Date post: | 07-May-2015 |
Category: |
Health & Medicine |
Upload: | maher-assaf |
View: | 3,814 times |
Download: | 1 times |
Management of Peri-arrest Arrhythmias
Presented: Dr Hesham Faisal, MD, MRCP, EDIC
Consultant Intensivist SFH-Dammam
Objectives
• ECG and rhythm information interpretation within the context of total patient assessment
• The concept of symptomatic &/or unstable• Basic ECG interpretation• Tachy-arrhythmias and Brady-arrhythmias• ECG strips
SymptomaticBradycardia and Tachycardia
• ACLS providers treatment decisions – Should not depend solely on rhythm interpretation and neglect clinical
evaluation.– must evaluate the patient’s symptoms and clinical signs (ventilation,
oxygenation, HR, BP, level of consciousness, and signs of inadequate organ perfusion)
– Must define the cause of the patient’s instability in order to properly direct treatment.
• unstable – vital organ function is acutely impaired or cardiac arrest is ongoing or
imminent• Symptomatic
– arrhythmia is causing symptoms (palpitations, lightheadedness, or dyspnea)– patient is stable and not in imminent danger
The Electrocardiogram
• Relationship of the ECG to Electrical Events in the Heart– ECG Components• P Wave• QRS Complex• T Wave• U Wave
The Electrocardiogram
The Electrocardiogram
The Electrocardiogram
The Electrocardiogram
The Electrocardiogram
The Electrocardiogram
The Electrocardiogram
The Electrocardiogram
– Refractory Periods• Absolute• Relative
Bradycardia
• HR <60 beat/minute• Symptomatic bradycardia < 50 beat/minute• hypoxemia is a common cause of bradycardia• Assessment:
– signs of increased work of breathing (tachypnea, intercostal retracions, suprasternal retracions, paradoxical abdominal breathing)
– Hypoxemia as determined by pulse oximetry• Action:
– provide supplementary oxygen. – Attach a monitor to the patient, – evaluate blood pressure– establish IV access. – If possible, obtain a 12-lead ECG to better define the rhythm.
Dysrhythmias Originating in the SA Node
NormalQRS
NormalPRI
Upright & normalP Waves
SA nodePacemaker Site
RegularRhythm
Less than 60Rate
Sinus BradycardiaRules of Interpretation
Bradycardia
• Signs & Symptoms of poor perfusion– Hypotension– acute altered mental status– ischemic chest discomfort,– acute heart failure, hypotension, or other signs of
shock,• the patient should receive immediate
treatment.
A first-degree AV block(generally benign)
Usually < 0.12 secondsQRS
> 0.20 SecondsPRI
NormalP Waves
SA node or atrialPacemaker Site
Usually regularRhythm
Depends on underlying rhythmRate
First-Degree AV BlockRules of Interpretation
Second Degree, Mobitz type I block, the block is at the AV node;
the block is often transient and asymptomatic
Usually < 0.12 secondsQRS
Increases until QRS is dropped, then repeatsPRI
Normal, some P waves not followed by QRSP Waves
SA node or arialPacemaker Site
Atrial, regular; ventricular, irregularRhythm
Atrial, normal; ventricular, normal to slowRate
Mobitz Type I Second-Degree AV Block
Rules of Interpretation
Second Degree Mobitz type II block block is usually below the AV node
often symptomatic potential to progress to complete AVblock.
Normal or > 0.12 secondsQRS
Constant for conducted beats, may be > 0.21 secondsPRI
Normal, some P waves not followed by QRSP Waves
SA node or atrialPacemaker Site
May be regular or irregularRhythm
Atrial, normal; ventricular, slowRate
Mobitz Type II Second-Degree AV Block
Rules of Interpretation
Third Degree AV block AV node,bundle of His, or bundle branches
0.12 seconds or greaterQRS
No relationship to QRSPRI
Normal,with no correlation to QRSP Waves
SA node and AV junction or ventriclePacemaker Site
Both atrial and ventricular are regularRhythm
Atrial, normal; ventricular, 40–60Rate
Third-Degree AV Block
Rules of Interpretation
Treatment of Bradycardia
Atropine:• first-line drug for acute symptomatic bradycardia
(Class IIa, LOE B)• Dose: 0.5 mg IV every 3 to 5 minutes to a maximum
total dose of 3 mg• Use cautiously in the presence of acute coronary
ischemia or MI• ineffective in cardiac transplant patient• Avoid in type II second-degree or third degree AV
block with a new wide-QRS complex
Treatment of Bradycardia
Transcutaneous pacing (TCP):• unstable patients who do not respond to
atropine (Class IIa, LOE B)• patient should be prepared for transvenous
pacing and expert consultation should be obtained.
