ecg essential

ecg interpretation

1. rate
-big square' is O.2s
-1 small square is  0.04s.
-2 small square = 0.08 s
-3 small square = 0.12 s
-4 small square = 0.16 s
-5 small square = 0.2 s
-5 small square= 1 big square
-

2. Rhythm

- Sinus rhythm is characterized by a P wave (upright in lead  II. Ill, & aVF; inverted in aVR) followed by a QRS complex

-AF has no discernible P waves and the QRS complexes are irregularly irregular

-Atrial flutter (has  a 'sawtooth baseline of atrial depolarization (300/min) and regular
QRS complexes.

-Nodal rhythm has a normal QRS complex but p waves  are absent or  occur just before or within the QRS complex.

-Ventricular rhythm has qrs complexes >0.12s   {  3 small square} with P waves following them.


3. P wave:

-Absent p wave:  AF, sinoatrial block,   junctional (AV nodal) rhythm.
- P mitrale: bifid P wave, indicates left atrial  hypertrophy.
-p pulmonale: peaked P wave, indicates right atrial  hypertrophy

4. P-R interval

-Normal range 0.12 - O.2s (3-5 small squares)

5. QRS complex: Normal duration: <0.12s.

-Normal Q wave <0.04s  {1 small square} duration wide and < 2mm { 2 small quare} deep.

-q wave: They are often seen in leads V5 and V 6, .aVL and I. and reflect normal septal
depolarization, which usually occurs from left to right.
-Pathological Q wave may occur within a few hours of an acute MI.

6. ST segment.
-Planar elevation (> 1mm) or depression  (>O.5mm) usually implies infarction or ischaemia.

7. Twave: Normally inverted in aVR, V1, and occasionally V2. Abnormal if inverted I. II, and V4-V6.
Peaked in hyperkalaemia flattened in hypokalaemia.