Emergency Medicine
Andrew Petrosoniak, MDPGY2 Emergency Medicine
University of TorontoCanada
Tachyarrhythmias & Cardioversion
Emergency Medicine
Objectives1. (Very) Briefly review pathophysiology
of arrhythymias (4 slides!)2. Cardioversion3. Tachydysrhythmias4. Special case of wide complex
tachyardia5. Example ECGs
Emergency Medicine
Cardiac conduction system
Emergency Medicine
Action Potentials
Emergency Medicine
Tachyarrhythmias: mechanisms1. Automaticity
– Increase/decrease rate of spontaneous depolarization of cells above their threshold
2. Re-entry– Impulse traveling in a circular movement
3. Triggered
Emergency Medicine
Re-entry mechanism
Necessary Conditions1.Two paths2.One path must be slower3.Critical timing
Emergency Medicine
Now, the patient!• IV, oxygen, monitor & defibrillator to
bedside• Rhythm strip • If possible obtain ECG• Ask yourself 4 questions every time
Emergency Medicine
Questions to ask when analyzing an ECG 1. Is the patient stable or unstable?2. Is the QRS narrow or wide?3. Is the rate regular or irregular?4. Are P waves visible?
Emergency Medicine
Questions to ask when analyzing an ECG 1. Is the patient stable or unstable?2. Is the QRS narrow or wide?3. Is the rate regular or irregular?4. Are P waves visible?
Emergency Medicine
1. Hypotension2. Chest pain (suggestive of
ischemia)3. Shortness of breath4. Decreased level of
consciousness
Stable vs. Unstable
Emergency Medicine
UNSTABLE = SYNCHRONIZED CARDIOVERSION
Emergency Medicine
Electrical Cardioversion • Electrical shock to heart (synchronized to QRS
complex)• Cardiac cells depolarize and restarts electrical
cardiac activity• SA node resumes pacemaker activity • Avoid shock during relative refractory period (may
cause VF)• Effective if etiology of arrhythmia is reentry circuit • Not effective if impulse originates from SA node
Emergency Medicine
Electrical Cardioversion• Synchronization = Prevent R on T phenomenon• Press “Sync” on the machine• Be familiar with your machine; do you need to press
sync after each shock?
Emergency Medicine
• Insufficient evidence to suggest either position is superior for effective cardioversion (AP vs. AL) Emerg Med J 2005 22(1):44-6
• Reasonable to try alternative position if unsuccessful with initial attempts Interact Cardiovasc Thorac Surg 2004 3:386-89
Electrical Cardioversion
FRONT BACKBotto G L et al. Heart 1999;82:726-730
Emergency Medicine
Narrow Complex QRS
Narrow Complex QRS
Wide Complex QRS
Wide Complex QRS
Irregular
Irregular
Regular
Regular
Regular
Regular
Polymorphic VT
Polymorphic VT
(Am J Emerg Med 2010;28:159-165, AHA 2010 guidelines)
Electrical Cardioversion
100 - 150J100 - 150J50J50J 100J100J 200J200J
**Double energy dose if unsuccessful
Unsynchronized
Emergency Medicine
Recap
• Re-entry mechanism: most common tachydysrhythmia
• Every ECG = 4 Questions • Unstable = synchronized
cardioversion• Atrial fibrillation requires most energy
(>100J)
Emergency Medicine
Questions to ask when analyzing an ECG 1. Is the patient stable or unstable?2. Is the QRS narrow or wide?3. Is the rate regular or irregular?4. Are P waves visible?
Emergency Medicine
Narrow Complex
Tachycardia
Narrow Complex
Tachycardia
Hemodynamically
Unstable
Hemodynamically
Unstable
Hemodynamically
Stable
Hemodynamically
Stable
IrregularIrregularRegularRegular
Synchronized cardioversionSynchronized cardioversion
Approach to narrow complex tachycardias
Emergency Medicine
Narrow complex tachycardiasREGULAR IRREGULAR
• Sinus Tachycardia
• Paroxysmal supraventricular tachycardia (PSVT)
• Atrial flutter with consistent conduction
• Atrial Fibrillation
• Atrial flutter with variable conduction
• Multifocal atrial tachycardia
Emergency Medicine
Case: 24 year old, healthy male Chief complaint: 1 hour of palpitations • No chest pain or shortness of breath• HR 180, BP 145/85, RR 18, 98% (room air)
Emergency Medicine
REGULAR • Sinus Tachycardia
• Paroxysmal supraventricular tachycardia (PSVT)
• Atrial flutter with consistent block
Narrow complex tachycardias
Emergency Medicine
Case: 24 year old, healthy male Palpitations, stable hemodynamicallyECG: regular, narrow complex tachycardia
What are the management options?
