Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Cardiology > Antiarrhythmic Drugs: Vaughan-Williams System > Flashcards

Antiarrhythmic Drugs: Vaughan-Williams System Flashcards

1
Q

Define Automaticity.

A

Ability of the heart to intrinsically generate rhythmic action potential in absence of external stimuli.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

List THREE Class IA drugs

A

Quinidine (prototype)

Procainamide

Disopyramide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

List THREE Class IB drugs

A

Lidocaine (prototype)

Mexiletine

Tocainide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

List TWO Class IC drugs

A

Flecainide

Propafenone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Main effect of Class I drugs

A

Reduces the CONDUCTION VELOCITY = Negative Dromotropic Effects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Effects of Class IA drugs

A

Moderately blocks fast Na channels

⬇️ Conduction velocity

⬇️ Vmax (peak of phase 0)

Prolong APD and ERP

⬇️ Slope of phase 4 spontaneous depolarisation (SA node) = ⬇️ Enhanced normal automaticity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name FIVE external factors that can significantly modify the SA node pacemaker activity.

A

Autonomic nerves

Hormones

Drugs

Ions

Ischaemia/hypoxia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

State THREE Usage of anti-arrhythmic drugs.

A

Decrease conduction velocity.

Suppress abnormal automaticity.

Change the duration of the ERP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Name two special properties of Quinidine.

A

Alpha-adrenergic blocking activity

Anticholinergic action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Clinical application of Quinidine.

A

A variety of arrhythmias:

Atrial

AV junctional

Ventricle

However, it is rarely used for supraventricular arrhythmias.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Name 4 possible unwanted effects of Quinidine.

A

Ventricular tachycardia.

Torsades de pointes.

AV Block.

Increases Digoxin Concentration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which symptoms may large doses of Quinidine induce.

A

Cinchonism

  • Blurred vision
  • Tinnitus
  • Headache
  • Disorientation
  • Psychosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Activity of Procainamide.

A

Alpha-blocker.

Mild anticholinergic effect.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What formulation is Procainamide available as?

A

I.V formulations only.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the duration of action of Procainamide?

A

2 to 3 hours.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

State Two therapeutic usage of Procainamide.

A
  • Haemodynamically stable ventricular tachycardia.

- Acute conversion of atria fibrillation including Wolff-Parkinson-White syndrome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

State 3 possible side effects of Procainamide.

A
  • Hypotension
  • Venticular arrhythmia
  • Hypersentivity = Agranulocytosis and Fever
    (Lupus-like syndrome in 25 - 30 % of patients)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which medications can be prescribed to treat REFRACTORY VENTRICULAR TACHYCARDIA.

A

Oral quinidine or Procainamide with Class III drugs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Name Four effects of Disopyramide.

A
  • No alpha blocking activity.
  • Strong anticholinergic activity.
  • Negative inotropic effect.
  • Peripheral vasoconstriction.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

State Three Uses of Disopyramide.

A
  • Important = decrease in myocardial contractility in patients with systolic heart failure.
  • Ventricular arrhythmias.
  • Maintenance of sinus rhythm in patients with atrial flutter or fibrillation.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

State a contraindication of Disopyramide.

A

Patients with uncompensated heart failure due to its negative inotropic activity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Effects of Class IB.

A

Weakly blocks fast Na channels in abnormal tissue.

Increases outflow of K+ and so shift phase 3 to the left

⬇️ ERP

⬇️ AP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does class IB drug not have an effect on?

A

NO effect on conduction velocity = NO effect on AV node = No effect on SUPRAVENTRICULAR ARRHYTHMIA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Clinical use of lidocaine.

