/
AI Flashcards
Save to my account
Sign up
AI Flashcards
Vaughan Williams Antiarrhythmic Drugs
Study
1
Question
What is the basis of the Vaughan Williams classification of antiarrhythmic drugs proposed in 1970?
Page 58
Answer
The classification is based on the electrophysiological effects of drugs on cardiac ion channels and receptors.
2
Question
Which drug examples are listed for Class Ia antiarrhythmic agents?
Page 58
Answer
Quinidine, Disopyramide, and Procainamide are listed as examples of Class Ia agents.
3
Question
What is the membrane-level mechanism of action for Class Ia antiarrhythmic drugs?
Page 58
Answer
Class Ia drugs block Na+ channels with intermediate dissociation kinetics (Na+ channel block, intermediate dissociation).
4
Question
Which drugs are given as examples of Class Ib antiarrhythmic agents in the table?
Page 58
Answer
Lidocaine and Mexiletine are given as examples of Class Ib antiarrhythmic agents.
5
Question
What dissociation characteristic defines Class Ib Na+ channel blockers?
Page 58
Answer
Class Ib drugs exhibit fast dissociation from the Na+ channel (Na+ channel block with fast dissociation).
6
Question
Which Class I antiarrhythmic drug is listed under Class Ic in the table?
Page 58
Answer
Propafenone is listed as an example of a Class Ic antiarrhythmic drug.
7
Question
How are Class Ic Na+ channel blockers characterized by their dissociation kinetics?
Page 58
Answer
Class Ic Na+ channel blockers have slow dissociation kinetics from the Na+ channel (slow dissociation).
8
Question
What is the principal mechanism of action for Class II antiarrhythmic drugs?
Page 58
Answer
Class II drugs act by β-adrenoceptor antagonism (beta-adrenoceptor antagonism).
9
Question
Which drug is provided as an example of a Class II antiarrhythmic agent in the table?
Page 58
Answer
Propranolol is provided as an example of a Class II antiarrhythmic agent.
10
Question
What is the main electrophysiological action of Class III antiarrhythmic drugs?
Page 58
Answer
Class III drugs block K+ channels, thereby affecting repolarization.
11
Question
Which drugs are listed as examples of Class III antiarrhythmic agents?
Page 58
Answer
Amiodarone and Sotalol are listed as examples of Class III antiarrhythmic agents.
12
Question
What is the electrophysiological mechanism assigned to Class IV antiarrhythmic drugs?
Page 58
Answer
Class IV drugs act by blocking calcium channels (calcium channel block).
13
Question
Which drug is listed as an example of a Class IV antiarrhythmic agent?
Page 58
Answer
Verapamil is listed as an example of a Class IV antiarrhythmic agent.
14
Question
What descriptive label is used in the notes for Class I antiarrhythmics?
Page 59
Answer
Class I agents are described as 'membrane stabilizers' that block Na+ channels and inhibit action potential propagation.
15
Question
How do Class I drugs affect the maximum rate of depolarization during phase 0?
Page 59
Answer
They reduce the maximum rate of depolarization in phase 0 by blocking Na+ channels.
16
Question
What does the term 'use-dependent channel block' mean as described for Class I agents?
Page 59
Answer
Use-dependent channel block means the more frequently Na+ channels are activated, the greater the degree of drug-induced block produced.
17
Question
Why are Class I drugs especially effective at blocking high-frequency excitation of the myocardium?
Page 59
Answer
Because they exhibit use-dependent block and preferentially bind to open or refractory channels, increasing block during high-frequency activation.
18
Question
To which channel states do Class I drugs bind most strongly according to the notes?
Page 59
Answer
They bind most strongly to channels in the open or refractory state and less strongly to channels in the resting state.
19
Question
What electrophysiological effects are produced by Class Ia drugs on action potentials?
Page 60
Answer
Class Ia drugs prolong the action potential, slow the rapid upstroke during phase 0, slow conduction velocity, and increase refractoriness.
20
Question
Which additional pharmacologic activities are noted for some Class Ia drugs?
Page 60
Answer
Some Class Ia drugs have mild α-adrenergic blocking and anticholinergic actions.
21
Question
Which Class Ia agent is noted as producing the most pronounced additional autonomic actions?
Page 60
Answer
Quinidine is noted as producing the most pronounced mild α-adrenergic blocking and anticholinergic actions.
22
Question
What clinical indications are listed for the use of Class Ia antiarrhythmic drugs?
Page 60
Answer
Indications include atrial, AV junctional, and ventricular tachyarrhythmias.
23
Question
How is Procainamide administration noted in the slides for acute use?
Page 60
Answer
Procainamide is noted for i.v. (intravenous) administration.
24
Question
What important negative cardiac effect is associated with Disopyramide according to the notes?
Page 60
Answer
Disopyramide produces a negative inotropic effect (decreased myocardial contractility).
25
Question
What plant is identified as the source of quinidine in the slides?
Page 61
Answer
Cinchona succirubra is identified as the plant source of quinidine.
26
Question
What cluster of symptoms is described as 'cinchonism' from large doses of quinidine?
Page 61
Answer
Cinchonism includes blurred vision, tinnitus, headache, disorientation, and psychosis.
27
Question
What adverse effect can intravenous Procainamide cause according to the slides?
Page 61
Answer
Intravenous administration of Procainamide may cause hypotension.
28
Question
Which general cardiac adverse effects are listed on the slide with Quinidine and Procainamide?
Page 61
Answer
Bradycardia and AV block are listed as cardiac adverse effects.
29
Question
For what ventricular conditions are Class Ib agents indicated according to the notes?
Page 62
Answer
Class Ib agents are indicated for ventricular fibrillation, ventricular tachycardia, and in the context of myocardial infarction.
30
Question
Which drugs are cited as examples of Class Ib antiarrhythmic agents on the slide?
Page 62
Answer
Lidocaine and Mexiletine are cited as examples of Class Ib antiarrhythmic agents.