Download Case 7 Bradycardia Case Scenario Case Scenario 87-Year

Case Scenario
Case Scenario
An 87-year-old woman reports
feeling weak and short of
breath for 2 hours while
walking short distances. She
feels exhausted moving from
the car to the ED stretcher.
Case 7
Bradycardia
On physical exam she
is pale and sweaty; HR = 35
bpm; BP = 90/60 mm Hg; RR
= 18 rpm. Rhythm: see next
slide.
© 2001 American Heart Association
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87-Year-Old Woman:
Symptomatic Bradycardia
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87-Year-Old Woman:
Symptomatic Bradycardia
Identify A, B, and C
Which one is most likely
A
to be her rhythm?
Learning Objectives
She experienced no chest
pain or ischemic symptoms
A
prior to the onset of her
weakness and shortness of
breath. Therefore, the only
rhythm not associated with
acute pain, rhythm A, is the
more likely cause of her
symptomatic bradycardia.
B
1. By the end of Case 7 be able to discuss
• Asymptomatic vs symptomatic bradycardia
• Signs and symptoms of symptomatic bradycardia
• Intervention agents and sequences to use
• Recognition criteria for heart blocks: 1st, 2nd (types
I and II), and 3rd degree
• Pathology of conduction system in heart blocks
C
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Learning Objectives
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What is Symptomatic?
2. By the end of Case 7 be able to discuss
• Significance of bradycardia in AMI patients
• Significance of RV infarction plus
bradycardia
• Atropine pharmacology: why atropine
helps some heart blocks and not others
• Set up, start, troubleshoot transcutaneous
pacing
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What is Symptomatic?
Bradycardia is symptomatic when:
• Heart rate is “slow” (absolute or relative)
• Patient has symptoms
• Symptoms are caused by bradycardia
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Symptoms
• Chest pain
• Dyspnea
• Weakness
• Altered LOC
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What is Symptomatic?
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What is Symptomatic?
Signs
• Hypotension
• Diaphoresis
• Pulmonary congestion
• PVCs
• Unstable angina
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What is Symptomatic?
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Drugs to Learn
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Drugs to Learn
Sinus bradycardia
Heart blocks
• 1st degree
• 2nd degree type I
• 2nd degree type II
• 3rd degree
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If the etiology is AMI:
• Treat the AMI (MONA)
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Rhythms to Learn
Key point:
• Treat the patient and NOT the monitor.
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Key question:
• Is the bradycardia causing the patient to be
ill? OR
• Is there some illness that is causing the
bradycardia?
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What is Symptomatic?
The actions, indications, administration, and
precautions for these drugs and therapies:
• Atropine
• Dopamine
• Epinephrine
• Transcutaneous pacing
• Isoproterenol (rarely used)
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Cardiac Conduction System 1
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Cardiac Conduction System 2
Bachmann’s bundle
 Remember:
Relationship of ECG to anatomy
Sinus node
• Atropine – will not work on
denervated hearts. Why?
• Epinephrine – must be used with
caution with some patients. Why?
Internodal pathways
AV node
Bundle of His
Left bundle branch
Posterior division
Anterior division
Right bundle branch
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Purkinje fibers
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Determining the Rate
Analyzing Rhythm Strips
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Relationship of P Waves and
QRS Complexes
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Key questions
• Are QRS complexes present?
• Are P waves present?
• How is the P wave related to the
QRS complex?
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What Is This Rhythm?
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AV Block
Every P wave is followed by a QRS complex
with a normal P–R interval
Every P wave is followed by a QRS complex
but the P–R interval is prolonged
Some P waves are not followed by a QRS
complex; more P waves than QRS complexes
First-degree AV block
Delay
This is First Degree Block.
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Diagnosis?
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Diagnosis?
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AV Block
Second-degree type I AV block
This is Sinus Bradycardia.
This is Second-degree type I AV block.
Note the progressive PRI.
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Diagnosis?
Differentiation of Second- and
Third-Degree AV Blocks
AV Block
Second-degree type II AV block
More P’s than QRSs
yes
Non-Conducting P waves
PR fixed?
yes
2nd-degree AV block
Fixed
Mobitz II
no
QRSs that
look alike
regular?
This is Second-degree type II AV block.
Note the non-conducting Ps.
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Bradycardia Algorithm (1 of 2)
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Primary ABCD Survey
• Assess ABCs
• Secure airway noninvasively
• Ensure monitor/defibrillator is available
Secondary ABCD Survey
Assess secondary ABCs (invasive airway management needed?)
