Class IA, IB and IC drugs act upon which ion pathway during AP formation?
Sodium ion channel.
Drugs of this classification are referred to as Sodium Channel Blockers.
Do class I drugs prolong or shorten the ventricular action potential?
Class I drugs prolong the ventricular action potential.
True / False
A prolonged ventricular action potential will result in prolonged AA / VV intervals.
False - It will result in shorter AA / VV intervals.
Resultantly there is less chance for re-entrant tachycardia provocation.
Class II drugs are referred to as _______ Blockers.
Beta Blockers.
Class III drugs act upon which ion pathway during action potential formation?
Potassium ion pathway.
Referred to as Potassium channel blockers.
Class IV drugs act upon which ion pathway during action potential formation?
Calcium ion pathway.
Referred to as Calcium channel blockers.
List the names of two Class V drugs and which ion pathway do they act upon during AP formation?
Adenosine and Digoxin
Mechanisms of these two drugs are not well described.
The following statement best describes which classification of drug?
‘Blocks beta-adrenergic binding sites in cardiac and vascular cell membranes’.
Class II Beta Blockers.
This mechanism moderates the effects of sympathetic activity.
List 5 cardiac outcomes with respect to Class II beta blockade.
- Decreased Inotropy (contractility)
- Dromotropy (conduction velocity)
- Reduced BP
- Moderated SA node automaticity
- Reduced ectopy
List two common examples of Class II Beta Blockers.
- Propanolol
- Metoprolol
The following statement best describes which classification of drug?
‘Binds to and blocks potassium channels responsible for phase 3 repolarisation’.
Class III - Potassium Channel Blockers.
The following statement best describes which classification of drug?
‘Increases Action Potential duration and ERP’.
Class III - Potassium Channel Blockers.
List two common examples of Class III - Potassium Channel Blockers.
- Amiodarone - Long half life (25-60days)
- Sotalol - Also has class II activity
List 3 cardiac effects of class IV drugs.
- Negative Inotropy (Decreased contractility)
- Negative chronotropy (Decreased HR)
- Negative dromotropy (Decreased conduction velocity)
List the 3 different types of calcium channel blockers available.
- Dihydropyridines
- Non-Dihydropyridines - Phenylalkylamine class
- Non-Dihydropyridines - Benzothiazepine class
The following two drugs are examples of which type of Class IV drug.
- Amlodipine
- Felodipine
Both are examples of Dihydropyridines
The following drug is an example of which type of Class IV drug?
- Verapamil
Example of Non - Dihydropyridines - Phenylalkylamine class.
The following drug is an example of which type of Class IV drug
- Ditiazem
Example of Non-Dihydropyridines - Benzothiazepine class.
True / False
Class II and IV drugs are suitable as a treatment strategy for Sinus Tachycardia.
True.
Treat underlying cause first if applicable.
Which drug classifications could be administered as a treatment arm for AF?
Class: IA, IC, II, III, IV.
Ventricular rate control is important here.
What classes would you give for PSVT.
IA, IC, II, III, IV.
Most likely to give adenosine, which will block the AV node.
What drug would you give for AVB?
Atropine.
What classes would you give for PVCs?
II or IV.
Most likely benign however - normally no treatment is required.
What classes could you give for Digitalis toxicity.
IB and V (Magnesium Sulphate)
List some common metabolic states that increase capture threshold.
- Acidosis (80%)
- Alkalosis (80%)
- Hypercarbia
- Hyperkalemia
- Hyperglycaemia
- Hypoxemia
- MI
- Ischemia
- Myxoedema
- Sleep
- Eating
List 4 classes of drugs that increase pacing threshold and give examples.
- IA = Quinidine, Procainamide, Disopyramide
- IC = Flecanide, Propafenone
- III = Amiodarone
- IV = Verapamil
List two classes of drug which potentially increase pacing threshold.
- IA - Procainamide, Quinidine
- Ib = Lidocaine
List 4 drugs / sympathetic agents, which can decrease pacing threshold.
- Atropine
- Epinephrine
- Isoproterenol
- Corticosteroids
List 3 drugs which have no known effect on threshold.
- Beta Blockers
- Digitalis
- ACE inhibitors
Which 5 drugs increase DFT?
- IA = Quinidine
- IB = Lidocaine
- IB = Mexiletine
- III = Amiodarone
- IV = Verapamil
Which 3 drugs may decrease DFT?
- Ic = Flecainide
- II = Metoprolol
- III = Sotalol
List 5 cardiac drugs which are excreted via renal system.
- Sotalol
- Digoxin
- Disopyramide
- Bretylium
- Tocainide
List 5 cardiac drugs which are eliminated by the Hepatic system.
- Lidocaine
- Flecainide
- Amiodarone
- Verapamil
- Propafenone
List 3 drugs which increase digoxin potency.
- Flecanide
- Amoidarone
- Verapamil
List 4 Drugs which add to beta blockers potency.
- Flecanide - additive to negative inotropic effect
- Amiodarone - additive to beta blocking effect
- Verapamil - additive to bradycardia
- Lidocaine = Increases Beta Blocker potency
What drug reverses the effects of: Midazolam / Diazepam / Temazepam?
Flumazenil.
What drug reverses the effects of: Fentanyl / Morphine / Diamorphine?
Naloxone.
Which drug class does this to the Action Potential?
1A = Slow conduction, Prolonged repolarisation.
Which drug class does this to the Action Potential?
Class 1b = Shorter repolarisation, no effect on conduction.
Which drug class does this to the Action Potential?
1c = Slow conduction, no effect on repolarisation.
Which drug class does this to the Action Potential?
Class III - Prolonged repolarisation, no effect on conduction.
Which class of drugs are pro-arrhyhtmic to torsades and may slow VT? (two examples)
Class Ia.
- Procainamide
- Quinidine
Which drug class may cause central nervous system side effects? (Two examples)
Class Ib.
- Lignocaine
- Mexiletine
Give two examples of drugs that are proarrhythmic for SCD in LV dysfunction?
- Flecanide
- Propafenone
Which class III drug
- Increases DFTs
- Decreases DFTs
Amiodarone Increases
Sotalol Decreases
Which drug class may cause or exacerbate CHB and HF? (Two examples)
Class IV - Potentiates Digoxin.
- Verapamil
- Diltiazem
Which class of drugs are predominantly prescribed for SVTs?
Class IV.
Which class of drugs can’t be used post MI? (CAST study)
Class I.
Also negatively inotropic so cannot be prescribed in patients with LV dysfunction.
List 3 major dawbacks of Sotalol.
- Relatively high Torsades rate
- Non cardioselective
- Reverse use dependence
Describe reverse use dependence.
Lesser effect at higher heart rates.
E.g. Good at preventing AF (as baseline HR is low), poor at converting AF once its started (as HR is now high).
Which of the following drugs is most likely to reduce DFT while minimally influencing VT CL?
- Lidocaine
- Flecanide
- Sotalol
- Amiodarone
- Digoxin
3 - Sotalol.
Which of the following is most likely to increase stim threshold post PPM implant?
- Digoxin
- Sotalol
- Flecanide
- Mexileine
3 - Flecanide.