Educational for Pharmacology students

1. EVALUATION OF
ANTIARRHYTHMIC DRUGS
Dr. Nitin Shinde
1st Year Resident
LTMMC & GH, Mumbai- 22
DATE- 22-02-2014.
1

2. CONTENTS
Introduction- Basic Understanding of Arrhythmia & ECG.
Classification Of Drugs
Genetical methods.
Clinical evaluation.
Conclusion.
In – Vitro methods:
1) Isolated guinea pig papillary
muscle.
2) Langendorff technique
3) Acetylcholine & potassium Induced
arrhythmia
In-Vivo Methods:
Chemically induced arrhythmia
Electrically induced arrhythmia
Mechanically induced arrhythmia
Exercise Induced Arrhythmia
2

3. SA NODE FIRES AT 60-100
BEATS/SEC
SPREADS THROUGH ATRIA
ENTERS THE AV NODE
(DELAY OF 0.15 SEC)
PROPAGATES THROUGH HIS
PURKINJE SYSTEM
DEPOLARIZES VENTRICLES
BEGINNING FROM
ENDOCARDIAL SURFACE OF
APEX TO EPICARDIAL SURFACE
OF BASE
Normal Sinus Rhythm
3

4. The Resting Membrane Potential of the cell is -95mV
This ionic gradient is maintained by
Active mechanisms like the
Na+ pump and Na+/K+
ATPase (Electrogenic)
Fixed anionic charges
within the cell
4

5. Phase 0:
RapidDepolarisation
(Na+ influx)
Phase 1:
Early Repolarisation
(Inward Na+ current
deactivated,
Outflow of K+):
Transient Outward Current
Phase 2:
Plateau Phase
(Slow inward Ca2+ Current balanced by
outward delayed rectifier K+ Current)
Phase 3:
Late Repolarisation
(Ca 2+current inactivates,
K+ outflow)
Action Potential of Cardiac Muscle
5

6. REGULATION BY AUTONOMIC TONE
Parasympathetic/Vagus Nerve
stimulation:
• Ach binds to M receptors, releasing G
protein βγ subunits
• Activate Ach dependent K+ current
• ↓ slope of Phase 4
Sympathetic stimulation:
• Activation of β1 receptors
• Augmentation of L-type Ca2+ current
and funny currents
• ↑ slope of Phase 4
6

7. Cardiac Arrhythmias
7

8. Arrhythmia means an Abnormal heart
rhythm
Results from the abnormalities of:
 Impulse generation (Rate or Site of origin)
 Conduction
 Both
8

9. CLASSIFICATION OF ARRHYTHMIAS
1. Characteristics:
a. Flutter – very rapid but regular contractions
b. Tachyarrhthmia – increased rate
c. Bradyarrhythmia – decreased rate
d. Fibrillation – disorganized contractile activity
2. Sites involved:
a. Ventricular
b. Atrial
c. SA Node
d. AV Node
Supraventricular
9

10. MECHANISMS OF CARDIAC ARRHYTHMIAS
(A) Enhanced Automaticity:
In cells which normally display spontaneous
diastolic depolarization (SA Node, AV Node, His-
Purkinje System)
Automatic behavior in sites that ordinarily lack
pacemaker activity
10

11. A normal cardiac action potential may be
interrupted or followed by an abnormal
depolarization
Reaches threshold & causes secondary upstrokes
2 Major forms:
1. Early Afterdepolarization
2. Late Afterdepolarization
(B) Afterdepolarization and
Triggered Automaticity
11

12. (C) Re-entrant Arrhythmia
Defined as circulation of an
activation wave around an
inexitable object
3 requirements for Re-entrant
Arrhythmia:
1. Obstacle to conduction
2. Unidirectional block
3. CT>ERP
12

13. Unidirectional
Block
Establishment of Re-entrant circuit
13

14. NORMAL ECG :
P wave – Atrial depolarisation.
QRS wave – ventricular depolarisation.
T wave – ventricular repolarisation.
14