Oxygen–IV access–monitor–fluids
Vital signs, pulse oximeter, monitor BP
Obtain and review 12-lead ECG
Obtain and review portable chest x-ray
Problem-focused history
Problem-focused physical examination
Consider causes (differential diagnoses)
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For example:
• OR you can say that each 6 gtts = 1 µg
• Prepare for transvenous pacer
• If symptoms develop, use
transcutaneous pacemaker until
transvenous pacer placed
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What Is This Rhythm?
Bradycardia Algorithm (2 of 2)
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Bradycardia Algorithm (2 of 2)
signs or symptoms?
For example: Serious
Due to bradycardia?
No
• 1 mg Epinephrine
or Isuprel inYes100 ccs NS
Type II second-degree
AV block/ cc or 60 gtts / min
– 10
µgs
Intervention sequence
or
Third-degree AV block?
• Atropine 0.5 to 1.0 mg
pacing if available
– 7.5 µgs = 45 gtts / min•• Transcutaneous
Dopamine 5 to 20 µg/kg per minute
2 to 10 µg/min
– 5 µgs = 30 gtts / min •• Epinephrine
Isoproterenol 2 to 10 µg/min
No
– 2.5 µgs = 15 gtts / min Yes
Observe
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Bradycardia Algorithm (2 of 2)
Bradycardia
•Slow (absolute bradycardia = rate <60 bpm)
or
•Relatively slow (rate less than expected
relative to underlying condition or cause)
3rd-degree AV block
2nd-degree AV block
Variable
Mobitz I
Wenckebach
no
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•
•
•
•
•
•
•
•
yes
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AV Block
Remember that Isoproterenol must only be
considered if the patient fails to respond to
other therapies.
You must exercise extreme caution when
using it. Why?
Third-degree AV block
Consistent P to P interval
This is Third-degree AV block.
Supranodal – note the atrial rate is between 48 - 70
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Treatment?
What Is This Rhythm?
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What Is This Rhythm?
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Indications for
Transcutaneous Pacing
Treatment?
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Hemodynamically unstable bradycardias
In the setting of AMI: sinus node dysfunction,
type II 2nd-degree block, 3rd-degree heart block
Bradycardia with symptomatic ventricular
escape beats
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Indications for
Transcutaneous Pacing
Indications for
Transcutaneous Pacing
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
In the presence of escape beats, you must
decide
• if the PVCs are effective contractions
• Should they be treated with pacing or
medications (rate related fix)
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Transcutaneous Pacing:
“Capture” vs “No Capture”
Transcutaneous Pacing
25 Feb 88
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Lead I
Size 1.0
HR=41
Bradycardia: No Pacing
25 Feb 88 Lead I
Size 1.0
HR=43
Bradycardia: no pacing
However, 3rd degree block should NEVER be
treated with lidocaine. Why?
Pacing Spike
35 mA
Pacing below threshold:
no capture
Capture:
• Spike + broad QRS
• QRS: opposite polarity
Pacing Below Threshold (35 mA): No Capture
25 Feb 88
Lead I
Size 1.0
HR=71
60 mA
Pacing above threshold:
with capture
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Pacing Above Threshold (60 mA): With Capture (Pacing-PulseMarker
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Rates of Intrinsic
Cardiac Pacemakers
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Pulse Generators for
Transvenous Pacing
Primary pacemaker
• Sinus node (60-100 bpm)
Escape pacemakers
• AV junction (40-60 bpm)
• Ventricular (<40 bpm)
Characteristics
 Variable output in milliamps
 Fixed versus demand mode
 Variable rate setting
 Firing and sensing indicators
 Familiarize yourself with the equipment!
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Dopamine
• Add 200 mgs into a 250 cc bag of IV NS
• Patient weight is 225 lbs.
• The initial dose would be ____ gtts?
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Drug Calculation
Dopamine
• 200 mgs into a 250 cc bag of IV NS
– 200 X 1000 µg = 200,000 µg OR
– 800 µg per cc OR
– 13.333 µg per gtt
• Patient weight is 225 lbs.
• The initial dose would be ____ gtts?
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Drug Calculation
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Drug Calculation
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Dopamine - effects
Dopamine
• So……
• Patient weight is 225 lbs.
– 225 / 2.2 lbs = 100 kgs
– 100 kgs X 5 µg/min = 500 µg/min
– 500 µg / 13.333 = 37.5 gtts per minute
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Infarct Location
Arrhythmias
RV
• Often present with increased
parasympathetic tone
Look for volume problems with associated
hypovolemia
Determining the pattern
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alpha
• heart:none
• arteries:constriction
lungs:constriction
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beta
• heart: > rate
arteries: dilation
lungs: mild dilation
Cardiac dosage range is 5 µg - 10 µg/kg/min
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Escape Patterns
Regular
Premature
Speeding/slowing
Pause
Group beats
Irregularly
Irregular
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Action Potential of
Pacemaker Cell
Second-Degree AV
Block Type I
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