9. Interpret the electrocardiograms of the horse

Question 1

What is ECG?

Answer 1

Electrocardiography

Question 2

When can we use ECG?

Answer 2

Rest and during natural work

Question 3

Name the different waves in a ECG:

Answer 3

P wave
QRS complex
T wave

Question 4

What is the P-wave?

Answer 4

Atrial depolarization.

The two atriums are contracting.

Question 5

What is the QRS-complex?

Answer 5

Ventricular depolarization.

Ventricles of the heart are contracting

Question 6

What is the T-wave?

Answer 6

Ventricular repolarisation.

Ventricles are relaxing

Question 7

Where is then atrial repolarisation?

Answer 7

It takes place within the QRS complex, taking place after the P-wave.

Question 8

Name segments and intervals of the ECG:

Answer 8

1. PR-interval
2. PR-segment
3. QRS-segment
4. ST-segment
5. QT-interval

Question 9

Answer 9

1. P-wave
2. Q-wave
3. R-wave
4. S-wave
5. T-wave

Question 10

Answer 10

Red = PR interval
Blue = PR segment
Green = QRS complex
Purple = ST segment
Pink = QT interval

Question 11

What is this?

Answer 11

An ECG chart.
The small blue squares = 0.04 seconds.
So in a big square, there are 5 = 0.20 seconds

Question 12

There are 6-steps to interpret an ECG:

Answer 12

1. Identify and examine P wave
2. Measure PR interval
3. Measure QRS complex
4. Identify rhythm
5. Determine the heart rate
6. Interpret strip

Question 13

Identify and examine P wave:

Answer 13

Normal P wave = Present and upright.

Question 14

PR interval

Answer 14

Beginning of P-wave to beginning of QRS-complex.

We count the small boxes between them and multiply with 0.04 seconds

Question 15

QRS complex

Answer 15

From Q wave - S-wave

We count the squares between them and multiply with 0.04 seconds.

Question 16

Identify the rythm

Answer 16

Can be regular or irregular.

We measure the distance between the R waves.
Same distance = Regular

Question 17

Name common irregular heart rythms:

Answer 17

1. Atrial premature complex/ depolarization
2. Atrial fibrilation
3. 1st and 2nd degree atrioventricular block
4. 3rd degree (complete) atrioventricular block
5. Ventricular premature complex/ depolarisation
6. Ventricular tachycardia (uniform)
7. Ventricular tachycardia (multiform)

Question 18

Atrial premature complex/ depolarization

Answer 18

1. Very visible clinical signs and exercise intolerance
2. All waves are visible
3. The P-wave is coming too early in 3rd cycle compared to previous
4. No ventricular depolarization

Question 19

Atrial fibrillation

Answer 19

1. Most common arrythmia
2. QRS complex are easy to locate
3. Large T-wave
4. Lack of P-wave - abnormal contractions of atrium

Question 20

1st and 2nd degree atrioventricular block

Answer 20

1. All 1st degree = physiological
2. Slows down the heart rate
3. Identify normal waves and cycles
4. 1st P-wave is not followed by QRS complex in normal time, longer duration of conduction.

Question 21

3rd degree (complete) atrioventricular block

Answer 21

1. Extreme level of exercise intolerance
2. We can identify seven P-waves but only three QRS-complexes = atrial und ventricular rate is completely different.
3. abnormal circulation of blood in the body
4. Treatment: peacemaker implantation possible in horses

Question 22

Ventricular premature complex/ depolarisation

Answer 22

1. Lack of P-waves
2. QRS-complex is normal
3. Every second cycle is abnormal

Question 23

Ventricular tachycardia (uniform)

Answer 23

1. Resting ECG, heart rate = 140-150 bpm
2. No p-waves

Question 24

Ventricular tachycardia (multiform)

Answer 24

1. Much worse than uniform
2. Can lead to ventricular fibrillation
3. Immediate treatment