Normal ECG

Question 1

P Wave

Answer 1

Atrial depolarization
Upright in 1, 2, V4-V6, aVF
Inverted in aVR
Variable in 3, aVL, other chest leads

Question 2

PR Interval

Answer 2

Beginning of P wave to beginning of QRS complex
Time from SA node to ventricular muscle fiber
0.12-0.20 sec

Question 3

QRS Complex

Answer 3

Ventricular Depolarization
0.05-0.10 sec duration
Q wave shouldn’t be more than 0.03 sec in width

Q eaves, narrow/small, 1-2 mm is normal in 1, aVL, aVF, V5, V6

Question 4

ST segment

Answer 4

After QRS Complex

Observe the level (relative to baseline; elevated or depressed) and shape

Normally isoelectric; sometimes normally elevated not more than 1mm in standard leads and 2 mm in chest leads; it is never normally depressed more than 1/2 ,, ST depression- Subendocardial ST elevation- Subepicardial or transmural injury or ischemia

Question 5

T wave

Answer 5

Ventricular repolarization

Upright 1, 2, V3-V6
Inverted aVR, variable 3, aVL, aVF, V1-V2

Shape is slightly rounded and asymmectrical
Height is not greater than 5 mm in standard leads no greater than 10 mm in chest leads

Inverted in ischemic pattern

Question 6

QT Duration

Answer 6

Length of Ventricular systole

Question 7

Sinus Rhythm

Answer 7

P wave before every ORS complex

P-R < 0.2 sec=no AV block
QRS < 0.12= no bundle branch block

Question 8

Rate

Answer 8

Above 100=tachycardia

Below 60=Bradycardia

Question 9

P wave follows QRS

Answer 9

SVT (AV nodal re-entry tachycardia

Junctional rhythm

Question 10

No P waves

Answer 10

Atrial fibulation, atrial flutter, junctional or ventricular escape rhythms, juctional tachycardia, ventricular tachycardia

Question 11

Axis

Answer 11

Normal axis= positive lead I and positive aVF

Left axis= positive in lead I and negative in aVF

Right axis=Negative in lead I and positive in aVF