Chapter 53 Arrhythmias

Question 1

When is vagal maneuver indicated and how do you do it?

Answer 1

Indicated when hemodynamic significant tachycardia. Carotid sinus massage or ocular pressure.

Question 2

When is atropine responsive test indicated and what dose is used?

Answer 2

Indicated when hemodynamic significant bradycardia. 0.04 mg/kg IV or IM.

Question 3

What are the differences in clinical signs that the owner notice at home between brady- and tacky arrhythmias.

Answer 3

There are no difference in clinical signs

Question 4

Why is a VPC wider than a normal sinus QRS on ECG?

Answer 4

Because myocyte-to-myocyte electrical transmission is more time-consuming than the normal rapid conduction through the ventricles’ His–Purkinje system.

Question 5

What is the ventricular escape rhythm (what rate)?

Answer 5

30-40beats/min

Question 6

What drugs are recommended for IV treatment for supraventricular tachycardia?

Answer 6

• Diltiazem

* Propranolol, esmolol

Question 7

What drugs are recommended for IV treatment for ventricular tachycardia?

Answer 7

• Lidocaine
• Magnesium
• Amiodarone (more used in human med)
• Sotalol (chronic treatment)
• Mexiletine

Question 8

What can be used instead of lidocaine in VTACH in cats?

Answer 8

Propranolol

Question 9

If a patient is symptomatic for bradycardia and responds to atropine test, what treatments could be initiated?

Answer 9

Terbutaline or theophylline (reduce vagal tone)

Question 10

If a patient is symptomatic for bradycardia and noes NOT responds to atropine test, what treatments could be initiated?

Answer 10

• Pacemaker

* Dobutamine or Isoproterenol can be used until pacemaker can be placed.

Question 11

Define ventricular tachycardia

Answer 11

Four or more VPCs consecutively at a rate of 160 beats/minute in dogs (240 beats/minute in cats) or greater

Question 12

Define accelerated idioventricular rhythm

Answer 12

Four or more VPCs occurring consecutively but where the rate is less than the defined rate for ventricular tachycardia (VT; 160 beats/minute) and faster than a ventricular escape rhythm (30–40 bpm)

Question 13

What are the the primary differentials for wide QRS morphology?

Answer 13

• Ventricular ectopic beat
• Aberrant conduction due to left or right bundle branch block
• Right axis deviation due to right ventricular enlargement or cardiac displacement
• Electrolyte abnormalities (i.e. hyperkalemia)

Question 14

Define re-entry

Answer 14

Reentry, due to a circuit within the myocardium, occurs when a propagating impulse fails to die out after normal activation of the heart and persists as a result of continuous activity around the circuit to re-excite the heart after the refractory period has ended

Question 15

How do anti-arrhythmics work to interrupt re-entry?

Answer 15

Antiarrhythmic drugs act by interrupting reentry either by prolonging the refractory period (class I and III) or by further impairing conduction (class I), converting an area of unidirectional block into an area of bidirectional block.