Glossary | Page 6 of 24 | Executive Electrocardiogram Education

EARLY TRANSITION (COUNTERCLOCKWISE ROTATION)

EARLY TRANSITION (COUNTERCLOCKWISE ROTATION): When determining the axis of the heart in the transverse (horizontal) plane, the point in which the QRS complex becomes isoelectric (transitions from negative to positive) occurs before lead V3. •If you were looking up at the heart from beneath, the heart appears to be rotated counterclockwise, making the […]

ECTOPIC ATRIAL RHYTHM

ECTOPIC ATRIAL RHYTHM: A rhythm originating from the atria at a rate between 55 and 100 beats per minute (the rate reflects atrial activity only. Ventricular activity may have a different rate).

ECTOPIC JUNCTIONAL RHYTHM

ECTOPIC JUNCTIONAL RHYTHM: A rhythm originating in the atrioventricular (AV) node (junction) at a rate of 40 -60 bpm.

ELECTRICAL ALTERNANS

ELECTRICAL ALTERNANS: An alternating QRS amplitude. As such, the height of the QRS complexes vary between beats. •Electrical alternans can also occur with P waves or T waves.

ELECTROCARDIOGRAM (ECG; EKG)

ELECTROCARDIOGRAM (ECG; EKG): A test that measures the electrical activity of the heart.

ELECTRODE

ELECTRODE: The conductive pads attached to the patient’s body surface that connects the ECG wires to the ECG machine. The term “lead” is sometimes used incorrectly to mean electrode.

ELECTROLYTE ABNORMALITIES

ELECTROLYTE ABNORMALITIES: See the individual electrolyte abnormality (e.g. hyperkalemia, hypokalemia, hypercalcemia, hypocalcemia, hypermagnesemia, hypomagnesemia, hypernatremia, hyponatremia).

EPSILON WAVES

EPSILON WAVES: Low-amplitude electrical potentials caused by delayed excitation found at the end of the QRS complex and the beginning of the T wave. These waves may indicate arrhythmogenic right ventricular dysplasia (ARVD). •ECG Criteria: •Small upward deflections (“blips”) on the end of QRS complexes.

EXTREME RIGHT (SUPERIOR) AXIS DEVIATION

EXTREME RIGHT (SUPERIOR) AXIS DEVIATION: An abnormal overall direction of depolarization of the ventricles represented by a QRS axis of -90 to -180 degrees.

FAILURE TO CAPTURE

FAILURE TO CAPTURE: A pacemaker produces a stimulus, but the heart fails to respond to the pacemaker’s impulse. On an ECG, the pacemaker produces a jolt of electricity and a spike on the ECG, but no complex follows the spike.