. We suspect this is what we are seeing in the Figure.
Clearly, clinical history and awareness of physical exam findings would be needed to know for certain what (if anything) the tall and pointed inferior P waves in the Figure mean. It turned out that this patient was slender, asymptomatic, and had a normal exam (no heart murmur). This ECG was performed for routine indication related to a job rather than because of symptoms. Under these circumstances, designation of "RAA" allows us to acknowledge unusual P wave appearance without necessarily attributing this to any cardiac pathology in this 27-year-old man who probably has a normal heart.
For more information on right atrial abnormality, please visit: http://ecg-interpretation.blogspot.com/2013/09/ecg-interpretation-review-75-chamber.html.