welcome

Case

• 85 y.o. F complaining of feeling “off” and

being “just so tired”

• SOB

• Vaguely recalls feeling a bit “unsteady” on a

couple of occasions

• Hx: osteoporosis, hypothyroidism and

depression

• Meds: Calcium, Vit D, Celexa, Synthroid

Case cont’d

• Vitals:

– HR 45, irregular

– RR 16

– BP 108/75

– Afebrile

:

Arrythmias

heart block

Presented by

Anu k george

Msc (N) II Year

TERMINOLOGIES

Common terms

REVIEW OF CONDUCTION SYSTEM OF HEART

ELECTROCARDIOGRAM

• The electrocardiogram (ECG) is a

representation of the electrical events of the

cardiac cycle.

• Each event has a distinctive waveform, the

study of which can lead to greater insight into

a patient’s cardiac pathophysiology

(300 / 6) = 50 bpm

What is the heart rate?

4 Mechanisms of Arrhythmia

• reentry (most common)

• automaticity

• parasystole

• triggered activity

Fast Conduction Path

Slow Recovery

Slow Conduction Path

Fast Recovery

Premature Beat Impulse

Cardiac

Conduction

Tissue

1. An arrhythmia is triggered by a premature beat

2. The fast conducting pathway is blocked because of its

long refractory period so the beat can only go down the

slow conducting pathway

Repolarizing Tissue

(long refractory period)

Reentry Mechanism

3. The wave of excitation from the premature beat

arrives at the distal end of the fast conducting

pathway, which has now recovered and therefore

travels retrogradely (backwards) up the fast pathway

Fast Conduction Path

Slow Recovery

Slow Conduction Path

Fast Recovery

Cardiac

Conduction

Tissue

Reentry Mechanism

4. On arriving at the top of the fast pathway it finds the

slow pathway has recovered and therefore the wave of

excitation ‘re-enters’ the pathway and continues in a

‘circular’ movement. This creates the re-entry circuit

Fast Conduction Path

Slow Recovery

Slow Conduction Path

Fast Recovery

Cardiac

Conduction

Tissue

Reentry Mechanism

Atrial Reentry

• atrial tachycardia

• atrial fibrillation

• atrial flutter

Atrio-Ventricular

Reentry

• WPW

• SVT

Ventricular Re-entry

• ventricular tachycardia

AV Nodal Reentry

•SVT

Reentry Circuits

SA Node

Automaticity

• Heart cells other than those of the SA node depolarize faster than SA node cells, and take control as the cardiac pacemaker.

• Factors that enhance automaticity include:

SANS, PANS, CO2, O2, H+, stretch, hypokalemia and hypocalcaemia.

Examples: Ectopic atrial tachycardia or multifocal tachycardia in patients with chronic lung disease OR ventricular ectopy after MI

Parasystole…

• is a benign type of automaticity problem that affects only a small region of atrial or ventricular cells.

• 3% of PVCs

Triggered activity…

• is like a domino effect where the arrhythmia is due to the preceding beat.

• Delayed after-depolarizations arise during the resting phase of the last beat and may be the cause of digitalis-induced arrhythmias.

• Early after-depolarizations arise during the plateau phase or the repolarization phase of the last beat and may be the cause of torsades de pointes (ex. Quinidine induced)

Definition

• The term "arrhythmia" refers to any change from the

normal sequence of electrical impulses. The electrical

impulses may happen too fast, too slowly, or erratically –

causing the heart to beat too fast, too slowly, or erratically.

When the heart doesn't beat properly, it can't pump blood

effectively

-American Heart Association

ETIOLOGY

• Dysrhythmias occur as the result of various

abnormalities and disease rate.

