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NORMAL ELECTRICAL
Dysrhythmias CONDUCTION
DYSRRHYTHMIAS
■ disorders of the formation or the conduction of the electrical ■ SA Node® AV node® Bundle of His® Purkinje Fibers
impulse within the heart.
■ Depolarization – electrical stimulation
■ can cause disturbances of the heart rate, rhythm, or both
■ Systole – mechanical contraction
■ diagnosed by analyzing the electrocardiographic waveform
■ Repolarization – electrical relaxation

■ Diastole – mechanical relaxation

■

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Sympathetic and
Parasympathetic Stimulation OBTAINING AN LEAD PLACEMENTS
ELECTROCARDIOGRAM
Electrodes are attached to cable wires, which are ■ V1—4th intercostal space, right sternal border
connected to one of the ff:
■ Inotropic Effect ■ An ECG machine placed at a patient’s side for ■ V2—4th intercostal space, left sternal border
■ Chronotropic Effect immediate recording ■ V3—diagonally between V2 and V4
■ Dromotropic Effect ■ A cardiac monitor at a patient’s bedside for
continuous reading ■ V4—5th intercostals space, left midclavicular
line
th ■ A small box that the patient carries and that
I know! SAX 5 avenue. continuously transmits the ECG information by radio ■ V5—same level as V4, anterior axillary line
waves to a central monitor
■ A small, lightweight tape recorder-like machine that ■ V6—same level as V4 and V5, midaxillary line
the patient wears and that continuously records the
ECG on a tape

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4 5 6

ANALYSIS OF THE
ANALYSIS OF THE
ELECTROCARDIOGRAM ELECTROCARDIOGRAM
■ U wave
■ P wave – represent repolarization of the Purkinje fibers, but
– represents the electrical it is sometimes seen in patients with hypokalemia,
impulse starting in the sinus
node and spreading through hypertension, or heart disease.
the atria
– represents the atrial muscle
depolarization
■ PR interval
■ QRS complex – measured from the beginning of the P wave to the
– represents ventricular muscle
depolarization
beginning of the QRS complex and represents the
– N= 0.04 to 0.1 sec time needed for sinus node stimulation, atrial
■ T wave depolarization, and conduction through the AV
– represents ventricular muscle
repolarization
node before ventricular depolarization
– N= 0.12 to 0.2 sec

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ANALYSIS OF THE
ANALYSIS OF THE ELECTROCARDIOGRAM ■

■
Small square = 0.04 sec

Large square – 0.20 sec

ELECTROCARDIOGRA ■ 300 large squares = 1 minute strip
M
■ 1500 small squares = 1 minute strip
■ ST segment ■ TP interval – Count the number of small boxes
within the RR interval and divide by
1500
– represents early – measured from the end of the T wave to the – Count the number of RR intervals in 6
ventricular beginning of the next P wave, an isoelectric seconds and multiply it by 10
repolarization, lasts period.
from the end of the QRS
complex to the ■ PP interval
beginning of the T wave
– measured from the beginning of one P wave to
■ QT interval the beginning of the next
– represents the total time – used to determine atrial rhythm and atrial rate. The 300 Method: Count the number
for ventricular of large boxes between 2 successive
depolarization and ■ RR interval DETERMINING R waves and divide by 300 to obtain
repolarization
– measured from the
– measured from one QRS complex to the next
QRS complex
VENTRICULAR HEART heart rate.

beginning of the QRS

complex to the end of T – used to determine ventricular rate and rhythm. RATE FROM THE ECG The 1500 Method: Count the number
wave of small boxes between two
successive R waves and divide this
– N = 0.32 to 0.4 sec number into 1500 to obtain heart rate.

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10 11 12

DETERMINING HEART
RHYTHM FROM THE ECG

RR interval - used to PP interval – used to

determine ventricular rhythm determine the atrial rhythm.

