Term
| Class I antiarrhythmic drugs |
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Definition
| Na channel blockers - decr. phase 0 slope and AP peak and suppress automaticity |
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Term
| Class Ia antiarrhythmic drugs |
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Definition
Moderate Na channel blockers and so moderate decr. in phase 0 slope.
Also prolong APD and ERP due to slow binding and unbinding of R.
Used for ventricular arrhythmias and prevention of paraoxysmal recurrent atrial fib.
e.g. Quinidine |
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Term
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Definition
A Class Ia antiarrhymic drug
i.e. moderate Na channel blocker and so moderate decr. in phase 0 slope.
Also prolong APD and ERP due to slow binding and unbinding of R.
Used for ventricular arrhythmias and prevention of paraoxysmal recurrent atrial fib. |
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Term
| Class Ib antiarrhythmic drugs |
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Definition
Weak Na channel blockers and so small reduction in phase 0 slope.
Results in decr. AP duration and paradoxical incr ERP
-Also decr. conduction
-Used in prevention and tx. immediately after MI and for VT
e.g.Lignocaine |
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Term
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Definition
Class Ib antiarrhythmic drug i.e. weak Na channel blocker and so small reduction in phase 0 slope.
Results in decr. AP duration and paradoxical incr ERP
-Also decr. conduction
-Used in prevention and tx. immediately after MI and for VT |
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Term
| Class Ic antiarrhythmic drugs |
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Definition
Strong Na channel blockers and so large decr. in phase 0 slope.
No effect on AP duration but do incr. refractory period. Also dec. cardiac contractility
Useful in syndromes w. abnormal conduction systems e.g. Wolff-Parkinson -White syndrome (WPW)
e.g. Propafenone |
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Term
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Definition
Class Ic antiarrhythmic drug i.e. strong Na channel blocker and so large decr. in phase 0 slope.
No effect on AP duration but does incr. refractory period. Also dec. cardiac contractility
Useful in syndromes w. abnormal conduction systems e.g. Wolff-Parkinson -White syndrome (WPW) |
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Term
| Class II antiarrhythmic drugs |
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Definition
beta-blockers - block sympathetic drive and so decr. HR and contractility.
Decr APD, incr. RP, dec. SAN and AVN conduction
Used mainly in supravent. tachycardias, also in post-MI to prevent unwanted compensatory change
e.g. atenolol |
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Term
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Definition
Class II antiarrhythmic drug i.e. beta-blocker - blocks sympathetic drive and so decr. HR and contractility.
Decr APD, incr. RP, dec. SAN and AVN conduction
Used mainly in supravent. tachycardias, also in post-MI to prevent unwanted compensatory change |
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Term
| Class III antiarrhythmic drugs |
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Definition
K+ channel blockers - delay repolarisation so incr APD and ERF
Used in WPW syndrome, VT and AF
e.g. Amiodarone |
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Term
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Definition
Class III antiarrhythmic drug i.e.
K+ channel blocker - delay repolarisation so incr APD and ERF
Used in WPW syndrome, VT and AF |
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Term
| Class IV antiarrhythmic drugs |
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Definition
Ca++ channel blockers - most effective in nodal tissue and decr. rate and conduction
-block AVN (good if supravent tachycardia, bad if AVN already blocked)
-may decr. O2 demand and cardiac work due to decr. contraction
-used to prevent recurrence of paroxysmal supravent. tachycardia and decr vent. rate in patient w. AF
e.g. verapamil |
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Term
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Definition
Class IV antiarrhythmic i.e. Ca++ channel blocker (preferentially cardiac)- most effective in nodal tissue and decr. rate and conduction
-block AVN (good if supravent tachycardia, bad if already blocked)
-may decr. O2 demand and cardiac work due to decr. contraction
-used to prevent recurrence of paroxysmal supraVT and decr vent. rate in patient w. AF |
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Term
| Class 'V' antiarrhythmic drugs |
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Definition
Vagal stimulants e.g. digoxin - suppress AV conduction and so decr. vent rate
-best for supravent. tachyarrhythmias |
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Term
| Digoxin as a Class 'V' antiarrhythmic drug |
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Definition
Vagal stimulant - suppresses AV conduction and so decr. vent rate
-best for supravent. tachyarrhythmias |
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Term
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Definition
-regular insulin followed by glucose may start the heart beating (results in K+ back into cells and helps restore K+ levels)
-if this fails, poor prognosis
