NTI 2010 Cardiovascular Boot Camp Bradyarrhythmias and Treatment

NTI 2010
Cardiovascular Boot Camp
Bradyarrhythmias and
Treatment
Cynthia Webner MSN, RN, CCNS, CCRN, CMC
Cardiovascular Nursing Education Associates
www.cardionursing.com
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Understanding Arrhythmias
Physiologically
Potential Causes of Bradycardias in
Critical Care
What does P
wave
represent?
Can we see
sinus node?
What does
normal PR
interval
represent?
(prolonged?)
What does
skinny QRS
represent?
Wide
QRS??
What
pacemaker
options exist?
What should be
the end result
of each sinus
impulse?
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Propofol
Cardiac disorders and medications
Vasovagal
CNS injury
Rule of thumb:
Hypothyroid
Pace if cause cannot
Hypothermia
be reversed.
Multiple other
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SA Block (SA Exit Block)
• Type I and Type II
• Signs of Wenckebach
• Fixed P to P
• Dropped P waves
• Typically transient
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SA Block
• Quality of sinus node
cells
• Sinus discharge
versus atrial
activation
Healthy young people
Trained athletes
Digitalis toxicity
Other antiarrhythmics
Infarction / myocarditis
Part of SSS
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
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Sinus Arrest or Sinus Pause
Sick Sinus Syndrome
• Failure of impulse formation
• Impossible definitive diagnosis on surface
ECG
• Clue: PP intervals of cycle cannot be walked
out across the pause and end on P wave
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Disorders of impulse generation and conduction
Failure of escape pacemakers
Susceptibility to atrial tachyarrhythmias
Bradycardia / tachycardia syndrome
• Long pause after tachycardia (overdrive suppression)
• Syncope
40% SSS: coronary atherosclerosis
5-10% SSS: ideopathic cardiomyopathy
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Heart Blocks – AV Blocks
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2nd Degree AV Blocks
• Classification
• One P Wave at a time fails to conduct to
ventricle
• Type I (Wenckebach)
– 1st Degree
– 2nd Degree
• Type I (Wenckebach)
• Type II
– Conduction fails in AV node
• Type II
– High Grade
– Third Degree
– Conduction fails below the AV node and
usually involves both bundles
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Wenckebach (2nd Degree Type I)
– Sinus node fires
regularly
– Disease in AV node
– Group beating is noted
– First P-R of group of
often longer than
normal with
progressive
lengthening of the P-R
until a beat is not
conducted
– In absence of BBB
QRS is normal
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
– Conduction ratios may
be 2:1, 3:2, 4:3 etc.
– May develop 2:1
conduction if sinus
rate increases
• Verify the block is still
type I
• P-R longer than normal
• Absence of prolonged
QRS
– Treatment: Often none
• Acutely with symptoms:
Atropine or TTVP
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2nd Degree Type (Wenckebach)
2nd Degree AV Block Type II
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Similar to Type I however no
progressive lengthening of P-R
interval
Disease within or below bundle of
His
P-R interval is fixed with normally
conducted beats
QRS: wide
•
If 2:1 conduction look for:
– Normal P-R interval with
conducted beats
– Wide QRS complex
•
Treatment: Usually requires
permanent pacing
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Third Degree AV Block –
Complete
Heart Blocks - High Grade AV
Block
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– No atrial impulses are conducted to the ventricles
– One form of AV dissociation
– Ventricular Rate: Maintained by junctional escape (narrow QRS)
or ventricular escape (wide QRS)
– Symptomatic if develops acutely
– May be well tolerated if develops overtime
– Treatment: Perm. Pacer
Two or more consecutive atrial impulses are blocked.
