End of Part 2 + part 3 arrhythmias

Question 1

ECG criteria for 3rd degree AV block

Answer 1

1. P waves with no QRS
2. Inconsistent PR intervals (AV dissociation)
3. Ventricular or Junctional escape beats
4. Low HR

Ventricular escape beat = wide QRS
Junctional escape beat = narrow QRS

Question 2

Main cause of Mobitz Type I 2nd degree AV block?

Answer 2

High vagal tone (PNS)

Question 3

Main cause of Mobitz Type II 2nd degree AV block?

Answer 3

• Structural heart disease of the AV node
  Ex: Hyperkalemia, myocarditis, fibrosis

Question 4

Main cause of 3rd degree AV block?

Answer 4

• Structural heart disease of the AV node
  Ex: Hyperkalemia, myocarditis, fibrosis

Question 5

ECG criteria for BBB (bundle branch blocks)?

Answer 5

• Wide QRS
• Every P has a QRS (sinus rhythm)

(Looks like AIVR and V-TACH, difference is these exhibit AV dissociation and BBB do not)

Question 6

Main cause of left sided BBB?

Answer 6

Cardiomyopathy / structural heart disease

Question 7

ECG criteria for Atrial standstill?

Answer 7

• No P waves at all (straight line before QRS)
• Normal QRS
• Usually bradycardia

Question 8

Causes of atrial standstill?

Answer 8

• Hyperkalemia (urinary obstruction, Addisons)
• Neuromyopathy in springer spaniels

Question 9

What breeds are predisposed to sick sinus syndrome?

Answer 9

• Mini schnauzer
• West highland terrier
• Dachshund
• Cocker spaniel

Question 10

What is Sick sinus syndrome?

Answer 10

Complex disturbance of impulse conduction resulting in sinus bradycardia and/or sinus arrest (prolonged sinus pause)

• SA node cells become fibrotic
• Can cause SVPCs or VPCs
• Can cause 1st or 2nd degree AV block

Question 11

Effects of hypokalemia?

Answer 11

• Prolongs repolarization
• Causes excitability due to K+ imbalance, resulting in ectopic complexes like SVPCs and VPCs

Question 12

Mild, Moderate, and Severe effects of hyperkalemia?

Answer 12

Mild: Shortened repol and Tented T waves (tall and pointy)

Mod: Wide QRS complexes (ventricles messed up)

Severe: Prolonged PR intervals or absent P waves, v-fib, death

Question 13

Hyperkalemia ___________ the time of repolarization, while hypokalemia _________ the time of repolarization

Answer 13

shortens, prolongs

Question 14

What arrhythmias can be seen with hypokalemia?

Answer 14

• Ectopic complexes like SVPCs and VPCs

Question 15

What electrolyte imbalance can result in atrial standstill?

Answer 15

Hyperkalemia

Question 16

What device records ECG continuously for 24-48 hours?

Answer 16

Holter monitor

Question 17

When is an arrhythmia considered hemodynamically significant?

Answer 17

If it results in low CO, low BP, and hypoperfusion

Question 18

4 indications for anti-arrhythmic therapy:

Answer 18

1. Hemodynamically significant
2. Causing CS
3. Potential to deteriorate into fatal arrhythmia (Ex: VPC or VT turning into V-fib)
4. Negatively impacting cardiac function

Question 19

List the drugs belonging to Class I anti-arrhythmics and their MOA

Answer 19

MOA: Na+ channel blocker

1. Lidocaine
2. Mexiletine (PO)
3. Procainamide
4. Quinidine

Question 20

List the drugs belonging to Class II anti-arrhythmics and their MOA

Answer 20

MOA: Beta blockers

1. Atenolol
2. Esmolol
3. Propanolol
4. Metoprolol

Question 21

List the drugs belonging to Class III anti-arrhythmics and their MOA

Answer 21

MOA: K+ channel blocker

1. Sotalol
2. Amiodarone

Question 22

List the drugs belonging to Class IV anti-arrhythmics and their MOA

Answer 22

MOA: Ca+ channel blocker

1. Diltiazem
2. Verapamil

Question 23

Effects of digoxin on the heart?

