17. Arrhythmia
❑ Normal heartbeat for adult: 60-100 bpm
❑ Irregular heartbeat
▪ Tachycardia: too fast (150-220 bpm)
▪ Bradycardia: too slow (<40 bpm)
▪ Premature contraction: too early
▪ Fibrillation: too irregular
18. Factors that trigger arrhythmia
❑Ischemia
❑Hypoxia
❑Acidosis or Alkalosis
❑Electrolyte Abnormalities
❑Excessive cathecolamine exposure
❑Autonomic influences
❑Drug toxicity (E.g. Digitalis)
❑Overstretching of cardiac fibers
❑Presence of scarred/diseased tissues
19. Factors that trigger arrhythmia
❑Ischemia
❑Hypoxia
❑Acidosis or Alkalosis
❑Electrolyte Abnormalities
❑Excessive cathecolamine exposure
❑Autonomic influences
❑Drug toxicity (E.g. Digitalis)
❑Overstretching of cardiac fibers
❑Presence of scarred/diseased tissues
24. 3 Conditions
Presence of obstacle (anatomic or physiologic)
Unidirectional block at some point in the
circuit; conduction must die out in one
direction
25. Conduction time around the circuit must be
long enough that the retrograde impulse does
not enter refractory tissue as it travels around
the obstacle
32. Aim of Therapy
To reduce ectopic pacemaker activity or
modify conduction or refractoriness in
reentry circuits to disable circus
movement
33. Major Mechanism of Action
• Sodium channel blockade
• Blockade of sympathetic autonomic
effects in the heart
• Prolongation of the effective refractory
period (Potassium Channel Blocker)
• Calcium Channel blockade
34. Major Mechanism of Action
• Sodium channel blockade
• Blockade of sympathetic autonomic
effects in the heart
• Prolongation of the effective refractory
period (Potassium Channel Blocker)
• Calcium Channel blockade
35. Major Mechanism of Action
• Sodium channel blockade
• Blockade of sympathetic autonomic
effects in the heart
• Prolongation of the effective refractory
period (Potassium Channel Blocker)
• Calcium Channel blockade
36. Major Mechanism of Action
• Sodium channel blockade
• Blockade of sympathetic autonomic
effects in the heart
• Prolongation of the effective refractory
period (Potassium Channel Blocker)
• Calcium Channel blockade
40. 1) PROCAINAMIDE
▪ slows conduction velocity and pacemaker
rate
▪ prolongs action potential duration and
dissociates from sodium channel with
intermediate kinetics
▪ direct depressant effects on SA and AV nodes
41. Clinical Applications
▪ Most atrial and ventricular arrhythmias
▪ Second line drug for most sustained
ventricular arrhythmias associated with
acute MI
42. Toxicity
▪ Hypotension
▪ QT interval prolongation
▪ Induction of Torsade de pointes
▪ Long term therapy produces reversible
lupus-related symptoms
45. Torsades de Pointes
▪is an uncommon and distinctive form of
polymorphic ventricular tachycardia (VT)
characterized by a gradual change in the
amplitude and twisting of the QRS complexes
around the isoelectric line.
46.
47. 3) DISOPYRAMIDE
▪similar to procainamide but significant
antimuscarinic effects; may precipitate
heart failure
50. 1) LIDOCAINE
▪Xylocaine®
▪has a low incidence of toxicity and a high
degree of effectiveness in arrhythmias
associated with myocardial infarction
▪given IV
55. Clinical Applications
▪ same with Lidocaine
▪ has significant efficacy in relieving chronic
pain, especially pain due to diabetic
neuropathy & nerve injury (off-label)
66. 1) Propanolol (Inderal®)
2) Esmolol (Brevibloc®) -
✓ a short acting β-blocker used primarily as an
antiarrhythmic drug for intraoperative and other acute
arrhythmiass
3) Sotalol
✓ a non-selective β-blocking drug that prolongs the
action potential
75. Other possible effects
▪ blocks the peripheral conversion of
thyroxine (T4) and triiodothyronine
(T3)
▪ a potential source of large amount of
inorganic iodine
76. 2) DRONEDARONE
▪ a structural analog of Amiodarone but lacks
iodine atoms
▪ the first antiarrhythmic drug to demonstrate
a reduction in mortality or hospitalization in
patients with atrial fibrillation
77. 3) VERNAKALANT
▪ an investigational multi-channel
blocker that was developed for the
treatment of atrial fibrillation
79. 4) SOTALOL
▪ Betapace®
▪ has both β-adrenergic blocking (Class
II) and action potential prolonging
actions (Class III)
80. 5) DOFETILIDE
▪ Tikosyn®
▪ approved for the maintenance of normal
sinus rhythm in patients with atrial
fibrillation
▪ S/E: Torsades de pointes
81. 6) IBUTILIDE
▪ Corvert®
▪ IV is used for the acute conversion of atrial
flutter and atrial fibrillation to normal sinus
rhythm
▪ S/E: Torsade de pointes, QT interval
prolongation
83. CLASS IV
▪ Calcium Channel Blocking drugs
▪ Verapamil - prototype
▪ first introduced as antianginal agents
▪ Dihydropyridines do not share antiarrhythmic
efficacy and may precipitate arrhythmias.
87. 2) DILTIAZEM
▪ Cardizem®
▪ appears to be similar in efficacy to
verapamil in the management of
supraventricular arrhythmias, including
rate control in atrial fibrillation