P waves: Regular, but 2 or > fail to conduct to the ventricles
QRS: Narrow in type I & wide in type II
Ventricular Rate: Slow, often symptomatic
Treatment: Atropine for Type I
Pacing for Type II - Usually
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Third Degree (Complete)
Heart Block
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Junctional Escape and Rhythm
• HR 35-60 beats per minute
• P’ waves may or may not be associated with
QRS complexes
• QRS complexes same as sinus beats
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
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Ventricular Escape Beats
II
V1
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Medications that Increase
Heart Rate
Idioventricular Ventricular Rhythm
• Sympathomimetics
that increase heart
rate (β1 receptors)
– Dopamine
– Epinephrine
– Isuprel (no longer
used except with
cardiac transplants)
II
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– Atropine
– Note: Will only work in
the location of
parasympathetic
nervous system fibers
– Clinical Clue: Skinny
or wide QRS
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Implantation of Permanent
Pacer
Pacing Basics
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
• Para Sympatholytics
that increase heart
rate (block
parasympathetic
nervous system)
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Bipolar vs. Unipolar System
Pacemaker Function
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Pace
• Ability of the
pacemaker to
send a stimulus
to the
myocardium
• Identified by a
pacemaker
spike on the
ECG
Capture
• Ability of the
pacing stimulus
to depolarize
chamber being
paced
• Identified by a
pacemaker
spike that is
immediately
followed by a P
wave or a QRS
complex on the
ECG
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Pacing
Sense
• Ability of the
pacemaker to
recognize and
respond to
intrinsic cardiac
depolarization
• Identified by
pacing when no
intrinsic beats
and not pacing
when intrinsic
beats are
present
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Capture
– Two consecutive pacer spikes
• Spikes should appear regularly unless
pacer is inhibited by sensed intrinsic
activity
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Sensing
• Pacing stimulus results in depolarization of
chamber being paced
• Each spike should be followed by a QRS
unless it falls in heart’s refractory period
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
• Identify automatic pacing interval (pacing
rate)
• Pacemaker sees and responds to intrinsic
activity
• Must be given opportunity to sense
– Must be in demand mode
– There must be intrinsic activity to be sensed
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Revised NASPE/BPEG Generic
Code for Antitachycardia Pacing
Position I Position II
AAI Pacing – Atrial Inhibited
Position
III
Position
IV
Position V
AAI
Chamber(s)
Paced
Chamber(s)
Sensed
Response to
Sensing
Rate
Modulation
Multisite
pacing
Paces the Atrium
O=None
O=None
O=None
O=None
O=None
AAI
R=Rate
modulation
A=Atrium
Senses the Atrium
AAII
AA
A=Atrium
A=Atrium
T=Triggered
V=Ventricle
V=Ventricle
I=Inhibited
V=Ventricle
D=Dual
(A+V)
D=Dual
(A+V)
D=Dual
(T+I)
D=Dual
(A+V)
Atrial sensing inhibits atrial pacing
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(Bernstein et al., 2002)
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VVI Pacing – Ventricular Inhibited
Pacing Modes AAI
VVI
Paces the Ventricle
VVI
Senses the Ventricle
VVI
Ventricular sensing inhibits ventricular pacing
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Dual Chamber Pacers
VVI Pacing
• Provide AV synchrony
– Maintains atrial kick
– Improves hemodynamics in those with heart
blocks
• Tracks atrial activity
– Ventricular pacing occurs in response to atrial
activity
– Improved hemodynamics
• Decreased incidence of pacemaker
syndrome
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
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DDDR Pacing
DDDR
Paces both Atrium and Ventricle
DDDR
Senses both Atrium and Ventricle
DDDR
1.
2.
Atrial sensing inhibits atrial pacing and triggers
ventricular pacing
Ventricular sensing inhibits ventricular and atrial
pacing
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Basic Pacemaker Timing
Basic Pacemaker Timing
Refractory Period
• AV Interval
Brief period of time when pacer is not allowed to
look for intrinsic events
Can be lengthened or shortened to eliminate in
appropriate sensing
– Period of time between an atrial event (sensed “P” wave or atrial
pace) and a paced ventricular event
• VV Interval
– Period of time from ventricular complex to ventricular complex
Absolute Refractory Period
• VA Interval
Nothing can be sensed
Relative Refractory Period
– Ventricular complex to atrial activity
– Also called AEI or atrial escape interval
Allows sensing but pacer will not respond
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DDD Pacing:
AV Sequential Pacing State
Basic Pacemaker Timing
• Low Rate
– Lowest rate allowed by the pacer before a
paced beat is initiated
• High Rate
– Upper rate limit
– Highest rate that can be achieved and still
maintain AV synchrony
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
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DDD Pacing:
Atrial Pacing Ventricular Sensing State
DDD Pacing:
Atrial Tracking Ventricular Pacing State
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DDD Pacing:
Atrial Sensing and Ventricular Sensing
State
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Effect of RV Pacing
• RV pacing results in mechanical desynchronization (mechanical
LBBB)
• Increased hospitalizations and mortality for HF (DAVID Trial)
• No improvement in mortality, HF hospitalizations or stroke free
survival when compared to VVI (MOST Trial, CTOPP Trial)
• Patients who survived to the 3-month follow-up had worse 12month event-free rates when the percentage of right ventricular
pacing by ICD interrogation was 41% to 100% (75.9%) than
when less than 40% (86.9%) (P=.09) (DAVID Trial)
• AAI pacing demonstrates improved outcomes
• Reducing RV pacing to less than 10% in patients with dual
chamber pacemakers reduced the relative risk of developing
persistent atrial fibrillation by 40% compared to conventional
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dual chamber pacing (SAVE PACe Trial)
Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
Managed Ventricular Pacing
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Minimizing Right Ventricular
Pacing
Managed Ventricular Pacing
– AAIR mode with mode switching
– VVI mode with low rate for those being paced
as defibrillation back up only
– Long AV delays
– Managed ventricular pacing
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– AV search historesis
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#1
What is your
priority
when it appears that the
pacemaker is not working?
