The main ECG manifestations of pericardial effusion are low voltage, tachycardia, arrhythmia, T wave abnormality, PR segment abnormality, and electrical alternans.
Since pericardial effusion affects the electrical conduction of the heart, low voltage may appear in the limb leads or chest leads, with the amplitude of the QRS wave in the chest leads <1 mV and the amplitude in the limb leads <0.5 mV. Tachycardia, with a heart rate of >100 beats/min, and arrhythmias, such as premature ventricular contractions, may also be seen in some cases of pericardial effusion.
Pericardial effusions are likely to have T-wave abnormalities, which may be characterized by depressed ST-segment elevation in the extensive leads and ST-segment depression in the aVR leads. There is a generalized downward shift of the PR segment in leads other than the aVR lead and V1 lead and elevation of the PR segment in the aVR lead. Voltage alternans is likely to occur.
When a pericardial effusion is present, it is important to actively seek medical attention and early treatment under the guidance of a physician.