SlideShare a Scribd company logo
1 of 82
Download to read offline
Antiarrhythmic Drugs
Rhythm
a regular, repeated pattern of sounds or movements.
Cardiac dysrhythmia
(also known as arrhythmia or irregular heartbeat)
is any of a group of conditions in which the electrical activity of the heart is irregular or
faster or slower than normal.
The heart beat may be:
Too fast (over 100 beats per minute).
Too slow (less than 60 beats per minute).
Regular or irregular.
A heart beat that is:
Too fast is called tachycardia.
Too slow is called bradycardia.
Antiarrhythmic agents
are a group of drugs that are used to suppress abnormal rhythms of the heart.
Cardiac
Electrophysiology
Properties of Cardiac Muscle
Autorhythmicity Excitability
Conductivity Contractility
The Conducting System
 The Nodal System
 Sinoatrial Node (S-A node) 1
 Atrioventricular Node (A-V node) 3
 The Internodal System
 Anterior, Middle & Posterior 2
 Bachmann`s bundle 7
 The Purkinje System
 Atrioventricular bundle (bundle of His) 4
 Right & left bundle branch 5
 Purkinje fibers 6
Normal conduction pathway:
1- SA node generates action
potential and delivers it to
the atria and the AV node
2- The AV node delivers the
impulse to purkinje fibers
3- purkinje fibers conduct the
impulse to the ventricles
Other types of
conduction that
occurs between
myocardial cells:
When a cell is
depolarized 
adjacent cell
depolarizes along
Pacemaker
SA-node
Primary pacemaker
105 impulse/min
Sinus rhythm
AV-node
Secondary pacemaker
45-60 impulse/min
Nodal rhythm
Purkinje System
Tertiary pacemaker
25-40 impulse/min
Idioventricular rhythm
Inhibitory vagal
tone
Myocardial Physiology
Autorhythmic Cells (Pacemaker Cells)
 Characteristics of Pacemaker Cells
 The membrane reach threshold potential (-40mV) by itself
 when the membrane potential is very negative (about -60 mV), ion
channels open that conduct slow, inward (depolarizing) Na+ currents.
These currents are called "funny" currents and abbreviated as "If".
 As the membrane potential reaches about -50 mV, another type of
channel opens. This channel is called transient or T-type Ca++ channel.
 When the membrane depolarizes to about -40 mV, a second type of
Ca++ channel opens. These are the so-called long-lasting, or L-type
Ca++ channels. Opening of these channels causes more Ca++ to enter
the cell and to further depolarize the cell until an action potential threshold
is reached.
 Repolarization occurs (Phase 3) as K+ channels open thereby increasing
the outward K+ currents. At the same time, the L-type Ca++ channels
become inactivated and close
Pacemaker AP
Phase 4: pacemaker
potential
Na influx and K efflux
and Ca influx until the
cell reaches threshold
and then turns into
phase 0
Phase 0: upstroke:
Due to Ca++ influx
Phase 3:
repolarization:
Due to K+ efflux
Pacemaker cells (automatic cells) have
unstable membrane potential so they can
generate AP spontaneously
Myocardial Physiology
Autorhythmic Cells (Pacemaker Cells)
 Characteristics of Pacemaker Cells
Pacemaker cells (automatic cells) have unstable membrane potential so they
can generate AP spontaneously
Myocardial Physiology
Contractile Cells
 Special aspects
 The action potential of a contractile cell
 Ca2+ plays a major role again
 Phases
4 – resting membrane potential @ -90mV
0 – depolarization
 Voltage gated Na+ channels open… close at 20mV
1 – temporary repolarization
 Open K+ channels allow some K+ to leave the cell
2 – plateau phase
 Voltage gated Ca2+ channels are fully open
3 – repolarization
 Ca2+ channels close and K+ permeability increases as more
activated K+ channels open, causing a quick repolarization
 What is the significance of the plateau phase?
Non-pacemaker action potential
Phase 0: fast
upstroke
Due to Na+
influx
Phase 3:
repolarization
Due to K+ efflux
Phase 4: resting
membrane potential
Phase 2: plateu
Due to Ca++
influx
Phase 1: partial
repolarization
Due to rapid efflux of K+
N.B. The slope of phase 0 = conduction velocity
Also the peak of phase 0 = Vmax
+30 mV
0 mV
-80 mV
-90 mV
OUTSIDE
MEMBRANE
INSIDE
Na+
0
4
3
2
1
K+
Ca++ K+ K+
Na+
K+
Ca++
Na+
K+
Na+
Resting
open
Inactivated
Phase zero
depolarization
Early
repolarization Plateau phase
Rapid
Repolarization
phase
Phase 4 Resting
membrane
potential
Myocardial Physiology
Contractile Cells
Effective and relative refractory periods
ERP RRP
ERP due to inactivated Na and Ca channels,
once they begin to recover the RRP begins.
The absolute refractory period
The absolute refractory period:
 During the absolute refractory period, the excitability level is 0%.
 No stimulus however strong can produce a propagated action potential
in the heart.
 This period begins with depolarization till mid-repolarization
 It lasts for the whole period of systole and the early part of diastole.
The relative refractory period
The relative refractory period:
 During the relative refractory period the excitability level is
more than 0 but less than 100% of the resting basal level.
 The heart responds only to stronger stimuli.
 It is a short period that begins at mid-repolarization and ends
shortly before complete repolarization.
 It lasts for a short period during diastole.
What is the Electrocardiogram?
ECG (EKG)
showing wave
segments
Contraction
of atria
Contraction of
ventricles
Repolarization of
ventricles
PR interval: represents
the rate of A-V
conduction
QS interval: represents
the duration of
ventricular systole
ANS Control of Heart
Cardiac Properties Parasympathetic (Vagal) Sympathetic
Supplies the atria, SA
node, AV node & AV
bundle but not the
ventricles
Supplies all cardiac
tissue including the
ventricles
Rhythmicity Slowing due to
depression of SA node
Acceleration due to ↑
of SA node
Excitability ↓ ↑
AV conduction ↓ (heart block) ↑
Contractility Depressed in atria Stimulated in atria
and ventricles
Rate of O2
consumption
↓ ↑
Arrhythmia
If the arrhythmia arises from the
ventricles it is called ventricular
arrhythmia
If the arrhythmia arises from
atria, SA node, or AV node it is
called supraventricular
arrhythmia
Causes of
arrhythmia
arteriosclerosis
Coronary artery
spasm
Heart block
Myocardial
ischemia
Mechanisms of Arrhythmogenesis
1- Abnormal impulse generation
Automatic rhythms Triggered rhythms
2-Abnormal conduction
Conduction block Reentry
Automatic rhythms
Enhanced normal
automaticity
Ectopic focus
↑AP from SA node
AP arises from sites other
than SA node
Ectopic foci
An ectopic focus is an area in the contractile myocardium, which
discharges electrical impulses.
Normally, the contractile myocardium has a stable resting
membrane potential
Under some non-physiological conditions, some myocardial cells
acquire rhythmic electrical activity and act as foci that send un-
timed electrical impulses or might even take over the heart and
act as the pacemaker.
 Factors that enhance automaticity include:
 SANS,  PANS,  CO2,  O2,  H+,  stretch, hypokalemia and hypocalcaemia.
Triggered rhythms
Delayed
afterdepolarization
Early
afterdepolarization
Triggered beats occur when problems at the level of the ion channels in
individual heart cells result in abnormal propagation of electrical activity and
can lead to sustained abnormal rhythm.
Early afterdepolarizations (EADs) occur
with abnormal depolarization during
phase 2 or phase 3, and are caused by
an increase in the frequency of abortive
action potentials before normal
repolarization is completed.
Before another action potential would
normally occur. Delayed afterdepolarizations
(DADs) begin during phase 4 - after
repolarization is completed
2-Abnormal conduction
Conduction block
1st
degree
2nd
degree
3rd
degree
Reentry
This is when the
impulse is not
conducted from
the atria to the
ventricles
First-degree heart block – The electrical impulses are slowed as they pass
through the conduction system, but they all successfully reach the
ventricles.
Second-degree heart block– The electrical impulses are delayed further and
further with each heartbeat until a beat fails to reach to the ventricles entirely.
Third-degree heart block – With this condition, also called complete heart
block, none of the electrical impulses from the atria reach the ventricles.