Troubleshooters Toolbox
Rhythm strip
V1 or the lead that best allows evaluation of
the pacemaker
Pacemaker information
Type
Programmed parameters
Intervals
Special features
Calipers
Magnet
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Chest x-ray
Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
Questions to Ask
• Are there pacemaker spikes?
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Questions to Ask
Questions to Ask
• Is there evidence of pacemaker capture
Ventricular
after a pacemaker spike?
Capture
• Does the pacemaker sense appropriately
– Inhibit the pacemaker when a natural beat
occurs?
Sensed appropriately
– Activate pacing when no intrinsic beat occurs
Atrial
Capture
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What are the three major malfunctions
with pacemakers?
Failure to ______?
• Failure to Fire
• Failure to Capture
• Failure to Sense
Fire?
– Oversensing
– Undersensing
Capture?
Sense?
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Troubleshooting Pacemakers
• Causes of Failure to
Fire
Failure to ___________?
• Interventions for Failure to
Fire
– Pacer turned off
– Loose or broken
connection
– Lead displacement
– Battery depletion
– Oversensing
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– Emergently treat patient as
condition requires
– Check connections if
temporary
– Replace battery or pulse
generator
– Lead repositioning or
replacement
– Convert pacer to
asynchronous mode – to
assess for sensitivity issues
Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
Fire?
Capture?
Sense?
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Troubleshooting Pacemakers
Failure to __________?
• Causes of Failure to • Interventions for Failure to
Capture
Capture
– Position patient on left side
– May need lead repositioned
or replaced
– Increase mA
– Chest x-ray, Labs
– Monitor for tamponade,
diaphragmatic pacing
– Lead displacement
– Increased pacing
thresholds
– Acute MI
– Chamber perforation
Fire?
Capture?
Sense?
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Sensitivity: “The Fence”
Troubleshooting Pacemakers
• Causes of Oversensing
(Seeing Too Much)
• Causes of Undersensing
(Not Seeing)
Sensitivity too low
(fence too high)
Pacer can’t see
QRS
Sensitivity too high
(fence too low)
Pacer “hallucinates”
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Troubleshooting Pacemakers
• Interventions for
Undersensing
• Interventions for
Oversensing
– Decrease sensitivity (turn
mV number higher)
– Decrease MA if set very
high
– Chest X-ray to verify
position and check for lead
fractures
– Remove from EMI
– Ensure that all equipment
is properly grounded
– Emergently treat patient
as condition requires
– Position on left side
– Lead repositioning (by
MD)
– Set in demand mode
– Increase sensitivity (lower
mV number)
– Check connections
– Treat PVC’s
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
– Fence too high – doesn’t see
QRS
– Asynchronous mode
– Sensitivity set too low
– Intrinsic ventricular activity in
refractory period
– Lead tip not in place with
myocardium
– Low QRS voltage (drugs,
electrolyte imbalance, disease)
– Break in connection, Faulty
generator, Battery failure
– Fence too low – sees too
much
– Sensitivity set too high
– Electromagnetic
interference
– Myopotentials
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True or False: When you
place the magnet over a
permanent pacemaker the
pacemaker should pace.
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Magnet Mode
Let’s Practice DDDR Pacer
Beware of the Magnet!
FUNCTIONS DIFFERENTLY WITH ICD’S
Turns sensing circuit off in permanent pacemakers (without ICDs)
Pacemaker paces asynchronously (no regard for intrinsic activity)
Identifies battery end of life
Determines lead location
RV Pacing
LV Pacing
Risk of pacemaker impulse occurring on the T wave
Should be used with caution
Avoid use in those patients susceptible to ventricular arrhythmias:
Fresh MI
Hypokalemia
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Fire?
Capture?
Sense?
Let’s Practice DDDR Pacer
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Let’s Practice VVI Pacer
Fire?
Capture?
Fire?
Sense?
Capture?
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Sense?
Let’s Practice VVI Pacer
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
Fire?
Capture?
Sense?
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Let’s Practice VVI Pacer
Let’s Practice DDDR Pacer
Fire?
Capture?
Sense?
Fire?
Capture?
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Sense?
Congratulations!!!
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Cynthia Webner MSN, CCNS, CCRNCMC 2010 Cardiovascular Nurisng
Education Associates
www.cardionursing.com
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