Cardiac conditions

• Cardiomyopathy

• Conduction defects

• Heart failure

• Myocardial cell degeneration & MI

• Valve disease

Non cardiac condition

• Acid base imbalance

• Alcohol ,Caffeine & tobacco

• Connective tissue disorder

• Drugs & Toxicity

• Electric shock, hypoxia & shock

• Emotional crisis

• Herbal supplements

• Near drowning and poisoning

• Metabolic condition

TYPES OF DYSRHYTHMIAS

SINUS BRADYCARDIA

• The conduction pathway is the same as that in sinus rhythm but the SA node fires at a rate less than 60beats/min

Absolute bradycardia

Relative bradycardia

Cont…Etiology:

Increased vagal tone

Hypothermia

Increased intraocular pressure

Administration of parasympathomimetic drugs

& adverse drug effects

Acute MI

Disease condition – hypothyroidism, increased

ICP & obstructive jaundice

Cont..Clinical manifestation:

At rest, asymptomatic

Pale, cool skin, hypotension, weakness and angina.

Dizziness or syncope

Confusion and disorientation

Shortness of breath

Cont…

Clinical association- for aerobically trained athletes.

ECG characteristics:

Regular P waves by regular QRS complex

Cont..

Therapy:

Atropine IV o.5mg to I mg

Transcutaneous pacing

Dopamine- 5 to 20µg/kg/min

Epinephrine – 2 to 10µg/min

Isoproterenol- 2 to 10µg/min

SICK SINUS SYNDROME

• SSS also called sinus node dysfunction is a group of

abnormal heart rhythms causes by malfunction of

sinus node.

• Bradycardia-tachycardia syndrome

Cont…

Etiology:

Medication: digitalis, sympatholytic drugs

Sarcoidosis, amyloidosis

Cardiomyopathies

CAD

Cont…

Symptoms:

Dizziness

Palpitation

Chest pain

Angina

Shortness of breath

Fatigue & headache

Nausea and fainting

Cont…

ECG Characteristics:

Combination of sinoatrial and atrioventricular conduction disturbances.

Cont…

• Treatment- artificial pacemaker

SINUS TACHYCARDIA

• Sinus rate more than 100beats/min and is

normally due to increase in sympathetic

activity.

• Conduction pathway is same. Discharge rate

from the sinus node is increased.

Cont…Etiology:

Physical and psychological stressors: exercise,

fever,pain, hypotension, hpovolemia, anemia,

hypoglycemia, MI, HF, anxiety

Adrenergic stimulation

Drugs

Pheochromocytoma

Caffeine

Cont…Clinical manifestation:

Patients intolerance to increased heart rate

Dizziness

Dyspnea

Hypotension

Increased myocardial oxygen consumption

Cont…ECG characteristics:

Treatment: no specific treatment

Never counter shock

Rate: morethan 100 b/min

Rhythm : sinus PR interval:</= 0.20sec

QRS complex-normal

PREMATURE ATRIAL CONTRACTION

PAC is a contraction originating from an ectopic focus in

the atrium in a location other than the sinus node

Cont…

Etiology:

☺Hypoxia

☺Electrolyte imbalance

☺Hyperthyroidism

☺COPD

☺Heart disease- CAD

☺Valvular disorder

Cont…

PATHOPHYSIOLOGY:

• The ectopic signal originates in the LA or RA and

travels across the atria by an abnormal pathway

creating a distorted P wave.

• At the AV node it may stopped (non conducted PAC),

delayed (lengthened PR interval) or conducted

normally.

Cont…

ECG characteristic:

Cont…

Treatment:

Beta blockers

Guess!!!!!!

ATRIAL FLUTTER• It is characterized by large re-entry circuit within the

right atrium, usually encircling the tricuapid annulus

• “Impulses take a circular course around the atria,setting up the flutter waves”

Cont…

Etiology:

♥ Acute coronary syndrome

♥ Mitral and tricuspid valve disorders

♥ Hypoxia, HT, chromic lung disease

♥ Cardiomyopathy

♥ Pulmonary embolus & cor pulmonale

♥ Hyperthyroidism

♥ Drug induced

Cont…Clinical manifestation:

Can be asymptomatic

Palpitation

High ventricular rate- flutter can cause decrease cardiac output--- HF

ECG characteristics:

Classic- saw tooth pattern & no true P wave

Ventricular response- a function of AV node block or conduction of atrial impulses.