A

Ventricular arrhythmias arising from myocardial ischaemia or from digoxin intoxication.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Clinical use of Mexiletine.
Chronic treatment of ventricular arrhythmias, often in combination with Amiodarone.
26
Formulation of Lidocaine.
IV due to extensive first-pass metabolism.
27
Possible side effects of Lidocaine.
Nystagmus (early indicator of toxicity) Drowsiness Slurred speech Paresthesia Agitation Confusion Convulsion **** Can cause Pulmonary Fibrosis ****
28
Possible side effects of Mexiletine.
Nausea Vomiting Dyspepsia
29
Effects of Class IC on cardiac electrical activity.
Strongly inhibits fast Na channels = slow down conduction velocity. Minor effects on AP and ERP. Reduce automaticity by increasing the threshold potential instead of decreasing the slope phase 4 spontaneous depolarisation.
30
In which risk group of patients can class IC compounds trigger sudden death.
A patient with prior history of myocardial infarction. Sustained Ventricular Arrhythmias.
31
State THREE effects of Flecainide
Blocks Na channels. Blocks K channels. Negative inotropic effect.
32
What can Flecainide aggravate?
Chronic heart failure.
33
Name two therapeutic usage of Flecainide.
Maintenance of sinus rhythm in atrial flutter or fibrillation in patients without structural heart disease. Treating refractory ventricular arrhythmias.
34
Name four structural heart diseases.
Left ventricular hypertrophy. Heart failure. Atherosclerosis. Heart disease.
35
Possible side effects of Flecainide.
Blurred vision Dizziness Nausea However it is generally well tolerated.
36
Electrical activity of Propafenone.
Blocks Na channels. Does not block K channels.
37
State THREE Therapeutic Usage of Propafenone.
Its use is restricted mainly to atrial arrhythmias: - Rhythm control of atrial fibrillation or flutter. - Wolff-Parkinson-White Syndrome. - Paroxysmal supraventricular tachycardia prophylaxis in patients with AV re-entrant tachycardias. (taking advantage of its beta blocking action)
38
Possible side effects of Propafenone.
Blurred vision Dizziness Nausea Bronchospasm due to it beta-blocking effects. (Therefore should be avoided in asthma) Beta blocking effects and Ca channel blocking effects can worsen heart failure.
39
Effect of Class II drugs on electrical activity of the heart.
- Reduce phase 4 and phase 0 in the AV and SA nodes. | - Prolongs repolarisation in the AV node.
40
State the FIVE Cardiac effects of Class II drugs.
Negative Inotropy (⬇️ contractility) Negative Chronotropy (⬇️ heart rate) Negative Dromotropy (⬇️ conduction velocity) Negative lusitropy (⬇️ relaxation rate) Negative Bathmotropy (⬇️ automaticity of ectopic focus)
41
Use of beta-blockers in treating arrhythmia.
- Sympathetic activity induced arrhythmia (Exercise or Stress-induced) - AV nodal tachycardia - Prophylaxis of ventricular arrhythmias - AF and flutter - Reduce mortality in post MI patients - Protection against sudden cardiac death
42
Prescribe one non-selective and two selective beta-blockers that can be used to treat arrhythmias.
- Propranolol (non-selective) - Metoprolol (selective) ⬇️ Bronchospasm risk - Esmolol (selective): i.v. for acute arrhythmia during surgery or emergency.
43
State Five Therapeutic Use of beta-blockers.
Hypertension Angina Myocardial Infarction Arrhythmias Heart failure
44
State the possible reasons why chronic treatment with beta-blockers lowers arterial pressure more than acute treatment.
- Reduced renin release (partly regulated by beta 1 receptors in the kidney). - Beta-blockade on CNS and PNS.
45
Prescribe two types of medications that must be used in conjunction to treat pheochromocytoma-induced hypertension.
First an alpha-channel blocker, such as phenoxybenxamine. Second a beta-blocker. ***beta-blocker can only be administered after adequate blockade of vascular alpha receptors has been established to mitigate against hypertensive crisis***
46
How does beta-blockers reduce mortality in post MI patients?
- Improve oxygen supply/ demand ratio. - Reduce arrhythmias. - Inhibit cardiac remodelling.
47
State Three Contraindications of beta-blockers usage.
- Patient with Sinus Bradycardia. - Patients with partial AV block. - Non-selective are contraindicated in patients with asthma and COPD.
48
State two important considerations when administering beta-blockers.
- Combination with cardiac selective calcium-channel blockers (e.g. Verapamil) because of their additive effects in producing electrical and mechanical depression. - Beta-blockers can mask the tachycardia that serves as a warning sign for insulin-induced hypoglycaemia in diabetic patients.
49
Activity of Class III drugs in the Vaughan-Williams classification.
- Binds K channels that are responsible for phase 3 repolarisation. - ⬆️ AP - ⬆️ ERP - ⬆️ Q-T Interval
