Lecture 2 Anti-arrhythmic drugs Flashcards
Classes of antiarrythmnics: 1 = \_\_\_ blockers 2 = \_\_\_\_ blockers 3= \_\_\_\_ blockers 4 = \_\_\_\_ blockers
sodium channel;
beta;
potassium (mainly) channel];
L-type calcium channel
in general, class ___ arrythmics act on cardiac myocytes, while class ____ act on pace maker cells
1, 3;
2, 4
which class decreases the phase 4 slope of pacemaker APs?
beta blockers (class 2)
what configurations of receptor to class 1 AA (anti-arrhythmics) bind to?
open or inactive Na channels (not resting)
in resting sodium channels, the ____ gate is closed, and class 1 AAs can’t bind. In inactivated sodium channels, the ___ gate is closed, but the ____ gate is open, so the class 1 AAs can bind
activation; inactivation, activation
class 1 binding is described as ___ or ____ dependent. Rank the classes in order of most binding to least.
use, state;
C > A > B
Class 1 AAs bind at a greater degree in tissues with an abnormally ____ frequency of depolarization, such as during ____
high;
tachycardia
during ischemia, the resting membrane potential is ____, so there will be an increased number of ___ Na channels and thus ____ binding of class 1 AAs
depolarized; inactivated; greater
class 1 AAs act on ___ channels, which are important in phase ____.
sodium; 0 (ie they change the slope of the upstroke)
Class 1A effect on AP duration and ERP =
increase AP duration, prolong ERP
Class 1B effect on AP duration and ERP:
decrease AP duration, shorter ERP
Class 1C effect on AP duration and ERP:
no effect on AP duration, no effefct on ERP in purkinje or ventricular tissue; (prolong ERP in AV node and accessory bypass tract according to FA)
what channel is affected that determines changing of the ERP? which class 1 subclasses affect these channels?
potassium;
1A and 1B
What are the class 1A AAs?
procainamide, quinidine, disopyramide
generally, class 1A AAs affect what location of arrhythmias? What side effect do they all have?
supraventricular (atrial) and ventricular;
long QT, can cause torsades de pointes
which of the class 1A AAs has metabolism via a P-gp efflux pump?
quinidine
most notable side effect associated with quinidine:
what about procainamide?
cinchonism (headache, tinnitus);
lupus like syndrome
disopyramide exhibits ____ side effects, which can cause or predispose patients to ____
anti-cholinergic; heart failure
What are the 3 class 1B AAs?
mexilitine, lidocaine, plus tocainide (not mentioned in sketchy or FA)
Class 1B AAs affect _____ purkinjke and ventricular tissue by blocking ____ channels. This _____ the refractory period
ischemic/depolarized;
potassium, decreases
not used for supraventricular things (ie not atrial afib)-IIB is “B”est post MI
general side effects of class 1B antiarrythmics:
CNS effects, cardiovascular depression
what are the two class 1C AAs?
flecainide, propanefone
class 1C AAs markedly slow ____ ____ but have minimal effect on _____; the ECG shows a _____ QRS
conduction velocity;
action potential duration/Effective refractory period;
widened
what part of the heart do class 1C AAs affect? (ie ventricles, atria etc)
both ventricular and supraventricular
both class 1Cs are ____ and are contraindicated in patients with what?
pro-arrythmic;
ischemic heart disease;typically last resort drugs
class 1 AAs: which prolongs the QT? which shortens it?Which widens the QRS?
prolong = class 1a shorten = class 1b widen QRS = 1a and 1c
Class 2 AAs cause a decrease in ____ at the nodes which closes ___ channels. this causes a prolonged phase ____
cAMP, Calcium;4
beta blockers cause a ____ in pacemaker activity, a ___ in conduction time through the AV node, and a ____ ERP
decrease, increase, increased
some beta blockers are membrane ____, such as propanolol. these ____ the QRS
stabilizers, prolong
which of the class 2 AAs is especially short acting and can be used in emergency?
esmolol (ie supraventricular arrythmias)
class 1 AAs help control the _____ in Afib. class 2 AAs help restore the ____.
rhythm; rate
name 4 class 3 AAs mentioned in FA/sketchy:
AIDS: amiodarone, ibutilide, dofetilide, sotalol
also bretylium
class 3 AAs prolong the ____ by increase phase ___ repolarization without affecting the depolarization phase (phase __)
action potential duration, 3;
0
class 3 AAs have the most effect at ____ rates. thus they are ____ dependent
low, reverse-use
all class 3 AAs have what side effect? What can occur do to this side effect?
prolong QT –> torsades
amiodarone has a ____ onset and ____ duration of action. is it a fun drug?
slow, long; no (hella side effects)
what class properties does amiodarone have ? what about sotalol?
amiodarone = class 1, 2, 3, 4; sotalol = classes 2 and 3
do class 3 AAs affect myocytes or pacemaker cells? do they help with control of rhythm or rate in Afib?
myocytes, rhythm
side effects of amiodarone:
pulmonary ____, _____ toxicity, acts as a hapten causing ____ deposits in the ____ and ____
fibrosis, hepatic;
grey-blue, cornea, skin (photodermatitis)
side effects of amiodarone continued:
it is 40% ___ by weight so it can cause ____, CNS effects, GI effects such as ____, cardiovascular effects such as ____ cardia and heart block
iodine hypo/hyperthyroidism; constipation, brady
to top it all off, amiodarone inhibits ____
CYP450 = drug interactions
class 4 AAs work by blocking ___ ____ channels. what are the 2 ones to know?
L-type calcium; verapamil and diltiazem
class 4 AAs depress phase ___ and ___ depolarization in the (nodes or myocytes?). they lengthen phase ___ repolarization and the ERP.
0, 4;
nodes;
3
Adenosine binds ___ receptors, causing an increase in ___ efflux out of cells. this hyperpolarizes the cell and decreases inward ____.
A1, potassium;
calcium
adenosine is first line treatment in what? what drug drug interactions does it have?
SVT; inhibited by theophylline and caffeine (aka methylxanthines)
what does binding of A2 receptors with adenosine cause? clinical use of this?
coronary vasodilation; used in cardiac stress test
side effects of adenosine:
____, ___tension, chest pain, sense of ___ ____, broncho____
flushing, hypo; impending doom, spasm
digoxin directly inhibits the ____ node. this increases the ____ and decreases conduction velocity
AV, ERP