15. Management Of
Arrhythmias
15

16. MANAGEMENT
Acute Management
Prophylaxis
Non Pharmacological
Pharmacological
16

17. NON PHARMACOLOGICAL
Acute
1. Vagal Maneuvers
2. DC Cardioversion
Prophylaxis
1. Radiofrequency Ablation
2. Implantable Defibrillator
Pacing (Temporary/ Permanent)
17

18. PHARMACOLOGICAL APPROACH
Drugs may be antiarrhythmic by:
Suppressing the initiator mechanism
Altering the re-entrant circuit
1. Terminate an ongoing arrhythmia
2. Prevent an arrhythmia
18

19. VAUGHAN WILLIAMS CLASSIFICATION
Phase 4
Phase 0
Phase 1
Phase 2
Phase 3
0 mV
-
80m
V
II
I
III
IV
Class I: block Na+ channels
Ia (quinidine, procainamide,
disopyramide) (1-10s)
Ib (lignocaine) (<1s)
Ic (flecainide) (>10s)
Class II: ß-adrenoceptor
antagonists (atenolol, sotalol)
Class III: block K+ channels
(amiodarone, dofetilide,sotalol)
Class IV: Ca2+ channel
antagonists (verapamil, diltiazem)
19

20. CLASSIFICATION OF ANTIARRHYTHMICS
(BASED ON MECHANISMS OF ACTION)
Class I – blocker’s of fast Na+ channels
Subclass IA
Cause moderate Phase 0 depression
Prolong repolarization
Increased duration of action potential
Includes
Quinidine – 1st antiarrhythmic used, treat both atrial and
ventricular arrhythmias, increases refractory period
Procainamide - increases refractory period but side effects
Disopyramide – extended duration of action, used only for
treating ventricular arrthymias
20

21. CLASSIFICATION OF ANTIARRHYTHMICS
(BASED ON MECHANISMS OF ACTION)
Subclass IB
Weak phase 0 depression
Shortened depolarization
Decreased action potential duration
Includes
Lidocane (also acts as local anesthetic) – blocks na+
channels mostly in ventricular cells, also good for digitalis-
associated arrhythmias
Mexiletine - oral lidocaine derivative, similar activity
Phenytoin – anticonvulsant that also works as antiarrhythmic
similar to lidocane
21

22. CLASSIFICATION OF ANTIARRHYTHMICS
(BASED ON MECHANISMS OF ACTION)
Subclass IC
Strong Phase 0 depression
No effect of depolarization
No effect on action potential duration
Includes
Flecainide (initially developed as a local anesthetic)
Slows conduction in all parts of heart,
Also inhibits abnormal automaticity
Propafenone
Also slows conduction
Weak β – blocker
Also some Ca2+ channel blockade
22

23. CLASSIFICATION OF ANTIARRHYTHMICS
(BASED ON MECHANISMS OF ACTION)
Class II – β–adrenergic blockers
Based on two major actions
1) blockade of myocardial β–adrenergic receptors
2) Direct membrane-stabilizing effects related to Na+ channel blockade
Includes
Propranolol
causes both myocardial β–adrenergic blockade and membrane-
stabilizing effects
Slows SA node and ectopic pacemaking
Can block arrhythmias induced by exercise or apprehension
Other β–adrenergic blockers have similar therapeutic effect
Metoprolol
Nadolol
Atenolol
Acebutolol
Pindolol
Stalol
Timolol
Esmolol 23

24. CLASSIFICATION OF ANTIARRHYTHMICS
(BASED ON MECHANISMS OF ACTION)
Class III – K+ channel blockers
Developed because some patients negatively
sensitive to na channel blockers (they died!)
Cause delay in repolarization and prolonged
refractory period
Includes
Amiodarone – Prolongs action potential by delaying K+ efflux
but many other effects characteristic of other classes
Ibutilide – slows inward movement of na+ in addition to
delaying K + influx.
Bretylium – First developed to treat hypertension but found to
also suppress ventricular fibrillation associated with
myocardial infarction
Dofetilide - Prolongs action potential by delaying K+ efflux
with no other effects
24

