2. What it looks like
when I’m reading an ECG
vs What’s actually happening
3. A 12-year-old boy presents to the
A&E department following a
syncopal episode in the middle of
a football game. The parents
report that he appeared pale and
remained unresponsive for 1min.
He recalls that he had some chest
discomfort but does not remember
the rest of the event. A 12-lead
ECG was obtained.
42. Corrected QT “QTc”
• The corrected QT interval (QTc) estimates the QT interval at a standard
heart rate of 60 bpm.
• This allows comparison of QT values over time at different heart rates
and improves detection of patients at increased risk of arrhythmias.
43. Corrected QT “QTc”
QT = 12 small boxes = 12 x 0.04 = 0.48
RR = 17 small boxes = 17 x 0.04 = 0.68
QTc = 0.48 / square root of 0.68 = 0.58
= Prolonged QT [Normal up to 0.45 sec]
* Causes : Electrolyte abnormalities, Myocarditis, Medications, Head injury.
* Symptoms : Palpitations, Chest pain, SOB, Dizziness, Syncope, Cardiac arrest.
47. A 12-year-old boy presents to the
A&E department following a
syncopal episode in the middle of
a football game. The parents
report that he appeared pale and
remained unresponsive for 1min.
He recalls that he had some chest
discomfort but does not remember
the rest of the event. A 12-lead
ECG was obtained.
54. 10 Rules of
a Normal ECG
1. P wave always positive in I & II, and negative in aVR
2. All waves are negative in lead aVR
3. QRS & T waves have same direction in limb leads
4. QRS should be dominantly upright in leads I & II
5. R wave grows from V1 to at least V4
6. ST segment isoelectric except in V1 & V2 where it
may be elevated
7. T wave in V1 inverts after 7 days till 7 years
8. In I & II + V2 to V6 P wave is upright
9. In I & II + V2 to V6 T wave is upright
10. In I & II + V2 to V6 No Q wave (or small Q)