Basic interpretation of ECG

Question 1 of 15

1

Here's some ECG paper. It's comprised of, in Dr Flynn's terms, "big squares" and "little squares". Each big square is 5x5 little squares. For one LITTLE square, select the correct size in mm, the correct voltage its height represents in mV of current, and the correct time period its width represents in seconds.

Select one or more of the following:

1mm x 1mm
0.5 mm x 0.5 mm
1mV
10mV
0.04 seconds
0.2 seconds

Explanation

Question 2 of 15

1

Here is a textbook-perfect segment of an ECG. What's the flat line, without any deflections, called?

Select one of the following:

The iso-electric line
The baseline
The flatline
Holt's line

Explanation

Question 3 of 15

1

What is the first upward wave called?

Select one of the following:

P wave
T wave
J wave
Q wave

Explanation

Question 4 of 15

1

Sometimes there is a downward deflection at this point. What is it called?

Select one of the following:

P wave
T wave
Q wave
J wave

Explanation

Question 5 of 15

1

What is the combination called of a downward deflection, followed by an upward deflection, followed by another download inflection?

Select one of the following:

ABC complex
QMT complex
JMP complex
QRS complex

Explanation

Question 6 of 15

1

In the six steps to interpreting ECGs, the first is to determine the rate. The heart rate is determined by the number of squares or mm between two R waves. What are the TWO easiest ways to determine the rate?

Select one or more of the following:

1500/(# of little squares between r waves)
300/(# of big squares between r waves)
500/(# of big squares between r waves)
3000/(# of little squares between r waves)

Explanation

Question 7 of 15

1

What is the second step to interpreting the ECG?

Select one of the following:

Determine the rhythm
Hand it to the cardiologist
Examine the p wave
Determine the heart axis

Explanation

Question 8 of 15

1

The third step is interpreting the p wave, which indicates depolarisation of the atria. When considering the p wave, first determine if it is present. If it is present, what should a normal p wave look like?

Select one of the following:

2.5 mm x 2.5 mm
1mm x 1 mm
2.5 mm x 5 mm
Less than half the height of the QRS complex

Explanation

Question 9 of 15

1

The PR interval should be 3-5mm. What does it represent?

Select one of the following:

Time taken for depolarisation to start at the AV node, travel through the atria and conducting system to the ventricular muscle
Time taken for depolarisation to start at the AV node, travel through the atria to the AV node
Time taken for depolarisation to start at the AV node, travel through the atria and conducting system to the Bundle of His

Explanation

Question 10 of 15

1

The fourth step is interpreting the QRS complex (representing depolarisation of the ventricles), which has several sub-steps. First, consider the cardiac axis. The wave of depolarisation spreads in multiple directions through the ventricles. The differing magnitudes and directions of the various depolarisation currents can be “summed” to form a resulting electrical vector, which is known as the cardiac axis.

If we consider the heart in the coronal plane (using the limb leads), an abnormal axis is outside -30 to +90 degrees. What are the steps to determining the cardiac axis?

Select one of the following:

Find the lead with the most biphasic QRS complex, determine the lead most perpendicular to it, and then determine whether the impulse is travelling towards (upwards deflection), or away from (downwards deflection) that lead. The resultant degree value is the cardiac axis.
Find the lead with the most biphasic QRS complex, and then determine whether the impulse is travelling towards (upwards deflection), or away from (downwards deflection) that lead. The resultant degree value is the cardiac axis.
Find the lead with the least biphasic QRS complex, determine the lead most perpendicular to it, and then determine whether the impulse is travelling towards (upwards deflection), or away from (downwards deflection) that lead. The resultant degree value is the cardiac axis.

Explanation

Question 11 of 15

1

What should q waves look like?

Select one of the following:

Less than 1mm in width, less than 2mm in depth, and pointed
More than 1mm in width, more than 2mm in depth, and pointed
Less than 1mm in width, less than 2mm in depth, and curved
Less than 2mm in width, less than 2mm in depth, and pointed

Explanation

Question 12 of 15

1

Considering QRS complexes from from V1 to V6, two trends are apparent: the R-wave becomes progressively larger, and the S-wave becomes progressively smaller. This is called R wave progression. What is a lack of R wave progression usually an indication of?