25. CLASSIFICATION OF ANTIARRHYTHMICS
(BASED ON MECHANISMS OF ACTION)
Class IV – Ca2+ channel blockers
slow rate of AV-conduction in patients with atrial
fibrillation
Includes
Verapamil – blocks Na+ channels in addition to Ca2+;
also slows SA node in tachycardia
Diltiazem
25

26. 26

27. 27

28. 28

29. Bradyarrhythmias
Resting heart rate of <60/min
Classified as Atrial/AV Nodal/Ventricular
Management:
• Acute→ iv atropine
• Permanent→ Pacemakers.
29

30. EXPERIMENTAL
EVALUATION OF
ANTIARRHYTHMIC DRUG
ACTION…………..
30

31. Evaluation of Antiarrhythmic Drug Action
 In-Vitro Models:
1) Isolated guinea pig papillary muscle.
2) Langendorff technique
3) Acetylcholine & potassium Induced arrhythmia
In-Vivo Methods:
Chemically induced arrhythmia
Electrically induced arrhythmia
Mechanically induced arrhythmia
Exercise Induced Arrhythmia
31

32. EVALUATION OF ANTIARRHYTHMIC DRUGS
32
IN VIVO METHODS

33. IN-VIVO METHODS :
I. Chemically induced arrhythmia
II. Electrically induced arrhythmia
III. Mechanically induced arrhythmia
IV. Exercise Induced arrhythmia.
33

34. I.CHEMICALLY INDUCED ARRHTHMIA
A large number of chemical agents alone or
in combination are capable of inducing
arrhythmia.
34

35. ACONITINE ANTAGONISM IN RATS
PRINCIPLE: Aconite persistently activate sodium
channel.
METHOD:
Continues infusion
in saphenous vein
ACONITE 5mg/kg
dissolved in 0.1 N HN03
MONITOR LEAD II
ECG EVERY 30
SECONDS
Anaesthetize with
Urathene 1.25 g/kg
Test compound
3 mg/kg orally
or IV 5 minutes
before aconite
infusion
35

36. EVALUATION
The anti-arrhythmic effect of the test compound is
measured by the amount of aconitine/100 gm animal
(infusion duration ), required to precipitate...
Ventricular extra systoles.
Ventricular tachycardia.
Ventricular fibrillation and death.
E.g- procainamide 5 mg/kg IV & lidocaine 5 mg/kg IV leads
to increase in lethal dose by 65%.
36

37. DIGOXIN INDUCED ARRHYTHMIA IN GUINEA
PIGS
PRINICPLE:Over dose of cardiac glycosides induces
ventricular extrasystoles, ventricular fibrillation, and
finally death.
37

38. METHOD :
Anesthetised male guinea pigs.(Marioth 350-500
gms)
Trachea, jugular vein and carotid artery are
catheterized.
Test grp receives Test drug either orally 1 hr or iv 1 min prior to
the infusion while controlol group receieves digoxin infusion only
at rate of 85 mg / kg in 0.266 ml/min. until cardiac arrest occurs.
Lead III ECG RECORDED
38

39. EVALUATION
 The period until the onset of ventricular extra systoles,
ventricular fibrillation and cardiac arrest is recorded.
 Total amount of infused Digoxin to induce ventricular
extra systoles, or ventricular fibrillation and cardiac arrest
is calculated.
 Using Student’s t-test the doses of digoxin needed to
induce VES, VF and Cardiac arrest respectivelyafter
treatment with aniarrhythmic drugs are compared with
control receiving digoxin only.
 Eg- Standard drugs are lidocaine 3 mg/kg iv .
39