Emergency Medicine
Regular narrow complex tachycardia
Modified from Neumar et al. Circulation 2010; 122;S729-S767
Emergency Medicine
Case: 24 year old, healthy male ECG: regular, narrow complex tachycardia
• Management is initiated• What does this rhythm strip demonstrate?
Emergency Medicine
62 M with palpitations and dyspneaPMHx: CHF, HTN
Emergency Medicine
REGULAR • Sinus Tachycardia
• Paroxysmal supraventricular tachycardia (PSVT)
• Atrial flutter with consistent block
Narrow complex tachycardias
Emergency Medicine
Atrial Flutter: Management• ACLS: classify unstable vs. stable
– Stable: rate control and only consider cardioversion if <48hrs
– Rate control (no CHF): IV metoprolol or IV diltiazem
– Rate control (with CHF): digoxin or amiodarone – Electrical Cardioversion if unstable
• Electrical cardioversion may be preferred method yet electrical dose is unclear (Ann Emerg Med 2011 Jan 21 Epub ahead of print)
Emergency Medicine
62 M with palpitations and dyspneaPMHx: CHF, HTN
Management• Further history: 7 days of palpitations• In ED, BP 130/65 P 150 98%1L NP• Decision to rate control and arrange follow-up
Emergency Medicine
Case: 68 yr old female1 day of palpitations, slight chest discomfort PMHx: NSTEMI 10 yrs ago, high cholesterol, hypertension
Vitals: 150-170bpm, BP 108/45, 95% 1L NP, RR 20
Emergency Medicine
IRREGULAR • Atrial fibrillation
• Atrial flutter with variable block
• Multi focal atrial tachycardia
Narrow complex tachycardias
Emergency Medicine
Questions to ask when analyzing an ECG 1. Is the patient stable or unstable?
A. HypotensionB. Chest painC. Shortness of breathD. Decreased LOC
2. Is the QRS narrow or wide?3. Is the rate regular or irregular?4. Are P waves visible?
Emergency Medicine
Management of Atrial Fibrillation in the ED
• Lack of strong evidence to guide ED management
• Decision to cardiovert new onset A. Fib, varies significantly between institutions: 42-82% at 8 Canadian EDs (Ann Emerg Med 2011 57(1):13-21)
• AFFIRM & AF-CHF only apply to outpatient population but suggests no difference between rate vs. rhythm control
• Significant controversy exists between rate vs. rhythm control in acute AF
Emergency Medicine
New Onset Atrial
Fibrillation
New Onset Atrial
Fibrillation
Hemodynamically
Unstable
Hemodynamically
Unstable
Hemodynamically
Stable
Hemodynamically
StableRate Control
IV metoprolol or diltiazem
Rate ControlIV metoprolol or
diltiazem
> 48hrs> 48hrs<48hrs <48hrs
Anti-arrhythmics +/- electric
cardioversion
Anti-arrhythmics +/- electric
cardioversion
TEE or 3wks anti-coagulation then cardioversion
TEE or 3wks anti-coagulation then cardioversion
Chest 2009; 135:849-859
Synchronized cardioversionSynchronized cardioversion
Emergency Medicine
Rate controlNo accessory pathway• Diltiazem IV 0.25mg/kg over 2min (Class I)
• Verapamil IV 0.075-0.15mg/kg over 2min (Class I)
Accessory Pathway• Amiodarone IV 150mg over 10min (Class IIa)
Heart Failure without accessory pathway• Digoxin IV 0.25mg q2h (Class I)
• Amiodarone IV 150mg over 10min (Class IIa)
ACC/AHA/ESC 2006 Atrial Fibrillation guidelines
Emergency Medicine
Rhythm control: Stable patients• Consider cardioversion especially if younger, without
hypertension or heart disease ACC/AHA/ESC Atrial Fibrillation guidelines 2006
• Ottawa protocol: IV 1g procainamide (in 250ml D5W) over 1hr; 58% conversion rate CJEM 2010 12(3):181-91
• Amiodarone 3-5mg/kg IV over 15-20min • Ibutilide 0.015-0.02mg/kg IV over 10-15min
• Electrical cardioversion: 80-90% conversion rates
• Admit AF patients if: – Unstable, MI, worse heart failure
Emergency Medicine
BACK TO THE CASE
Case: 68 yr old female1 day of palpitations, slight chest discomfort Vitals: 150-170bpm, BP 108/45, 95% 1L NP, RR 20
MANAGEMENT• if patient becomes unstable then synchronized cardioversion• Probably reasonable to rate control • Decide whether chemical or electrical cardioversion is appropriate
Emergency Medicine
RecapNarrow complex tachycardias
