Anti arr Flashcards
Describe the phases of Action potential in myocardium cells
Phase 0 = Na enters the cell
Phase 1 = Some K leaves the cell
Phase 2 = Ca enters the cell platue
Phase 3 = all k channels open and k leaves
Phase 4 = resting membrane potential is restored cell is ready to get another stimulus
What Absolute Refractory period ? and it extends from? whats its other name?
ARP is the same as the Action potential duration, its a period where the myocardium cannot be stimulated until its over. extends from phase 0 to phase 3
Whats the main point of antiarrh drugs?
either shorting AP duration or increase it to move phase 4 around, make it so that ectopic focus does not send stimulus during it and time it so it they attack during APR and then it will be pointless.
at which phase do ectopic focus send stimulus that causes problems?
Phase 4
Describe the phases of action potential in SA node
Similar to myocardium except that phase 4 is a slop, the slope is due to Na leaking from HCN funny sodium channels in until it reaches a threshold then it will depolarize ———> this why SA can stimulate on its own called automaticity.
No phase 1 and 2 innit too, only 4, 0,3
Whats the relation between the slope in phase 4 and the firing rate of SA node?
If the slope moves up ( More Na leaking in = shorter time to reach threshold ) then it will increase the firing rate.
If it the slopes moves down (less Na leaking in = takes longer to reach threshold) it will decrease firing rate .
Whats the risk factor of elongating AP/AFP
Torsade de pointe
how do you treat torsade de pointe
magnesium sulfate injection
What are the 4 classes of anti arrhythmic drugs?
Von williams classifications :
Class 1
Class 2
Class 3
Class 4
Others
what is class 1 and its subtypes and give example?
Class 1 are Na channel blockers :
Class 1A they block NA channels and elongate AP duration :- Quinidine, procainamide, disopyramide
Class 1B- they block na channels and shortens the AP duration :-
Lidocaine ( lignocaine/xylocaine ), Mixilletine
Class 1C- block na channels but doesnt affect Ap duration work by different mechanism , flaccind , propafeonone
What is class 2? and give examples
Class 2 are beta blockers :-
Propranolol none selective
Metaprolol selective ( lipophilic metabolized in liver in bile along with propranolol )
atelolol selective ( lipophobic secreted in kidneys unchanged along with sotalol)
What is class 3? and give examples
class 3 are k channels blockers , they elongate ap duration:-
Amiodarone , dronedarone, satolol
what is class 4 and give examples
class 4 are calcium channel blockers, elongate the platue ( phase 2 ), elonagtes AP duration,
Verapmil , diltiam , phenlyalkylamines and benzothiazepines respectively.
Class 1 quinidine what its MOA
1- Block Na channels and elongating AP duration ( cuz its class 1A)
2- Blocks Na channels and moves DOWN the slope in phase 4 in SA node leading to decreased firing rate,
Works on both firing rate and conducting ( chromotopic and dromotopic respectively)
What are the other actions of quinidine ?
1- blocks muscarinic receptors producing atropine like effects ( dry mouth, urine retention, mydrasis, bronchodilation)
2- block alpha –> lead to vasodilation and hypotension
3- negative inotropic effect —> decrease contractility
which forms can quinidine be given as?
IV, IM, Orally
whats the relation between digoxin and quinidine
quinidine displaces digoxin increasing its toxicity
Uses of Quinidine?
its broad spectrum treat many arrhthymia :-
Atrial fibrillation
Venticular arrthymia
Adverse effects of quinidine
1- Hypotension and vasodilation due to alpha blockage
2- cincohism تسمم
3- paradoxical tachycardia ( when given at low doses due to the muscarinic blocking effect including tachycardia) we give verapmil or digoxin to counter this
4- Torsade de pointe and syncope due to elongations of AP duration
5- minimum SLE like symptoms. rash, arthritis, increased creatinine
6- heart failure due to negative inotropic effect ( decreased contractility )
What is the mechanism of procainamide
Same as quinidine
Block na channels and elongate ap duration
block na leaking channels and Move DOWN the slope decreasing firing rate
Whats the difference between procainamide and quinidine in mechanism?
procainamide has less muscarinic blockage effect —> no paradoxical tachycardia –> no need for digoxin or verapmil to counter
how is procainamide administered?
js like quinidine iv, im, orally
Side effects of procainamide?
1- SLE like symptoms —> rash, arhtritis, increased creatinine
2- hematotoxicity –> thrombocytopenia, agranuloctye
3- torsado de pointe and syncome due to elongation of AP duration
what are the 3 drugs that cause SLE like symptoms
1- Procainamide
2- hydralazine —> vasodilator that is used in hypertensive emergencies and pregnancy
3- quinidine
Whats Disopyramides MOA?
sicne its CLASS 1A its similar to quinidine
Bloack Na channels and elongates AP duration
block na leaking during phase 4 moving the slope down and decreasing firing rate
Adverse effects of disopyramide?
heart failure due to negative inotropic effect and decreased contractility
paradoxical tachycardia due to atropine like effects and muscarinic block –> need verapimil and digoxin
Torsade de pointe due to elongated AP duration
What is the MOA of Lidocaine?
Its class 1B :-
Blocks Na channels but DECREASE AP duration ( by speeding up the other phases)
Works primary on dead tissue –> number 1 for arrthymia after MI or ischemia
NO EFFECT ON CONDUCTION COMPARED TO CLASS 1A, NO EFFECT ON SLOPE
Uses of lidocaine?
1- since it primary works on dead tissue its given to treat arrhthymia after MI or ischemia or heart surgery ( NUMBER 1)
2- used by dentists as an anthesia
What are the pharmacodynamics and kinetics of lidocaine?
