Transcript Arrythmia 411

Cardiac Arrhythmias
Dr. Ahmad Hersi
Myocardium Muscle Action Potential
Action Potential of a Myocardial Cell
+25
1
Overshoot
+10 mv
Corresponding ECG Overlay
0
2
-25
-50
0
Active Transport
Na+ out K+ back in
-75
Resting Potential
- 90 mv
-100
4
RRP
ARP
K+
Na+ Ca++
SNP
Normal Cardiac Cycle
Systole
Diastole
Electrical
Depolarization
“activate”
Repolarization
“recovery”
Mechanical
Contract
“empty”
Relax
“fill”
What does it tell us?
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the electrical conduction through the heart
areas of ischemia or myocardial damage
LV Hypertrophy
electrolyte disturbances / drug toxicity
The Electrical System of the Heart
SA
Node
AV
Node
Bundle of
HIS
Right Bundle
Branch
Inter- nodal
Tracts
Left Bundle
Branch
Anterior Superior
Fascicle
Posterior Inferior
Fascicle
Septal
Depolarization
Fibers
Purkinjie Fibers
Conduction System of
the Heart:
A Conceptual Model
for Illustration
SA
Node
Inter-nodal
Tract
Left
Bundle
Branch
AV
Node
Bundle
of HIS
James Fibers
Right
Bundle
Branch
Bundle
of Kent
Septal
Depolarization
Fibers
Anterior
Superior
Fascicle
Posterior
Inferior
Fascicle
SA
SA Node – “pacemaker” of Node
the heart (60-100bpm)
AV
Node
AV Node – junction of the
atria and ventricles (40-60bpm)
Bundles – Bundle of His
connects the AV node to the
bundle branches (20-40bpm)
Bundle of
HIS
Inter- nodal
Tracts
What Is In Each Beat?
(the cardiac cycle in waves, complexes, and intervals)
• P Wave – atrial contraction or depolarization, (usually upright)
• QRS Complex – time for ventricular contraction or depolarization
(usually upright) (0.04 - 0.12sec) (delays in the bundle branches will widen the
QRS)
• T Wave – ventricular repolarization “recharging” (usually upright)
• PR Interval – time between atrial depolarization to ventricular
depolarization (beginning of P wave to beginning of QRS)(0.12 - 0.20sec)
(prolonged PR = delays in the AV node conduction)
• QT Interval – represents one complete ventricular depolarization and
repolarization (beginning of QRS to the end of the T wave) (0.32 – 0.44sec)
(disturbances are usually due to electrolyte disturbances or drug effects)
The ECG Complex with Interval and Segment Measurements
ECG Paper and related Heart Rate & Voltage Computations
Memor
ize
Reading a Rhythm Strip
What Do I Look For?
► Regularity - What is the R – R Interval?
► Rate - Is the rate normal (60-100), slow, or fast?
***Six-second strip method - (30 big boxes) & multiply times
ten
► P Wave – Is there a P wave before every QRS? Is it upright?
► QRS Complex – Is there a normal QRS complex
following each P wave? Wide or normal?
► T wave – How does your T wave look? Upright?
► Measure your intervals – PR Interval, QRS, QT
Pacemakers of the Heart
• SA Node - Dominant pacemaker with an
intrinsic rate of 60 - 100 beats/minute.
• AV Node - Back-up pacemaker with an
intrinsic rate of 40 - 60 beats/minute.
• Ventricular cells - Back-up pacemaker with
an intrinsic rate of 20 - 45 bpm.
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Rhythm Analysis
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Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
Calculate rate.
Determine regularity.
Assess the P waves.
Determine PR interval.
Determine QRS duration.
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Step 1: Calculate Rate
3 sec
3 sec
Option 1
– Count the # of R waves in a 6 second rhythm
strip, then multiply by 10.
Interpretation?
9 x 10 = 90 bpm
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Step 1: Calculate Rate
R wave
• Option 2
– Find a R wave that lands on a bold line.
– Count the # of large boxes to the next R wave.