-can directly admin. atropine and AD to attempt to generate impulses in nodal tissue |
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Term
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Definition
Lidocaine to block excited focus
-if ineffective after 2 boluses then defibrilliation may be necessary |
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Term
| Ventricular fibrillation tx |
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Definition
Defibrillation - attempt to abruptly stop electrical activity, allowing 1 strong focus to take over
-in fine fib., there are multiple weak foci and defib. is less effective - use AD or lidocaine first to try and convert to coarse fib (fewer stonger foci) |
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Term
| Pulseless idioventricular rhythm tx |
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Definition
-aim to slow vent rhythm:
dexamethasone (steroid), vasopressors or positive inotropes
-AD may be given
-NOT lidocaine - can eliminate the single focus |
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Term
| Electromechanical dissociation |
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Definition
-electrical activity in heart but no muscular activity
-AD and GCC to attempt to incr. force of contraction |
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Term
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Definition
Used to decr afterload in tx. of HF
e.g. Hydrazaline (relaxes vasc. sm. musc. by Ca++ release)
Amlodipine (Ca++ channel blocker) |
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Term
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Definition
An arteriolar dilator used to decr. afterload in HF tx
-relaxes art. sm. musc. by Ca++ release from SR and affecting IP3 production |
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Term
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Definition
A calcium channel blocker used to decr. afterload in HF tx
-causes arteriolar dilation, esp. of coronary vessels |
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Term
| Arterio- and veno- dilators |
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Definition
Used to decr. afterload and preload in HF tx
e.g. Organic nitrates and nitrales e.g. Nitroglycerin, Nitroprusside
Prazosin (alpha-1-R-blocker)
Atenolol and propanol (beta-blockers) |
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Term
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Definition
Decr. preload via venodilation in HF tx.
-shifts blood from pul. to systemic vessels and decr. myocardial workload
-used in acute/emergency CHF tx, esp associated w. pul. oedema |
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Term
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Definition
| one of most potent vasodilators available - used to decr. preload and afterload in HF tx. |
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Term
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Definition
| An alpha-1-R-blocker i.e. vasodilator - used to decr. preload and afterload in HF tx. |
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Term
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Definition
Drugs which alter the force or energy of muscle contraction - used to incr. contractility of heart in HF
e.g. cardiotonic steroids, e.g. digoxin / digitalis
Receptor sympathomimetics e.g. dopamine, dobutamine
Transduction sympathomimetics e.g. Pimobenden |
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Term
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Definition
e.g. digoxin / digitalis
Incr Force
Incr Excitability
Decr A-V Conduction
Decr Rate |
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Term
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Definition
Cardiac steroids - used to incr. contractility in HF tx
(also used as Class 'V' antiarrhythmic by suppressimg AV conduction)
-act by inhibiting Na+/K+ ATPase, so incr Na+ and then Ca++ in cell, so incr. Ca++ available for contraction |
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Term
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Definition
Receptor sympathomimetic
-used in HF tx by incr HR and contractility
- block beta-receptors - beta-1-selective and so cardioselective |
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Term
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Definition
Receptor sympathomimetic
-used in HF tx by incr HR and contractility
- block beta-receptors - attempts beta-1-selectivity (alpha-1 and beta-2 effects cancel) and so cardioselective |
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Term
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Definition
A transduction sympathomimetic - used in HF tx, incr. contractility
-incr. cAMP by decr. cAMP phosphodiesterase, and so incr. PKA
-high mordity in man w. little effect - unsure in animals, but used as last effort / attempt |
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Term
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Definition
| Used in HF tx to attempt to dec. preload by decr. vol (loop diuretics e.g. furosemide and thiazides e.g. hydrochlorothiazide) and inhibiting RAS (aldosterone antagonist and K+ sparer spironolactone) |
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Term
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Definition
| An ACE inhibitor used in HF tx by inhibiting RAS- inhibits angiotensin II production and so inhibits aldosterone production (so K+ sparing and dec. vol) and causes vasodilation |
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