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Normal Sinus Rhythm Sinus Bradycardia

■ Occurs when the electrical impulse starts at a regular rate and ■ Occurs when the sinus node creates an impulse at a
rhythm in the sinus node and travels through the normal slower than normal rate.
conduction pathway.
■ Ventricular and atrial rate: less than 60 in the adult
■ Ventricular and atrial rate: 60 to 100 in the adult
■ Ventricular and atrial rhythm: regular
■ Ventricular and atrial rhythm: Regular
■ QRS shape and duration: Usually normal, but may be regularly ■ QRS shape and duration: usually normal, but may be
regularly abnormal
■ abnormal
■ P wave: normal and consistent shape; always in front of
■ P wave: Normal and consistent shape; always in front of the the QRS
QRS
■ PR interval: consistent interval between 0.12 and 0.20
■ PR interval: Consistent interval between 0.12 and 0.20 seconds seconds
■ P: QRS ratio: 1:1 ■ P: QRS ratio: 1:1

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H’s and T’s H’s and T’s

■ H’s ■ T’s
– Hypovolemia – Toxins
– Hypoxia – Tamponade
– Hypo/hyperK – Tension pneumothorax
– Hypoglycemia – Thrombosis
– hypothermia – Trauma

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Occurs when the sinus node creates an

Sinus Bradycardia impulse in a faster than normal rate.
Ventricular and atrial rate: greater than 100
■ MANAGEMENT in the adult
– If the bradycardia is from a medication such as a beta-blocker, Ventricular and atrial rhythm: regular
the medication may be withheld.
– Atropine, 0.5 to 1.0 mg given rapidly as an intravenous (IV) bolus QRS shape and duration: usually normal,
– Catecholamines and emergency transcutaneous pacing Sinus but may be regularly abnormal

Tachycardia P wave: normal and consistent shape;

always in front of the
QRS, but may be buried in the preceding T
wave
PR interval: consistent interval between
0.12 and 0.20 seconds
P: QRS ratio: 1:1

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Sinus Tachycardia Atrial Flutter

Sinus
■ MANAGEMENT ■ occurs in the atrium and creates impulses at an
Arrhythmia
– Calcium channel blockers and beta-blockers atrial rate between 250 to 400 times per minute.
■ occurs when the sinus node
creates an impulse at an
irregular rhythm; the rate
usually increases with
■ S/Sx: chest pain, shortness of breath, and low
inspiration and decreases with
expiration. blood pressure
■ Ventricular and atrial rate: 60
to 100 in the adult ■ Ventricular and atrial rate: Atrial rate ranges
■ Ventricular and atrial rhythm:
Irregular between 250 and 400; ventricular rate usually
■ QRS shape and duration: ranges between 75 and 150.
Usually normal, but may be

■
regularly abnormal
P wave: Normal and consistent
■ Ventricular and atrial rhythm: The atrial rhythm is
shape; always in front of the
QRS regular; the ventricular rhythm is usually regular
■ PR interval: Consistent interval
between 0.12 and 0.20
but may be irregular because of a change in the AV
seconds conduction.
■ P: QRS ratio: 1:1

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Atrial Flutter Atrial Flutter

■ QRS shape and duration: Usually normal, ■ MANAGEMENT
– If the patient is unstable, electrical cardioversion is
but may be abnormal or may be absent usually indicated.
■ P wave: Saw-toothed shape. These waves – If the patient is stable, diltiazem, verapamil, beta-
blockers, or digitalis may be given intravenously to slow
are referred to as F waves. the ventricular rate.
■ PR interval: Multiple F waves may make it
difficult to determine the PR interval.
■ P: QRS ratio: 2:1, 3:1, or 4:1 ATRIAL
FLUTTER

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■ causes a rapid, disorganized, and uncoordinated twitching of ■ QRS shape and duration: Usually normal, but may be
atrial musculature. abnormal

■ Ventricular and atrial rate: Atrial rate is 300 to 600. ■ P wave: No discernible P waves; irregular undulating waves
Ventricular rate is usually 120 to 200 in untreated atrial are seen and are referred to as fibrillatory or f waves
fibrillation ■ PR interval: Cannot be measured
■ Ventricular and atrial rhythm: Highly irregular ■ P: QRS ratio: many:1

Atrial Fibrillation Atrial Fibrillation

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■ MANAGEMENT ■ Digoxin is used as a second line to control the ventricular rate in