Reentry
Circus
movement
Reflection
Re-entry is a common cause of arrhythmias.
Ventricular tachycardia and AV-nodal re-entry are typical
examples. Re-entry can occur when a conduction path is
partly slowed down.
Here is an accessory
pathway in the heart
called Bundle of Kent
•Present only in small populations
•Lead to reexcitation  Wolf-Parkinson-White
Syndrome (WPW)
Abnormal anatomic conduction
Wolff–Parkinson–White syndrome (WPW) is one of several disorders of
the conduction system of the heart. WPW is caused by the presence of an
abnormal accessory electrical conduction pathway between the atria and
the ventricles.
Electrical signals travelling down this abnormal pathway (known as the
bundle of Kent) may stimulate the ventricles to contract prematurely.
Bradyarrhythmias
THE SLOW POKES (HR<60)…
First Degree AV Block
 Delay at the AV node results in prolonged
PR interval
 PR interval>0.2 sec.
 Leave it alone
Second Degree AV Block Type
1 (Wenckebach)
 Increasing delay at AV node until a p wave is not
conducted.
 Often comes post inferior MI with AV node ischemia
 Gradual prolongation of the PR interval before a
skipped QRS. QRS are normal!
 No pacing as long as no bradycardia.
Second Degree AV Block Type
2
 Diseased bundle of HIS with BBB.
 Sudden loss of a QRS wave because p
wave was not transmitted beyond AV node.
QRS are abnormal!
 May be precursor to complete heart block
and needs pacing.
Third Degree AV Block
 Complete heart block where atria and
ventricles beat independently AND atria beat
faster than ventricles.
 Must treat with pacemaker.
Supraventricular Arrhythmias
 Sinus Tachycardia: high sinus rate of 100-180 beats/min, occurs during
exercise or other conditions that lead to increased SA nodal firing rate.
 Atrial Tachycardia: a series of 3 or more consecutive atrial premature beats
occurring at a frequency >100/min
 Paroxysmal Atrial Tachycardia (PAT): tachycardia which begins and
ends in acute manner.
 Atrial Flutter: sinus rate of 250-350 beats/min.
 Atrial Fibrillation: uncoordinated atrial depolarizations.
AV blocks
A conduction block within the AV node , occasionally in the bundle of His, that
impairs impulse conduction from the atria to the ventricles.
Types of Arrhythmia
 Ventricular Premature Beats (VPBs): caused by ectopic
ventricular foci; characterized by widened QRS.
 Ventricular Tachycardia (VT): high ventricular rate caused by
abnormal ventricular automaticity or by intraventricular reentry; can
be sustained or non-sustained (paroxysmal); characterized by
widened QRS; rates of 100 to 200 beats/min; life-threatening.
 Ventricular Flutter: ventricular depolarizations >200/min.
 Ventricular Fibrillation: uncoordinated ventricular depolarizations
Ventricular Arrhythmias
Pharmacologic Rationale & Goals
 The ultimate goal of antiarrhythmic drug therapy:
o Restore normal sinus rhythm and conduction
o Prevent more serious and possibly lethal arrhythmias from occurring.
 Antiarrhythmic drugs are used to:
 decrease conduction velocity
 change the duration of the effective refractory period (ERP)
 suppress abnormal automaticity
Antyarrhythmic drugs
class mechanism action notes
I Na+ channel blocker
Change the slope of
phase 0
Can abolish
tachyarrhythmia
caused by reentry
circuit
II β blocker
↓heart rate and
conduction velocity
Can indirectly alter K
and Ca conductance
III K+ channel blocker
1. ↑action potential
duration (APD) or
effective refractory
period (ERP).
2. Delay repolarization.
Inhibit reentry
tachycardia
IV Ca++ channel blocker
Slowing the rate of rise
in phase 4 of SA node
↓conduction velocity
in SA and AV node
•Most antiarrhythmic drugs are pro-arrhythmic (promote arrhythmia)
•They are classified according to Vaughan William into four classes according to their
effects on the cardiac action potential
Proarrhythmia is a new arrhythmias, paradoxically
precipitated by antiarrhythmic therapy, which means it is a
side effect associated with the administration of some
existing antiarrhythmic drugs, as well as drugs for other
indications.
In other words, it is a tendency of antiarrhythmic drugs to
facilitate emergence of new arrhythmias
Class I
IA IB IC
They ↓ conduction velocity in non-nodal
tissues (atria, ventricles, and purkinje fibers)
They act on open
Na+ channels or
inactivated only
Have moderate K+
channel blockade
So they are used
when many Na+
channels are opened
or inactivated (in
tachycardia only)
because in normal
rhythm the channels
will be at rest state
so the drugs won’t
work
Class I drugs
 Slowing of the rate of rise in phase 0 
↓conduction velocity
 ↓of Vmax of the cardiac action potential
 They prolong muscle action potential &
ventricular (ERP)
 They ↓ the slope of Phase 4 spontaneous
depolarization (SA node)  decrease
enhanced normal automaticity
Class IA
Quinidine Procainamide
They make the
slope more
horizontal
Class IA Drugs
 They possess intermediate rate of association and dissociation
(moderate effect) with sodium channels.
Pharmacokinetics:
procainamide
Good oral
bioavailability
Used as IV to
avoid
hypotension
quinidine
Good oral
bioavailability
Metabolized
in the liver
Procainamide metabolized into N-acetylprocainamide (NAPA) (active class
III) which is cleared by the kidney (avoid in renal failure)
Class IA Drugs Uses
 Quinidine is rarely used for supraventricular arrhythmias
 IV procainamide is used for acute conversion of atrial
fibrillation
 Oral quinidine/procainamide are used with class III drugs in
ventricular tachycardia
 IV procainamide used for hemodynamically stable
ventricular tachycardia
Class IA Drugs Toxicity
quinidine
AV block
Torsades de pointes
arrhythmia because it
↑ ERP (QT interval)
Shortens A-V nodal
refractoriness (↑AV
conduction) by
antimuscarinic like
effect
↑digoxin concentration
by :
1- displace from tissue
binding sites
2- ↓renal clearance
Ventricular
tachycardia
procainamide
Asystole or
ventricular
arrhythmia
Hypersensitivity : fever,
agranulocytosis
Systemic lupus erythromatosus (SLE)-like
symptoms: arthralgia, fever, pleural-
pericardial inflammation.
Symptoms are dose and time dependent
Common in patients with slow hepatic
acetylation
Systemic lupus erythematosus (also called lupus or SLE) is a
disease where a person's immune system attacks and injures
the body's own organs and tissues. Almost every system of
the body can be affected by SLE.
Arthralgia means joint pain. It is a combination of two Greek
words – Arthro – joint and algos – pain.
Agranulocytosis a failure of the bone marrow to make enough
white blood cells (neutrophils).
Notes:
Torsades de pointes: twisting of the point . Type of
tachycardia that gives special characteristics on ECG
At large doses of quinidine  cinchonism occurs:blurred vision, tinnitus, headache,
psychosis and gastrointestinal upset
 Both a defibrillator and a pacemaker are used in patient with heart
disease.
 A defibrillator is used to shock the heart when a patient goes into
cardiac arrest.
 A pacemaker is used to regulate abnormal heart rate or rhythm.
Class IB Drugs
 They shorten Phase 3
repolarization
 ↓ the duration of the cardiac
action potential
 They suppress arrhythmias
caused by abnormal automaticity
 They show rapid association &
dissociation (weak effect) with
Na+ channels with appreciable
degree of use-dependence
 No effect on conduction velocity
Class IB
lidocaine mexiletine tocainide
Agents of Class IB
Lidocaine
 Used IV because of extensive 1st
pass metabolism
 Lidocaine is the drug of choice in
emergency treatment of ventricular
arrhythmias
 Has CNS effects: drowsiness,
numbness, convulstion, and
nystagmus
Mexiletine
 These are the oral analogs of lidocaine
 Mexiletine is used for chronic
treatment of ventricular arrhythmias
associated with previous myocardial
infarction
Uses
They are used in the treatment of ventricular arrhythmias arising during myocardial
ischemia or due to digoxin toxicity
They have little effect on atrial or AV junction arrhythmias (because they don’t act on
conduction velocity)
Adverse effects:
1- neurological effects
2- negative inotropic activity
Class IC Drugs
 They markedly slow Phase 0 fast
depolarization
 They markedly slow conduction in