40. STROPHANTHIN OR OUABAIN INDUCED ARRHYTHMIA
IN DOG:
Principle :Strophanthin K induces ventricular
tachycardia and multifocal ventricular arrhythmia
in dogs.
METHOD: Dogs of either sex are first anesthetized &
artificial respiration is given
Two peripheral veins are cannulated for the
administration of the arrhythmia inducing
substance and the test compound.
For intraduodenal administration of the test
drug, the duodenum is cannulated..
40

41. METHOD CTD..
Strophanthin K administered by
continuous i.v infusion at a rate of
3mg/kg/min
When the arrhythmias are stable for 10 min,
the test substance is administered i.v ( 1.0
and 5.0 mg/kg) or i.d ( 10 and 30 mg/kg)
ECG recordings are obtained
at 0.5, 1, 2, 5 and 10 min
following administration of
test drugs and further
duration increased if required
41

42. EVALUATION
Ajmalin , quinidine and lidocaine reestablish normal sinus
rhythm at 1 mg/kg ,3 mg/kg iv and 10 mg/kg id.
Test compound is said to
have an ant arrhythmic
effect if extra systoles
disappear within 15 min .
The test drug is considered
to have “ NO Effect” if it
does not improve
strophanthin intoxication
within 60 min.
Test compound is said to have an
ant arrhythmic effect if the extra
systoles immediately disappear .
If not then the increasing doses
are administered at 15 min-
intervals. If the test substance
does reverse the arrhythmias the
next dose is administered after
the reappearance of stable
arrhythmias.
I.D
I.V
42

43. ADRENALINE INDUCED ARRHTHMIA
PRINCIPLE: Adrenaline at high dose may
precipitate arrhythmia.
43

44. METHOD:
Evaluation: A test compound is said to have
antiarrhythmic effect if the extrasystole disappears
immediately after drug administration.
Dogs (10-11 kg) are anaesthetized with
pentobarbitone (30-40 mg/kg ) i.p
Femoral vein is cannulated and adrenaline
is infused at a rate of 2-2.5 mg/kg via
femoral cannula
Test drug is administered 3 mins. After adrenaline infusion and
Lead II ECG Recorded.
44

45. HALOTHANE-ADRENALINE ARRHYTHMIA
Normal pacemaker activity of the heart is under the control
of sympathetic and vagal influences
Sympathomimetic drugs are known to increase pacemaker
activity
Certain anesthetics, are known to highly sensitize the
myocardium to catecholamines
Dogs and Guinea pigs
45

46. METHOD
1% halothane vaporized by 100% oxygen used for
anesthesia
The infusion rate around 2 – 3 µg/kg/min
Intravenous infusion of adrenaline
Adjusting the infusion speed enough to produce stable
vt lasting about 20 min
Drugs injected by iv bolus
46

47. II.ELECTRICALLY INDUCED ARHYTHMIAS
47

48. VENTRICULAR FIBRILLATION ELECTRICAL
THRESHOLD
Principle :Ventricular fibrillations can be induced
by various tec. Of electrical stimulation like
single pulse stimulation , train of pulse
stimulation , continous 50 HZ stimulation.
Ventricular fibrillation threshold :The minimal
current intensity of the pulse train required to
induce sustained ventricular fibrillation.
Requirement:
Animals – Adult dogs (8-12kg)
Anesthetic – Sodium pentobarbital (35mg/kg)
48

49. PROCEDURE
↓
Sinus node is crushed and electrical
stimulation is provided with Ag-AgCl
stimulating electrode embedded in a Teflon
disc sutured to anterior surface of left venticle.
Chest cavity is opened
Heart suspended in pericardial cradle
Artificial respiration – Harvard
respiratory pump
B.P – monitored
Body temperature – maintained by
thermal blanket
Adult dogs are anaesthetized and
heart is exposed.
49

50. PROCEDURE CTD…
Test drug/ std/control Drugs are
administered through the femoral
vein.
Anodal const. current for 400ms is
applied through the driving
electrode
ECG of lead II is recorded
50