■ Intravenous adenosine (Adenocard, Adenoscan) those patients with poor cardiac function
– Cardioversion if atrial fibrillation has been present for
less than 48 hours. ■ To prevent recurrence and to maintain sinus rhythm, ■ Warfarin is indicated if the patient is at higher risk for a stroke
(ie, is elderly or has hypertension, heart failure, or a history of
– Cardioversion of atrial fibrillation that has lasted longer quinidine, disopyramide, flecainide, propafenone, sotalol, or
amiodarone may be prescribed. stroke).
than 48 hours should be avoided unless the patient has
received anticoagulants, due to the high risk for ■ Aspirin may be substituted for warfarin for those with
■ Calcium-channel blockers [diltiazem (Cardizem, Dilacor, contraindications to warfarin and those who are at lower risk of
embolization of atrial thrombi. Tiazac) and verapamil (Calan, Isoptin, Verelan)] and beta
stroke.
– Medications: quinidine, ibutilide, flecainide, dofetilide, blockers for controlling the ventricular rate in atrial
propafenone, procainamide (Pronestyl), disopyramide, or fibrillation, especially during exercise ■ Transesophageal echocardiography.
amiodarone
■ Pacemaker implantation or surgery

Atrial Fibrillation Atrial Fibrillation Atrial Fibrillation

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Premature Ventricular
Premature Ventricular Bigeminy - every
Complex
other complex is a
Complex PVC.
■ MANAGEMENT
– Lidocaine - medication most
Premature Trigeminy - every commonly used for immediate,
PVCs that are (1) more frequent Ventricular third complex is a short term therapy.
PVC.
an impulse that starts in a ventricle
and is conducted through the
than 6 per minute, (2) multifocal or
polymorphic (having different
shapes), (3) occur two in a row
Complex – Decreasing automaticity of
ventricles before the next normal
sinus impulse.
(pair), and (4) occur on the T wave
(the vulnerable period of vetricular cells.
ventricular depolarization) have not
been found to be precursors of VT
Quadrigeminy - – Anti-arrythmic and local anesthetic
every fourth
complex is a PVC.

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Ventricular Tachycardia Ventricular Tachycardia

■ Defined as three or more pvcs in a row, occurring at a rate ■ QRS shape and duration: Duration is 0.12
exceeding 100 beats per minute.
seconds or more; bizarre, abnormal shape
■ Ventricular and atrial rate: ventricular rate is 100 to 200
beats per minute; atrial rate depends on the underlying ■ P wave: Very difficult to detect, so atrial
rhythm (eg, sinus rhythm)
rate and rhythm may be indeterminable
■ Ventricular and atrial rhythm: usually regular; atrial rhythm
may also be regular. ■ PR interval: Very irregular, if P waves seen.
■ P: QRS ratio: Difficult to determine, but if
P waves are apparent, there are usually
more QRS complexes than P waves. VENTRICULAR TACHYCARDIA

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Ventricular Tachycardia Ventricular Fibrillation Ventricular Fibrillation

■ MANAGEMENT ■ Is a rapid but disorganized ventricular rhythm that causes
ineffective quivering of the ventricles.
■ Ventricular rhythm: Extremely irregular, without specific
pattern

– 12-lead ECG monitoring if stable ■ Often characterized by the absence of an audible heartbeat, ■ QRS shape and duration: Irregular, undulating waves without
a palpable pulse, and respirations. recognizable QRS complexes
– Cardioversion is the choice for ■ Ventricular rate: greater than 300 per minute
monophasic VT in asymptomatic
patient
– Immediate defibrillation if
unconcious and pulse less

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Ventricular Fibrillation Ventricular Asystole

■ MANAGEMENT ■ commonly called flatline
■ characterized by absent QRS complexes
– immediate defibrillation and ■ no heartbeat, no palpable pulse, and no respiration
activation of emergency services
Ventricular
– administering vasoactive and
Fibrillation antiarrhythmic medications
alternating with defibrillation

