Download cardiovascular – anti-arrhythmics

CARDIOVASCULAR – ANTI-ARRHYTHMICS
1. Antiarrythmic drugs may work in any of the following ways EXCEPT:
a. Reducing ectopic pacemaker activity
b. Modifying conduction in reentrant circuits
c. Sodium channel blockade
d. Calcium channel blockade
e. Reducing the effective refractory period – prolong, by blocking IKr (Class III)
2. Lignocaine
a. Has poor oral bioavailability – 3% due to extensive hepatic first pass
b. Blocks sodium channels not inactivated channels – bocks both activated and inactivated
c. Is effective in AF – no, VF
d. Exacerbates VT in 30% - ?
e. Suppresses electrical activity of normal and arrythmogenic tissue equally – selective for tissue with
decreased RMP (i.e. arrythmogenic)
3. Flecainide
a. Has poor oral bioavailability – it is high
b. Is safe in ischaemia induced arrythmias - no
c. May be used in reentry tachycardia’s - true
d. Is a class Ia antiarrythmic - Ic
e. Reduces mortality in post MI PVCs - increases
4. Adenosine
a. has a half life of 2 minutes - <10sec
b. increases AV nodal conduction - inhibits
c. predominantly inhibits sinoatrial nodal function – AV > SA
d. directly inhibits AV nodal conduction - correct
e. is more effective in the presence of theophylline or caffeine – adenosine receptor blockers
5. Adenosine
a. has a half life of 30 seconds - <10sec
b. is the drug of choice for ventricular tachyarrythmias – will not work on most ventricular
tachyarythmias
c. works by directly inhibiting the sinoatrial node with only mild effect on the atrioventricular node opposite
d. causes flushing in over 50% of patients – 20%
e. is less effective in the presence of caffeine and theophylline - true
6. regarding antiarrythmics
a. adenosine alters QRS duration
b. amiodarone has a short half life
c. lignocaine is also useful in supraventricular arrythmias
d. flecainide is unsafe in people with ischaemic heart disease
e. quinidine has no effect on QRS duration
7. amiodarone
a. has a short half life
b. stimulates Na channels
c. is only effective against ventricular arrythmias
d. has antianginal effects
e. can cause emphysema in 5-15% of people
8. In the Vaughan-Williams classification
a. Class 1 drugs affect potassium channels
b. Class II drugs affect calcium channels
c. Class II drugs affect sodium channels
d. Class III drugs affect potassium channels
e. Class IV drugs affect chloride channels
9. In therapeutic doses, adenosine:
a. Acts by affecting sodium channels – activation of inward K rectifier and inhibition of Ca current
b. Is administered as a slow IV push - fast
c. Is metabolized in the liver
d. Produces a bradycardia by vagal stimulation
e. Affects adenosine receptors at the AV node
10. adenosine
a. opens K+ - activation of inward K rectifier and inhibition of Ca current
b. opens Cl- channels
c. half life of 10min - <10sec
d. profoundly blocks SA node – AV nose
e. blocks Ca2+ dependent action potential
This is mediated via the A1 receptor, inhibiting adenylyl cyclase, reducing cAMP and so causing cell
hyperpolarization by increasing outward K+ flux.
11. regarding adenosine
a. its receptors are ion channels – G-protein coupled
b. it increases AV nodal conduction - inhibits
c. it enhances K+ conductance – true, efflux
d. it is the drug of choice in VF
e. it has a half life of 2 minutes - <10sec
12. which doesn’t prolong the refractory period in normal cells?
a. Amiodarone
b. Lignocaine
c. Sotalol
d. Quinine
e. Procainamide
13. amiodarone
a. is only effective in suppression of ventricular arrythmias – also useful in AF
b. causes peripheral vasodilation via alpha-adrenergic effects – true, katzung lists as related to the
action of the vehicle
c. commonly causes corneal opacification – asymptomatic corneal micodeposits
d. increases warfarin clearance – inhibits metabolism
e. decreases AV nodal refractory period - increases
14. lignocaine displays all of the following EXCEPT:
a. increased action potential duration – class IIb –> shortens ADP
b. binding to both activated and inactivated sodium channels - true
c. predominant metabolism ? – assume predominant hepatic or significant
d. decreased clearance associated with concomitant propranolol administration – true due to
decreased hepatic flow
e. ineffectiveness against arrhythmias in normally polarized tissues – true, favors ‘sick’ depolarized
cells
15. which of the following does NOT prolong the effective refractory period in the
atrioventricular node?
a. Propranolol
b. Amiodarone
c. Flecainide – “despite IK blocking doesn’t prolong AP or QT”, Class Ic – minimal effect on APD
d. Verapamil
e. Phenytoin – similar effects to a Class Ib which shorten the APD
16. adenosine
a. is effective in converting atrial flutter - SVT
b. depresses conduction through the AV node - true
c. requires reduction of dose in patients with hepatic failure
d. has a half life of 30-60 seconds - <10sec
e. is safe in sick sinus syndrome - ?
17. regarding amiodarone
a. it has no alpha adrenergic effects - weak
b. it has no beta adrenergic effects - weak
c. it has low affinity for activated sodium channels – true, affinity is for inactivated
d. it increases warfarin clearance - decreases
e. it enhances conduction through accessory pathways – assume decreases
18. amiodarone
a. has a low affinity for activated sodium channels
b. is associated with thyroid dysfunction in 50% of patients
c. has a half-life of 8-20 days
d. increases clearance of warfarin
e. commonly causes peripheral vasoconstriction - vasodilation
19. which does not prolong the refractory period of normal cells
a. amiodarone
b. lignocaine
c. quinidine
d. sotalol
e. procainamide
20. the most common adverse effect of procainamide is
a. bradycardia
b. pulmonary infiltrates
c. fever
d. hypotension
e. anaphylaxis