51. EVALUATION
To determine VFT :- A 0.2 to 1.8 second train of
50 Hz pulses is delivered 100 ms after every
18thbasic driving stimulus. The current intensity
is increased from diastolic threshold. When
ventricular fibrillation occurs, the heart is
immedietely defibrilleted and allowed to recover
for 15-20 mins.
VFT is determined before and after
administration of test drugs at given time
intervals.
Compared using student - t Test.
51

52. PROGRAMMED ELECTRICAL STIMULATION INDUCED
RE- ENTRY ARRHYTHMIA
In dogs with old MI reopening of thoracic incision
Bipolar electrodes sutured on the non- infarcted left
ventricle
3 premature extra stimuli applied to induce vt or vf
If sustained vt or vf occurred, epicardial defibrillation
performed to stop them
After 2 control runs, iv bolus injection of drug given
Same protocol of arrhythmia induction repeated
52

53. COMMENTS
Since arrhythmias induced by applying premature extra
stimuli
mechanism of generation is thought to be re-entry around
the scar tissue of the old MI.
Drug effects demonstrated by the change in severity before
and after the drug administration
This arrhythmia model can used to demonstrate the
proarrhythmic potentials
53

54. III.MECHANICALLY INDUCED ARRHYTHMIA
Coronary artery occlusion/reperfusion
arrhythmia
54

55. CORONARY ARTERY
OCCLUSION/REPERFUSION ARRHYTHMIA
Arrhythmias –induced directly by ischemia and
reperfusion
• Coronary artery ligation in anesthetized dog
results in:
 ↑ in HR
 ↑in heart contractility
 ↑ in BP
 Ventricular arrhythmias
55

56. REQUIREMENTS
Animals – Dogs (20-25Kg)
Anesthetic – Thiobutobarbital sodium (30mg/kg)
PROCEDURE:
Animals – selected
↓
Anesthetized
↓
Artificial respiration – positive pressure respirator
↓
Femoral artery – cannulated and connected to pressure
transducer
↓
Chest cavity –opened
LAD is exposed
↓
56

57. Silk suture is placed around LAD
↓
After 45 min(equilibration) – test/std/control-
administered through saphenous vein
↓
After 20 min- ligature of coronary artery is closed for
90 min
↓
Occlusion released – reperfusion period maintained
for 30 min.
• All the parameters – recorded
• At the end – surviving animals are sacrificed by an
overdose of Pentobarbital sodium.
57

58. EVALUATION
Mortality
Hemodynamics
Arrhythmia
 Ventricular fibrillation
 % animals with VF.
58

59. CANINE TWO-STAGE CORONARY LIGATION
ARRHYTHMIA
“Two-stage” first stage is the stage of partial occlusion
second stage of permanent occlusion
59

60. METHOD
In the first stage, isolated LAD surgically isolated
The first ligature was drawn snugly but not tightly around the artery
a state of partial occlusion for 30 min then chest is closed
electrocardiogram (ECG) shows only premature ventricular
contractions (PVC)
then another suture is used to completely occlude the LAD
Arrhythmia develops 24-48 hrs after ligation and abate in 3-5 days
60

61. CONTD….
Arrhythmic ratio:
The number of ventricular ectopic beats (/min)
Total QRS complexes (/min).
For example, the arrhythmic ratio is 0 during the sinus
rhythm, while it is 1 during ventricular tachycardia.
61

62. ADVANTAGES
Produces lesser mortality as compared to complete
occlusion
Very stable arrhythmias, PVC and VT can be obtained
which usually appear several hours later
Thus resembles late arrhythmias in post mi patients
Another advantage :- Drugs administered in a conscious
state evaluation cns side effects
62

63. LIMITATIONS
Cardiac surgery under anesthesia in a sterile environment
is needed
The technique of LAD isolation requires skill
Guinea pigs never develop ischemia by in vivo coronary
ligation
63