the myocardial tissue
 They possess slow rate of
association and dissociation
(strong effect) with sodium
channels
 They only have minor effects on
the duration of action potential
and refractoriness
Class IC
flecainide propafenone
Uses:
 Refractory ventricular arrhythmias.
 Flecainide is a particularly potent suppressant of premature ventricular
contractions (beats)
Toxicity and Cautions for Class IC Drugs:
 They are severe proarrhythmogenic drugs causing:
1. severe worsening of a preexisting arrhythmia
2. de novo occurrence of life-threatening ventricular tachycardia
 In patients with frequent premature ventricular contraction (PVC)
following MI, flecainide increased mortality compared to placebo.
Notice: Class 1C drugs are particularly of low safety and have
shown even increase mortality when used chronically after MI
Compare between class IA, IB, and IC drugs as
regards effect on Na+ channel & ERP
 Sodium channel blockade:
IC > IA > IB
 Increasing the ERP:
IA>IC>IB (lowered)
Because of
K+
blockade
Class II ANTIARRHYTHMIC DRUGS
(β-adrenergic blockers)
Mechanism of action
 Negative inotropic and
chronotropic action.
 Prolong AV conduction
(delay)
 Diminish phase 4
depolarization  suppressing
automaticity(of ectopic focus)
Uses
 Treatment of increased sympathetic
activity-induced arrhythmias such as
stress- and exercise-induced arrhythmias
 Atrial flutter and fibrillation.
 AV nodal tachycardia.
 Reduce mortality in post-myocardial
infarction patients
 Protection against sudden cardiac death
Class II ANTIARRHYTHMIC DRUGS
 Propranolol (nonselective): was proved to reduce the incidence of
sudden arrhythmatic death after myocardial infarction
 Metoprolol
 reduce the risk of bronchospasm
 Esmolol:
 Esmolol is a very short-acting β1-adrenergic blocker that is used by
intravenous route in acute arrhythmias occurring during surgery or
emergencies
selective
Class III ANTIARRHYTHMIC
DRUGS
K+ blockers
 Prolongation of phase 3
repolarization without altering
phase 0 upstroke or the resting
membrane potential
 They prolong both the duration of the action
potential and ERP
 Their mechanism of action is still not clear but
it is thought that they block potassium
channels
Uses:
 Ventricular arrhythmias, especially ventricular fibrillation or tachycardia
 Supra-ventricular tachycardia
 Amiodarone usage is limited due to its wide range of side effects
Class III
sotalol amiodarone ibutilide
Sotalol (Sotacor)
 Sotalol also prolongs the duration of action potential and
refractoriness in all cardiac tissues (by action of K+ blockade)
 Sotalol suppresses Phase 4 spontaneous depolarization and
possibly producing severe sinus bradycardia (by β blockade
action)
 The β-adrenergic blockade combined with prolonged action
potential duration may be of special efficacy in prevention of
sustained ventricular tachycardia
 It may induce the polymorphic torsades de pointes ventricular
tachycardia (because it increases ERP)
Ibutilide
Used in atrial fibrillation or flutter
IV administration
May lead to torsade de pointes
Only drug in class three that possess pure K+ blockade
Amiodarone (Cordarone)
 Amiodarone is a drug of multiple actions and is still not well understood
 It is extensively taken up by tissues, especially fatty tissues (extensive
distribution)
 t1/2 = 60 days
 Potent P450 inhibitor
 Amiodarone antiarrhythmic effect is complex comprising class I, II, III, and
IV actions
• Dominant effect: Prolongation of action potential duration and refractoriness
• It slows cardiac conduction, works as Ca2+ channel blocker, and as a weak β-
adrenergic blocker
Toxicity
 Most common include GI intolerance, tremors, ataxia, dizziness, and hyper-or
hypothyrodism
 Corneal microdeposits may be accompanied with disturbed night vision
 Others: liver toxicity, photosensitivity, gray facial discoloration, neuropathy,
muscle weakness, and weight loss
 The most dangerous side effect is pulmonary fibrosis which occurs in 2-
5% of the patients
Class IV ANTIARRHYTHMIC
DRUGS
(Calcium Channel Blockers)
 Calcium channel blockers decrease inward Ca2+
currents resulting in a decrease of phase 4
spontaneous depolarization (SA node)
 They slow conductance in Ca2+ current-dependent
tissues like AV node.
 Examples: verapamil & diltiazem
Because they act on the heart only and not on blood
vessels.
 Dihydropyridine family are not used
because they only act on blood vessels
Mechanism of
action
 They bind only to depolarized (open) channels  prevention of repolarization
 They prolong ERP of AV node  ↓conduction of impulses from the atria to the ventricles
So they act only in cases of arrhythmia because many Ca2+
channels are depolarized while in normal rhythm many of them
are at rest
More effective in treatment of atrial than ventricular arrhythmias.
Treatment of supra-ventricular tachycardia preventing the
occurrence of ventricular arrhythmias
Treatment of atrial flutter and fibrillation
Uses
contraindication
 Contraindicated in patients with pre-existing depressed heart function
because of their negative inotropic activity
Adverse effects
 Cause bradycardia, and asystole especially when given in combination
with β-adrenergic blockers
Miscellaneous Antiarrhythmic Drugs
Adenosine
o Adenosine activates A1-purinergic receptors decreasing the SA
nodal firing and automaticity, reducing conduction velocity,
prolonging effective refractory period, and depressing AV nodal
conductivity
o It is the drug of choice in the treatment of paroxysmal supra-
ventricular tachycardia
o It is used only by slow intravenous bolus
o It only has a low-profile toxicity (lead to bronchospasm) being
extremly short acting for 15 seconds only
Magnesium indications.
 1. Torsades de point from any reason.
 2. Arrhythmias in a patient with known
hypomagnesaemia.
 3. Consider its use in acute ischaemia to prevent
early ventricular arrhythmias.
 4. Digoxin induced arrhythmias.
 A. Digoxin
 Digoxin [di-JOX-in] shortens the refractory period in atrial and ventricular
myocardial cells while prolonging the effective refractory period and
diminishing conduction velocity in the AV node.
 Digoxin is used to control the ventricular response rate in atrial fibrillation
and flutter. At toxic concentrations, digoxin causes ectopic ventricular beats
that may result in ventricular tachycardia and fibrillation.
 [Note: This arrhythmia is usually treated with lidocaine or phenytoin.]
class ECG QT Conduction
velocity
Refractory
period
IA ++ ↓ ↑
IB 0 no ↓
IC + ↓ no
II 0 ↓In SAN and
AVN
↑ in SAN and
AVN
III ++ No ↑
IV 0 ↓ in SAN and
AVN
↑ in SAN and
AVN
1st: Reduce thrombus formation by using anticoagulant warfarin
2nd: Prevent the arrhythmia from converting to ventricular arrhythmia:
First choice: class II drugs:
•After MI or surgery
•Avoid in case of heart failure
Second choice: class IV
Third choice: digoxin
•Only in heart failure of left ventricular dysfunction
3rd: Conversion of the arrhythmia into normal sinus rhythm:
Class III:
IV ibutilide, IV/oral amiodarone, or oral sotalol
Class IA:
Oral quinidine + digoxin (or any drug from the 2nd step)
Class IC:
Oral propaphenone or IV/oral flecainide
Use direct current in case
of unstable hemodynamic
patient
First choice: class II
•IV followed by oral
•Early after MI
Second choice: amiodarone
Avoid using
class IC after
MI  ↑
mortality
First choice: Lidocaine IV
•Repeat injection
Second choice: procainamide IV
•Adjust the dose in case of renal failure
Third choice: class III drugs
•Especially amiodarone and sotalol
Premature ventricular beat (PVB)
Recommendations for focal Atrial
Tachycardia
‫تجميعات‬
:
(IA, IC, class III)  torsades de pointes.
Classes II and IV  bradycardia (don’t combine the two)
In atrial flutter use (1st ↓impulses from atria to ventricular to prevent
ventricular tachycardia)
1. Class II
2. Class IV
3. Digoxin.
(
‫الترتيب‬ ‫على‬
)
2nd convert atrial flutter to normal sinus rhythm use:
1. Ibutilide
2. Sotalol
3. IA or IC.
(
‫الترتيب‬ ‫على‬
)
If you use quinidine combine it with digoxin or β blocker (because of its anti
muscarinic effect)
Avoid IC in myocardial infarction because it ↑ mortality
 Vernakalant
 Ajmaline
 Pilsicainide
 Ranolazine

