Mod12 Cardiac Drugs Flashcards
Antiarrhythmic drug classes
to treat arrhythmias to alleviate symptoms or prolong life
Vaughan Williams Classification
most commonly used drug classification system; classifies arrhythmias into four classes (Ia,b,c, II, III, IV) based on their electrophysiological properties/effects on myocardial APs
IA (Quindine, procainamide, disopyramide)
prolonged PR interval and QRS duration; Inhibit fast Na+ channel depression of Phase O of AP
Prolong AP
Complications of class IA
quindine has dangers associated with it; proarrhythmic complications (prolonged QT or depression of conduction, and promote re-entry tachyardias
IB (lidocaine, phenytoin, mexiletine, tocainide)
acts selectively on diseased or ischemic tissue by shortening their APs and inhibiting fast Na+ current; causes only minimal slowing of depolarization and conduction
IC (felcainide, propafenone)
prolonged PR and QRS interval; marked depression of Phase O of AP; variably prolong AP duration and marked inhibitory effects on conduction of the HIs purkinje; may have proarrhythmic effects
Class II drugs (beta-andrenergic antagonists)
atenolol, metroprolol, timolol, propranolol
function of Class II drugs
promote proarrhythmic depolarization in damaged heart tissues and the inward Ca2+ current; vary in their selection for Beta-I receptors and intrinsic sympathomimetic activity (ISA); each drug is therefore slightly different
Indications for B-blockers
Inappropriate sinus tachycardia hereditary prolong QT syndrome HF arrhythmias from mitral valve prolapse VF VT
Contraindications of Class II drugs (reasons not to take them)
pulmonary problems
conductions defects
overt treated HF
Class III drugs (mixed examples)
Amiodarone (Na channel blocker) Sotalol (acts as beta-blocker) ; these have more beneficial effects than class I
Class III drugs (pure examples )
Ibutilide, dofetilide
Class III drugs mode of action
prolong AP and refractory period (prolongs QT)
**only supposed to effect the repolarization phase of AP
Class IV drugs
verapamil and diltiazem; Ca2+ channel blockers
effects and actions of verapamil and diltiazem (class Iv)
Ca2+ channel blockade slows conduction of AV node; increases refractory period in nodal tissue
ACTS: to prevent AV nodal reentry and slow ventricular response in atrial arrhythmias
Contraindications of Class IV drugs
ventricular tachyarrhythmias (because of heamodynamic effects)
Class IV-LIKE DRUG
Adenosine
Adenosine (class IV like drug)
first line drug used to terminate narrow complex supraventricular tachyarrhythmias
for diagnosis of wide complex tachycardias of unknown origin
side effects of adenosine
headache
chest pain
flushing
excess sinus or AV node inhibition
Contraindications of adenosine (don’t use if have…)
asthma (or history of)
2nd or 3rd degree heart block
sick sinus snydrome
atrial flutter
ACE inhibitors
group of pharmaceuticals used primarily in treatment of HF, hypertension and cardiovascular protection
ACE inhibitor function
lessen the effects of Angiotensin II
Major indications for ACE inhibitors
cardiovascular protection HF acute MI hypertension post-infarct renal protection diabetic nephropathy (diabetes is RF for atherosclerosis)
Major side effects of ACE inhibitors
cough (from pulmonary congestion assoc with left HF and hypotension)
