antiarrhythmia drugs 2

Question 1

direct results of block of L-type Ca2+ channels are?

Answer 1

1. Slowed upstroke

2. reduced AP amplitude

Question 2

What results indirectly from L channel block?

Answer 2

Slowed repolarization (phase 3)

Question 3

In SA and AV node, adenosine (via A1 adenosine receptor) works to?

Answer 3

1. ↑ K+ current
2. ↓ L-type Ca2+ current (dihydropyridine-sensitive, slow inward current)
3. ↓ If in SA and AV nodes

Question 4

adenosine action

Answer 4

similar to β-adrenergic receptor blockers, but adenosine is not a β-blocker.

Question 5

Adenosine-induced changes in membrane currents:

Answer 5

↓ SA node and AV node firing rate

↓ conduction rate in the AV node

Question 6

Antiarrhythmic drugs are primary therapy for

Answer 6

1. atrial fibrillation only

2. Ablation or ICD equal or superior in management of all other arrhythmias

Question 7

PSVT: tx acute with

Answer 7

adenosine (short half-life is advantageous)

Question 8

PSVT: tx chronic with

Answer 8

1. AV nodal blockers
2. Class II (β-blockers)
3. Class IV (Ca2+ channel blockers)
4. Class III (amiodarone, sotalol)
5. catheter ablation of ectopic focus

Question 9

Ventricular tachycardias/fibrillation pathophysiology via

Answer 9

afterdepolarizations + re-entry

Question 10

Ventricular tachycardias/fibrillation: treat acute with

Answer 10

1. amiodarone

2. lidocaine

Question 11

esmolol metabolize by

Answer 11

blood esterase

Question 12

amiodarone side effects

Answer 12

1. heart block
2. thyroid dysfunction
3. corneal deposits
4. pulmonary fibrosis

Question 13

Drug prevention of sudden cardiac death:

Proven benefit

Answer 13

1. β-blockers
2. angiotensin converting enzyme (ACE) inhibitors
3. aspirin
4. statins

Question 14

Drug prevention of sudden cardiac death:

perhaps benefit

Answer 14

1. amiodarone

2. digoxin

Question 15

Drug prevention of sudden cardiac death:

perhaps harmful

Answer 15

1. Class I drugs (Na+ channel blockers)

2. Class IV drugs (Ca2+ channel blockers)

Question 16

Procainamide major side effect

Answer 16

1. Lupus syndrome (occurs in 1/3 of patients on long-term therapy).
2. class Ia

Question 17

Lidocaine major side effects

Answer 17

1. Least cardiotoxic agent of Class I drugs.
2. Side effects: paresthesia, tremors, seizures, agitation, confusion.
3. class Ib

Question 18

Flecainide and Propafenone Major side effects

Answer 18

1. Highly pro-arrhythmic, particularly with ventricular tachycardia.
2. class Ic

Question 19

B-blocker major side effects

Answer 19

1. Hypotension
2. aggravation of heart failure
3. bronchospasm
4. impotence.

Question 20

amiodarone major side effects

Answer 20

1. Cardiac problems include bradycardia and heart block.
2. Dose-related effects include:
   a. thyroid dysfunction,
   b. corneal deposits,
   c. pulmonary fibrosis and
   d. skin discoloration.
3. Problems with side effects are exacerbated by the very long half-life of amiodarone (13-100 days).
4. Class 3

Question 21

sotalol major side effects

Answer 21

1. Structurally, this drug is a β-adrenergic receptor ligand.
2. Principal side effects are similar to those of the other β-blockers.
3. class 3

Question 22

verapamil major side effects

Answer 22

1. The major adverse effect of these drugs is hypotension
   (via action on vascular smooth muscle.)
2. Negative cardiac inotropy
3. class 4

Question 23

what explains adenosine’s side effects?

Answer 23

Adenosine action on coronary circulation