Cont…

Treatment:

Calcium channel blocker

Beta adrenergic

blockers

To control ventricular

rate

Cont…

• Electrical cardio version

• Radio frequency catheter ablation

• High risk of stroke-

– Anticoagulate for 3 weeks if more than 48 hours

occurrence – 4 weeks

– IV heparin

ATRIAL FIBRILLATION

• It is characterized by presence of

multiple, interacting re-entry circuit

looping around the atria.

• Total disorganisation of atrial electrical

activity due to multiple ectopic foci

resulting in loss of effective atrial

contraction

Cont…

Etiology:

Thyrotoxicosis, alcohol intoxication, caffeine use, electrolyte disturbance, stress and cardiac surgery

Atrial impulse faster than the SA node impulses, impulses take multiple , choatic, random pathways

through the atria

Cont…Clinical manifestation:

Atrial fibrillatory waves- AF with rapid ventricular

response

Thrombi form- 5 fold increase risk to get stroke

Decreased cardiac output.

Cont…ECG Characteristics:

“irregularly irregular rhythm- with variation in both interval & amplitude from R wave to R wave”

Rate- wide ranging ventricular response to atrial rate of 300-400 beats/min

Cont…Treatment:

♫ Calcium channel blockers

♫ Beta adrenergic blockers

♫ Antiarrythmic drugs

♫ Anti coagulation therapy

♫ Maze procedure:

• Cryoablation (use of cold)

• Heat (high intensity ultrasound)

Cont…

Rhythm control

• Immediate cardio version after administration of IV

heparin

• To restore sinus rhythm flecainide= 2mg/kg over

30min max dose 150mg

• INR to be maintained 2.0 to 3.0 for a minimum of 3

weeks

Cont…Rate control:

o Digoxin

o Beta blokers

o Rate limiting calcium antagonist

– Verapamil

– diltiazem

o Combination therapy:

• Digoxin + atenolol

WOLFF PARKINSON WHITE SYNDROME

WPW is one of the severe disorder of the conduction

system. WPW is caused by the presence of an

abnormal electrical conduction pathway between

atria and ventricle

0.1% to 0.3%

PRKAG-2 gene/ congenital

Cont…

• Notching of positive upstroke of QRS complex

Rate: 60-100b/minRhythm: normal sinus except pre-excitation tachycardiaPR interval: shorter

Cont…

Clinical manifestation:

Asymptomatic

Sometimes signs of tachycardia

Treatment:

• Cardio verison

• Anti arrythmic drugs

• Digoxin

• Ca channel blockers and beta blockers

JUNCTIONAL TACHYCARDIA

• It originates in the area of the AV node, primarily

because the SA node has failed to fire or the signal

has been blocked.

Cont…

• Impulse from the AV node usually moves in a

retrograde (backward fashion) that produce an

abnormal P wave just occuring before or after QRS

complex

MULTIFOCAL ATRIAL TACHYCARDIA

• Area of automaticity (impulse formation)

originate irregularly and rapidly at different

points in the atria

Cont…

ECG Characteristic:

“wandering atrial pacemaker”

P waves- 3 or more P wave that differ in polarity(up/down) shape and size since the atrial impulse isgenerated from multiple foci

Cont…

Clinical manifestation:

Signs of less ejection fraction and tachycardia.

Treatment:

Beta blocker

Calcium channel blockers

Amiodarone

No cardio version

PAROXYSMAL SUPRAVENTRICULAR TACHYCARDIA

Ectopic focus anywhere above the bifuraction of

the bundle of his.

Etiology:

Over exersion

Emotional stress

Deep inspiration

RHD, CAD, COPD & CHF

Cont…• PATHOPHYSIOLOGY:

Impulse arise and recycle repeatedly in the AV nodebecause of areas of unidirectional block in thepurkinjie fibers

Reexcitation of the atria when there is a one wayblock

PSVT occurs because of a reentrant phenomenon

Cont…Clinical manifestation:

Prolonged episode and HR greater than 180beats/min

Decreased CO- Hypotension, dyspnea & angina

Anxious and uncomfortable

ECG Feature:

Cont…

Treatment:

Vagal stimulation

IV adenosine

IV Verapamil- 5-10mg

Beta blockers

Cardio version

PREMATURE VENTRICULAR CONTRACTION

Originating ectopic focus in the ventricles.

