ECG problems Flashcards
which leg moved and how do you know
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
what is causing the baseline to go up and down
normal respiration
what is causing this baseline interference
muscle tremor (purring of cat)
artefact?
60 cycle electrical interference
what is the length of the P wave
0.08s
how many boxes are there in a minute in a 25 mm/sec
1500
how many boxes in a minute on a 50mm/sec ecg
3000
a long P wave is suggestive of what
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
whats the height of the P wave
0.5 mV
because 1 box = 0.5 cm and 1 cm = 1 mV
a tall P wave is suggestive of what
right atrial enlargement
if more tissue (enlargement) then there is more electircal activity (height measures electrical activity)`
P wave dimesions:
0.04s X 0.2 mV
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
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
what are the normal values for the P wave/PR interval/QRS complex/QT interval
“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).
A tall QRS complex is suggestive of what
right ventricular enlargement
a wide QRS complex is suggestive of what
left ventricular enlargement
HR?
115 bmp
HR?
250 bmp
sinus rhythm (p wave followed by QRS)
describe the rhythm and where does it originate from? what most likely attributes to the irregularity in the rhythm
regularly irregular
originated for SA node (has P wave)
- probably associated with respiratory activity
sinus arrythmia
is sinus arryhmia normal
in dogs yes
NOT IN CATS
what is the origin of this rhythm. is it a nomral ECG? what is the dysrhythmia called
the SA nodde (know because every QRS preceeded by P wave)
wide and bizzareq
- sinus arrythmia (b/c we see P waves)
in which part of the QRST complex would AV nodal disease manifest
- PQ interval
a long PQ interval is known asL
first degree AV block
intermittent failure of impulse transmission through the AV node is known as
second degree AV block
complete failure of impulse transmission through the AV node is known as:
third degree AV block
in third degree AV block transmission of electrical activity through the AV node fails and as a result:
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
AV node
the complex indicated by the arrow is premature. what is the origin of the complex
atrium
- premature but has a P wave
