Clinical ECG (normal)

Question 1

2 Grid Dimensions

Answer 1

Horizontal small box = 0.04 sec/big box = 0.20 sec

Vertical Small Box = 0.1 mV/big box = 0.5 mV

Question 2

J Point

Answer 2

End of QRS/1st part of “ST”

Question 3

1/2 Standard

Answer 3

1 mV = 5mm instead of 10, used when large deflections don’t fit

Question 4

300 Rule

Answer 4

HR = 300/# of large boxes in R-R interval

Question 5

3 Conditions of Sinus Rhythm

Answer 5

Rate b/w 60-100
Every normal P wave followed by QRS
P wave upright in Lead I and II, inverted aVR

Question 6

ECG Systole Interval

Answer 6

QT. Everything else diastole

Question 7

3 Normal Interval Ranges/Values

Answer 7

QRS Interval: =< 0.10 sec
PR Interval: = 0.12-0.20 sec
QTC (Corrected because varies w/ HR): =< 44 sec HR 60

Question 8

Chest Leads 3 Things Evaluated by Lead (mostly) Pairs

Answer 8

V1-2: Atrial/septal
V2-4: Anterior LV
V5-6: Lateral LV

Question 9

3 Features That Will Shift Axis Clockwise or Counterclockwise

Answer 9

Age: Younger more clockwise
Weight/height: Taller and skinnier more clockwise
Hypertrophy: LVH is counterclock and RVH is clockwise

Question 10

4 Axises (Axes? That’s a different word) Starting from 0 -> Clockwise

Answer 10

Normal
Right
Extreme
Left

Question 11

Determining Axis (3) from Lead I, II and aVF

Answer 11

Normal: +, +, either
Left: +, -, either
Right: -, either, +

Question 12

Normal P Wave Morphology (3)

Answer 12

I and II Positive
aVR negative
V1 usually diphasic

Question 13

Ventricular Depolarization Progression Across Chest Leads

Answer 13

R gets bigger and S gets smaller (R->L)

Question 14

Transition Zone

Answer 14

Where QRS changes from negative to positive across chest leads. Should be after V2 (early transition if +) and before V5 (late if negative)

Question 15

Main Point about T Wave Polarity

Answer 15

Across chest leads, once it is positive it should stay positive