If the second R wave is 1 large box away the
rate is 300, 2 boxes - 150, 3 boxes - 100, 4
boxes - 75, etc. (cont)
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Step 1: Calculate Rate
3 1 1
0 5 0 7 6 5
0 0 0 5 0 0
• Option 2 (cont)
– Memorize the sequence:
300 - 150 - 100 - 75 - 60 - 50
Interpretation?
Approx. 1 box less than
100 = 95 bpm Tehran Arrhythmia Center
Step 2: Determine regularity
R
R
• Look at the R-R distances (using a caliper or
markings on a pen or paper).
• Regular (are they equidistant apart)? Occasionally
irregular? Regularly irregular? Irregularly
irregular?
Interpretation?
Regular
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Step 3: Assess the P waves
• Are there P waves?
• Do the P waves all look alike?
• Do the P waves occur at a regular rate?
• Is there one P wave before each QRS?
Interpretation? Normal P waves with 1 P wave for
every QRS
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Step 4: Determine PR interval
• Normal: 0.12 - 0.20 seconds.
(3 - 5 boxes)
Interpretation?
0.12 seconds
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Step 5: QRS duration
• Normal: 0.04 - 0.12 seconds.
(1 - 3 boxes)
Interpretation?
0.08 seconds
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Rhythm Summary
• Rate
• Regularity
• P waves
• PR interval
• QRS duration
Interpretation?
90-95 bpm
Regular
Normal
0.12 s
0.08 s
Normal Sinus Rhythm
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Normal Sinus Rhythm
• Normal and constant P wave contours
• Normal P wave axis
• Rate between 60 and 100 bpm
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Anatomical Aspects of Normal
Sinus Node
• Located at the superior anterolateral portion
of right atrium near its border with the
superior vena cava
• It is an epicardial structure near sulcus
terminalis
• From endocardial approach the closest
approach is near the superior end of crista
terminalis
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Sinus Node Function
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The dominant cardiac pacemaker
Highly responsive to autonomic influences
Decreasing rate with vagal stimulation
Increasing rate with sympathetic activity
Normal sinus rate under basal conditions is
60-100 bpm.
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Sinus Tachycardia
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
130 bpm
Regular
Normal
0.16 s
0.08 s
Interpretation? Sinus Tachycardia
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Sinus Tachycardia
• Sinus rhythm exceeding 100 bpm in adults
• Usually between 100 and 180 bpm but may
be higher with extreme exertion
• Maximum heart arte decreases wit age from
near 200 bpm to less than 140 bpm
• Gradual onset and termination
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Sinus Tachycardia
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Sinus Tachycardia
Causes
• Common in infancy and childhood
• Normal response to a variety of physiological and
pathological stresses
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Exertion, anxiety
Hypovolemia, anemia
Fever
Congestive heart failure
Myocardial ischemia
Thyrotoxicosis
• Drugs
• Inflammation
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Sinus Bradycardia
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
30 bpm
Regular
normal
0.12 s
0.10 s
Interpretation? Sinus Bradycardia
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Sinus Bradycardia
• Sinus rhythm at a rate less than 60 bpm
• Can result from excessive vagal or
decreased sympathetic tone as well as
anatomic changes in sinus node
• Frequently occurs in healthy young adults,
particularly well-trained athletes
• Sinus arrhythmia often coexists
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Sinus Bradycardia
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Sinus Bradycardia
Junctional Escape Beats
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Sinus Bradycardia
Causes
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Hypothyroidism
Drugs
During vomiting or vasovagal syncope
Increased intracranial pressure
Hypoxia, hypothermia
Depression
Jaundice
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Sinus Arrhythmia
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
50-75 bpm
Phasic variations
normal
0.12 s
0.10 s
Interpretation? Sinus Arrhythmia
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Sinus Pause
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Sick Sinus Syndrome
• A combination of symptoms (dizziness,
fatigue, confusion, syncope and congestive
heart failure) caused by sinus node dysfunction
• Atrial tachyarrhythmias may accompany
sinus node dysfunction
<bradycardia-tachycardia syndrome>
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AV Block
Types
• First degree AV block
• Second degree AV block
– Mobitz type I (Wenckebach)
– Mobitz type II
• Third degree AV block (Complete heart block)
• High degree (advanced) AV block
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First Degree AV Block
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
60 bpm
Regular
Normal
0.36 s
0.08 s
Interpretation? 1st Degree AV Block
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PR Interval
PR interval
< 0.12 s
0.12-0.20 s
> 0.20 s
High catecholamine states
Wolff-Parkinson-White
Normal
AV nodal blocks
Wolff-Parkinson-White
1st Degree AV Block
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First Degree AV Block
• Conduction time is prolonged but
all impulses are conducted.