Premature occurrence of a QRS complex which is wide and distorted in shape.

Multifocal PVC

UnifocalPVC

VENTRICULAR FIBRILLATION

• Ventricle consist of areas of normal myocardium

alternating with areas of ischemic, injured or

infracted myocardium, leading to chaotic pattern of

ventricular depolarization

Cont…

Etiology:

♯ Acute coronary syndrome

♯ Stable to unstable VT

♯ PVC’S with R on T phenomenon

♯ Multiple drug

♯ Electrolyte disturbance

♯ Hypoxia, metabolic acidosis

Cont…

• Quickering ventricle no effective contraction

Cont…

Clinical manifestation:

Pulse disappears with onset of VF

Collapse, unconsiousness

Agonal breath

Onset of reversible death

Cont…

TREATMENT:

• Defibrillation

• Oxygen, CPR, INTUBATION

• Epinephrine

• Vasopressin

• Antiarrythmic

VENTRICULAR TACHYCARDIA

VT Monomorphic

VT polymorphic

Torsades de pointes

MONOMORPHIC VT

• Impulse conduction is slowed around area ofventricular injury, infarct or ischemia

• Ectopic impulses (irritable foci)

• Area of injury can cause the impulse to take acircular course, leading to the re-entryphenomenon and rapid repetitivedepolarization

Cont…

Clinical manifestation:

Asymptomatic

Symptoms of decreased cardiac output

ECG CRITERIA:

Φ 3 or more consecutive PVCs: VT

Φ < 30 sec- non sustained VT

Φ > 30 sec- sustained VT

Wide QRS complex

POLYMORPHIC VT

• Impulse conduction is slowed around multiple areas

of ventricular injury, infarcts or ischemia

• Irritable foci occur in multiple area of the ventricles

• Asymptomatic

TORSADES DE POINTES

• Twisting of the points

• QT interval is abnormally long

• Lead to increase in the relative refractory period

• Increase probability that an irritable focus (PVC) will occur on the T-wave

PULSELESS ELECTRICAL ACTIVITY

• PEA a situation in which electrical activity can be

observed on the ECG, but there is no mechanical

activity of the ventricles and the patient has no

pulse.

• Causes: 5H & 5T

Cont…

• Cardiac conduction impulses occur in organized

pattern , but this fails to produce myocardial

contraction (electromechanical dissociation) or

insufficient filling during diastole or ineffective

contractions

Cont…

Clinical manifestation:

Collapse, unconscious

Agonal respiration or apnea

No pulse

ASYSTOLE

• Total absence of ventricular electrical activity,

• Occasional P wave can be seen

DEFINITION :

This is the inhibition or failure of the

electrical impulses generated in the SA node to

be conducted through the conduction system

to the ventricles . This can occur because of an

abnormality of conduction velocity or complete

refractoriness in the conduction system .

HEART BLOCK

TYPES

AV NODAL BLOCKS (HEART BLOCKS)

Disturbances of the conduction through the heart, occurring at the AV Node

AV Node – damaged/diseased – delay or total block of impulses at the AV Node

This conduction defect can be seen on the ECG

AV Node• AV nodal conduction time is represented on

the ECG as the PR segment.

• But - we always measure the PR interval.

FIRST DEGREE HEART BLOCK (1º)

DEFINITION

It is a type of heart block in which every impulse is

conducted to the ventricles but the duration of AV

conduction is prolonged. After the impulse moves

through the AV node, it is usually conducted normally

through the ventricles.

