Transcript What Is This Rhythm?

Bradycardia Algorithm
Review
Romulo B. Babasa III, MD
[email protected]
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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. On physical exam she
is pale and sweaty; HR = 35 bpm;
BP = 90/60 mm Hg; RR = 18 rpm.
Rhythm: see next slide.
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87-Year-Old Woman:
Symptomatic Bradycardia
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Identify A, B, and C
Which one is most likely
A
to be her rhythm?
B
C
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Rhythms to Learn
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Sinus bradycardia
Heart blocks
• 1st degree
• 2nd degree type I
• 2nd degree type II
• 3rd degree
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Cardiac Conduction System 1
Sinus node
Internodal pathways
AV node
Bundle of His
Left bundle branch
Posterior division
Anterior division
Right bundle branch
Purkinje fibers
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Cardiac Conduction System 2
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Rates of Intrinsic
Cardiac Pacemakers
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Primary pacemaker
• Sinus node (60-100 bpm)
Escape pacemakers
• AV junction (40-60 bpm)
• Ventricular (<40 bpm)
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Determining the Rate
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Determining the Rate
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Analyzing Rhythm Strips
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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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Relationship of P Waves and
QRS Complexes
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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
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What Is This Rhythm?
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Sinus Bradycardia
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What Is This Rhythm?
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First Degree AV Block
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Diagnosis?
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Second Degree AV Block Type I
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Diagnosis?
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Second Degree AV Block Type II
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What Is This Rhythm?
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Third Degree AV Block Type III
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Differentiation of Second- and
Third-Degree AV Blocks
More P’s than QRSs
yes
PR fixed?
yes
2nd-degree AV block
Fixed
Mobitz II
yes
3rd-degree AV block
no
QRSs that
look alike
regular?
no
2nd-degree AV block
Variable
Mobitz I
Wenckebach
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Bradycardia Algorithm (1 of 2)
Bradycardia
Heart Rate less than 60 bpm and
inadequate for clinical condition
•
•
•
•
Maintain patent airway; assist breathing as needed
Give oxygen
Monitor ECG (identify rhythm), blood pressure, oximetry
Establish IV access
Serious signs or symptoms of poor
perfusion caused by the bradycardia?
(eg. acute altered mental status, ongoing chest pain,
hypotension or other signs of shock)
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Bradycardia Algorithm (2 of 2)
Observe/Monitor
Adequate
Perfusion
Reminders
• If pulseless arrest develops go to
Pulseless Arrest Algorithm
• Search for and treat possible contributing
factors:
• Hypovolemia
• Hypoxia
• Hydrogen ion (acidosis)
• Hypo/Hyper-kalemia
• Hypoglycemia
• Hypothermia
• Toxins
• Tamponade, cardiac
• Tension pneumothorax
• Thrombosis (coronary or
pulmonary)
• Trauma (hypovolemia, inc ICP)
Poor Perfusion
• Prepare for transcutaneous
pacing; use without delay for
high degree block (type II
second -degree block or thirddegree AV block)
• Consider Atropine 0.5 mg/IV
while awaiting pacer. May
repeat to a total dose of 3 mg. If
ineffective, begin pacing.
• Consider Epinephrine (2 to 10
µg/min) or dopamine (2 to 10
µg/kg/min infusion while
awaiting pacer or if pacing
ineffective.
• Prepare for transvenous pacing
• Treat contributing causes
• Consider expert consultation
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What Is This Rhythm?
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Treatment?
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Treatment?
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Transcutaneous Pacing
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Indications for
Transcutaneous Pacing
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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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Transcutaneous Pacing
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Transcutaneous Pacing
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The pacing rate is set at 80 beats per minute.
In conscious bradycardic patients, pacing is
begun in the demand mode at rates slightly faster
than the native rhythm and at minimal current
output
The current is gradually increased by 5 to 10 mA
at a time until cardiac capture is documented,
which defines the pacing threshold. The final
current output should be set at the pacing
threshold or 5 to 10 mA above it.
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Transcutaneous Pacing
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In the setting of a bradysystolic arrest or with
unconscious patients, it is recommended to turn
the stimulating current to maximal output (200
mA) to ensure ventricular capture
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Once capture is achieved, the current may be
gradually decreased until loss of capture, which
defines the pacing current threshold
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Transcutaneous Pacing
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Transcutaneous Pacing:
“Capture” vs “No Capture”
25 Feb 88
Lead I
Size 1.0
HR=41
Bradycardia: No Pacing
25 Feb 88 Lead I
Size 1.0
HR=43
Bradycardia: no pacing
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
Pacing Above Threshold (60 mA): With Capture (Pacing-PulseMarker
)
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