64. IV .EXERCISE
INDUCED
ARRHYTHMIA
64

65. EXERCISE INDUCED VENTRICULAR
FIBRILLATION
PURPOSE AND RATIONALE:
Tests combining coronary constriction with physical
exercise may resemble most closely the situation in
coronary patients
65

66. • REQUIREMENTS:
Animals – Mongrel dogs (15 -19 kg)
Anesthetic – Sodium pentobarbitone (10mg/kg) i.v.
SURGICAL PREPARATION:
Animals – selected
↓
Anesthetized
↓
Chest cavity – opened
↓
Heart suspended in pericardial cradle
↓
Around left circumflex artery – Doppler flow inducer-
to measure blood pressure
- Hydraulic occluder - to occlude coronary artery
are placed
66

67. ↓
Pair of insulated silver coated wires – sutured on left
and right ventricles- measure HR (By Gould
biotachometer)
↓
Occlusion of LAD(Two stage)
↓
Myocardial infarction
↓
After 24 hrs- test drug/std/control - administered
During this experiment:
• Transdermal fentanyl patch (↓post operative
discomfort)
• Bupivacaine HCl
• Antibiotic therapy(amoxicillin)
67

68. EXERCISE-PLUS-ISCHEMIA TEST
68

69. 3-4 weeks after the production of MI
↓
Animals – run on a motor –driven treadmill at speed
6.4 km/hr (o%) grade.
↓
Work load - ↑every 3 min for total of 18 mins(0,4,8,12,16%)
↓
During last minute-treadmill is stopped- left circum flex artery-
occluded for additional 1 min.
↓
After 10-20 sec of VF – defibrillation is achieved without any delay
by placing large metal plates across animal’s chest.
EVALUATION: The exercise plus ischemia test is repeated after
administration of the test drug and compared to control (saline)
group.The effect of drugs intervention on arrhythmia formation
are determined using chi square test with yates correction.
69

70. IN VITRO METHOD:
1) Isolated guinea pig papillary muscle.
2) Langendorff technique
3) Acetylcholine & potassium Induced
arrhythmia
70

71. 1)ANTI-ARRHYTHMIC ACTIVITY IN THE ISOLATED
RIGHT VENTRICULAR GUINEA-PIG PAPILLARY
MUSCLE:
Principle: In right ventricular guinea pig papillary muscle
developed tension (DT), excitability (EX), and effective
refractory period (ERP) are measured.
71

72. METHOD:
The heart is removed & placed into a pre-warmed, pre-
oxygenated PSS & right ventricle is opened
The tendinous end of the papillary muscle is ligated with a
silk thread and the chordae tendinae are freed from the
ventricle
The preparation is mounted in organ bath &
experimental conditions are maintained
The silk thread is used to connect the muscle to
forced transducer and muscles are field stimulated to
contract isometrically at a duration of 1 ms.
72

73. Pulses are delivered using constant voltage
stimulator and
the developed tension is recorded using
polygraph recorder.
The force frequency curve is obtained by
measuring the developed tension over a
range of stimulus frequencies
(0.3,0.5,0.8,1.0,1.2 HZ)
The percentage change in post treatment
versus pretreatment developed tension at 1 HZ
is used to quantitate the agents inotropic
effect.
73

74. EVALUATION:
Change in Effective Refractory Period (Post treatment minus
pretreatment)
Degree of shift in the strength-duration curve.i.e.(area
between post and pre treatment curve)
percentage changes in post treatment developed tension.
Duration of action potential.
Contraction force.
The results of above calculations are to classify the
compounds as class I ,III or IV antiarrhythmic agents on the
basis of its effect on developed tension, excitability and
effective refractory period.
EVALUATION MOA OF DRUG
EXCITABILITY Na+ Channel
Contraction Force Ca+2 Channel
Effective Refractory period K + Channel
74

75. LANGENDORFF TECHNIQUE
75

76. PRINCIPLE: Heart is perfused in a retrograde direction from
aorta either at constant pressure or at constant flow with
oxygenated saline soln.
Retrograde perfusion closes the aortic valve , just as in situ
heart during diastole .
The perfusate is displaced through the coronary artery using a
canula inserted in the ascending aorta following of the
coronary sinus and opened right atrium and flows out via the
right ventricle and pulmonary artery.
76