More Related Content

Similar to arrhythmia-211205224744.pdf33333333333333

Arrhythmia: Mechanism, Classification, ECG features
Arrhythmia: Mechanism, Classification, ECG featuresArrhythmia: Mechanism, Classification, ECG features
Arrhythmia: Mechanism, Classification, ECG featuresFarheen Ansari
 
arrhythbbbbbbbbbbbbbbbbbbbbbbbbmia .pptx
arrhythbbbbbbbbbbbbbbbbbbbbbbbbmia .pptxarrhythbbbbbbbbbbbbbbbbbbbbbbbbmia .pptx
arrhythbbbbbbbbbbbbbbbbbbbbbbbbmia .pptxeman458700
 
arrhythnnnnnnnnnnnnnnnnnnnnmia post.pptx
arrhythnnnnnnnnnnnnnnnnnnnnmia post.pptxarrhythnnnnnnnnnnnnnnnnnnnnmia post.pptx
arrhythnnnnnnnnnnnnnnnnnnnnmia post.pptxeman458700
 
Anti arrhythmic drug thereapy
Anti arrhythmic drug thereapy Anti arrhythmic drug thereapy
Anti arrhythmic drug thereapy Dr. Pravin Wahane
 
Electrical conductance of Heart
Electrical conductance of HeartElectrical conductance of Heart
Electrical conductance of HeartJaineel Dharod
 
Lecture 13 abn conduction- Pathology
Lecture 13 abn conduction- Pathology Lecture 13 abn conduction- Pathology
Lecture 13 abn conduction- Pathology Areej Abu Hanieh
 
Arrhythmias general
Arrhythmias generalArrhythmias general
Arrhythmias generalAdarsh
 
Tachyarrhythmias
TachyarrhythmiasTachyarrhythmias
TachyarrhythmiasSmita Jain
 
Cardiac arrhythmia
Cardiac arrhythmiaCardiac arrhythmia
Cardiac arrhythmiaMahesh Kumar
 
Prof.-Randa-Cardiac-Arrhythmias.ppt
Prof.-Randa-Cardiac-Arrhythmias.pptProf.-Randa-Cardiac-Arrhythmias.ppt
Prof.-Randa-Cardiac-Arrhythmias.pptbesoneso
 
APPROACH TO NARROW COMPLEX TACHYCARDIA
APPROACH TO NARROW COMPLEX TACHYCARDIAAPPROACH TO NARROW COMPLEX TACHYCARDIA
APPROACH TO NARROW COMPLEX TACHYCARDIAPDT DM CARDIOLOGY
 
approach to narrow comlex tachycardia
approach to narrow comlex tachycardiaapproach to narrow comlex tachycardia
approach to narrow comlex tachycardiakrishna7717
 
PERIOPERATIVE ARRYTHMIAS
PERIOPERATIVE ARRYTHMIASPERIOPERATIVE ARRYTHMIAS
PERIOPERATIVE ARRYTHMIASashishnair22
 
Basics of arrhythmias&antiarrhythmic drugs
Basics of arrhythmias&antiarrhythmic drugsBasics of arrhythmias&antiarrhythmic drugs
Basics of arrhythmias&antiarrhythmic drugsIslam Ghanem
 

Similar to arrhythmia-211205224744.pdf33333333333333 (20)

Arrhythmia: Mechanism, Classification, ECG features
Arrhythmia: Mechanism, Classification, ECG featuresArrhythmia: Mechanism, Classification, ECG features
Arrhythmia: Mechanism, Classification, ECG features
 
Antiarrythmic drugs
Antiarrythmic drugsAntiarrythmic drugs
Antiarrythmic drugs
 
arrhythbbbbbbbbbbbbbbbbbbbbbbbbmia .pptx
arrhythbbbbbbbbbbbbbbbbbbbbbbbbmia .pptxarrhythbbbbbbbbbbbbbbbbbbbbbbbbmia .pptx
arrhythbbbbbbbbbbbbbbbbbbbbbbbbmia .pptx
 
arrhythnnnnnnnnnnnnnnnnnnnnmia post.pptx
arrhythnnnnnnnnnnnnnnnnnnnnmia post.pptxarrhythnnnnnnnnnnnnnnnnnnnnmia post.pptx
arrhythnnnnnnnnnnnnnnnnnnnnmia post.pptx
 
Anti arrhythmic drug thereapy
Anti arrhythmic drug thereapy Anti arrhythmic drug thereapy
Anti arrhythmic drug thereapy
 
Electrical conductance of Heart
Electrical conductance of HeartElectrical conductance of Heart
Electrical conductance of Heart
 
Cardiovascular system
Cardiovascular systemCardiovascular system
Cardiovascular system
 
Arrhythmias
ArrhythmiasArrhythmias
Arrhythmias
 
Lecture 13 abn conduction- Pathology
Lecture 13 abn conduction- Pathology Lecture 13 abn conduction- Pathology
Lecture 13 abn conduction- Pathology
 
arrythmia 1.pptx
arrythmia 1.pptxarrythmia 1.pptx
arrythmia 1.pptx
 
Arrhythmias general
Arrhythmias generalArrhythmias general
Arrhythmias general
 
Tachyarrhythmias
TachyarrhythmiasTachyarrhythmias
Tachyarrhythmias
 
CARDIAC ARRHYTHMIAS
CARDIAC ARRHYTHMIASCARDIAC ARRHYTHMIAS
CARDIAC ARRHYTHMIAS
 
Cardiac arrhythmia
Cardiac arrhythmiaCardiac arrhythmia
Cardiac arrhythmia
 
Prof.-Randa-Cardiac-Arrhythmias.ppt
Prof.-Randa-Cardiac-Arrhythmias.pptProf.-Randa-Cardiac-Arrhythmias.ppt
Prof.-Randa-Cardiac-Arrhythmias.ppt
 
APPROACH TO NARROW COMPLEX TACHYCARDIA
APPROACH TO NARROW COMPLEX TACHYCARDIAAPPROACH TO NARROW COMPLEX TACHYCARDIA
APPROACH TO NARROW COMPLEX TACHYCARDIA
 
approach to narrow comlex tachycardia
approach to narrow comlex tachycardiaapproach to narrow comlex tachycardia
approach to narrow comlex tachycardia
 
Cardiac Arrhythmias
Cardiac ArrhythmiasCardiac Arrhythmias
Cardiac Arrhythmias
 
PERIOPERATIVE ARRYTHMIAS
PERIOPERATIVE ARRYTHMIASPERIOPERATIVE ARRYTHMIAS
PERIOPERATIVE ARRYTHMIAS
 
Basics of arrhythmias&antiarrhythmic drugs
Basics of arrhythmias&antiarrhythmic drugsBasics of arrhythmias&antiarrhythmic drugs
Basics of arrhythmias&antiarrhythmic drugs
 

Recently uploaded

Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual NeedsBangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual NeedsGfnyt
 
Bangalore Call Girls Majestic 📞 9907093804 High Profile Service 100% Safe
Bangalore Call Girls Majestic 📞 9907093804 High Profile Service 100% SafeBangalore Call Girls Majestic 📞 9907093804 High Profile Service 100% Safe
Bangalore Call Girls Majestic 📞 9907093804 High Profile Service 100% Safenarwatsonia7
 
Lucknow Call girls - 8800925952 - 24x7 service with hotel room
Lucknow Call girls - 8800925952 - 24x7 service with hotel roomLucknow Call girls - 8800925952 - 24x7 service with hotel room
Lucknow Call girls - 8800925952 - 24x7 service with hotel roomdiscovermytutordmt
 
Call Girls Darjeeling Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Darjeeling Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Darjeeling Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Darjeeling Just Call 9907093804 Top Class Call Girl Service AvailableDipal Arora
 
Russian Escorts Girls Nehru Place ZINATHI 🔝9711199012 ☪ 24/7 Call Girls Delhi
Russian Escorts Girls  Nehru Place ZINATHI 🔝9711199012 ☪ 24/7 Call Girls DelhiRussian Escorts Girls  Nehru Place ZINATHI 🔝9711199012 ☪ 24/7 Call Girls Delhi
Russian Escorts Girls Nehru Place ZINATHI 🔝9711199012 ☪ 24/7 Call Girls DelhiAlinaDevecerski
 
Call Girls Colaba Mumbai ❤️ 9920874524 👈 Cash on Delivery
Call Girls Colaba Mumbai ❤️ 9920874524 👈 Cash on DeliveryCall Girls Colaba Mumbai ❤️ 9920874524 👈 Cash on Delivery
Call Girls Colaba Mumbai ❤️ 9920874524 👈 Cash on Deliverynehamumbai
 
VIP Russian Call Girls in Varanasi Samaira 8250192130 Independent Escort Serv...
VIP Russian Call Girls in Varanasi Samaira 8250192130 Independent Escort Serv...VIP Russian Call Girls in Varanasi Samaira 8250192130 Independent Escort Serv...
VIP Russian Call Girls in Varanasi Samaira 8250192130 Independent Escort Serv...Neha Kaur
 
Call Girls Service Pune Vaishnavi 9907093804 Short 1500 Night 6000 Best call ...
Call Girls Service Pune Vaishnavi 9907093804 Short 1500 Night 6000 Best call ...Call Girls Service Pune Vaishnavi 9907093804 Short 1500 Night 6000 Best call ...
Call Girls Service Pune Vaishnavi 9907093804 Short 1500 Night 6000 Best call ...Miss joya
 
