Arrhythmias and ECGs

Question 1

What part of the ECG is missing with atrial fibrillation?

Answer 1

P waves

Question 2

What are the 3 types of AV block?

Answer 2

1st degree - slowing conduction
2nd degree - partial AV block
3rd degree - complete AV block

Question 3

What is seen on an ECG with 1st degree block?

Answer 3

Prolonged P-R interval

Slowing conduction

Question 4

What is seen on an ECG with 2nd degree block? (2 types)

Answer 4

P wave fails to generate QRS
Mobitz I (Wenckebach) - progressive lengthening of P-R until no QRST
Mobitz II - intermittently one or more non-conducted beat

Question 5

What is seen on an ECG with 3rd degree block?

Answer 5

Unrelated P and QRST complexes

Question 6

What is the treatment for 3rd degree AV block?

Answer 6

Pacemaker

Question 7

What is the normal MEA for a dog?

Answer 7

+40 to +100

Question 8

What is the normal MEA for a cat?

Answer 8

0 to +160

Question 9

Describe the method used to estimate MEA by looking at the biggest QRS

Answer 9

If it’s mainly above baseline, read +ve end
If it’s mainly below baseline, read -ve end
MEA is within 30 degrees of this

Question 10

Describe the method used to estimate MEA by looking at the isoelectric lead

Answer 10

Find the isoelectric lead and read 90 degrees to this

If it’s mainly above the baseline, read the positive end

Question 11

Describe the method used to estimate MEA by the quadrant graphing method

Answer 11

Use leads I and AVF to divide Bailey’s hexaxial diagram into quadrants
See if these leads are positive or negative
The MEA will be within this quadrant (larger lead = close r to this)

Question 12

Is sinus arrhythmia normal in cats and dogs?

Answer 12

Yes in dogs - due to high vagal tone

Not in cats

Question 13

Sinus arrhythmia in cats may indicate what type of disease?

Answer 13

Respiratory disease

E.g. feline asthma

Question 14

A period of sinus arrest up to how long is normal in sleeping dogs?

Answer 14

Up to 5 seconds

Question 15

What breed is prone to sick sinus syndrome and how can this be treated?

Answer 15

Westies

Pacemaker implantation

Question 16

Give examples of conditions that cause secondary VPCs

Answer 16

GDV
Pyometra
Pancreatitis
Splenic lesions
CNS lesions
Sepsis
Myocardial contusions - trauma

Question 17

What is the treatment for ventricular tachycardia?

Answer 17

IV lidocaine
(prevent ventricular fibrillation as leads to death)

Question 18

Which breed of dog has a heart more like a horse, that can be associated with DCM and atrial fibrillation?

Answer 18

Irish Wolfhounds

Question 19

Give examples of primary and secondary causes of VPC

Answer 19

Primary - arrhythmia (but require Holter to investigate further)
Secondary - GDV, pyo, pancreatitis, sepsis etc

Question 20

Does atrial fibrillation have a wobbly baseline on ECGs?

Answer 20

Not in cats and dogs (baseline abnormalities due to artefact)
Yes in horses!