• Unstable vs. stable• Synchronized cardioversion if unstable• If stable Adenosine first if stable• Rate control especially if unknown duration• Chemical cardioversion: consider amiodarone or
procainamide• Electricity more effective than medication
Emergency Medicine
Wide complex tachycardias
Emergency Medicine
Approach to wide complex tachycardias
Wide Complex Tachycardia
Wide Complex Tachycardia
Hemodynamically
Unstable
Hemodynamically
Unstable
Hemodynamically
Stable
Hemodynamically
Stable
IrregularIrregularRegularRegular
Synchronized cardioversionSynchronized cardioversion
Emergency Medicine
1. Hypotension2. Chest pain (suggestive of
ischemia)3. Shortness of breath4. Decreased level of
consciousness
Wide Complex TachycardiaStable vs. Unstable
Unstable = Immediate Synchronized Cardioversion
Emergency Medicine
Regular• Monomorphic VT
• SVT with aberrancy (BBB)
• Antidromic Wolf Parkinson White syndrome
• Electrolyte abnormalities or overdoses
Wide Complex TachycardiasDifferential Diagnosis
Irregular• Polymorphic VT (including Torsades)
• A. Fib with aberrancy (BBB)
• A. Fib + accessory pathway
Emergency Medicine
Wide Complex TachycardiasVentricular Tachycardia vs. SVT
Emergency Medicine
Wide Complex Tachycardias
Regular wide complex tachycardia is ventricular tachycardia until proven
otherwise
Emergency Medicine
Wide Complex TachycardiasManagement: Stable, regular WCT
• Consider adenosine ONLY if regular WCT • Procainamide (Class IIa)
• Amiodarone (Class IIb)
• Electrical cardioversionACLS guidelines 2010
*** If ONE anti-arrhythmic fails then proceed to electrical cardioversion***
Emergency Medicine
Case 1: 33 M severe palpitations; healthy; BP 145/85
Case 2: 75 F chest pain; PMHx MI; BP 109/75
Emergency Medicine
Impression: most likely SVT w/ aberrancy
Management • Consider Adenosine – ensure regular rhythm• Other options: Amiodarone, Procainamide, Electrical cardioversion
Impression: most likely VT
Management: • Avoid adenosine • Amiodarone or Procainamide or Electrical cardioversion • Concern about hemodynamic stability
Case 2: 75 F chest pain; PMHx MI; BP 109/75
Case 1: 33 M severe palpitations; healthy; BP 145/85
Emergency Medicine
FUSION BEAT CAPTURE BEATS
Wide Complex TachycardiasECG Findings Suggestive of VT
AV DISSOCIATION
Emergency Medicine
Wide Complex TachycardiasAccessory Pathways
Orthodromic/AnterogradeQRS typically normalMore common
Antidromic/RetrogradeQRS typically wideLess common
Emergency Medicine
Why do accessory pathways matter?
Wide Complex TachycardiasAccessory Pathways
Wide complex, irregular tachycardia can degenerate to ventricular fibrillation with
AV nodal blockade
Calcium Channel BlockersBeta BlockersAdenosine
Emergency Medicine
Wide Complex TachycardiasAccessory Pathways
Emergency Medicine
Wide Complex TachycardiasAccessory Pathways
When to suspect accessory pathway?• Rapid ventricular response (>200bpm)• Wide, irregular QRS complexes • Bizarre QRS morphology• History of accessory pathway dysrhythmia
Management• Unstable = Synchronized cardioversion• Check previous ECG for PR interval & Delta wave • Always have defibrillator available with infusions • Amiodarone (AHA 2005 guidelines)
• Procainamide (Intern Emerg Med 2010;5:421-426)
Emergency Medicine
RecapWide complex tachycardias
• Unstable vs. stable• Synchronized cardioversion if unstable• ONLY try adenosine if convinced it is regular WCT• Assume VT if cardiovascular history or >50yrs • No AV nodal blocker if irregular WCT
Emergency Medicine
Objectives: recap1. (Very) Briefly review pathophysiology
of arrhythymias (4 slides!)2. Cardioversion3. Tachydysrhythmias4. Special case of wide complex
tachyardia5. Example ECGs
Emergency Medicine
References• Rosen’s Emergency Medicine (7th edition)• Lilly LS. Pathophysiology of heart disease. 2003• Cvphysiology.com• Simplified approach to tachyarrhythmias (EMRap.com)• EMCrit.org• References listed in presentation
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