1 Getting aquainted with the ECG gridSample 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 mmAt 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 sec1 small box = 0.04 seconds or 1 mm

5 Boxes 1 big box = 0.2 seconds or 5 mm 1 small box = 0.04 sec1 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 PRWidest 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 activityAtrial activation P R AV conduction PR Ventricular depolarization QRS T Ventricular repolarization ST-T P U Q S