CAUSES

Myocardial infarction

Chronic ischemic heart disease

Rheumatic fever

Hyperthyroidism

Vagal stimulation

Drugs as digitalis, - adrenergic blockers, verapamil

AV nodal dysfunction accounts for the

majority of cases. First-degree AV block

caused by conduction delay in the His-Purkinje

system often is associated with bundle-branch

block.

PATHOPHYSIOLOGY

ECG CHARACTERISTICS

• SA Node – normal

• Normal P wave

• AV Node conducts more slowly than normal

• Prolonged PR Interval

• Rest of conduction is normal

• Normal QRS

Cont...

Type

of

block

Rate

and

Rhyth

m

P wave PR

Interv

al

QRS

complex

P:QRS

Ratio

First

Degree

Heart

Block

Normal

and

regular

Normal >0.20

sec

Normal 1:1

FIRST DEGREE HEART BLOCK (1º)

PR Interval > 0.2 seconds (5 small sq)

• Note – the PR Interval is constant

CLINICAL SIGNIFICANCE

• Precursor of higher AV block

TREATMENT

• None, monitoring of the rhythm if changes

• Note – this can progress to 2º or 3º heart block

There is no treatment for first degree heart block .

Temporary pacing .

MANAGEMENT

SECOND DEGREE HEART BLOCK (2º)

DEFINITION

It occurs when one atrial impulse at a time

fails to be conducted to the ventricles.

TYPES

• Mobitz Type I (Wenkebach)

• Mobitz Type II

• 2 : 1

SECOND DEGREE HEART BLOCK (2º) MOBITZ TYPE I (WENKEBACH)

DEFINITION

It is a progressive increase in conduction times

of consecutive atrial impulses into the

ventricles until one impulse fails to conduct or

is dropped

CAUSES

Chronic ischemic heart disease

Drugs as digoxin, - adrenergic blockers

ECG CHARACTERISTICS

PR Interval prolongs with each beat until a

dropped beat is seen

The PR Interval is NOT constant

After each dropped beat, the PR interval is

normal and the cycle starts again

CONT….Type of

block

Rate and

Rhythm

P wave PR

Interv

al

QRS

Complex

P:

QRS

Ratio

Mobitz

Type I

Atrial:

Normal and

regular

Ventricular

: slower and

irregular

Normal Progres

sively

lengthe

ned

Normal

QRS

width, with

pattern of

one

nonconduc

ted QRS

3:2, 4:3,

5:4

SECOND DEGREE HEART BLOCK (2º) MOBITZ TYPE I (WENKEBACH)

PR PR

PR DROPPED BEAT

TREATMENT

Symptomatic = atropine or temporary pacemaker

Asymptomatic = the rhythm should be observed

with a transcutaneous pacemaker on standby.

SECOND DEGREE HEART BLOCK (2º)MOBITZ TYPE II

DEFINITION

It is sudden failure of conduction of an atrial

impulse to the ventricles without progressive increases in

conduction time of consecutive P waves. It occurs below the

AV node and is usually associated with bundle- branch

block; therefore, the dropped beats are usually a

manifestation of bilateral bundle- branch block.

CAUSES

Anterior myocardial infarction

Coronary heart disease

Rheumatic heart disease

Digitalis toxicity

ECG CHARACTERISTICS

PR Interval normal & constant

Occasionally a dropped beat is seen

CONT….Type

of

block

Rate and

Rhythm

P wave PR

Interv

al

QRS

Complex

P:QR

S

Ratio

Mobitz

Type II

Atrial :

Usually

normal and

regular or

irregular

Ventricular:

slower and

regular or

irregular

P wave

occurs in

multiples

Normal

or

prolong

ed

Widened

QRS, no

connectio

n with P

waves

2:1,

3:1,

4:1,

5:1

Second Degree Heart Block (2º)Mobitz Type II

PR PR DROPPED BEAT PR

CLINICAL SIGNIFICANCE

• significant disease.

• This can progress to third degree heart blockand is associated with a poor prognosis.

TREATMENT

• pacemaker

• Drugs as atropine, epinephrine, isoproterenolor dopamine can be used to increase heartrate.