Answer 23

Increases vagal tone (PNS) in the SA and AV nodes

(Neg chronotropy, slows down HR)

Question 24

Treatment for sinus tachycardia?

Answer 24

• No antiarrhythmic therapy needed (physiological response, treat underlying cause)

Exception: ST due to toxicity/drugs - Use Esmolol (slows down HR)

Question 25

Drug treatment protocol for supraventricular tachycardia?

Answer 25

Goal: Slow down HR - **Diltiazem is first choice for SVT** - Second choices: Beta blockers, Digoxin, Sotalol

Question 26

________ is the first line DOC for treatment of supraventricular tachycardia

Answer 26

Diltiazem - Ca+ channel blocker, Class IV anti-arrhythmic

Question 27

Drug treatment protocol for atrial fibrillation?

Answer 27

Goal: control rate and rhythm Rate: - **Diltiazem is first choice for A fib**, slows down AV conduction - +/- Digoxin Rhythm: - Electrical cardioversion (defibrillation shock), restores AV synchrony

Question 28

Drug treatment protocol for SVPCs?

Answer 28

- Not necessary unless frequent or sustained bigeminy, in that case use **Diltiazem**

Question 29

When is anti-arrhythmic therapy for VPCs indicated?

Answer 29

- > 1000 single VPCs/24 hrs - Frequent or sustained ventricular bi or trigeminy OR - R or T phenomenon (T wave goes into QRS complex without finishing repol)

Question 30

Any frequency or duration of _________ warrants anti-arrhythmic treatment

Answer 30

Ventricular tachycardia

Question 31

Drug treatment protocol for V-tach?

Answer 31

**Lidocaine!!! - first choice** Second choices: Procainamide, amiodorone, magnesium If VT is not sustained and patient is not hemodynamically unstable start with **PO Mexiletine or Sotalol**

Question 32

Positive atropine response test

Answer 32

- Bradycardia turns into tachycardia, meaning bradyarrhythmia was due to high vagal tone

Question 34

Negatice atropine response test

Answer 34

- HR stays the same after inj - Bradyarrhythmia likely due to structural heart disease and not high vagal tone (Ex: SSS vs sinus bradycardia due to PNS)

Question 34

Which arrhythmias require a pacemaker?

Answer 34

1. High grade Mobitz type II 2nd degree AVB (Ps without QRSs) 2. 3rd degree AV block/ Complete AV block (Ps with no normal QRS, only escape beats) 3. Sick sinus syndrome (sinus bradycardia or sinus arrest) - only if symptomatic 4. Atrial standstill (must rule out hyperkalemia first)

Question 34

Drug treatment protocol for 1st, 2nd, and 3rd degree AV block

Answer 34

Only High grade Mobitz type II 2nd degree AVB and 3rd degree AV block require anti-arrhythmic therapy - Requires pacemaker, high risk of sudden death if not - Dopamine, dobutamine, atropine while waiting No tx needed, look for underlying cause of high vagal tone 1. 1st degree AVB 2. Mobitz type I 2nd degree AVB 3. Low grade Mobitz type II 2nd degree AVB

Question 35

True or False: Sick sinus syndrome is associated with high risk or sudden death

Answer 35

False

Question 36

What drugs can be given in an emergency setting while awaiting pacemaker implantation?

Answer 36

- Dopamine, dobutamine, isoproteronol (sympathomimetics)

Question 37

Sinus tachycardia vs supraventricular tachycardia?

Answer 37

Sinus tachycardia - every P has a QRS, normal rhythm, consistent RR intervals - Everything normal just high HR - Due to high sympathetic tone Supraventricular tachycardia - > 3 SVPCs - pre-mature QRS complexes close together - Regular irregular rhythm - Due to atrial dilation