Concise simple Demonstration of antiarrhythmic drugs phamacological action and simple algorithm for treatment of different types of arrhythmias

2. In contrast to skeletal muscle, which contracts
only when it receives a stimulus, the heart
contains specialized cells that exhibit
automaticity. ““pacemaker” cells “

3. Ventricular VS.
SA node (pace-maker) action potential

4. Cardiac muscle action potential

7. Class I (sodium channel blockers)
IA : Quinidine IB : lidocaine
• Adverse effects:
• Quinidine:
-arrhythmia (k + channel block)
-cinchonism
• Lidocaine:
- wide therapeutic index
- CNS effects
Mechanism of action:

9. -Several studies have cast serious doubts on the safety of
the class IC drugs, particularly in patients with structural
heart disease.
- Flecainide:
-generally well tolerated
- blurred vision, dizziness, and nausea
- Propafenone:
-similar side effect profile
-may cause bronchospasm due to its β-blocking effects
Adverse effects

10. Class II : B- blockers (ex: metoprolol)
Mechanism of action:

11. CLASS III ANTIARRHYTHMIC DRUGS:
Amiodarone
Mechanism of action:

15. Digoxin
inhibits the Na+/K+-ATPase pump, ultimately shortening the refractory
period in atrial and ventricular myocardial cells while prolonging the
effective refractory period and diminishing conduction velocity in the
AV node.

17. Bradycardia:
A slow ventricular rate, usually defined as <60bpm, but may be
absolute (<40bpm) or relative
-If asymptomatic and rate >40bpm, no treatment is required.
-If rate <40bpm or patient is symptomatic:
Follow the next algorithm

19. Tachyarrhythmias
Narrow complex
ECG shows rate of
>100bpm and QRS
complex duration of
<120ms
Wide complex
ECG shows rate of >100
and QRS complexes
>120ms (>3 small
squares).

21. • Vagal maneuvres
• Adenosine (DOC)
• Verapamil - B- blocker

23. Carotid sinus massage and IV adenosine transiently block the AV node
and may unmask flutter waves.
Cardioversion may be indicated (anticoagulate before). Anti-AF drugs
may not work—but consider amiodarone to restore sinus rhythm, and
amiodarone or sotalol to maintain it. Aim to control rate as above; if
the IV route is needed, a b-blocker is preferred.

28. Ventricular extrasystoles (ectopics)
- the commonest post-MI arrhythmia.
- Post-MI they suggest electrical instability, and the risk is VF
if the ‘R on T’ pattern (ie no gap before the T wave) is seen.
- If frequent (>10/min), consider amiodarone IV as above.
Otherwise, just observe patient.