💎VVIP Kolkata Call Girls Parganas🩱7001035870🩱Independent Girl ( Ac Rooms Avai...
💎VVIP Kolkata Call Girls Parganas🩱7001035870🩱Independent Girl ( Ac Rooms Avai...💎VVIP Kolkata Call Girls Parganas🩱7001035870🩱Independent Girl ( Ac Rooms Avai...
💎VVIP Kolkata Call Girls Parganas🩱7001035870🩱Independent Girl ( Ac Rooms Avai...Taniya Sharma
 
Aspirin presentation slides by Dr. Rewas Ali
Aspirin presentation slides by Dr. Rewas AliAspirin presentation slides by Dr. Rewas Ali
Aspirin presentation slides by Dr. Rewas AliRewAs ALI
 
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...astropune
 
High Profile Call Girls Coimbatore Saanvi☎️ 8250192130 Independent Escort Se...
High Profile Call Girls Coimbatore Saanvi☎️  8250192130 Independent Escort Se...High Profile Call Girls Coimbatore Saanvi☎️  8250192130 Independent Escort Se...
High Profile Call Girls Coimbatore Saanvi☎️ 8250192130 Independent Escort Se...narwatsonia7
 
College Call Girls Pune Mira 9907093804 Short 1500 Night 6000 Best call girls...
College Call Girls Pune Mira 9907093804 Short 1500 Night 6000 Best call girls...College Call Girls Pune Mira 9907093804 Short 1500 Night 6000 Best call girls...
College Call Girls Pune Mira 9907093804 Short 1500 Night 6000 Best call girls...Miss joya
 
VIP Call Girls Tirunelveli Aaradhya 8250192130 Independent Escort Service Tir...
VIP Call Girls Tirunelveli Aaradhya 8250192130 Independent Escort Service Tir...VIP Call Girls Tirunelveli Aaradhya 8250192130 Independent Escort Service Tir...
VIP Call Girls Tirunelveli Aaradhya 8250192130 Independent Escort Service Tir...narwatsonia7
 
Vip Call Girls Anna Salai Chennai 👉 8250192130 ❣️💯 Top Class Girls Available
Vip Call Girls Anna Salai Chennai 👉 8250192130 ❣️💯 Top Class Girls AvailableVip Call Girls Anna Salai Chennai 👉 8250192130 ❣️💯 Top Class Girls Available
Vip Call Girls Anna Salai Chennai 👉 8250192130 ❣️💯 Top Class Girls AvailableNehru place Escorts
 
Artifacts in Nuclear Medicine with Identifying and resolving artifacts.
Artifacts in Nuclear Medicine with Identifying and resolving artifacts.Artifacts in Nuclear Medicine with Identifying and resolving artifacts.
Artifacts in Nuclear Medicine with Identifying and resolving artifacts.MiadAlsulami
 
Call Girl Number in Panvel Mumbai📲 9833363713 💞 Full Night Enjoy
Call Girl Number in Panvel Mumbai📲 9833363713 💞 Full Night EnjoyCall Girl Number in Panvel Mumbai📲 9833363713 💞 Full Night Enjoy
Call Girl Number in Panvel Mumbai📲 9833363713 💞 Full Night Enjoybabeytanya
 
Call Girl Number in Vashi Mumbai📲 9833363713 💞 Full Night Enjoy
Call Girl Number in Vashi Mumbai📲 9833363713 💞 Full Night EnjoyCall Girl Number in Vashi Mumbai📲 9833363713 💞 Full Night Enjoy
Call Girl Number in Vashi Mumbai📲 9833363713 💞 Full Night Enjoybabeytanya
 
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...CALL GIRLS
 
Russian Call Girls in Pune Tanvi 9907093804 Short 1500 Night 6000 Best call g...
Russian Call Girls in Pune Tanvi 9907093804 Short 1500 Night 6000 Best call g...Russian Call Girls in Pune Tanvi 9907093804 Short 1500 Night 6000 Best call g...
Russian Call Girls in Pune Tanvi 9907093804 Short 1500 Night 6000 Best call g...Miss joya
 

Recently uploaded (20)

Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual NeedsBangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
 
Bangalore Call Girls Majestic 📞 9907093804 High Profile Service 100% Safe
Bangalore Call Girls Majestic 📞 9907093804 High Profile Service 100% SafeBangalore Call Girls Majestic 📞 9907093804 High Profile Service 100% Safe
Bangalore Call Girls Majestic 📞 9907093804 High Profile Service 100% Safe
 
Lucknow Call girls - 8800925952 - 24x7 service with hotel room
Lucknow Call girls - 8800925952 - 24x7 service with hotel roomLucknow Call girls - 8800925952 - 24x7 service with hotel room
Lucknow Call girls - 8800925952 - 24x7 service with hotel room
 
Call Girls Darjeeling Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Darjeeling Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Darjeeling Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Darjeeling Just Call 9907093804 Top Class Call Girl Service Available
 
Russian Escorts Girls Nehru Place ZINATHI 🔝9711199012 ☪ 24/7 Call Girls Delhi
Russian Escorts Girls  Nehru Place ZINATHI 🔝9711199012 ☪ 24/7 Call Girls DelhiRussian Escorts Girls  Nehru Place ZINATHI 🔝9711199012 ☪ 24/7 Call Girls Delhi
Russian Escorts Girls Nehru Place ZINATHI 🔝9711199012 ☪ 24/7 Call Girls Delhi
 
Call Girls Colaba Mumbai ❤️ 9920874524 👈 Cash on Delivery
Call Girls Colaba Mumbai ❤️ 9920874524 👈 Cash on DeliveryCall Girls Colaba Mumbai ❤️ 9920874524 👈 Cash on Delivery
Call Girls Colaba Mumbai ❤️ 9920874524 👈 Cash on Delivery
 
VIP Russian Call Girls in Varanasi Samaira 8250192130 Independent Escort Serv...
VIP Russian Call Girls in Varanasi Samaira 8250192130 Independent Escort Serv...VIP Russian Call Girls in Varanasi Samaira 8250192130 Independent Escort Serv...
VIP Russian Call Girls in Varanasi Samaira 8250192130 Independent Escort Serv...
 
Call Girls Service Pune Vaishnavi 9907093804 Short 1500 Night 6000 Best call ...
Call Girls Service Pune Vaishnavi 9907093804 Short 1500 Night 6000 Best call ...Call Girls Service Pune Vaishnavi 9907093804 Short 1500 Night 6000 Best call ...
Call Girls Service Pune Vaishnavi 9907093804 Short 1500 Night 6000 Best call ...
 
💎VVIP Kolkata Call Girls Parganas🩱7001035870🩱Independent Girl ( Ac Rooms Avai...
💎VVIP Kolkata Call Girls Parganas🩱7001035870🩱Independent Girl ( Ac Rooms Avai...💎VVIP Kolkata Call Girls Parganas🩱7001035870🩱Independent Girl ( Ac Rooms Avai...
💎VVIP Kolkata Call Girls Parganas🩱7001035870🩱Independent Girl ( Ac Rooms Avai...
 
Aspirin presentation slides by Dr. Rewas Ali
Aspirin presentation slides by Dr. Rewas AliAspirin presentation slides by Dr. Rewas Ali
Aspirin presentation slides by Dr. Rewas Ali
 
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
 
High Profile Call Girls Coimbatore Saanvi☎️ 8250192130 Independent Escort Se...
High Profile Call Girls Coimbatore Saanvi☎️  8250192130 Independent Escort Se...High Profile Call Girls Coimbatore Saanvi☎️  8250192130 Independent Escort Se...
High Profile Call Girls Coimbatore Saanvi☎️ 8250192130 Independent Escort Se...
 
College Call Girls Pune Mira 9907093804 Short 1500 Night 6000 Best call girls...
College Call Girls Pune Mira 9907093804 Short 1500 Night 6000 Best call girls...College Call Girls Pune Mira 9907093804 Short 1500 Night 6000 Best call girls...
College Call Girls Pune Mira 9907093804 Short 1500 Night 6000 Best call girls...
 
VIP Call Girls Tirunelveli Aaradhya 8250192130 Independent Escort Service Tir...
VIP Call Girls Tirunelveli Aaradhya 8250192130 Independent Escort Service Tir...VIP Call Girls Tirunelveli Aaradhya 8250192130 Independent Escort Service Tir...
VIP Call Girls Tirunelveli Aaradhya 8250192130 Independent Escort Service Tir...
 