50
Half life of Amiodarone.
60 days.
51
Properties of Amiodarone.
Class I Class II = weak beta-blocker Class III Class IV (thus decreases phase 4 slope and conduction velocity)
52
Therapeutic indications for Amiodarone.
Ventricular tachycardia (including ventricular fibrillation). Atrial fibrillation and flutter (off-label use).
53
Possible side effects of Amiodarone.
- Pulmonary fibrosis (2-5%) - Blue-grey skin discolouration - GI disturbance - Neuropathy - Hepatotoxicity - Corneal micro-deposits - Hypo- or hyperthyroidism
54
Which is the least pro-arrhythmic drug of all class I and III?
Amiodarone
55
What distinguishes Class II drugs from the rest?
It has no pro-arrhythmic effects.
56
Difference between Dronedarone and Amiodarone.
Dronedarone is a non-iodinated congener of amiodarone.
57
Half-life of Dronedarone.
25-30 hours.
58
Therapeutic indications of Dronedarone.
Non-permanent atrial fibrillation. Atrial flutter.
59
Contraindication of Dronedarone.
Severe or recently decompensated, symptomatic heart failure.
60
When can Dronedarone be prescribed ?
Patients with sinus rhythm with a history of non-permanent atrial fibrillation. Due to: Increased risk for severe liver injury and serious cardiovascular adverse events in patients with permanent atrial fibrillation.
61
Describe the racemix mixture of Sotalol.
D-isomer = Class III L-isomer = Class III and beta-blocker
62
Therapeutic indications for Sotalol.
Atrial fibrillation and Atrial flutter.
63
State a known caution when employing the use of Sotalol.
Suppression of phase 4 depolarisation and possibly produces severe sinus bradycardia (beta-blockade action).
64
Therapeutic indications of Ibutilide.
Atrial fibrillation and Atrial flutter.
65
Route of administration of Ibutilide.
I.V. bolus due to extensive first pass metabolism.
66
Which out of the class III drugs has pure K+ blockade?
Ibutilide
67
Main caution during the use of class III drugs.
They prolong QT interval and induce torsades de pointes VT which can lead to SUDDEN CARDIAC DEATH. Treated by Magnesium Sulfate (i.v.)
68
Activity of Vaughan-Williams Class IV Drugs: Calcium Channel Blockers.
Binds to L-type calcium channels located on the: - Vascular smooth muscle - Cardiac myocytes - Cardiac nodal tissue (SA and AV nodes)
69
Calcium channel blockers cardiac effects.
- Negative Inotropy: Decrease contractility - Negative Chronotropy: Decrease heart rate - Negative Dromotropy: Decrease Conduction Velocity
70
Calcium channel blockers vascular effects.
Smooth-muscle relaxation (Vasodilation).
71
Therapeutic Indicators of Calcium-Channel Blockers.
- Hypertension (systemic and pulmonary) - Angina - Arrhythmias
72
Anti-arrhythmic effects of calcium-channel blockers.
- Slows phase 0 and phase 4 depolarisation (particularly in the AV node) - Prolongs repolarisation - Slows the conductance in Ca++ dependent tissue like AV node
73
Prescribe two Class IV drugs that can be used to combat arrhythmias.
- Verapamil (Phenylakylamine Class) | - Diltiazem (Benzothiazepine Class)
74
Therapeutic indications of class IV drugs.
Supraventricular tachycardia - By prolonging the ERP of the AV node and thus preventing arrhythmias.
75
Contraindications of non-dihydropyridine calcium channel blockers.
- Excessive bradycardia. - Impaired electrical conduction (e.g. AV block). - Depressed contractility.
76
Adverse drug reactions of non-dihydropyridine calcium channel blockers.
- Bradycardia - AV block - Gum hyperplasia - Constipation (mainly verapamil)
77
You should never combine non-hydropyridine drugs with?
- Beta-blockers | - Digoxin
78
State the main distinguishing factor between dihydropyridines and non-dihydropyridines.
- Dihydropyridines are highly selective to smooth muscle. - Relative selectivity towards vascular L-type calcium channels. - They are used to reduce systemic vascular resistance and arterial pressure, and therefore are used to treat hypertension. - Non-dihydropyridine have a relative selectivity towards cardiac L-type calcium channels.
79
Benefits of Diltiazem.
- It is intermediate between verapamil and dihydropyridines in its selectivity for cardiac and vascular calcium channels. - By having both cardiac depressant and vasodilator actions, it is able to reduce arterial pressure without producing the same degree of reflex cardiac stimulation caused by dihydropyridines.
80
Side effects of dihydropyridine calcium channel blockers.
- Flushing - Headache - Excessive hypotension - Oedema - Reflex Tachycardia
81
Which two dihydropyridine drugs would you prescribe for treating hypertension?
Long-acting dihydropyridines: - Amlodipine - Nifedipine They have shown to be the “safer” anti-hypertensive drugs, in part, because of reduced reflex responses.

Cardiology (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions