Select Dysrhythmias and Therapeutic Modalities J.O. Medina, NP Education Specialist Nurse Practitioner Nurse Practitioner Critical Care & Emergency Services.

Select Dysrhythmias andSelect Dysrhythmias andTherapeutic ModalitiesTherapeutic Modalities

J.O. Medina, NPJ.O. Medina, NPEducation Specialist Education Specialist

Nurse PractitionerNurse Practitioner

Critical Care & Emergency ServicesCritical Care & Emergency Services

California Hospital Medical CenterCalifornia Hospital Medical Center

Premature Atrial Contractions Premature Atrial Contractions (PACs)(PACs)

• Rateusually within normal range but depends on underlying rhythm

• Rhythm regular with premature beats

• P waves premature (occurring earlier than the next sinus P wave),

positive in lead II, one precedes each QRS complex, often differ in shape from sinus P waves : may be flattened, notched, pointed, biphasic, or lost in preceding T wave


• PR interval may be normal or prolonged, depending on prematurity of beat

• QRS Duration usually less than 0.10 sec but may be wide (aberrant) or absent, depending on the prematurity of the beat; the QRS of the PAC is similar in shape to those of the underlying rhythm unless the PAC is aberrantly conducted


• PAC is not an entire rhythm - it is a single beat. Therefore identify the underlying rhythm and the ectopic beat(s)

• Types– non-conducted or blocked PAC

• only P wave with no QRS after it appearing as pause

– conducted PAC


• PAC Patterns:– pairs (couplet) : two sequential PAC– “runs” or “bursts” : three or more sequential PACs

often called:• paroxysmal (sudden)• atrial tachycardia (PAT)• paroxysmal SVT (PSVT)

– atrial bigeminy– atrial trigeminy– atrial quadrigeminy


• Clinical Significance– very common– presence does not imply underlying cardiac

disease

Atrial Tachycardia Atrial Tachycardia

• Rate 150 - 250 beats/min

• Rhythm regular

• P waves one positive P wave precedes each QRS complex in

lead II but the P waves differ in shape from sinus P waves; with rapid rates, it is difficult to distinguish P waves from T waves

Atrial TachycardiaAtrial Tachycardia

• PR interval may be shorter or longer than normal and may be difficult to measure because P waves may be hidden in T waves

• QRS duration 0.10 sec or less unless an interventricular conduction delay exists

Atrial TachycardiaAtrial Tachycardia

• Clinical Significance– rapid ventricular rate may decrease cardiac

output

Atrial FlutterAtrial Flutter• Rate atrial rate 250 - 450 / min, typically

300 / min; ventricular rate variable determined by AV blockade

• Rhythm atrial regular ; ventricular regular or irregular

• P waves no identifiable P waves; saw-toothed “flutter”, “picket fence”

• PR interval non measurable

• QRS usually < 0.10 sec

Atrial FlutterAtrial Flutter

• Clinical Significance– is accompanied by a rapid ventricular rate,

there is decreased cardiac output; may deteriorate to atrial fibrillation

Atrial FibrillationAtrial Fibrillation• Rate atrial rate usually greater than 400 -

600 beats/min; ventricular rate variable

• Rhythm ventricular rhythm usually irregularly irregular

• P waves no identifiable P waves; fibrillatory waves present; erratic, wavy baseline

• PR interval not measurable

• QRS duration usually< 0.10 sec but may be widened if an intraventricular conduction delay exists

Atrial FibrillationAtrial Fibrillation

• Types :– controlled– uncontrolled

Atrial FibrillationAtrial Fibrillation

• Clinical Significance– if accompanied by a rapid ventricular rate,

there is decreased cardiac output, increased stroke risk

Junctional RhythmsJunctional Rhythms• AV node

– a group of specialized cells located in the lower portion of the right atrium, above the base of the tricuspid valve

• Bundle of His– cardiac fibers located in the upper portion of the

interventricular septum; connects the AV node with the two bundle branches

• AV junction– the AV node and the nonbranching portion of the

bundle of his

Premature Junctional Complex Premature Junctional Complex (PJC)(PJC)

• Rate usually within normal range but

depends on underlying rhythm

• Rhythm regular with premature beats

• P waves may occur before, during or

after the QRS ; if visible, the

P wave is inverted in leads II,

III, and aVF


• PR interval if P wave occurs before the

QRS, the PR interval will

usually be less than or equal

to 0.12 sec; if no P wave

occurs before the QRS, there

will be no PR interval

• QRS duration usually 0.10 sec or less

unless an interventricular conduction

delay exists


• May occur in patterns :– couplets– bigeminy– trigeminy– quadrigeminy


• Clinical Significance– most individuals with PJCs are asymptomatic;

lightheadedness, dizziness, and other signs of decreased cardiac output may be evident if PJCs are frequent; if the patient is taking digitalis, check digoxin level

• Clinical Significance– signs and symptoms of decreased cardiac output

may be present because of underlying bradycardic rate and/or SA node dysfunction; if the patient is taking digitalis, check digoxin level

Junctional TachycardiaJunctional Tachycardia

• Rate 101 - 180 beats / min• Rhythm regular• P waves may occur before, during, or after

the QRS; if visible, the P wave is inverted in lead II, III, and aVF

• PR interval if P wave is present before the QRS, usually less than or equal to 0.12 sec; if no P wave occurs before the QRS complex, there will be no PR interval


• QRS duration usually 0.10 sec or less unless an intraventricular conduction delay exists


• Clinical Significance– the more rapid the rate, the greater the

incidence of symptoms caused by increased myocardial oxygen demand

– signs of decreased cardiac output if patient taking digitalis, check digoxin level

