ST AND T CHANGES/ABNORMALITIES:     ECG changes of the ST segments and the T waves. Changes can be primary, secondary or nonspecific. Primary ST and T changes are strictly due to a problem with ventricular repolarization, whereas secondary ST and T changes occur when a problem in ventricular depolarization causes a problem with repolarization. […]

ST SEGMENTS:     Deflections on the ECG that occurs between the QRS complex and the T wave.

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

SUPRAVENTRICULAR TACHYCARDIAS (SVT):     Any tachyarrhythmia that originates from above the atrioventricular node, but usually it refers to two (2) reentrant arrhythmias:  Atrioventricular Nodal Reentrant Tachycardia (AVNRT), and Atrioventricular Reentrant Tachycardia (AVRT).   •See: Atrioventricular nodal reentrant tachycardia (AVNRT) and Atrioventricular reentrant tachycardia (AVRT).

SVT:     See:  Supraventricular tachycardia

SWEEP SPEED:     The time required to complete one sweep of data. On an ECG the sweep speed refers to the speed in which the ECG machine record heart beats over time. •Standard sweep speed is 25 mm/second.

T WAVE AXIS:     The major direction of overall electrical activity within the ventricles during repolarization. •Normal:       0 to +90 degrees (within 45 degrees of the QRS axis). •An abnormal T wave axis may be caused by primary or secondary repolarization abnormalities.

T WAVES:     Deflections on the ECG after the ST segment

THIRD DEGREE ATRIOVENTRICULAR (AV) BLOCK (Complete Heart Block):     A disorder of the atrioventricular (AV node) in which there is complete failure of atrial impulses to conduct to from the atria to the ventricles. •Atrioventricular (AV) node does not function resulting in independent atrial and ventricular rhythms superimposed. •P to P interval: •PR interval: […]