Anti arrhytmics

Question 1

Afib tx

Answer 1

• Quinidine – Class IA anti arrhythmic
• Digoxin
• Flecainide – Class IC antiarrhythmic

Question 2

Quinidine: class

Answer 2

Class IA anti arrhythmic

Question 3

Most common use Quinidine

Answer 3

Afib: Most commonly used/effective for conversion to sinus rhythm

Question 4

Quinidine: route of administration

Answer 4

o Oral: nasogastric intubation only (risk of oral ulceration)
o IV: Quinidine gluconate → for acute Afib <2weeks duration

Question 5

Quinidine: actions

Answer 5

o Vagolytic
o ↑ fibrillation threshold of atrial myocardium
o ↑ concealed conduction in AV node
o ↑ effective refractory period
o α adrenergic antagonist
 ↓ vascular tone and mean BP
 Negative inotropic effect
 Positive chronotropic effect

Question 6

Quinidine: can be administered with

Answer 6

o Na+ bicarbonate can be administered IV to ↑ % of quinidine bound to proteins
 Binding to plasma proteins is pH dependent (↑ with ↑pH)
o Digoxin:
 Negative chronotropic and positive inotropic effects
 ↓AV nodal conduction and ventricular response rate
 ↑ Quinidine plasma levels: activated charcoal can be administered to prevent continued absorption of oral quinidine

Question 7

What can predispose to Torsade de pointes w/ quinidine

Answer 7

HypoK+
↑QT interval

Question 8

Quinidine: monitoring

Answer 8

o Narrow therapeutic range → [plasma] monitoring
 ↑ levels if used w digoxin

Question 9

Quinidine: toxicity

Answer 9

hypotension, cardiovascular collapse, depression, ataxia, weakness, colic, nasal mucosal congestion, convulsions, acute laminitis, sudden death

 ECG changes
* Widening/↑ amplitude of QRS
* ↑ ventricular rate
* T wave reversal

Question 10

Indications of digoxin for Afib Eq

Answer 10

• Can facilitate conversion to sinus rhythm
  o Indications: HR >60bpm, FS <25%
  o Often added to tx plan if Quinidine for 24h failed to convert
   Study: successful in converting 85% of Eq that failed converting w Quinidine alone

Question 11

Digoxin: actions

Answer 11

o ↑ vagal tone
o ↓AV nodal conduction and HR
o ↑ effective refractory period
o Positive inotrope

Question 12

Digoxin: toxicity eq

Answer 12

anorexia, nausea, salivation, diarrhea, colic, neurologic signs, rashes, depression

o ECG:
 Premature beats
 Excessive slowing of AV conduction → AVB
 AV dissociation
 Sinus bradycardia
 Sagging ST segments
 ↑PR interval
 ↑QRS duration

Question 13

Flecainide class

Answer 13

Class IC antiarrhythmic

Question 14

Flecainide use Eq

Answer 14

• Reported successful to convert Afib to sinus rhythm
• Toxicity ↓ compared to quinidine tx