Vip Call Girls Anna Salai Chennai 👉 8250192130 ❣️💯 Top Class Girls Available
Vip Call Girls Anna Salai Chennai 👉 8250192130 ❣️💯 Top Class Girls AvailableVip Call Girls Anna Salai Chennai 👉 8250192130 ❣️💯 Top Class Girls Available
Vip Call Girls Anna Salai Chennai 👉 8250192130 ❣️💯 Top Class Girls Available
 
Artifacts in Nuclear Medicine with Identifying and resolving artifacts.
Artifacts in Nuclear Medicine with Identifying and resolving artifacts.Artifacts in Nuclear Medicine with Identifying and resolving artifacts.
Artifacts in Nuclear Medicine with Identifying and resolving artifacts.
 
Call Girl Number in Panvel Mumbai📲 9833363713 💞 Full Night Enjoy
Call Girl Number in Panvel Mumbai📲 9833363713 💞 Full Night EnjoyCall Girl Number in Panvel Mumbai📲 9833363713 💞 Full Night Enjoy
Call Girl Number in Panvel Mumbai📲 9833363713 💞 Full Night Enjoy
 
Call Girl Number in Vashi Mumbai📲 9833363713 💞 Full Night Enjoy
Call Girl Number in Vashi Mumbai📲 9833363713 💞 Full Night EnjoyCall Girl Number in Vashi Mumbai📲 9833363713 💞 Full Night Enjoy
Call Girl Number in Vashi Mumbai📲 9833363713 💞 Full Night Enjoy
 
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
 
Russian Call Girls in Pune Tanvi 9907093804 Short 1500 Night 6000 Best call g...
Russian Call Girls in Pune Tanvi 9907093804 Short 1500 Night 6000 Best call g...Russian Call Girls in Pune Tanvi 9907093804 Short 1500 Night 6000 Best call g...
Russian Call Girls in Pune Tanvi 9907093804 Short 1500 Night 6000 Best call g...
 

