ECG problems

Question 1

which leg moved and how do you know

Answer 1

lead 1 is attached to RF and LF
Lead 2 is attached to RF/LH
Lead 3 is attached to LF and LH

both lead 2 and 3 show a movement artefact, indicating there was an issue with one of the limbs attached to either of those leads. leads 2 and 3 share the left hind limb so therefore it was likely the left hind that moved

Question 2

what is causing the baseline to go up and down

Answer 2

normal respiration

Question 3

what is causing this baseline interference

Answer 3

muscle tremor (purring of cat)

Question 4

artefact?

Answer 4

60 cycle electrical interference

Question 5

what is the length of the P wave

Answer 5

0.08s

Question 6

how many boxes are there in a minute in a 25 mm/sec

Answer 6

1500

Question 7

how many boxes in a minute on a 50mm/sec ecg

Answer 7

3000

Question 8

a long P wave is suggestive of what

Answer 8

left atrial enlargement
P wave = depolarisation of atria
SA node in RA so if LA gets big it means it takes longer to signal LA

Question 9

whats the height of the P wave

Answer 9

0.5 mV
because 1 box = 0.5 cm and 1 cm = 1 mV

Question 10

a tall P wave is suggestive of what

Answer 10

right atrial enlargement
if more tissue (enlargement) then there is more electircal activity (height measures electrical activity)`

Question 11

P wave dimesions:

Answer 11

0.04s X 0.2 mV

Question 12

For a paper speed of 25mm/sec (2.5 cm/sec)
There are 1,500 small (1mm) boxes/minute
1,500 divided by the number of small boxes between complexes = HR/min
1 box = 0.04 sec

Question 13

For a paper speed of 50 mm/sec (5cm /sec)
There are 3,000 small (1mm) boxes/minute
3,000 divided by the number of small boxes between complexes = HR/min
1 box = 0.02 sec

Question 14

what are the normal values for the P wave/PR interval/QRS complex/QT interval

Answer 14

“NORMAL” VALUES.

P WAVE: upto 0.4 mV X upto 0.04secs in the dog.
upto 0.2 mV X upto 0.04secs in the cat.

PR INTERVAL: 0.06-0.13 secs in the dog.
0.05-0.09 secs in the cat.

QRS COMPLEX: upto 2.5 mV X upto 0.05 secs in small dogs.
upto 3.0 mV X upto 0.06 secs in large dogs.
upto 0.9 mV X upto 0.04 secs in cats.

QT INTERVAL: 0.14-0.25 secs in the dog.
upto 0.16 secs in the cat.
Varies with heart rate (usually approx half preceding RR interval).

Question 15

A tall QRS complex is suggestive of what

Answer 15

right ventricular enlargement

Question 16

a wide QRS complex is suggestive of what

Answer 16

left ventricular enlargement

Question 17

HR?

Answer 17

115 bmp

Question 18

HR?

Answer 18

250 bmp
sinus rhythm (p wave followed by QRS)

Question 19

describe the rhythm and where does it originate from? what most likely attributes to the irregularity in the rhythm

Answer 19

regularly irregular
originated for SA node (has P wave)
- probably associated with respiratory activity

sinus arrythmia

Question 20

is sinus arryhmia normal

Answer 20

in dogs yes
NOT IN CATS

Question 21

what is the origin of this rhythm. is it a nomral ECG? what is the dysrhythmia called

Answer 21

the SA nodde (know because every QRS preceeded by P wave)
wide and bizzareq
- sinus arrythmia (b/c we see P waves)

Question 22

in which part of the QRST complex would AV nodal disease manifest

Answer 22

• PQ interval

Question 23

a long PQ interval is known asL

Answer 23

first degree AV block

Question 24

intermittent failure of impulse transmission through the AV node is known as

Answer 24

second degree AV block

Question 25

complete failure of impulse transmission through the AV node is known as:

Answer 25

third degree AV block

Question 26

in third degree AV block transmission of electrical activity through the AV node fails and as a result:

Answer 26

a rhythm is generated from the ventricles that is slower than normal
- SA node cells spontaneously depolarize quickly (so do other cells in heart but SA node cells depolarize quicker than other cells so their early deoplarisation keeps the pace)
- ventricles are being drien by a pacemaker slower than normal because cells in the AV node depolarize slower but are normlally depolarised mechanically by SA node

Question 27

Answer 27

AV node

Question 28

the complex indicated by the arrow is premature. what is the origin of the complex

Answer 28

atrium
- premature but has a P wave