CONCORDANCE:     A condition on an ECG when all of the QRS complexes in the precordial (chest) leads are either predominantly positive or predominantly negative. Concordance suggests that a wide complex tachycardia is more likely of ventricular origin than supraventricular with aberrancy.

CORNELL CRITERIA:     One of many criteria for determining left ventricular hypertrophy (LVH) on an ECG. •ECG findings: •Men: (RaVL + SV3) ≥ 28 •Women: (RaVL + SV3) ≥ 20

CORRECTED QT (QTC) INTERVAL:     Time from the beginning of the QRS complex to the end of the T wave that having been corrected based on the heart rate.

COUNTERCLOCKWISE ROTATION (EARLY TRANSITION):     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 […]

COUPLET:     Two abnormal beats in a row (e.g. atrial couplet – Two premature atrial complexes in a row; ventricular couplet – Two premature ventricular complexes in a row).

DELTA WAVE:     An initial slurring of the QRS complex due to conduction through an accessory pathway directly connecting the atria to the ventricles.

DEXTROCARDIA:     A congenital condition in which the heart’s position is reversed. With dextrocardia, the apex (tip) of the heart is in the right chest rather than in its normal position on the left. This makes the limb leads of an electrocardiogram appear like left/right arm lead reversal, and abnormal transition in the chest […]

DIGOXIN:     Digoxin is a cardiac glycoside medication used for systolic heart failure and arrhythmias such as atrial fibrillation. Digoxin toxicity can cause ECG changes and arrhythmias. •Digoxin Effects on the ECG: •Diffuse ST segment scooping and depression. •QT shortening. •Flattening of the T wave or biphasic T wave. •U waves. •Arrhythmias: •Atrioventricular (AV) […]

DRUG EFFECTS:     See Digoxin; See antiarrhythmic agents.