arrhythmia-211205224744.pdf33333333333333

  • 2. Rhythm a regular, repeated pattern of sounds or movements. Cardiac dysrhythmia (also known as arrhythmia or irregular heartbeat) is any of a group of conditions in which the electrical activity of the heart is irregular or faster or slower than normal. The heart beat may be: Too fast (over 100 beats per minute). Too slow (less than 60 beats per minute). Regular or irregular. A heart beat that is: Too fast is called tachycardia. Too slow is called bradycardia. Antiarrhythmic agents are a group of drugs that are used to suppress abnormal rhythms of the heart.
  • 4. Properties of Cardiac Muscle Autorhythmicity Excitability Conductivity Contractility
  • 5. The Conducting System  The Nodal System  Sinoatrial Node (S-A node) 1  Atrioventricular Node (A-V node) 3  The Internodal System  Anterior, Middle & Posterior 2  Bachmann`s bundle 7  The Purkinje System  Atrioventricular bundle (bundle of His) 4  Right & left bundle branch 5  Purkinje fibers 6
  • 6. Normal conduction pathway: 1- SA node generates action potential and delivers it to the atria and the AV node 2- The AV node delivers the impulse to purkinje fibers 3- purkinje fibers conduct the impulse to the ventricles Other types of conduction that occurs between myocardial cells: When a cell is depolarized  adjacent cell depolarizes along
  • 7.
  • 8. Pacemaker SA-node Primary pacemaker 105 impulse/min Sinus rhythm AV-node Secondary pacemaker 45-60 impulse/min Nodal rhythm Purkinje System Tertiary pacemaker 25-40 impulse/min Idioventricular rhythm Inhibitory vagal tone
  • 9. Myocardial Physiology Autorhythmic Cells (Pacemaker Cells)  Characteristics of Pacemaker Cells  The membrane reach threshold potential (-40mV) by itself  when the membrane potential is very negative (about -60 mV), ion channels open that conduct slow, inward (depolarizing) Na+ currents. These currents are called "funny" currents and abbreviated as "If".  As the membrane potential reaches about -50 mV, another type of channel opens. This channel is called transient or T-type Ca++ channel.  When the membrane depolarizes to about -40 mV, a second type of Ca++ channel opens. These are the so-called long-lasting, or L-type Ca++ channels. Opening of these channels causes more Ca++ to enter the cell and to further depolarize the cell until an action potential threshold is reached.  Repolarization occurs (Phase 3) as K+ channels open thereby increasing the outward K+ currents. At the same time, the L-type Ca++ channels become inactivated and close
  • 10. Pacemaker AP Phase 4: pacemaker potential Na influx and K efflux and Ca influx until the cell reaches threshold and then turns into phase 0 Phase 0: upstroke: Due to Ca++ influx Phase 3: repolarization: Due to K+ efflux Pacemaker cells (automatic cells) have unstable membrane potential so they can generate AP spontaneously
  • 11. Myocardial Physiology Autorhythmic Cells (Pacemaker Cells)  Characteristics of Pacemaker Cells Pacemaker cells (automatic cells) have unstable membrane potential so they can generate AP spontaneously
  • 12. Myocardial Physiology Contractile Cells  Special aspects  The action potential of a contractile cell  Ca2+ plays a major role again  Phases 4 – resting membrane potential @ -90mV 0 – depolarization  Voltage gated Na+ channels open… close at 20mV 1 – temporary repolarization  Open K+ channels allow some K+ to leave the cell 2 – plateau phase  Voltage gated Ca2+ channels are fully open 3 – repolarization  Ca2+ channels close and K+ permeability increases as more activated K+ channels open, causing a quick repolarization  What is the significance of the plateau phase?
  • 13. Non-pacemaker action potential Phase 0: fast upstroke Due to Na+ influx Phase 3: repolarization Due to K+ efflux Phase 4: resting membrane potential Phase 2: plateu Due to Ca++ influx Phase 1: partial repolarization Due to rapid efflux of K+ N.B. The slope of phase 0 = conduction velocity Also the peak of phase 0 = Vmax
  • 14. +30 mV 0 mV -80 mV -90 mV OUTSIDE MEMBRANE INSIDE Na+ 0 4 3 2 1 K+ Ca++ K+ K+ Na+ K+ Ca++ Na+ K+ Na+ Resting open Inactivated Phase zero depolarization Early repolarization Plateau phase Rapid Repolarization phase Phase 4 Resting membrane potential
  • 16. Effective and relative refractory periods ERP RRP ERP due to inactivated Na and Ca channels, once they begin to recover the RRP begins.
  • 17. The absolute refractory period The absolute refractory period:  During the absolute refractory period, the excitability level is 0%.  No stimulus however strong can produce a propagated action potential in the heart.  This period begins with depolarization till mid-repolarization  It lasts for the whole period of systole and the early part of diastole.
  • 18. The relative refractory period The relative refractory period:  During the relative refractory period the excitability level is more than 0 but less than 100% of the resting basal level.  The heart responds only to stronger stimuli.  It is a short period that begins at mid-repolarization and ends shortly before complete repolarization.  It lasts for a short period during diastole.
  • 19. What is the Electrocardiogram?
  • 20.
  • 21. ECG (EKG) showing wave segments Contraction of atria Contraction of ventricles Repolarization of ventricles PR interval: represents the rate of A-V conduction QS interval: represents the duration of ventricular systole
  • 22.
  • 23.
  • 24. ANS Control of Heart Cardiac Properties Parasympathetic (Vagal) Sympathetic Supplies the atria, SA node, AV node & AV bundle but not the ventricles Supplies all cardiac tissue including the ventricles Rhythmicity Slowing due to depression of SA node Acceleration due to ↑ of SA node Excitability ↓ ↑ AV conduction ↓ (heart block) ↑ Contractility Depressed in atria Stimulated in atria and ventricles Rate of O2 consumption ↓ ↑
  • 25. Arrhythmia If the arrhythmia arises from the ventricles it is called ventricular arrhythmia If the arrhythmia arises from atria, SA node, or AV node it is called supraventricular arrhythmia Causes of arrhythmia arteriosclerosis Coronary artery spasm Heart block Myocardial ischemia
  • 26. Mechanisms of Arrhythmogenesis 1- Abnormal impulse generation Automatic rhythms Triggered rhythms 2-Abnormal conduction Conduction block Reentry
  • 27. Automatic rhythms Enhanced normal automaticity Ectopic focus ↑AP from SA node AP arises from sites other than SA node
  • 28. Ectopic foci An ectopic focus is an area in the contractile myocardium, which discharges electrical impulses. Normally, the contractile myocardium has a stable resting membrane potential Under some non-physiological conditions, some myocardial cells acquire rhythmic electrical activity and act as foci that send un- timed electrical impulses or might even take over the heart and act as the pacemaker.  Factors that enhance automaticity include:  SANS,  PANS,  CO2,  O2,  H+,  stretch, hypokalemia and hypocalcaemia.
  • 29. Triggered rhythms Delayed afterdepolarization Early afterdepolarization Triggered beats occur when problems at the level of the ion channels in individual heart cells result in abnormal propagation of electrical activity and can lead to sustained abnormal rhythm. Early afterdepolarizations (EADs) occur with abnormal depolarization during phase 2 or phase 3, and are caused by an increase in the frequency of abortive action potentials before normal repolarization is completed. Before another action potential would normally occur. Delayed afterdepolarizations (DADs) begin during phase 4 - after repolarization is completed
  • 30. 2-Abnormal conduction Conduction block 1st degree 2nd degree 3rd degree Reentry This is when the impulse is not conducted from the atria to the ventricles
  • 31. First-degree heart block – The electrical impulses are slowed as they pass through the conduction system, but they all successfully reach the ventricles. Second-degree heart block– The electrical impulses are delayed further and further with each heartbeat until a beat fails to reach to the ventricles entirely. Third-degree heart block – With this condition, also called complete heart block, none of the electrical impulses from the atria reach the ventricles.
  • 32. Reentry Circus movement Reflection Re-entry is a common cause of arrhythmias. Ventricular tachycardia and AV-nodal re-entry are typical examples. Re-entry can occur when a conduction path is partly slowed down.
  • 33.
  • 34. Here is an accessory pathway in the heart called Bundle of Kent •Present only in small populations •Lead to reexcitation  Wolf-Parkinson-White Syndrome (WPW) Abnormal anatomic conduction Wolff–Parkinson–White syndrome (WPW) is one of several disorders of the conduction system of the heart. WPW is caused by the presence of an abnormal accessory electrical conduction pathway between the atria and the ventricles. Electrical signals travelling down this abnormal pathway (known as the bundle of Kent) may stimulate the ventricles to contract prematurely.
  • 36. First Degree AV Block  Delay at the AV node results in prolonged PR interval  PR interval>0.2 sec.  Leave it alone
  • 37. Second Degree AV Block Type 1 (Wenckebach)  Increasing delay at AV node until a p wave is not conducted.  Often comes post inferior MI with AV node ischemia  Gradual prolongation of the PR interval before a skipped QRS. QRS are normal!  No pacing as long as no bradycardia.
  • 38. Second Degree AV Block Type 2  Diseased bundle of HIS with BBB.  Sudden loss of a QRS wave because p wave was not transmitted beyond AV node. QRS are abnormal!  May be precursor to complete heart block and needs pacing.
  • 39. Third Degree AV Block  Complete heart block where atria and ventricles beat independently AND atria beat faster than ventricles.  Must treat with pacemaker.
  • 40. Supraventricular Arrhythmias  Sinus Tachycardia: high sinus rate of 100-180 beats/min, occurs during exercise or other conditions that lead to increased SA nodal firing rate.  Atrial Tachycardia: a series of 3 or more consecutive atrial premature beats occurring at a frequency >100/min  Paroxysmal Atrial Tachycardia (PAT): tachycardia which begins and ends in acute manner.  Atrial Flutter: sinus rate of 250-350 beats/min.  Atrial Fibrillation: uncoordinated atrial depolarizations. AV blocks A conduction block within the AV node , occasionally in the bundle of His, that impairs impulse conduction from the atria to the ventricles. Types of Arrhythmia
  • 41.  Ventricular Premature Beats (VPBs): caused by ectopic ventricular foci; characterized by widened QRS.  Ventricular Tachycardia (VT): high ventricular rate caused by abnormal ventricular automaticity or by intraventricular reentry; can be sustained or non-sustained (paroxysmal); characterized by widened QRS; rates of 100 to 200 beats/min; life-threatening.  Ventricular Flutter: ventricular depolarizations >200/min.  Ventricular Fibrillation: uncoordinated ventricular depolarizations Ventricular Arrhythmias
  • 42.
  • 43.
  • 44. Pharmacologic Rationale & Goals  The ultimate goal of antiarrhythmic drug therapy: o Restore normal sinus rhythm and conduction o Prevent more serious and possibly lethal arrhythmias from occurring.  Antiarrhythmic drugs are used to:  decrease conduction velocity  change the duration of the effective refractory period (ERP)  suppress abnormal automaticity
  • 45. Antyarrhythmic drugs class mechanism action notes I Na+ channel blocker Change the slope of phase 0 Can abolish tachyarrhythmia caused by reentry circuit II β blocker ↓heart rate and conduction velocity Can indirectly alter K and Ca conductance III K+ channel blocker 1. ↑action potential duration (APD) or effective refractory period (ERP). 2. Delay repolarization. Inhibit reentry tachycardia IV Ca++ channel blocker Slowing the rate of rise in phase 4 of SA node ↓conduction velocity in SA and AV node •Most antiarrhythmic drugs are pro-arrhythmic (promote arrhythmia) •They are classified according to Vaughan William into four classes according to their effects on the cardiac action potential
  • 46. Proarrhythmia is a new arrhythmias, paradoxically precipitated by antiarrhythmic therapy, which means it is a side effect associated with the administration of some existing antiarrhythmic drugs, as well as drugs for other indications. In other words, it is a tendency of antiarrhythmic drugs to facilitate emergence of new arrhythmias
