Pgs 9-21

Question 1

What is the definition of a sinus complex?

Answer 1

When a sequence of beats originates from the SA node.

Question 2

What are the four common sinus rhythms?

Answer 2

Normal sinus rhythm, sinus arrhythmia, sinus tachycardia, sinus bradycardia

Question 3

What are ECG characteristics of normal sinus rhythm?

Answer 3

Normal P wave followed by normal QRS-T wave. The rhythm is regular (constant) and the rate is within normal for age and breed.

Question 4

What are the ECG characteristics of sinus arrhythmia (respiratory sinus arrhythmia)?

Answer 4

The rate varies (increases and decreases regularly. This is a normal and common rhythm that is associated with an increase in parasympathetic activity (vagal tone) on the SA node.

Question 5

A finding of normal sinus arrhythmia in a dog with a murmur make it more or less likely that the dog is in heart failure?

Answer 5

Less likely, since one of the compensatory responses in dogs with heart failure is an increase in sympathetic tone.

Question 6

What are the clinical findings with ALL sinus rhythms?

Answer 6

There is a pulse for every heart beat.

Question 7

How does one identify a ventricular ectopic complex?

Answer 7

First, identify the morphology of the normal QRS complex.
The QRS of a ventricular ectopic complex is different from the QRS complex of one that has arisen from the AV node.
Ventricular ectopic complexes are not associated with a preceding p wave (except by coincidence)

Question 8

What is the difference between a ventricular premature complex (VPC) and a ventricular escape complex?

Answer 8

A VPC occurs quickly (or early) and a ventricular escape complex occurs after a pause, or with delay.

Question 9

Which two categories can supraventricular ectopic complexes be divided?

Answer 9

Those occurring in atrial muscle mass (atrial ectopics) and those arising from within the AV node (junctional or nodal ectopics)

Question 10

How does one identify a supraventricular ectopic complex?

Answer 10

The morphology of the QRS complex is the same as a normal sinus complex and is primarily recognized by its premature timing.

Question 11

What are the five ways ectopic complexes can be classified?

Answer 11

1. Site of origin (ventricular vs supraventricular)
2. Timing (premature vs escape)
3. Morphology (uniform vs multiforme)
4. Number of ectopics (single, pairs, runs of three or more/tachycardia). A tachycardia may be continuous (persistent/sustained) or intermittent (paroxysmal)
5. Frequency - occasional to very fruquent. Bigeminy = one sinus complex: one ectopic complex. Trigeminy = one ectopic: 2 sinus complexes