Download Cardiac Arrythmias

Conduction Disturbances:
Cardiac Arrhythmias and
Heart Block
Normal Sinus Rhythm
 Normal rate 60-100bpm
 P Wave: 0.08 seconds
 Depolarisation starts at the sinus
node
 QRS: 0.08-0.10 seconds
 All parts of blood flow and
conduction are within normal
limits
 QT Interval: 0.42 seconds or less
 Rate: 60-100pbm
 T wave: 0.16 seconds
 Rhythm: Regular
 PR Interval: 0.12-0.20 seconds
 ST Segment: 0.8-0.12 seconds
Supraventricular Arrhythmias
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Sinus Tachycardia
Sinus Bradycardia
Atrial Premature Contractions
Atrial Fibrillation
Atrial Flutter
Sick Sinus Syndrome
Sinus Tachycardia
 Most common tachycardia
 Often Asymptomatic
 Cardiac output can fall secondary to reduced ventricular filling time
 ECG findings: rate>100bpm, regular rhythm
 Normal physiologic response to exertion, emotional distress, fever
 Valsalva maneuver can slow rate
 Other causes: anemia, hyperthyroidism, dehydration
 Treatment: address the underlying cause
 If anemic: correct anemia and tachycardia will correct
Sinus Bradycardia
 Definition: rate <60bpm with a normal rhythm
 Symptoms caused by decreased cardiac output and include:
 Lightheaded, dizzy, hypotension, syncope, vertigo
 May be a normal physiologic response in athletes
 Causes: hypothermia, hypothyroidism, sick sinus syndrome, drugs (beta
blockers, calcium channel blockers)
 ECG findings: rate <60bpm, normal rhythm
 treatment,: treat the underlying cause
 ie: correct hypothyroidism
Atrial Premature/Atrial Premature
Contractions
 Definition: premature heartbeats originating from the atria
 Occurs when another region in the atria depolarizes before the sinoatrial
node, firing spontaneously resulting in an earlier beat than expected
 May have unifocal or multifocal origins
 Symptoms: usually asymptomatic but can feel palpitations
 ECG findings: p wave present earlier than expected, abnormal shape to p
wave because it is coming from an abnormal focus, normal QRS complex
 Treatment: usually benign/no treatment, beta blockers can be used for
symptomatic patients
Atrial Flutter
 Definition: Supraventricular Tachycardia with a sawtooth pattern
 Symptoms: may be asymptomatic. Palpitations, chest pain, lightheadeness
 Signs: Tachycardia
 ECG Findings:
 Rate: 250-350bpm
 Rhythm: atria is regular, ventricle is variable “SAW TOOTH”
 Atria depolarization to ventricle depolarization ratio of 2:1,3:1,4:1 or greater
 P wave: buried in the QRS complex
 QRS: <0.12 seconds
Atrial Fibrillation
 Definition: rapid, irregular rhythm increasing risk of Stroke, MI, thrombosis
 Most common chronic arrhythmia
 Symptoms: palpitations, angina, fatigue, CHF. May be asymptomatic
 Signs: pulse on exam is irregular and rapid
 ECG Findings: Irregularly Irregular.