• PR interval exceeds 0.2 sec in
adults
• Site of conduction delay may be
in the AV node (most
commonly), in the His-Purkinje
system or both.
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First Degree AV Block
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Wenckebach AV Block
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
50 bpm
Regularly irregular
Nl, but 4th no QRS
Lengthens
0.08 s
Interpretation? 2nd Degree AV Block, Type I
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Mobitz Type I Second Degree
AV Block
• Also called Wenckebach block
• Typical type characterized by progressive
PR prolongation culminating in a nonconducted P wave
• Narrow QRS in most cases
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WB
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Wenckebach Block
• Atypical pattern in over half the cases
• The site of block is almost always in the AV
node.
• Generally benign and does not advance to
more advanced AV block
• Can occur in normal children and welltrained athletes
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Mobitz Type II AV Block
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
40 bpm
Regular
Nl, 5th P no QRS
0.18 s
0.11 s
Interpretation? 2nd Degree AV Block, Type II
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Mobitz Type II Second Degree
AV Block
• PR interval remains constant prior to the
blocked P wave
• Commonly associated with bundle branch
blocks
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2:1 AV Block
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2:1 AV Block
AV Nodal Level
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2:1 AV Block
Infra-nodal Level
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2:1 AV block
Infra-nodal Level
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Complete Heart Block
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
40 bpm
Regular
No relation to QRS
None
Wide (> 0.12 s)
Interpretation? 3rd Degree AV Block
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Complete AV block
• No atrial activity conducts to the ventricles
• AV dissociation is present. The atria and
ventricles are controlled by independent
pacemakers.
• Ventricular focus is usually located just
below the site of block.
• Higher sites are more stable with a more
faster escape rate.
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Complete AV block
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Remember
• When an impulse originates in a ventricle,
conduction through the ventricles will be
inefficient and the QRS will be wide and
bizarre.
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AV Conduction Disturbances
Etiology
• Degenerative diseases are the most common
causes
• A variety of other diseases may be
responsible: myocardial infarction, drugs,
acute infections, infiltrative diseases,
neoplasms, etc.
• Hypervagotonia
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Premature Beats
• Premature Atrial Contractions
(PACs)
• Premature Ventricular Contractions
(PVCs)
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PAC
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
Interpretation?
70 bpm
Occasionally irreg.
2/7 different contour
0.14 s (except 2/7)
0.08 s
NSR with Premature Atrial
Contractions
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Narrow QRS Beats
• When an impulse originates anywhere in the
atria (SA node, atrial cells, AV node, Bundle
of His) and then is conducted normally
through the ventricles, the QRS will be
narrow (0.04 - 0.12 s).
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PVC
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
60 bpm
Occasionally irreg.
None for 7th QRS
0.14 s
0.08 s (7th wide)
Interpretation? Sinus Rhythm with 1 PVC
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Wide QRS Beats
• When an impulse originates in a ventricle,
conduction through the ventricles will be
inefficient and the QRS will be wide and
bizarre.
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Ventricular Conduction
Normal
Signal moves rapidly
through the ventricles
Abnormal
Signal moves slowly
through the ventricles
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Ventricular Premature Complexes
Compensatory
Pause
Interpolated VPC
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Atrial Fibrillation
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
100 bpm
Irregularly irregular
None
None
0.06 s
Interpretation? Atrial Fibrillation
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Atrial
Fibrillation
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Atrial Fibrillation
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The most common sustained arrhythmia
Incidence increases progressively with age.
Prevalence: 0.4% of overall population
Mortality rate double that of control
AF is characterized by disorganized atrial
activity without discrete P waves
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Atrial Fibrillation
• Undulating baseline or atrial deflections of
varying amplitude and frequency ranging
from 350 to 600 bpm.
