SECONDARY ST AND T CHANGES/ABNORMALITIES:     ST and T changes occur when a problem in ventricular depolarization causes a problem with repolarization. •ECG findings: •Diffuse process. •Generally involves both the ST and T waves. •T wave axis is opposite from the QRS axis. •Typical examples: •Left ventricular hypertrophy, left bundle branch block, others. •Primary […]

SEPTAL/POSTERIOR LEADS:     Leads V1 and V2

SHORT PR INTERVAL:     A PR interval that is less than 0.12 seconds •Normal PR interval: 0.12 – 0.20 seconds. •Short PR interval: < 0.12 seconds. •Causes of a short PR interval: •Normal variant. •Enhanced atrioventricular nodal conduction (EAVNC). •Infra-nodal connection between the atria and the bundles (James Fiber). •Lown-Ganong-Levine syndrome (Short PR interval; […]

SINOATRIAL (SA) EXIT BLOCKS:     A disorder of the sinus node in which there is intermittent complete failure of sinus impulses to conduct to from the sinus node to the atria. •First Degree SA Exit Block: •Delay from the time the SA node creates an action potential to the time the atrium actually depolarizes. […]

SINUS ARREST:     A long pause devoid of sinus beats (typically > 2 seconds).

SINUS ARRHYTHMIA:     A rhythm originating from the sinus node with a variable rate (typically at least a 0.16 sec variation between the fastest and slowest beats).

SINUS BRADYCARDIA:     A rhythm originating from the sinus node at a rate < 60 beats per minute.

SINUS PAUSE:     A sinus beat is not present and skips during a sinus rhythm.

SINUS TACHYCARDIA:     A rhythm originating from the sinus node at a rate > 100 beats per minute.