Ventricular Rhythms : OverviewVentricular Rhythms : Overview

• Ventricles are efficient pacemaker• the ventricles assumed the pacing

responsibility of the heart if :– SA node fails to discharge– impulse from SA node is generated but blocked as

it exits the SA node– rate of discharge of SA node is slower than that of

the ventricles– irritable site in either ventricle produces an early

beat or rapid rhythm

Premature Ventricular Premature Ventricular Complexes (PVCs)Complexes (PVCs)

• Rateusually within normal range but depends on underlying rhythm

• Rhythm essentially regular with premature beats; if the PVC is an interpolated PVC the rhythm will be regular

• P waves usually absent or with retrograde conduction to the atria, may appear after the QRS (usually upright in the ST segment or T wave)


• PR interval none with the PVC because

the ectopic beat originates in

the ventricle• QRS duration greater than 0.12 sec,

wide and bizarre, T

wave frequently in

opposite direction of the

QRS complex


• PVCs may occur in patterns:– Pairs (couplets)– “runs” or “bursts”– bigeminal PVCs– trigeminal PVCs– quadrigeminal PVCs

• Uniform PVCs• Multiform PVCs• Interpolated PVCs• R on T PVCs


• Clinical Significance– May or may not produce palpable pulses; may

be asymptomatic or complain of palpitations, a “racing heart”, skipped beats, or chest or neck discomfort

Ventricular TachycardiaVentricular Tachycardia

• Monomorphic

• Polymorphic– Long QT syndrome (LQTS)

• acquired (iatrogenic)• congenital (idiopathic)

– Normal QT

Monomorphic Monomorphic Ventricular TachycardiaVentricular Tachycardia

• Rate 101 - 250/min• Rhythm essentially regular• P waves may be present or absent; if

present, they have no set

relationship to the QRS

complexes, appearing between the QRSs at a rate different from that of the VT

• PR interval none

Monomorphic Monomorphic Ventricular TachycardiaVentricular Tachycardia

• QRS duration > 0.12 sec; often difficult to differentiate between the QRS and T wave

• Clinical significance– palpitations– SOB– chest pain– LOC if VT prolonged or sustained

Torsades De Pointes (TDP)Torsades De Pointes (TDP)

• Rate 150 - 300 beats/min;

typically 200 - 250 beats/min

• Rhythm may be regular or irregular

• P waves none

• PR interval none

• QRS duration > 0.12 sec; gradual

alteration in amplitude and direction of QRS complexes

Torsades De Pointes (TDP)Torsades De Pointes (TDP)

• Clinical significance– palpitations– syncope– dizziness

Ventricular FibrillationVentricular Fibrillation

• Rate can not be determined because

there are no discernible waves or

complexes• Rhythm rapid, chaotic with no pattern

or regularity

P waves not discernible

PR interval not discernible

QRS duration not discernible

Ventricular FibrillationVentricular Fibrillation

• Types– coarse– fine

• Clinical significance– unresponsive– pulseless– apneic

Atrioventricular (AV) Blocks : Atrioventricular (AV) Blocks : OverviewOverview

• AV junction – area of specialized conduction tissue that provides

electrical links between the atria and the ventricle

• delay or interruption in impulse conduction within the AV node, bundle of his, or his purkinje system is called AV blocks

• classification– according to degree of block– according to site of block

First Degree AV BlockFirst Degree AV Block• Rateusually within normal range but

depends on underlying rhythm• Rhythm regular• P waves normal in size and shape• PR Interval normal in size and shape,

one positive upright before

each QRS• QRS duration usually 0.10 sec or less unless an

interventricular conduction delay exists

First Degree AV BlockFirst Degree AV Block

• Clinical significance– patient usually asymptomatic– first degree AV block that occurs with acute

MI should be monitored closely for increasing heart block

Second Degree AV Block Type ISecond Degree AV Block Type I

• Rate atrial rate is greater than the

ventricular rate

• Rhythm atrial regular; ventricular

irregular

• P waves normal in size and shape,

some P waves are not

followed by a QRS complex


• PR interval lengthens with each cycle

until a P wave appears

without a QRS complex; the

PRI after the nonconducted

beat is shorter than the

interval preceding the

nonconducted beat• QRS duration usually 0.10 sec or less but is

periodically dropped


• Clinical significance– usually asymptomatic

Second Degree AV Block Second Degree AV Block Type IIType II

• Rate atrial rate is twice the ventricular

rate

• Rhythm atrial regular; ventricular regular

• P waves normal in size and shape;

every other P wave is

followed by QRS complex

• PR interval constant

Second Degree AV Block Second Degree AV Block Type IIType II

• QRS duration within normal limits if the block occurs above the bundle of his (type I); wide if the block occurs below the bundle if his (type II); absent after every other P wave

• Clinical significance– may rapidly progress to complete AV block

without warning

Complete AV BlockComplete AV Block

• Rateatrial rate is greater than

ventricular rate; the ventricular

rate is determined by the origin of

the escape rhythm• Rhythm atrial regular; ventricular

regular; there is no

relationship between atrial

and ventricular rhythms


• P waves normal in size and shape

• PR interval none - the atria and

ventricles beat

independently of each other;

thus there is no true PR

interval


• QRS duration narrow or wide,

depending on the location

of the escape pacemaker

and the condition of the

interventricular conduction system; narrow indicates junctional pacemaker; wide indicates ventricular pacemaker


• Clinical significance– signs and symptoms will depend on the origin

of escape pacemaker and patient’s response to ventricular rate

Questions?Questions?

Thank You !

Select Dysrhythmias and Therapeutic Modalities J.O. Medina, NP Education Specialist Nurse Practitioner Nurse Practitioner Critical Care & Emergency Services.

Documents

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atrial tachycardia rate

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atrial fibrillation

atrial flutter rateatrial