Antidysrhyrhmic Drugs Flashcards
Arrhythmias are always symptomatic. True or false?
False. They may be symptomatic or asymptomatic.
Common symptoms of arrhythmia
sudden death
Syncopal attacks
Heart failure
Dizziness
Palpitations
Factors precipitating arrythmias:
MS HIDI
Mechanical injury
Stretching
Hypoxia
Ischemia
Drugs (anti-arrhythmics etc)
Imbalance of electrolyte / pH imbalance
Causes of Arrhythmias:
Atherosclerosis
Coronary artery spasms
Myocardial ischemia
Conduction block.
Types of arrhythmias
2SE2A2PV
Sinus tachycardia: HR > 100bpm
Sinus bradycardia: HR < 60bpm
Extrasystoles
Atrial flutter
Atrial fibrillation
Paroxysmal atrial tachycardia
Paroxysmal ventricular tachycardia
Ventricular fibrillation
Torsade de pointes occurs when
…a long QT causes undulating baseline/rapid asynchronous complexes on ECG.
Atrial rate in atrial tachycardia
100 - 250 bpm
What is so unique about PSVT?
Electrical signals, starting in the upper chambers fire irregularly, preventing the heart from having enough time to fill with blood before pumping out to the rest of the body
What on an ECG is indicative of ventricular tachycardia?
Widened QRS
What is the heart rate in ventricular tachycardia?
100 to 120bpm
What is the heart rate in PSVT?
120 to 230
Difference between V tach and V fib
In Vtach, spontaneous ventricular automaticity causes chaotic faster HR with widened QRS. Drugs like cocaine, meth, and structural heart dx are responsible.
In VFib, the ventricles contract rapidly and uncoordinatedly, causing sudden cardiac arrest and even death. It is caused by prior heart disease or electrolyte imbalance.
The four parameters explained in the electrophysiology of the heart include:
Automaticity
conduction
Excitability
refractory period
HIS/Purkinje fibres are specialised conducting tissues. True or false?
True
What are the automatic cardiomyocytes?
- SAN
- AVN
- HIS/Purkinje
Non-pacemaker AP occurs in how many phases?
5
Give brief overview of events in Phases 0 to 4
0 - Na channels open (rapid depolarisation)
1 - Na channels close (early repolarisation)
2 - Ca channels open, fast K channels close (plateau)
3 - Ca channels close, fast K channels open (repolarisation)
4 - Resting potential
What kind of abnormal conduction is seen in PSVT and WFW syndrome?
Reentry
Give examples of conditions with micro entry circuit
Ventricular extrasystole
Ventricular tachycardia
V.fib
What is a Conduction block?
Conduction from SA node to AV node could be slowed down by ischemia, causing partial to complete AV block or sick sinus.
2nd degree AV block
Some supraventricular complexes are not conducted, missed beat.
3rd degree AV block
No supraventricular complexes are not conducted, ventricles generate own impulse.
What is the most common cause of conduction block?
Ischemia
When are arrhythmias left untreated?
Simple arrhythmic agents e.g. Atrial extrasystole and ventricular extrasystole in a normal heart
In what kind of arrhythmias are vigorous therapies required?
- Life threatening conditions like Ventricular tachycardia.
- Arrhythmias causing hypotension , breathlessness or heart failure.
- Marked palpitation as in PSVT, sustained V.tach, Atrial fib, torsades de pointes.
What are the classes of antiarrhythmic drugs?
Class I to V
Class 1A antiarrhythmics
D-Disopyramide
P-Procainamide
Class 1B antiarrhythmics
L-Lidocaine
M-Mexiletine
Class 1C antiarrhythmics
Propafenone
Flecainide
Class II antiarrhythmics
Esmolol
Sotalol
Propranolol
Class III antiarrhythmics
Sotalol
Amiodarone
Dronedarone
Dofetilide
Class IV antiarrhythmics
Verapamil
Diltiazem
Class V antiarrhythmics
Adenosine
Digoxin
Magnesium sulfate
Pharmacological action of quinidine
Decrease automaticity in purkinje fibers and other ectopic focus to extinguish extrasystoles and prophylaxis of re entrant arrythmias.
How do class 1A drugs reduce membrane responsiveness?
Via anti-vagal action, it reduces the rate of 0 phase depolarization thereby reducing membrane responsiveness.
ECG reading of class 1A
Increase PR and QR intervals, broaden QRS complex
Pneumonic to know the drugs in anti-arrhythmic drugs and their classes
“Daring Paramedics Love Managing Potentially Fatal Episodes Since Patients Are Demanding Defibrillation Ventures Daily”
D - Disopyramide
P - Procainamide
L - Lidocaine
M - Mexiletine
P - Propafenone
F - Flecainide
E - Esmolol
S - Sotolol
P - Propranolol
A - Amiodarone
D - Dronedarone
D - Dofetilide
V - Verapamil
D - Diltiazem
How many classes would amiodarone fit in?
Four - I, II, III, IV
In what way is quinidine the opposite of digoxin?
It depresses myocardial contractility where digoxin increases it
Lidocaine is effective for atrial tachyarrhythmia. True or false?
False. It affects ventricular re-entry only
