Select Dysrhythmias and Therapeutic Modalities J.O. Medina, NP Education Specialist Nurse Practitioner Nurse Practitioner Critical Care & Emergency Services.
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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
Premature Atrial Contractions Premature Atrial Contractions (PACs)(PACs)
• 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
Premature Atrial Contractions Premature Atrial Contractions (PACs)(PACs)
• 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
Premature Atrial Contractions Premature Atrial Contractions (PACs)(PACs)
• 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
Premature Atrial Contractions Premature Atrial Contractions (PACs)(PACs)
• 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
Premature Junctional Complex Premature Junctional Complex (PJC)(PJC)
• 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
Premature Junctional Complex Premature Junctional Complex (PJC)(PJC)
• May occur in patterns :– couplets– bigeminy– trigeminy– quadrigeminy
Premature Junctional Complex Premature Junctional Complex (PJC)(PJC)
• 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
Junctional TachycardiaJunctional Tachycardia
• QRS duration usually 0.10 sec or less unless an intraventricular conduction delay exists
Junctional TachycardiaJunctional Tachycardia
• 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)
Premature Ventricular Premature Ventricular Complexes (PVCs)Complexes (PVCs)
• 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
Premature Ventricular Premature Ventricular Complexes (PVCs)Complexes (PVCs)
• 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
Premature Ventricular Premature Ventricular Complexes (PVCs)Complexes (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
Second Degree AV Block Type ISecond Degree AV Block Type I
• 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
Second Degree AV Block Type ISecond Degree AV Block Type I
• 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
Complete AV BlockComplete AV Block
• 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
Complete AV BlockComplete AV Block
• 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
Complete AV BlockComplete AV Block
• Clinical significance– signs and symptoms will depend on the origin
of escape pacemaker and patient’s response to ventricular rate
Questions?Questions?
Thank You !
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