CVS - Antiarrhythmic drugs

Question 1

What do anti-arrhythmic drugs act on?

Answer 1

supraventricular arrhythmias (e.g. verapamil hydrochloride)
both supraventricular and ventricular arrhythmias (e.g. amiodarone hydrochloride)
ventricular arrhythmias (e.g. lidocaine hydrochloride)

Question 2

Non-pacemaker cells
(cardiomyoctes)

Answer 2

4 chambers
Contract and pump blood
AP 5 phases

Question 3

What are class 1 antiarrhythmic drugs?

Answer 3

1. Na channel blockers
2. dec. influx of Na into cardiac myocyte during phase 0 - slower depolarisation
3. dec. conduction of Ap thus wide QRS - slows heart rate

Question 4

MoA

Answer 4

inhibits the AP of Na and K ion channels in heart, raising threshold for depolarization

Question 5

Class II of antiarrhythmic drugs (“olol’s)

Answer 5

Propranolol is a non-selective β adrenergic antagonist used to treat supraventricular tachycardias: atrial fibrillation and atrial flutter

Question 6

Selective 𝜷𝟏 adrenergic blockers

Answer 6

Atenalol
Esmolol
Metropolol

Non-Selective 𝜷𝟏 adrenergic blockers
-Timolol
- Propranolol

Question 7

SA node depression

Answer 7

sinus bradycardia, heart block, and heart failure

Question 8

extracardiac side effects

Answer 8

include fatigue, sedation, sleep disturbance, sexual dysfunction, dyspnea, and bronchospasm

Question 9

describe the mechanisms of beta blockers:

Answer 9

1. BB compete w noradrenaline and adrenaline to bind to B1 adrenergic receptor
2. if BB boind > cAMP fails to activate PKA
3. PKA does not actiavte T-type calcium channels that allow an influx of Ca into cell
4. PKA does not activate SR release of Ca into cell
5. OPKA does not activate myosin phosphorylation which results in a stringer contraction of myocardial cells

Question 10

What is the results of BB?

Answer 10

• less strong heart muscle contraction
• lower BP

Question 11

Class II - propanalol

Answer 11

B blockers reduce the effect of catecholamines on heart

-ive ionotropic effect (red. contractility) and dec. O2 consumption

• dec. cellular exitability
• • ive chronotropic ffect
• prolonged diastole

Question 12

Class III - amiodarone

Answer 12

indicated for the treatment of recurrent hemodynamically unstable VT and recurrent VF

Question 13

what are effects of class III drugs - treatment of recurrent hemodynamically unstable VT and recurrent VF

Answer 13

Slower rate of repolarisation

Prolonged AP

Prolonged effective refractory period

Prolongs the QRS duration and QT interval

Question 14

Class IV antiarrhythmias : CCB Non-Dihydropyridine (Verapamil)

Answer 14

Selective for cardiac Calcium channels
Angina
Nodal arrhythmias
Supraventricular Tachycardia

Question 15

What are the unclassified anti-arrhythmia drugs?

Answer 15

• digoxin = for mild/moderate HF
• adenosine = rapid reversion of sinus rhythms of parazymal supraventricular tachycardias