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Ventricular Asystole occurs when all the atrial

impulses are conducted through
■ MANAGEMENT the AV node into the ventricles
at a rate slower than normal.
– CPR
– Transcutaneous
pacing may be Ventricular and atrial rate:
First-degree Depends on the underlying
attempted. Atrioventricula rhythm
– bolus of intravenous r Block
epinephrine should
be administered and
repeated at 3 to 5 Ventricular and atrial rhythm:
minute intervals, Depends on the underlying
followed by 1 mg rhythm
bolus of atropine at
3 to 5 minute
intervals. 55
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First-degree Atrioventricular
Block occurs when all but one
of the atrial impulses
■ QRS shape and duration: Usually normal, but may be
abnormal are conducted through
■ P wave: In front of the QRS complex; shows sinus rhythm, the AV node into the
regular shape Second- ventricles.
■ PR interval: Greater than 0.20 seconds; PR interval degree
measurement is constant. Atrioventricula
■ P: QRS ratio: 1:1 r Block, type 1
Ventricular and atrial
rate: Depends on the
underlying rhythm

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Second-degree Second-degree
Atrioventricular Block, type Atrioventricular Block, type
1 ■ Ventricular and atrial rhythm: The PP interval is regular if the 1 ■ QRS shape and duration: Usually normal,
patient has an underlying normal sinus rhythm; the RR but may be abnormal
interval characteristically reflects a pattern of change.
Starting from the RR that is the longest, the RR interval ■ P wave: In front of the QRS complex; shape
gradually shortens until there is another long RR interval depends on underlying rhythm
■ PR interval: PR interval becomes longer
with each succeeding ECG complex until
there is a P wave not followed by a QRS.
The changes in the PR interval are repeated
between each “dropped” QRS, creating a
pattern in the irregular PR interval
measurements.
■ P: QRS ratio: 3:2, 4:3, 5:4, and so forth
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60 61 62

Second-degree Second-degree Second-degree

Atrioventricular Block, type Atrioventricular Block, type Atrioventricular Block, type
2 ■ occurs when only some of the atrial impulses are conducted 2 ■ Ventricular and atrial rhythm: The PP interval is regular if the 2 ■ Punderlying
wave: In front of the QRS complex; shape depends on
through the AV node into the ventricles. patient has an underlying normal sinus rhythm. The RR rhythm.
interval is usually regular but may be irregular, depending on
■ Ventricular and atrial rate: Depends on the underlying rhythm the P_QRS ratio. ■ PR interval: PR interval is constant for those P waves just
before QRS complexes.
■ QRS shape and duration: Usually abnormal, but may be
normal ■ P: QRS ratio: 2_1, 3_1, 4_1, 5_1, and so forth

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Third-degree Atrioventricular Third-degree Atrioventricular

Block Block
■ occurs when no atrial impulse is conducted through the AV ■ QRS shape and duration: Depends on the escape rhythm; in
node to the ventricles. junctional escape, QRS shape and duration are usually normal,
and in ventricular escape, QRS shape and duration are usually
■ Ventricular and atrial rate: Depends on the escape and
underlying atrial rhythm abnormal.
■ P wave: Depends on underlying rhythm
■ Ventricular and atrial rhythm: The PP interval is regular and the
RR interval is regular; however, the PP interval is not equal to ■ PR interval: Very irregular
the RR interval.
■ P: QRS ratio: More P waves than QRS complexes

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MANAGEMENT OF HEART
BLOCKS
■ If the patient is short of breath, complains of
chest pain or lightheadedness, or has low
blood pressure, an intravenous bolus of
atropine is the initial treatment of choice.
■ If the patient does not respond to atropine or
has an acute MI, transcutaneous pacing
should be started.
■ A permanent pacemaker may be necessary
if the block persists

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MANAGEMENT OF MANAGEMENT OF
DYSRHYTHMIAS DYSRHYTHMIAS Artificial Cardiac Pacemakers
■ VAGAL MANEUVER
– Valsalva Maneuver
– Carotid sinus massage
■ Instruct the client to bear down ■ Electronic device which delivers direct stimulation to the heart
■ Physician instructs the client to turn causing electrical depolarization and cardiac contraction
or induce gag reflex
the head away from the side to be ■ It initiate and maintains the heart rate when the natural
massaged ■ Monitor VS especially HR and BP pacemaker of the heart its ineffective