77. PROCEDURE
Animal – Guinea pig (300-500g)
Animal – selected

Sacrificed (stunning)

heart – removed – placed in Ringer’s solution
(37⁰C)

Aorta – located and cut – cannulated with Ringer’s
solution (perfused at 40 mm Hg)

Ligature – placed around LAD
77

78. Ligature – placed around LAD

Test /std/control - administered.

Occluded for 10 minutes

reperfusion

ECG electrode – pulsatile stimulation, induction of
arrhythmia

Heart rate and contractile force measured
78

79. Heart rate measured through chronometer
coupled to polygraph,
Contractile force measured by force transducer.
Incidence and duration of ventricular fibrillation
or ventricular tachycardia is recorded in the
control as well as test group.
79

80. 80

81. 3)ACETYLCHOLINE & POTASSIUM INDUCED
ARRHYTHMIA
New Zealand White rabbits 0.5 to 3 kg .
The animals are sacrified and heart removed
immediately.Atria dissected from other tissue in
Ringer’s solution.
Fibrillation is produced when atria are exposed
to Acetylcholine 3x10-4 g/ml or 0.1 gm potassium
chloride.
After 5 mins exposure to Ach. Or KCL the atria
are stimulated with rectangular pulses of 0.75
ms duration of 10 V.
81

82. A mechanical record is taken on kymograph.
Controlled arrhythmia are produced and allowed
to continue for 6 to 10 mins.
After rest period of 30 mins test compound is
added to bath.
Evaluation:- Test compound is found to be
effective if fibrillation disappears immediately or
within 5 mins following test drug
supplementation to organ bath.
82

83. Genetic models
83

84. Mutations in the γ 2 subunit (PRKAG2) of AMP
activated protein kinase produce an unusual human
cardiomyopathy characterized by ventricular
hypertrophy and wolf–parkinson white syndrome .
Mutations of the K+ channel genes HERG and KVLQT 1
cause the autosomal dominant long QT syndrome,
Lande et al., Evaluated a transgenic mouse over-
expressing a dominant negative kvlqt 1 isoform, as an
in vivo screening model for ikr blocking drugs.
Transgenic mice over-expressing the inflammatory
cytokine tumour necrosis factor tnf-α (tnf-α mice) in
the heart develop a progressive heart failure syndrome
. These transgenic animals are more prone to re-
entrant arrhythmia.
84

85. HUMAN AND MOUSE CARDIAC GENES
RELATED TO INHERITED ARRHYTHMIA
85

86. 86

87. Arrhythmia type Experimental model
Wolff Parkinson white
syndrome
Transgenic PRKAG2 model
Atrial Flutter Atrial flutter induced by Ach and rapid
pacing.
Atrial flutter by aconite.
Canine right atrial occlusion injury
model.
Atrial Fibrillation Atrial fibrillation in the isolated
langendorff perfused heart.
Canine model of chronic atrial
fibrillation.
PACAP-27 induced atrial fibrillation.
Ventricular Fibrillation Ventricular fibrillation electrical
threshold.
Canine model of two stage ligation.
Ventricular arrhythmia during
exercise by ischemia.
87

88. CLINICAL
EVALUATION:
88

89. BIOEQUIVALENCE STUDY
Inclusion criteria:
 A healthy male or female 18 to 59 years of age.
 BMI range - 18-35 kg/m2,
 No significant disease or abnormal laboratory values
 Normal 12-lead ECG
 Adequately informed of the nature and risks of the study
 written informed consent
89

90. EXCLUSION CRITERIA
Women who are pregnant or breast feeding.
Known hypersensitivity or allergy to drug.
A history or presence of asthma or other pulmonary
disease, thyroid disease (hypo- or hyperthyroidism),
hepatitis or other liver disease.
Any Medical Disease or surgical condition.
The presence of abnormal lab values which are
considered clinically significant.
History of smoking or alcohol within past 1 year.
90