• Irregularly irregular ventricular response.
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Atrial Fibrillation
• Morbidity related to:
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Excessive ventricular rate
Pause following cessation of AF
Systemic embolization
Loss of atrial kick
Anxiety secondary to palpitations
Irregular ventricular rate
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Atrial Fibrillation
• Persistent AF usually in patients with
cardiovascular disease
– Valvular heart disease
– Hypertensive heart disease
– Congenital heart disease
• Paroxysmal AF may occur with acute hypoxia,
hypercapnia or metabolic or hemodynamic
derangements
• Normal people with emotional stress or surgery or
acute alcoholic intoxication
• Lone AF
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Atrial Fibrillation
• Therapeutic Goals:
– Control of ventricular rate
– Restoration and maintenance of sinus rhythm
– Prevention of thromboembolism
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CHADS2 Score and Risk of Stroke
JAMA 2001;285:2864
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Atrial Flutter
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
70 bpm
Regular
Flutter waves
None
0.06 s
Interpretation? Atrial Flutter
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Atrial Flutter
• Regular atrial tachyarrhythmia with atrial
rate between 250-350 bpm.
• Flutter waves are seen as saw-tooth like
atrial activity
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Atrial Flutter
• Atrial Flutter is a form of atrial reentry
localized to right atrium.
• Typically the ventricular rate is half the
atrial rate, but the ventricular response may
be 4:1, 2:1, 1:1 etc.
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Atrial Flutter Circuit
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Atrial Flutter
• Most often in patients with organic heart
disease
• Usually less long-lived than AF and may
convert to AF.
• Control of ventricular rate is difficult in
atrial flutter
• The most effective treatment is DC
cardioversion
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PSVT
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
Interpretation?
74 148 bpm
Regular  regular
Normal  none
0.16 s  none
0.08 s
Paroxysmal Supraventricular
Tachycardia
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Paroxysmal Supraventricular
Tachycardia (PSVT)
• Usually at a rate of 150-250 bpm
• No organic heart disease in the majority
• Presentations
– Palpitations
– Chest discomfort,dyspnea, lightheadedness
– Frank syncope
– SCD
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Preexcitation
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VT
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
160 bpm
Regular
None
None
Wide (> 0.12 sec)
Interpretation? Ventricular Tachycardia
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Ventricular Arrhythmias
Definitions
• Premature Ventricular beats
– Single beats
– Ventricular Bigeminy, the appearance of one PVC after each sinus
beat
– Couplets, two consecutive premature beats
– Triplets, three consecutive premature beats
– Salvos, runs of 3-10 premature beats
• Accelerated Idioventricular Rhythm (Slow VT), rate 60100 bpm
• Ventricular Tachycardia (VT), rate over 100 bpm
• Ventricular Flutter, regular large oscillations at a rate of
150-300 bpm
• Ventricular Fibrillation (VF), irregular undulations of
varying contour and amplitude
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Ventricular Tachycardia
Classification
• Duration
– Sustained VT defined as VT that persists for than 30 s
or requires termination because of hemodynamic
collapse
– Nonsustained VT, 3 beats to 30 s
• Morphology
– Monomorphic
– Polymorphic
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Salvos
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Sustained Monomorphic VT
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Sustained Polymorphic VT
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VT Etiology
• VT generally accompanies some form of
structural heart disease most commonly:
– Ischemic heart disease
– Cardiomyopathies
• Primary electrical abnormalities
– Long QT syndromes
– Brugada syndrome
• Idiopathic VT
Tehran Arrhythmia Center
VF
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
None
Irregularly irreg.
None
None
Wide, if recognizable
Interpretation? Ventricular Fibrillation
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Sudden Death Syndrome
• Incidence
– 400,000 - 500,000/year in U.S.
– Only 2% - 15% reach the
hospital
– Half of these die before
discharge
• High recurrence rate
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Clinical Substrates Associated
with VF Arrest
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Coronary artery disease
Idiopathic cardiomyopathy
Hypertrophic cardiomyopathy
Long QT syndrome
RV dysplasia
Rarely: WPW syndrome
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