1. Getting aquainted with the ECG grid
Sample module on ECG
Getting aquainted with the ECG grid
JDMagno
Feb 2017

2. Before interpreting the electrocardiogram, what is one important preliminary step?

3. Standardization 1 mV = 10 mm
At proper standardization, 10 small boxes high will be equivalent to 10 mm. The standard paper speed will be 25 mm/sec, making one small box equivalent to 0.04 seconds.

4. Boxes 1 big box = 0.2 seconds or 5 mm 1 big box = 0.2 sec
1 small box = 0.04 seconds or 1 mm

5. Boxes 1 big box = 0.2 seconds or 5 mm 1 small box = 0.04 sec
1 small box = 0.04 seconds or 1 mm

6. Waves T P U
WAVE: curvilinear deflection from baseline representing a specific phase of the cardiac cycle

7. Segments PR ST TP
SEGMENT: horizontally-directed line representing the numeric distance (in mm) between two waves or complexes

8. Intervals
PR interval
INTERVAL: the time frame (in seconds) that elapses as the distance between two reference points on the ECG tracing is traversed

9. Intervals
QRS
INTERVAL: the time frame (in seconds) that elapses as the distance between two reference points on the ECG tracing is traversed

10. Intervals
QT interval
INTERVAL: the time frame (in seconds) that elapses as the distance between two reference points on the ECG tracing is traversed

11. Intervals
RR interval
INTERVAL: the time frame (in seconds) that elapses as the distance between two reference points on the ECG tracing is traversed

12. Intervals
PP interval
INTERVAL: the time frame (in seconds) that elapses as the distance between two reference points on the ECG tracing is traversed

13. Where to look... R T P U Q S
Which leads should you look at when measuring specific parts of the ECG?

14. Where to look... Leads II and V1 P R Shortest interval PR
Widest complex
QRS T
Longest interval with NO prominent U waves QT P U Q
Midprecordial leads U S

15. Normal values... <0.12 sec <0.25 mV in limb leads
<0.1 mV terminal negative deflection in V1 P R
< sec PR T
< sec
QRS P U
QTc
<0.48 (female)
< 0.47 (male) Q
Braunwald (0.44 to 0.46) T S
<5 mm (limb leads)
<10 mm (chest leads)

16. Correlating the ECG with electrical activityP R PR
QRS T
ST-T P U Q S
How does the ECG correlate with electrical activity of the heart?

17. Correlating the ECG with electrical activity
Atrial activation P R
AV conduction PR
Ventricular depolarization
QRS T
Ventricular repolarization
ST-T P U Q S