91. 91

92. STUDY DESIGNS IN IMPLANTABLE CARDIOVERTER-
DEFIBRILLATOR TRIALS
92

93. MINIMAL CLINICAL PARAMETERS THAT
SHOULD BE STUDIED AT BASELINE
Left ventricular ejection
fraction
Treatment at enrolment
Antiarrhythmic drugs
Rhythm control drugs
Rate control drugs
Anticoagulation
Antihypertensive therapy
(special report of angiotensin
Receptor inhibition is
suggested)
Other cardiac medication
Concomitant cardiac disease
Age, gender
Type of AF (first detected,
paroxysmal, Persistent, permanent)
Duration of AF since first detection
Prior antiarrhythmic drug treatment
Number of antiarrhythmic drugs
tested
Number of cardioversions
Number of catheter ablations or
surgical interventions
CHADS2 score
Prior antithrombotic treatment
Duration of anticoagulation (vitamin K
antagonists,other anticoagulant)
Anti-platelet treatment (aspirin,
clopidogrel, etc)
Symptoms due to AF
Arrhythmia-related symptoms (EHRA
score)
Prior stroke/transitoric ischaemic 93

94. PRIMARY OUTCOME PARAMETER
Death: Most Important primary outcome.
All-cause death should be classified in the following groups.
 Non-cardiovascular, excluding sudden death
 Cardiovascular death
 Cardiac
 Sudden (including arrhythmic, myocardial infarction,others)
 Non-sudden
 Vascular (e.g. embolic, subarachnoidal bleeds, stroke,
other)
 Treatment- or procedure-related (is also a serious adverse
event)
94

95. 95
SECONDARY OUTCOME PARAMETERS
Symptoms and quality of life
Recommended as secondary outcome parameter
No reliable instruments to quantify them
Sevirity of atrial fibrillation (SAF SCALE)
Atrial fibrillation symptoms scale (AFSS)
EHRA atrial fibrillation symptoms classification
T/t expected to primarily affect symptoms and quality of life

96. 96

97. EHRA ATRIAL FIBRILLATION SYMPTOMS
CLASSIFICATION
97

98. 98
ASSESSMENT OF RHYTHM & ECG-BASED OUTCOME
PARAMETERS
AVAILABLE ECG METHODS
•Non-continuous standard ECG recording
Symptom-activated ECG (. During
triggered visits,.Patient-activated devices)
Algorithm-activated (device monitors
rhythm)
Scheduled
Resting ECG
Transtelephonic monitoring
(24–168 h) Holter recording
Loop recorders
•Continuous ECG monitoring
Pacemakers/implanted defibrillators
ECG garment equipped with radio data
transmission
(E.C.G. GSM-based)
ECG-based outcome
parameters
Freedom from AF (suitable
for time-based assessment)
Change in AF pattern (e.G.
Altered AF burden, altered
AF type,
Among many others)
Proarrhythmia (e.G. Sudden
death, ventricular
tachycardia,
Torsades de pointes, atrial
flutter, bradycardia, AV nodal
Block)
Ventricular rate during AF at
rest and during exercise

99. CURRENT STATUS OF ANTIARRHYTHMIC DRUGS
Based on results of large Randomized controlled trials
Cardioversion /defibrillator devices as compared to
Antiarrhythmic drugs have proved to
Be superior in prolonging survival
99

100. CONCLUSION
Although no animal model can accurately
resemble with human disease condition and
species differences also exist, close similarities
with humans suffering from or threatened by
arrhythmias can be developed by selecting
appropriate model and species.
Rather than a single model or experimental
technique, combinations of investigations, like
isolated heart (langendorff arrangement or
working heart), whole hearts in anesthetized or
conscious animals, excised cardiac preparations,
testing the function can be used.
100

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