ECGs Flashcards
An electrocardiograph is the ___1____
An electrocardiogram is the ____2_____
1 machine
2 information generated
When depolarisation moves towards the recording electrode the ECG generates ____1_____
When depolarisation moves away from the recording electrode the ECG generates ____2____
1 an upwards deflection
2 a downwards deflection
There are __1___ leads and ____2___ electrodes (___3___)
1 12 leads
2 10 electrodes
3 6 chest and 4 limb
Placement of V1
4th ICS immediately right of the sternum
Placement of V2
4th ICS left of sternum
Placement of V3
Midway between V2 and V4
Placement of V4
5th ICS mid clavicular line
Placement of V5
Same horizontal level as V4 but on anterior axillary line
Placement of V6
Same horizontal level as V4 but on mid axillary line
Lead 1 is from
Right arm to left arm
Lead 2 is from
Right arm to left leg
Lead 3
Left arm to left leg
P wave is
Atrial depolarisation
QRS complex is
Ventricular depolarisation
T wave is
Ventricular repolarisation
PR interval is
Start of p wave to start of QRS. Reflects the time for SA impulse to reach the ventricles, normally ).12-0.2 seconds. Strongly influenced by the AV node delay.
ST segment is
End of QRS to start of T wave. Normally isoelectric. Elevation or depression is abnormal.
QT interval is
start of QRS to end of T wave. Primarily reflects that time for ventricular depolarisation and depolarisation normally 0.44s in males and 0.46s in females. Prolongation may be caused by drugs.
Calibration of ECG?
25mm/s
10mm/mV
Normal resting ECG doesn’t exclude?
- Myocardial Infarction (heart attack)! May or may not cause characteristic ECG changes (e.g. ST elevation)
- Intermittent Rhythm Disturbance! If suspected do ambulatory ECG recording for 24 hrs or 7 days
- Stable Angina (a form of Ischaemic Heart Disease) If suspected do exercise ECG. Look for ST changes during/after exercise. Usually absent during rest!
Tall QRS complexes usually imply
Left ventricular hypertrophy
Inferior view of heart from
2, 3 and avF
Lateral view of the heart from
1, avL, V5 and V6
Anterior view of the heart from
V3-4
Septal view
V1, V2
If heart rate regular work out rate from
If irregular
300/ no of large squares between beats
number of QRS complexes in 30 squares x 10
If lead 1 and AvF are both upright the axis is
normal
If lead 1 is upright but AVF downwards the axis is
left
If lead 1 is downwards but AVF upwards the axis is
right
Ventricular ectopics may have broad
QRS complexes
Length of normal qrs?
0.12 seconds (3 small squares)
What change will occur first on ECG in acute MI?
Tall T waves
Common artery affected in inferior MI?
Right coronary artery
Common artery affected in anterior MI?
Left anterior descending
Common artery affected in high lateral MI?
A diagonal branch of LAD
Common artery affected by low lateral MI?
Obtuse marginal branch of the circumflex artery
What is a narrow qrs typical of?
SVT