SECOND DEGREE HEART BLOCK (2º)2 : 1

DEFINITION

It is failure of conduction of every otheratrial impulse. The ratio will be as 2 P waves :1 QRS.

• Unable to strictly classify as Mobitz Type I or II

• Particular type of second degree Heart Block

• Ratio 2 P waves : 1 QRS

ECG CHARACTERISTICS

PR interval

• Type I- Longer than normal (more than 0.20

second)

• Type II- Normal

QRS complex

• Type I- Narrow

• Type II- Wide

Second Degree Heart Block (2º)2 : 1

Cont...

CLINICAL SIGNIFICANCE

• Unable to classify as Mobitz type I or II

• Will be associated with symptoms, dizziness, lethargy etc.

• This can deteriorate to 3º Heart Block

TREATMENT

• Pacemaker

THIRD DEGREE HEART BLOCK (3º)(COMPLETE)

DEFINITION

It constitutes one form of AVdissociation in which no impulses from the atriaare conducted to the ventricles. The atria arestimulated and contract independently of theventricles. The ventricular rhythm is an escaperhythm and the ectopic pacemaker may beabove or below the bifurcation of the Hisbundle.

CAUSES

Fibrosis or calcification of cardiac conduction

system

Coronary artery disease

Cardiomyopathy

Myocarditis

Myocardial infarction

• Surgery

ECG CHARACTERISTICS

Complete failure of the AV Node

No impulses from Sinus Node will pass through to the ventricles

Some part if the conducting system will take over as pacemaker of the heart (even a myocardial cell 10-15 bpm)

CONT…

• P wave rate – normal

• Ventricular rate – slow

• Ventricular complex may be broad

• Complete dissociation between P waves & QRS

CONT…

Type

of

block

Rate

and

Rhythm

P wave PR

Interv

al

QRS

Complex

P:QRS

Ratio

Third

degree

heart

block

Ventricula

r rate 20-

40

beats/min

and

regular

Normal

but no

connectio

n with

QRS

complex

Variable Normal

or

widened

QRS, no

connectio

n with P

waves

More P

waves

than

QRS

complex

Third Degree Heart Block (3º)(Complete)

P P P P P

QRS QRS

Cont....CLINICAL SIGNIFICANCE

• Symptoms LOC, Confusion, Dizziness, Low

BP

• Can lead to standstill, VT or VF (stokes

Adams)

TREATMENT - pacemaker

Types of infra-hisan block

Left bundle branch block

Left anterior fascicular block

Left posterior fascicular block

Right bundle branch block

CLINICAL MANIFESTATIONS

Slow heart rate

Irregular heart rate

Arrhythmias

In case of severe block ;

Breathlessness

Breathlessness with exertion

Dizziness

Fainting

Fatigue

Heart block

Chest pain

Shortness of breath

Seizures

Light headedness

MANAGEMENT

Cont…

ANTI ARRYTHMIC DRUGS

DEFIBRILLATION

SYNCHRONIZED DEFIBRILLATOR

IMPLANTABLE CARDIOVERTER DEFIBRILLATOR

RADIOFREQUENCY ABLATION CATHETER

Anti-arrhythmic drugs

• Class I membrane stabilizing agents

• Class II β-adrenoceptor antagonist β blockers

• Class III Amiodarone drugs – prolong action potential

• Class IV Slow calcium channel blockers

Cont…Atropine Sulphate

0.6 mg IV

Maximum 3mg

Adenosine

3 mg IV over 2sec followed by 6mg( if needed)

12 mg 1-2 min interval

Cont…

DIGOXIN

0.2-0.5 mg oral / IV

Digoxin toxity

Extracardiac manifestations – Anorexia, Nausea, Vomiting, Diarrhea, Altered colour vision.

Cardiac manifestations

• Bradycardia, ventricular ectopics

• Atrial & ventricular tachycardia

• Ventricular fibrillation & bigeminy

Radio frequency catheter ablation

It is a procedure that can cure many

types of fast heart beats. Using a special wires

or catheters threaded into the heart. Here

they are using radiofrequency energy.