 P waves: Absent p waves; chaotic fibrillatory waves only
 Rate: >350bpm with a varying ventricular response from slow to rapid
 QRS: <0.12seconds
Atrial Fibrillation/Flutter Treatment
 3 Foci of Treatment: Rate control, Rhythm control, Anticoagulation
 No mortality benefit from rhythm control, thus rate control is the focus
 Rhythm control is used primarily in those who are symptomatic
 Anticoagulation use is determined by the CHADS2 score or the CHA2DS2VASc score
 CHADS2 is a more commonly used tool though CHA2DS2-VASc is a newer
calculator and recent research is showing is to be more sensitive and
specific than CHADS2
Atrial Fibrillation/Flutter Treatment:
Options
 Rate Control:
 Beta Blocker with or without digoxin
 Ca Channel Blocker with or without Digoxin
 AV node Ablation and pacemaker
 Rhythm Control
 Cardioversion via atrial defibrillator
 Antiarrhythmic medications
 Propafenone, flecainide, sotalol, amiodarone, quinidine, procainamide
 Catheter ablation via pulmonary vein
 Surgery
 MAZE procedure
 Anticoagulation
 Done for all patients based on the CHADS2 score or CHA2DS-VASc score
Atrial Fibrillation/Flutter Treatment:
CHADS2 vs CHA2DS2-VASc
CHADS2 Risk
Score
CHA2DS2-VASc
Risk
Score
CHF
1
CHF or LVEF < 40%
1
Hypertension
1
Hypertension
1
Age> 75
2
Diabetes
1
Age >75
1
Diabetes
1
Stroke/TIA/Thromb
oembolism
2
Stroke or TIA
2
Vascular Disease
1
Age 65-74
1
Female
1
Score
Risk
Recommendation
0
Low
No anticoagulation
1
Moderate Consider anticoagulation
2
High
Anticoagulation
recommended
Atrial Fibrillation/Flutter Treatment:
Warfarin and NOACs
 The anticoagulants available are the traditional warfarin and the new drug
class NOACs ((Dabigatran (Pradaxa), Rivaroxaban (Xarelto), Apixaban (Eliquis))
 The NOAC have a lower rate of intracranial bleeding compared to warfarin, do
not require regular lab testing, is not limited by dietary intake
 Most bleeding on NOACs are minor and will resolve on their own with
discontinuation of the medication
 If a major bleed occurs (although rare,<3%) while taking a NOAC, there is not a
direct reversal agent
 Warfarin is inexpensive, has lower rates of GI bleeding compared to NOAC,
requires regular INR monitoring
 Both warfarin and NOACs have major drug interactions
 warfarin interacts negatively with most chemotherapy so NOACs are favored in this
setting
 NOACs have twice the risk of bleeding if combined with ASA or Clopidogrel(Plavix), so
warfarin is favored in this setting
Atrial Fibrillation/Flutter:
Warfarin and NOACs Dosing
 NOACs
 Dabigatran (Pradaxa): 150 mg or 110 mg twice daily
 Rivaroxaban (Xarelto): 20 mg daily
 Apixaban (Eliquis): 5 mg twice daily
 Warfarin
 Dose changes in accordance with the desired INR range
 Goal INR for a patient with atrial fibrillation is 2.0-3.0
Atrial Fibrillation/Flutter Treatment:
Bleeding Risk with HAS-BLED
Condition
Points
Hypertension
1
Abnormal Renal or liver function
1 or 2
Stroke
1
Bleeding
1
>65 years of age
1
Drugs or EtOH
1 or 2
• Always calculate the bleeding risk in a patient initiating anticoagulation therapy
• A score or 3 or higher is considered high risk.
• A high risk HAS-BLED score is not a reason to avoid anticoagulation in an patient
with Atrial Fibrillation.
Sick Sinus Syndrome
“tachy-brady syndrome”
 Arrhythmia group that encompasses several types of arrhythmias
originating from the atria. Commonly alternates between fast and slow.
 Signs/Symptoms: BP may be normal to low. Syncope, light-headedness.
Can be asymptomatic
 Treatment: dual chamber pacemaker is the mainstay of treatment and
usually resolves symptoms
 ECG findings: Can produce a variety of ECG findings such as: bradycardia,
tachycardia, heart block and alternating bradycardia and tachycardia.
Ventricular Arrythmias
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Ventricular Premature Beats
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Ventricular Tachycardia/Torsades de points
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Ventricular Fibrillation
Ventricular Premature
Beats/Contractions
 VPCs are extra, abnormal beats that originate from the ventricles
 Sign of decreased oxygen to the heart
 Signs/Symptoms: palpitations, dyspnea, dizziness. May be asymptomatic.
 Treatment: beta blockers, calcium channel blockers, anti-arrhythmic meds.
Cardioverter-defibrillator can also be used.