■ Physician massages over one carotid ■ Provide an emesis basin and

artery initiate aspiration precaution if
■ Client should be on a cardiac monitor gag reflex is being induced
■ ECG should be monitored before and
after the procedure

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Artificial Cardiac Pacemakers

Types of Artificial Cardiac Types of Artificial Cardiac Modes
Pacemakers Pacemakers
■ Temporary Pacemakers ■ Permanent Pacemakers Demand Mode (Synchronous, Noncompetitative)
– Temporary Pacing of the heart is usually done as an – May be implanted in the following techniques
emergency procedure that allows observation of the •Electrode is threaded to the cephalic or • Triggers electrical firing only if HR goes down
effects of pacing on heart function before a permanent Transvenous external jugular vein in the right • Does not compete with heart’s natural rhythm
pacemaker is implanted ventricle
– TRANSVENOUS APPROACH to position the electrode in
(Endocardial) •Done under local anesthesia
the apex of the right ventricle is done
– An external generator is attached to the patient Fixed Rate (Asynchronous, Competitive)
•Aterior chest wall is opened and
Transthoracic electrodes are sutured to the surface of • Delivers impulses in a preset CONSTANT
(Epicardial) the heart, then threaded rate (independent from heart’s own
subcutaneously to the abdominal wall rhythm)
• Valuable in complete heart blocks
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Cardioversion Cardioversion Defibrillation

■ anticoagulation for a few weeks before may be indicated
■ involves the delivery of a timed electrical current to terminate a ■ used in emergency situations as treatment
tachydysrhythmia. The defibrillator is set to synchronize with ■ patient is instructed not to eat or drink 8 hours before the
the ECG on a cardiac monitor so that the electrical impulse procedure
of choice for ventricular fibrillation and
discharges during ventricular depolarization. pulseless VT.
■ patient is given IV sedation and anesthesia
■ depolarizes a critical mass of myocardial
cells at once; when they repolarize, the sinus
node usually recaptures its role as the
heart’s pacemaker.
■ use of epinephrine or vasopressin may make
it easier to convert the dysrhythmia to
normal sinus rhythm with defibrillation.

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Defibrillation INTERVENTIONS FOR CARDIOVERSION

AND DEFIBRILLATION
■ Use multifunction conductor pads or paddles with a
■ 1 shock = 200 Joules
st
conducting agent between the paddles and the skin (the
conducting agent is available as a sheet, gel, or paste).
■ 2nd shock = 200 – 300 Joules
■ Place paddles or pads so that they do not touch the
■ 3rd shock = 360 Joules patient’s clothing or bed linen and are not near
medication patches or direct oxygen flow.
■ If cardioverting, ensure that the monitor leads are
attached to the patient and that the defibrillator is in
sync mode.
***If defibrillating, ensure that the defibrillator is not in
sync mode (most machines default to the “not-sync” mode).

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INTERVENTIONS FOR CARDIOVERSION INTERVENTIONS FOR CARDIOVERSION INTERVENTIONS FOR CARDIOVERSION

AND DEFIBRILLATION AND DEFIBRILLATION AND DEFIBRILLATION
■ Do not charge the device until ready to shock; then keep ■ Before pressing the discharge button, call “Clear!” three
thumbs and fingers off the discharge buttons until paddles or times:
pads are on the chest and ready to deliver the electrical (1) As “Clear” is called the first time, ensure that you
charge. are not touching the patient, bed or equipment; ■ After the event is complete,
■ Exert 20 to 25 pounds of pressure on the paddles to ensure
good skin contact.
(2) as “Clear” is called the second time, ensure that no
one is touching the bed, the patient, or equipment,
inspect the skin under the pads or
including the endotracheal tube or adjuncts; and as paddles for burns; if any are
(3) “Clear” is called the third time, perform a final
visual check to ensure you and everyone else are detected, consult with the
clear of the patient and anything touching the
patient. physician or a wound care nurse
■ Record the delivered energy and the results (cardiac about treatment.
rhythm, pulse).

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