Cardiology & ECGs

Question 1

Normal PR interval?

Answer 1

120-200ms

Question 2

How many ms is one small square?

Answer 2

1 small square = 40ms (which is 1mm in diameter)

Question 3

How many squares is 1 second?

Answer 3

5 big squares (=25 small squares)

Question 4

Cause of elongated PR interval?

Answer 4

First degree AV block
>200ms (> 5 small squares/1 big square)

Question 5

How do we know 1 small square is 40ms?

Answer 5

Each ECG has speed of 25mm/s.
which means 25mm = 1 second

Each small square measures 1mm
1 second = 1000ms
1000/25 = 40ms

Question 6

Normal P wave duration?

Answer 6

<120ms

Question 7

Normal QRS duration?

Answer 7

about 100ms

Question 8

Causes of shortened PR interval?

Answer 8

Ventricular depolarisation is occuring too early; showing that there is an alternative pathway present.
Such as; Wolfff-Parkinson White syndrome

<120ms

Question 9

NORMAL AXIS DEVIATION

Answer 9

Lead I and AvF are both positive

Question 10

RIGHT AXIS DEVIATION

Answer 10

Lead 1 = negative

lead AvF = positive

REACHING for eachother = RIGHT

Question 11

LEFT AXIS DEVIATION

Answer 11

Lead 1 = positive

lead AvF = negative

(lead 2 = also negative)

LEAVING eachother = LEFT

Question 12

EXTREME AXIS DEVIATION

Answer 12

Lead 1 + AvF are both NEGATIVE

(both negative as it is a bad thing)

Question 13

Causes of widened QRS complex?

Answer 13

Bundle branch blocks (R or L) = WiLLiaM MaRRoW