 ECG findings: rhythm can be bigeminy, trigeminy, or quadrigeminy.
 broad QRS complex (≥ 0.120 seconds) with abnormal morphology.
 occurs earlier than would be expected
 followed by a full compensatory pause
Ventricular Tachycardia/Torsades de
points
A sustained Vtach run is >30/ Torsades has a QRS with a point
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Can be difficult to distinguish from supraventricular tachycardia
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Pulse may or may not be present
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Treatment: Shockable rhythm/CPR
 give 1 shock, resume CPR for 5 cycles or 2 min
 Shock again followed by epinephrine 1mg IV q 3-5min or vasopressin 40U IV
 Shock again and resume CPR for 5 cycles or 2 min.
 For Torsades: use magnesium 1-2G IV
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ECG findings:
 Rate: 150-250
 Rhythm: regular
 P wave: none
 QRS: wide and abnormal
Ventricular fibrillation
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V. fib. Causes cardiac arrest and sudden cardiac death
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Occurs when ventricle depolarizes randomly rather than contracting in unison.
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Most often occurs in diseased hearts.
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Treatment
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Defibrillation
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Implantable cardioverter
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Precordial thump can be given if no defibrillator is available
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ACLS: 1 shock followed by CPR for 5 cycles or 2 min followed by shock and CPR with epinephrine 1mg IV or vasopressin 40U IV, Shock and resume CPR for 5 cycles with one of
the following:
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Amiodarone 300mg IV, then 150mg IV
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Lidocaine 1-1.5mg/kg, the 0.5-0.75mg/kg IV (max 3 doses
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Magnesium 1-2g IV for torsade's
ECG findings:
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Rate: indeterminate
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Rhythm: chaotic
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P wave: none
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QRS: none
Atrioventricular Blocks
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1st Degree AV Block
2nd Degree AV Block Type I (Wenkebach)
2nd Degree AV Block Type II (Mobitz II)
3rd Degree AV Block
Bundle Branch Block
RBBB
LBBB
First Degree AV Block
 The communication between the atrial and ventricular depolarization is
delayed. Dysfunction of the AV node
 PR interval is prolonged >0.2 seconds
 P wave is blocked and conducts to the ventricles
 Does not progress to complete heart block
 Cause: Electrolyte imbalances, meds (beta-blockers, calcium channel
blockers, cholinesterase inhibitors)
 Signs/Symptoms: usually asymptomatic.
 Treatment: Correct any electrolyte imbalance or hold medication
Second Degree AV Block Type I
(Wenkebach/Mobitz I)
 Intermittent Dysfunction of the AV node
 PR interval increasingly prolonged until the QRS is dropped.
 QRS is narrow, <0.12 seconds
 Treatment: This is usually benign and requires no treatment
Second Degree AV Block Type II
(Mobitz II)
 There is a p wave for every QRS, but now a QRS for every p wave
 The QRS is wide, >0.12 seconds
 QUICKLY PROGRESSES TO COMPLETE HEART BLOCK!
 Treatment: pacemaker
Third Degree AV Block
 Complete AV disassociation and ventricles kick into to pace the heart
 No relationship between p waves and QRS
 Slow heart rate
 Stokes-Adams Syndrome: 3rd degree AV block has such a slow ventricular
rate that blood does not get to the brain and patient loses consciousness.
 Signs/Symptoms: syncope, confusion, dyspnea, severe chest pain, sudden
death
 Treatment: dual chamber artificial pacemaker and ACLS when needed.
 Do not give atropine as this drug increases conductivity through the AV
node but AV node is not functioning in this case.
Left Bundle Branch Block
 Blocked left bundle branch which delays depolarization to the left ventricle
 One ventricle depolarizes later than the other resulting ins a wide, coupled
QRS complex
 QRS >0.12 Seconds
 Displayed in Leads V5and V6
 Treatment: re-synchronization treatment and pacemaker
Right Bundle Branch Block
 Blocked right bundle branch which delays depolarization to the right
ventricle
 One ventricle depolarizes later than the other resulting ins a wide, coupled
QRS complex
 QRS >0.12 Seconds
 Displayed in Leads V1 and V2
 Treatment: re-synchronization treatment and pacemaker
Heart Block Poem
From Princeton Surgical Group
If the R is far from P, then you have a First
Degree.
Longer, Longer, Longer, Drop! then you have a
Wenkebach.
If some Ps don’t get through, then you have a
Mobitz II.
If Ps and Qs don’t agree, then you have a third
degree.