Select one of the following:

Right ventricular enlargement or an old anterior infarct
Left ventricular enlargement or an old anterior infarct
Septal enlargement or an old full-thickness infarct
Atrial enlargement

Explanation

Question 13 of 15

1

The QRS complex duration should be less than 2.5mm. When considering amplitude, we need to consider whether there is indication of left ventricular hypertrophy or right ventricular hypertrophy. Is the following criteria to determine LVH or RVH?
a. Sokolow-Lyon criteria:
S-wave in lead V1 + R-wave in either lead V5 or V6 > 35 mm.

b. Cornell criteria:
Males: S-wave in lead V3 + R-wave in lead aVL > 28 mm.
Females: S-wave in lead V3 + R-wave in lead aVL > 20 mm.

Select one of the following:

Left VH
Right VH

Explanation

Question 14 of 15

1

For the fifth step, consider the ST segment. ST segments can be elevated or depressed from the iso-electric line. The ST-segment is said to be depressed if it slopes down 1mm or more from the J-point, or is depressed 1mm or more horizontally. ST-segment elevation of up to 3 mm in the right-sided chest leads, and up to 1 mm in the limb leads may be normal, and is referred to as early repolarisation.

What conditions do these phenomena indicate?

Select one of the following:

ST-segment depression: subendocardial ischaemia, digoxin, “strain”;
ST-segment elevation: full-thickness ischaemia, pericarditis
ST-segment depression: full-thickness ischaemia, pericarditis;
ST-segment elevation: subendocardial ischaemia, digoxin, “strain”

Explanation

Question 15 of 15

1

For the sixth and final step, we need to consider the t wave. What should the amplitude of the t wave be?

Select one of the following:

> 1/8 but < 2/3 the size of the preceding R-wave
Between 2 and 10 mm
< 1/2 the size of the preceding R-wave
Less than 8mm

	Created by No No about 10 years ago

What is and what isn't normal? (For PBL at the University of New England)

Basic interpretation of ECG

Question 1 of 15

Select one or more of the following:

Explanation

Question 2 of 15

Here is a textbook-perfect segment of an ECG. What's the flat line, without any deflections, called?

Select one of the following:

Explanation

Question 3 of 15

What is the first upward wave called?

Select one of the following:

Explanation

Question 4 of 15

Sometimes there is a downward deflection at this point. What is it called?

Select one of the following:

Explanation

Question 5 of 15

What is the combination called of a downward deflection, followed by an upward deflection, followed by another download inflection?

Select one of the following:

Explanation

Question 6 of 15

In the six steps to interpreting ECGs, the first is to determine the rate. The heart rate is determined by the number of squares or mm between two R waves. What are the TWO easiest ways to determine the rate?

Select one or more of the following:

Explanation

Question 7 of 15

What is the second step to interpreting the ECG?

Select one of the following:

Explanation

Question 8 of 15

The third step is interpreting the p wave, which indicates depolarisation of the atria. When considering the p wave, first determine if it is present. If it is present, what should a normal p wave look like?

Select one of the following:

Explanation

Question 9 of 15

The PR interval should be 3-5mm. What does it represent?

Select one of the following:

Explanation

Question 10 of 15

Select one of the following:

Explanation

Question 11 of 15

What should q waves look like?

Select one of the following:

Explanation

Question 12 of 15

Considering QRS complexes from from V1 to V6, two trends are apparent: the R-wave becomes progressively larger, and the S-wave becomes progressively smaller. This is called R wave progression. What is a lack of R wave progression usually an indication of?

Select one of the following:

Explanation

Question 13 of 15

Select one of the following:

Explanation

Question 14 of 15

Select one of the following:

Explanation

Question 15 of 15

For the sixth and final step, we need to consider the t wave. What should the amplitude of the t wave be?

Select one of the following:

Explanation