- Rapid onset of offse of action
- no effect on hemodynamics ( cuz no effect on conduction or contractility, or vessels )
- its extensively metabolized in the liver 96% whenever given orally so must be given IV
- Half life is 1-2 hours
how is lidocaine administered?
IV only cuz when given orally 96% of its metabolized
Adverse effects of lidocaine?
- Asystole when given without prophylaxis
- CNS toxicity - dizziness , confusion, seizures
Whats the difference of lidocaine and mixidiltin?
they are the same except that mixidiltin is given ORALLY. AND ITS USED IN CHRONIC MI not acute, acute is lidocaine but chronic mixidilin
What is flecainide MOA?
its CLASS 1C :-
-Blocking NA channel without affecting the duration of AP.
-Its main function is blocking the na leaking in SA node decreasing firing rate and conduction ( moves the SLOPE DOWN )
- Blocks AV conduction
what are the uses of flecainide?
- Atrial fibrillations
- SVT
-its like a pharmacological DC, will treat firbrillations, if patient come and you do DC on him and you discharge him you give him flecainide incase he gets fibrillations in home.
how is flecainide administered?
-orally
how is flecainide excreted?
excreted renally in urine, reduce dose in renal failure
Adverse effects of flecainide?
- pro arrhthymtic
- patients with cast
- nausea , confusional, ataxia
when is flecainide contraindicated?
in patients with structural heart damage, like MI, ischemia , heart surgery —> might lead to sudden death
whats half life of flecainide?
12 hours
whats the MOA of propafenone ?
Its class 1C:
Block na channels but doesnt affect AP duration .
Works primary in conduction :- Decrease conduction in all cardiac tissue. SIMILAR TO FLECAINIDE .
What are the uses of propafeonone ?
- Rhythm control in Artial fribrillation —> atrial fibrillation like flacainide
- paroxysmal SVT prophylaxis –> svt like flacainide
Whats the MOA of amiodarone?
its class 3
blocks k channels and elongates AP duration .
Also blocks :
- Blocks K channels
- Blocks Calcium channels
- Blocks Na channels
- Causes coronary vasodilation
Blocks everything –> broad specturm
amiodarone administered?
IV and orally
What happens when you give amiodarone orally?
no hemodynamics effect, no effect on blood
what happens you give amiodarone IV?
vasodilation and cardiac depressent effect
what is amiodarone mainly composed of?
Iodine (40%)
Uses of amiodarone?
Broad spectrum :-
-SVT
- all tachycardiac arrhtyhm
-arrthymia + IM and ischemia cuz it causes coronary vasodilation?
- WPW syndrome
SAFE IN PATIENTS WITH CARDIAC FAILURE UNLIKE SOTALOL AND DRODARONE
What are the kinetics/dynamics of amiodarone?
- Variable absorption
-Large volume of distribution ( lipophilic )
Wheres amiodarone excreted and metabolized?
metabolized in liver and excreted in bile
whats amiodarone half life?
80 days –> very long and requires loading.
Adverse effects of amiodarone?
ALL the side effects are related to high Iodine
-Pulmonary infiltration and toxicity
-liver toxicity
-cornea microdeposits
-bradycardia/hypotension
-photosensitivity -> grey bluish skin color when exposed to light
-thyroid dysfunction either hypo or hyper
-torsado de pointe cuz of AP elongated duration
what requires monitoring in patients taking amniodarone?
- Pulmonary function test and chest x ray due to potential pulmonary infiltration and toxicity
- Liver enzymes due to potential liver toxicity
- thyroid function due to potential dysfunction
whats the relation between amiodarone and warfarin?
amiodarone inhibit CYP2C9 which metabolize warfarin so it enhances warfarin effect.
the name the drugs that amiodarone increase their in lvl in blood?
-digoxin ( quinidine and verapmil also increase its lvl )
- quinidine
- flecaindine
what 2 drugs class that works in synergy with amiodarone?
BB and CC
when is amnioadarone is contraindicated ?
-Arrhthymia due to thyrodism
-perm atrial fibrillation
What is the difference between drodarone and amiodarone?
drodarone is benze form of amiodarone and it doesnt have IODINE and LESS SIDE EFFECTS
is drodarone lipophilic or phobic?
its lipophobic so it has low volume of disribution
when is drodarone contraindicated ?
- Heart failure cuz it depresses the heart
-Permament atrial fibrillation js like amiodarone
ITS NOT CONTRAINDICATED IN THYRODISM CUZ IT DOESNT HAVE IODINE
whats the MOA of sotalol?
its previous BB and class 3
- Blocks bb
- Blocks K channels
does sotalol have good absorption and bioavailability ?
it is well absorbed and good availability unlike amiodarone
how is sotalol excreted?
unchanged in kidney, reduce dose in renal failure like flecaindine
its lipophobic like atenolol (AS) both secreted unchanged by kidneys
whats the half life of sotalol?
12 hours like flecaindine, allows b.d dosing
what are the uses of sotalol?
Broad spectrum like amiodarone
- Mainly in venticular arrhthymia
- USED IN IMPLANTABLE DEFIBRILLATORS
What are the adverse effects of Sotalol?
- Pro arrhtyhmic like flecainide
- Torsado de pointe cuz it elongates AP duration
- Heart failure cuz of depressing heart effect
when are BB used for arrthymia?
- Arrhtyhmia + thyrodism
- Arr + HOCM
- Arr + increased sympathetic activity
- Arr + mitral prolapse
when are BB contraindicated for arrhtyhmia?
arr + heart block
which drug is used for svt?
Adeonosine ( shortest half life )
Flecainide
profenone
amiodarone
drodarone
satolol
Bb
Verapmil
Diltiazem
what drug is used for rapid atrial fibrillation
digoxin
