Cardiac arrhythmias occur when the heart beats with an irregular rhythm. There are two main types - bradycardia, which is a slow heart rate below 60 bpm, and tachycardia, which is a fast heart rate over 100 bpm. Arrhythmias can be caused by coronary artery disease, electrolyte imbalances, heart muscle changes after injury or surgery. Symptoms include palpitations, dizziness, chest pain, fainting. Treatment depends on the type of arrhythmia but may include sodium channel blockers, beta blockers, drugs that prolong the action potential, calcium channel blockers, or other drugs like adenosine or magnesium.
3. ABNORMAL RHYTHM
CAN BE OF TWO EXTREME FORMS
1. Bradycardia - Cardiac beats below 60
beats per minute .
2. Tachycardia – Cardiac beat above 100
beats per minute.
5. Healing process after heart surgery.
Irregular heart rhythms can also occur in
"normal, healthy" hearts.
Ischemic Heart Disease
Drugs related
Others
10. 2. Blockage of Conduction from SA node
AV node Blockage
Causes
• Ischemia
• Fibrosis
• Viral Infection
RESULTS in HEART ATTACK
11.
12. LEFT BUNDLE BRUNCH BLOCK (LBBB)
• No Impulse conduction through Bundle
Brunch
• Action Potential transferred through Right
Ventricle to Left Ventricle
RESULTS in Wide QRS complex
16. • loss of the normal organised propagation
of electrical activity
• atria fibrillate, they no longer contract in a
mechanically useful way
• a degree of stasis to blood flow and
predisposing to clot (thrombus) formation
within the chambers
18. • Uncoordinated contraction of
the Cardiac Muscle
• Quiver rather than contract properly
• Commonly identified arrhythmia in
Cardiac Arrest patients
• As a consequence, Sudden Cardiac Death
20. • WPW is caused by the presence of an
abnormal accessory electrical conduction
pathway between the atria and
the ventricles.
• Electrical Signals through abnormal
pathway stimulate the ventricles to contract
prematurely
• A unique type of supraventricular
tachycardia referred to as
an ”atrioventricular reciprocating
tachycardia”.
21. Atrioventricular nodal re-entrant
tachycardia
• Most common regular supraventricular
tachycardia
• Re-entry circuit forms within or just next
to the atrioventricular node.
• Same as WPW except reentry is in or
around AV node
27. Class Action Drugs
I A. Na Channel blockers Quinidine, procainamide
I B. Na Channel blockers Lidocaine
I C. Na Channel blockers Flecainide
II Beta-adrenergic blockers Propranolol, esmolol
III Prolong repolarization Amiodarone, Sotolol
Dofetalide, ibutilide
IV Calcium channel blockers Verapamil, diltiazem
29. Class 1A agents:
• Procainamide
• quinidine
• disopyramide
Effects on cardiac activity
• conduction
30. • refractory period ( (K+) and Na
inactivation)
• automaticity
• increase threshold (Na+)
Quinidine has anticholinergic (atropine
like action) to speed AV conduction used
with digitalis, β blocker or Ca channel
blocker
• Quinidine is also an alpha receptor
antagonist
31. Uses
Quinidine : maintain sinus
rhythms in atrial fibrillation and
flutter and to prevent
recurrent tachycardia and
fibrillation
Procainamide: acute treatment of
supraventricular and ventricular
arrhythmias
32. Side effects
• Hypotension, reduced cardiac output
• Proarrhythmia (generation of a new
arrhythmia)
• Dizziness, confusion, insomnia,
seizure (highdose)
• Gastrointestinal effects (common)
33. Class 1B agents:
• Lidocaine
• mexiletine
• Henytoin
Administration
Lidocaine: iv only
Tocainide and mexiletine: oral
35. Uses
• Acute : Ventricular tachycardia and
fibrillation (esp. during ischemia)
• Not used in atrial arrhythmias or AV
junctional arrhythmias
Side effects
CNS effects: dizziness, drowsiness
36. Class 1C agents:
• Flecainide
• propafenone
Effects on cardiac activity
• automoticity ( threshold)
• APD (K+) and refractory
period, especially in rapidly
depolarizing atrial tissue.
37. Uses
• Wide spectrum
• Used for supraventricular
arrhythmias (fibrillation and flutter)
• Premature ventricular contractions
(caused problems)
• Wolff-Parkinson-White syndrome
38. Side effects
• Proarrhythmia and sudden death
especially with chronic use
• increase ventricular response to
supraventricular arrhythmias
• CNS and gastrointestinal effects like
other local anesthetics
40. Class II agents:
• propranolol
• acebutolol
• esmolol
Administration
Propranolol: oral, iv
Esmolol: iv only
(very short acting T½, 9 min)
41. Cardiac effects
• APD and refractory period in AV node to
slow AV conduction velocity
42. Uses
• Treating sinus and catecholamine
dependent tachyarrhythmias
• converting reentrant arrhythmias in
AV
• protecting the ventricles from high
atrial rates (slow AV
conduction)
44. CLASS III - Drugs That Prolong
Effective Refractory Period By
Prolonging the Action Potential
45. Class III agents:
• amiodarone
• sotalol
• Ibutilide
• dofetilide
Amiodarone
Administration
Oral or iv (T 1/2 about 3 months)
46. Cardiac effects
• increase refractory period and APD
(K+)
• conduction (Na+)
• (β block and Ca++ block)
• speed of AV conduction
47. Uses
• Very wide spectrum: effective for most
arrhythmias
Side effects:
Many serious that increase with time
• Pulmonary fibrosis
• Hepatic injury
• Increase LDL cholesterol
• Thyroid disease
• Photosensitivity
57. Uses
• control ventricles during
supraventricular tachycardia
• convert supraventricular tachycardia
(re-entry around AV)
Side effects
• Caution when hypotension,
decreased CO or sick sinus.Some
gastrointestinal problems
63. Atropine
Mechanism
• selective muscarinic antagonist
Cardiac effects
• block vagal activity to speed AV conduction and
increase HR
Uses
• treat vagal bradycardia
Magnesium
• treatment for tachycardia resulting from long QT
64. References
Basic and Clinical Pharmacology Katzung 13 Edition
Pharmacotherapy Handbook - Ninth Edition by Barbara G.
Wells (Author), Joseph T. Dipiro (Author), Terry L.
Schwinghammer (Author)
www.youtube.com - Pathophysiology of Cardiac Arrhythmias by
Andrew Wolf
Wikipedia