  • 47. Class I IA IB IC They ↓ conduction velocity in non-nodal tissues (atria, ventricles, and purkinje fibers) They act on open Na+ channels or inactivated only Have moderate K+ channel blockade So they are used when many Na+ channels are opened or inactivated (in tachycardia only) because in normal rhythm the channels will be at rest state so the drugs won’t work Class I drugs
  • 48.  Slowing of the rate of rise in phase 0  ↓conduction velocity  ↓of Vmax of the cardiac action potential  They prolong muscle action potential & ventricular (ERP)  They ↓ the slope of Phase 4 spontaneous depolarization (SA node)  decrease enhanced normal automaticity Class IA Quinidine Procainamide They make the slope more horizontal
  • 49. Class IA Drugs  They possess intermediate rate of association and dissociation (moderate effect) with sodium channels. Pharmacokinetics: procainamide Good oral bioavailability Used as IV to avoid hypotension quinidine Good oral bioavailability Metabolized in the liver Procainamide metabolized into N-acetylprocainamide (NAPA) (active class III) which is cleared by the kidney (avoid in renal failure)
  • 50. Class IA Drugs Uses  Quinidine is rarely used for supraventricular arrhythmias  IV procainamide is used for acute conversion of atrial fibrillation  Oral quinidine/procainamide are used with class III drugs in ventricular tachycardia  IV procainamide used for hemodynamically stable ventricular tachycardia
  • 51. Class IA Drugs Toxicity quinidine AV block Torsades de pointes arrhythmia because it ↑ ERP (QT interval) Shortens A-V nodal refractoriness (↑AV conduction) by antimuscarinic like effect ↑digoxin concentration by : 1- displace from tissue binding sites 2- ↓renal clearance Ventricular tachycardia procainamide Asystole or ventricular arrhythmia Hypersensitivity : fever, agranulocytosis Systemic lupus erythromatosus (SLE)-like symptoms: arthralgia, fever, pleural- pericardial inflammation. Symptoms are dose and time dependent Common in patients with slow hepatic acetylation
  • 52. Systemic lupus erythematosus (also called lupus or SLE) is a disease where a person's immune system attacks and injures the body's own organs and tissues. Almost every system of the body can be affected by SLE. Arthralgia means joint pain. It is a combination of two Greek words – Arthro – joint and algos – pain. Agranulocytosis a failure of the bone marrow to make enough white blood cells (neutrophils).
  • 53. Notes: Torsades de pointes: twisting of the point . Type of tachycardia that gives special characteristics on ECG At large doses of quinidine  cinchonism occurs:blurred vision, tinnitus, headache, psychosis and gastrointestinal upset
  • 54.  Both a defibrillator and a pacemaker are used in patient with heart disease.  A defibrillator is used to shock the heart when a patient goes into cardiac arrest.  A pacemaker is used to regulate abnormal heart rate or rhythm.
  • 55. Class IB Drugs  They shorten Phase 3 repolarization  ↓ the duration of the cardiac action potential  They suppress arrhythmias caused by abnormal automaticity  They show rapid association & dissociation (weak effect) with Na+ channels with appreciable degree of use-dependence  No effect on conduction velocity Class IB lidocaine mexiletine tocainide
  • 56. Agents of Class IB Lidocaine  Used IV because of extensive 1st pass metabolism  Lidocaine is the drug of choice in emergency treatment of ventricular arrhythmias  Has CNS effects: drowsiness, numbness, convulstion, and nystagmus Mexiletine  These are the oral analogs of lidocaine  Mexiletine is used for chronic treatment of ventricular arrhythmias associated with previous myocardial infarction Uses They are used in the treatment of ventricular arrhythmias arising during myocardial ischemia or due to digoxin toxicity They have little effect on atrial or AV junction arrhythmias (because they don’t act on conduction velocity) Adverse effects: 1- neurological effects 2- negative inotropic activity
  • 57. Class IC Drugs  They markedly slow Phase 0 fast depolarization  They markedly slow conduction in the myocardial tissue  They possess slow rate of association and dissociation (strong effect) with sodium channels  They only have minor effects on the duration of action potential and refractoriness Class IC flecainide propafenone
  • 58. Uses:  Refractory ventricular arrhythmias.  Flecainide is a particularly potent suppressant of premature ventricular contractions (beats) Toxicity and Cautions for Class IC Drugs:  They are severe proarrhythmogenic drugs causing: 1. severe worsening of a preexisting arrhythmia 2. de novo occurrence of life-threatening ventricular tachycardia  In patients with frequent premature ventricular contraction (PVC) following MI, flecainide increased mortality compared to placebo. Notice: Class 1C drugs are particularly of low safety and have shown even increase mortality when used chronically after MI
  • 59. Compare between class IA, IB, and IC drugs as regards effect on Na+ channel & ERP  Sodium channel blockade: IC > IA > IB  Increasing the ERP: IA>IC>IB (lowered) Because of K+ blockade
  • 60. Class II ANTIARRHYTHMIC DRUGS (β-adrenergic blockers) Mechanism of action  Negative inotropic and chronotropic action.  Prolong AV conduction (delay)  Diminish phase 4 depolarization  suppressing automaticity(of ectopic focus) Uses  Treatment of increased sympathetic activity-induced arrhythmias such as stress- and exercise-induced arrhythmias  Atrial flutter and fibrillation.  AV nodal tachycardia.  Reduce mortality in post-myocardial infarction patients  Protection against sudden cardiac death
  • 61. Class II ANTIARRHYTHMIC DRUGS  Propranolol (nonselective): was proved to reduce the incidence of sudden arrhythmatic death after myocardial infarction  Metoprolol  reduce the risk of bronchospasm  Esmolol:  Esmolol is a very short-acting β1-adrenergic blocker that is used by intravenous route in acute arrhythmias occurring during surgery or emergencies selective
  • 62. Class III ANTIARRHYTHMIC DRUGS K+ blockers  Prolongation of phase 3 repolarization without altering phase 0 upstroke or the resting membrane potential  They prolong both the duration of the action potential and ERP  Their mechanism of action is still not clear but it is thought that they block potassium channels
  • 63. Uses:  Ventricular arrhythmias, especially ventricular fibrillation or tachycardia  Supra-ventricular tachycardia  Amiodarone usage is limited due to its wide range of side effects Class III sotalol amiodarone ibutilide
  • 64. Sotalol (Sotacor)  Sotalol also prolongs the duration of action potential and refractoriness in all cardiac tissues (by action of K+ blockade)  Sotalol suppresses Phase 4 spontaneous depolarization and possibly producing severe sinus bradycardia (by β blockade action)  The β-adrenergic blockade combined with prolonged action potential duration may be of special efficacy in prevention of sustained ventricular tachycardia  It may induce the polymorphic torsades de pointes ventricular tachycardia (because it increases ERP) Ibutilide Used in atrial fibrillation or flutter IV administration May lead to torsade de pointes Only drug in class three that possess pure K+ blockade
  • 65. Amiodarone (Cordarone)  Amiodarone is a drug of multiple actions and is still not well understood  It is extensively taken up by tissues, especially fatty tissues (extensive distribution)  t1/2 = 60 days  Potent P450 inhibitor  Amiodarone antiarrhythmic effect is complex comprising class I, II, III, and IV actions • Dominant effect: Prolongation of action potential duration and refractoriness • It slows cardiac conduction, works as Ca2+ channel blocker, and as a weak β- adrenergic blocker Toxicity  Most common include GI intolerance, tremors, ataxia, dizziness, and hyper-or hypothyrodism  Corneal microdeposits may be accompanied with disturbed night vision  Others: liver toxicity, photosensitivity, gray facial discoloration, neuropathy, muscle weakness, and weight loss  The most dangerous side effect is pulmonary fibrosis which occurs in 2- 5% of the patients
  • 66. Class IV ANTIARRHYTHMIC DRUGS (Calcium Channel Blockers)  Calcium channel blockers decrease inward Ca2+ currents resulting in a decrease of phase 4 spontaneous depolarization (SA node)  They slow conductance in Ca2+ current-dependent tissues like AV node.  Examples: verapamil & diltiazem Because they act on the heart only and not on blood vessels.  Dihydropyridine family are not used because they only act on blood vessels
  • 67. Mechanism of action  They bind only to depolarized (open) channels  prevention of repolarization  They prolong ERP of AV node  ↓conduction of impulses from the atria to the ventricles So they act only in cases of arrhythmia because many Ca2+ channels are depolarized while in normal rhythm many of them are at rest More effective in treatment of atrial than ventricular arrhythmias. Treatment of supra-ventricular tachycardia preventing the occurrence of ventricular arrhythmias Treatment of atrial flutter and fibrillation Uses
  • 68. contraindication  Contraindicated in patients with pre-existing depressed heart function because of their negative inotropic activity Adverse effects  Cause bradycardia, and asystole especially when given in combination with β-adrenergic blockers
  • 69. Miscellaneous Antiarrhythmic Drugs Adenosine o Adenosine activates A1-purinergic receptors decreasing the SA nodal firing and automaticity, reducing conduction velocity, prolonging effective refractory period, and depressing AV nodal conductivity o It is the drug of choice in the treatment of paroxysmal supra- ventricular tachycardia o It is used only by slow intravenous bolus o It only has a low-profile toxicity (lead to bronchospasm) being extremly short acting for 15 seconds only
  • 70. Magnesium indications.  1. Torsades de point from any reason.  2. Arrhythmias in a patient with known hypomagnesaemia.  3. Consider its use in acute ischaemia to prevent early ventricular arrhythmias.  4. Digoxin induced arrhythmias.
  • 71.  A. Digoxin  Digoxin [di-JOX-in] shortens the refractory period in atrial and ventricular myocardial cells while prolonging the effective refractory period and diminishing conduction velocity in the AV node.  Digoxin is used to control the ventricular response rate in atrial fibrillation and flutter. At toxic concentrations, digoxin causes ectopic ventricular beats that may result in ventricular tachycardia and fibrillation.  [Note: This arrhythmia is usually treated with lidocaine or phenytoin.]
  • 72. class ECG QT Conduction velocity Refractory period IA ++ ↓ ↑ IB 0 no ↓ IC + ↓ no II 0 ↓In SAN and AVN ↑ in SAN and AVN III ++ No ↑ IV 0 ↓ in SAN and AVN ↑ in SAN and AVN
  • 73.
  • 74. 1st: Reduce thrombus formation by using anticoagulant warfarin 2nd: Prevent the arrhythmia from converting to ventricular arrhythmia: First choice: class II drugs: •After MI or surgery •Avoid in case of heart failure Second choice: class IV Third choice: digoxin •Only in heart failure of left ventricular dysfunction 3rd: Conversion of the arrhythmia into normal sinus rhythm: Class III: IV ibutilide, IV/oral amiodarone, or oral sotalol Class IA: Oral quinidine + digoxin (or any drug from the 2nd step) Class IC: Oral propaphenone or IV/oral flecainide Use direct current in case of unstable hemodynamic patient
  • 75.
  • 76. First choice: class II •IV followed by oral •Early after MI Second choice: amiodarone Avoid using class IC after MI  ↑ mortality First choice: Lidocaine IV •Repeat injection Second choice: procainamide IV •Adjust the dose in case of renal failure Third choice: class III drugs •Especially amiodarone and sotalol Premature ventricular beat (PVB)
  • 77.
  • 78. Recommendations for focal Atrial Tachycardia
  • 79.
  • 80.
  • 81. ‫تجميعات‬ : (IA, IC, class III)  torsades de pointes. Classes II and IV  bradycardia (don’t combine the two) In atrial flutter use (1st ↓impulses from atria to ventricular to prevent ventricular tachycardia) 1. Class II 2. Class IV 3. Digoxin. ( ‫الترتيب‬ ‫على‬ ) 2nd convert atrial flutter to normal sinus rhythm use: 1. Ibutilide 2. Sotalol 3. IA or IC. ( ‫الترتيب‬ ‫على‬ ) If you use quinidine combine it with digoxin or β blocker (because of its anti muscarinic effect) Avoid IC in myocardial infarction because it ↑ mortality
  • 82.  Vernakalant  Ajmaline  Pilsicainide  Ranolazine