Arrythmia Flashcards
بسم الله الرحمن الرحيم وبه نستعين
arrhthmia more common in?
MI
, anesthesia
& with drugs e.g. Digoxin
Treatment includes:
❶ Cardioversion. ❷ Pacing ❸ Drug
Disturbances in normal automaticity:
- ↑ Sympathetic (thyrotoxicosis) → ↑ Ca++ influx → ↑ slop of phase 4 → Sinus tachycardia (Treated by Beta blockers)
- ↑Vagal tone (Digoxin toxicity & Carotid sinus syndrome) → ↑ K+ outflux → ↓ slope of phase 4 → Sinus bradycardia (Treated by Atropine)
Abnormal automaticity (ectopic focus):
Ischemia →
abnormal depolarization →
↑ slope of phase 4 →
initiates abnormal automaticity in( non) automatic tissues
❶ Heart block
- 1st degree: All impulses reach
- 2nd degree: some impulses reach
- 3rd degree: Complete AV Block
Re-entry arrhythmia: Occurs when continues circulation of an impulse occur → re-enter the point of origin →
re excite the same part of the heart more than once (circus movement):
A. Ventricular tachycardia, ventricular fibrillation جدا خطر & QT syndrome
B. Atrial flutter (Single focus/ regular) & Atrial fibrillation (multiple/ irregular) خطوره أقل
C. PSVT (paroxysmal Supraventricular tachycardia)
• AV nodal re-entrant tachycardia (AVNRT)
• Atrioventricular re- entrant tachycardia (AVRT) e.g. WPW syndrome: Pre-excitation Syndrome is a heart condition in which part of the cardiac ventricles are activated too early due to presence of accessory bundle (e.g Bundle of Kent)
Classification according to mechanism of action (Vaughn William classification)
Class I: Na+ channel blockers
Ia: Procainamide Ib: Lidocaine, Phenytoin Ic: Propafenone
Class II: beta blockers: Propranolol, Esmolol, Atenolol
Class III: K+channel blockers: Amiodarone
Class IV: CCBs: Verapamil
Miscellaneous: Adenosine, Digoxin
Class I:
Ia: Procainamide Ib: Lidocaine, Phenytoin Ic: Propafenone
Na+ channel blockers
Class II: ?: Propranolol, Esmolol, Atenolol
beta blockers
Class III:?: Amiodarone
K+channel blockers
Class IV:?: Verapamil
CCBs
All can be given orally except
Lidocaine
Esmolol
Adenosine
Na+channel blocker(fast fiber)
A.↓Vmax & conduction velocity
B.↓Automaticity (↓ slope phase 4)
C. ↑ ERP
Rate of dissociation from Na+
channels
Ia: Procainamide moderate
Ib lidocaine : rapid
Ic Propafenone : slow dissociation most
Procainamide and K channels?
BLOCK BOTH?
Increasing APD and ERP
Ib lidocaine ?>
Open K channels
Decrasing APD and ERP
Propafenone ? Ic K channels
No effect on K channels
No effect on APD
Increasing ERP ?
Effect on AVN
pROCAIMIDE INCREASING APD AND ERP
LIDOCAINE NO EFFECT
Propfaenone : BB EFFET INCREASING ERP
Procainamid on ecg?
prolong pr and qt intervals and QRS
Lidocaine and ecg?
No effect on PR interval nor AVN ?
Shorten the QT interval due to opening of the K channels
propfanone and ecg?
Prlolng pr interval due to BB effect
Prlong qrs and qt interval due to Na channel blcking and slow dissociation
Procainamide autoniomic effect? A
ANTIM MUSCARIN
GANGLIONO BLOCKADE
ALPHA BLOCKADE
pROPAFENONT AUTOMNOMIC EFFECT?
BB
Theraputic users of procaimaide?
BS
Lidocaine?
NS/V
Digtalis induced arrhytmia
after Myocardial infarction
Adverse effects of the Procaiameide? s
TSC2
Cardiac toxixity HMQ
Myocardial depression
prlong qt interval torsade de pointes
Hypotension block sympathatic ganglia
Cinnchonism
Thromboemolism
Systemic lupus
Lidocaine?
Least Cardiotoxic
CNS Perioral parathesia
dizzness
convulsions
AF AND Af due to low ERP
PSVT NO effect on AVN
Propafenone therpautic uses?
BS
Propafenone adverse effects ?
BAC :
Bronchospasm
blurred vision
AVN block
constipation
Block Na channels → ? & block K channels → ?
↑ERP without ↑ APD
↑ ERP & APD
Ia ; procainamide effects?
Electrophysiolpgy:
Block Na channels:
with moderate rate of dissociation → moderate ↓ in Vmax & conduction velocity
Block K channels:
↑ repolarization time (class III activity)
Autonomic effect:
antimuscarinin:
Atropine like action) → ↑ conduction in AVN (↓ APD): Disopyramide> Quinidine > Procainamide
Block ganglion sympahtthic: (↓ BP): Procainamide
Block alpha receptors: ( ↓ BP): Quinidine
Clinical implication of antimuscarinic effect of class Ia: • Paradoxical ↑ AVN conduction → ventricular tachycardia in patients with Atrial fibrillation (AF)
ايه الحل؟
فيونكه! adenosine bb ccb:verapamil digoxin