Treatment of Bradycardia
Alternative Drugs:• unresponsive for atropine• Temporizing measure awaiting TCP• overdose of a β blocker or Ca channel blocker.Dopamine• 2-10 mcg/kg/minute and titrate to patient responseEpinephrine• 2 -10 mcg/min and titrate to patient responseIsoproterenol• 2 to 10 mcg/min by IV infusion, titrated according to heart
rate and
Tachycardia• Heart rate > 100 beats/minute• clinical significance ≥ 150 beats/minute• hypoxemia is a common cause of tachycardia,
Assessment:– signs of increased work of breathing (tachypnea, intercostal retracions,
suprasternal retracions, paradoxical abdominal breathing)– Hypoxemia as determined by pulse oximetry
Action:– provide supplementary oxygen. – Attach a monitor to the patient, – evaluate blood pressure– establish IV access. – If possible, obtain a 12-lead ECG to better define the rhythm immediate cardioversion should not be delayed if the patient is
unstable
Unstable tachycardia
Evaluate • unstable tachycardia • with severe signs and symptoms related to a suspected
arrhythmia– acute altered mental status, – ischemic chest discomfort, – acute heart failure,– hypotension, or other signs of shock
Treat:• Immediate Cardioversion• Selected cases of regular narrow complex tachycardia:
Adenosine
Synchronized Cardioversion
• establish IV access before cardioversion• sedation if the patient is conscious• shock delivery that is timed (synchronized) with the QRS
complex• avoids shock delivery during the relative refractory period of
the cardiac cycle when a shock could produce VF• recommended to treat
1. unstable atrial fibrillation →120 - 200 J2. unstable SVT → 50 - 100 J3. Unstable atrial flutter → 50 - 100 J4. unstable monomorphic (regular) VT → 100 J.
The Electrocardiogram
– Refractory Periods• Absolute• Relative
Stable tachycardia
Evaluate:• narrow-complex or wide-complex tachycardia• rhythm is regular or irregular• Wide complexes QRS morphology is – monomorphic– Polymorphic
Treat:• Tailored accordingly
Narrow–QRS-complex (SVT) tachycardias
QRS< 0.12 second in order of frequency• Sinus tachycardia• Atrial fibrillation• Atrial flutter• AV nodal reentry• Accessory pathway–mediated tachycardia• Atrial tachycardia (including automatic and reentry• forms)• Multifocal atrial tachycardia (MAT)• Junctional tachycardia (rare in adults)
Sinus Tachycardiaphysiologic compensation rather than the cause of instability
NormalQRS
NormalPRI
Upright & normalP Waves
SA nodePacemaker Site
RegularRhythm
>100 (220-age )Rate
Sinus TachycardiaRules of Interpretation
Supraventricular Tachycardia (Re-entry SVT)
Usually normalQRS
Usually normalPRI
Often buried in preceding T waveP Waves
Atrial (outside SA Node)Pacemaker Site
RegularRhythm
150–250Rate
Paroxysmal Supraventricular Tachycardia
Rules of Interpretation
Treatment of stable PSVT
Vagal Maneuvers• Valsalva maneuver or carotid sinus massage• preferred initial therapeutic choices for the termination of
stable PSVT• may transiently slow the ventricular rate & assist rhythm
diagnosisAdenosine (Class I, LOE B)• 6 mg rapid IV push followed by a 20 mL saline flush• 12 mg rapid IV push• Defibrillator should be available• Side effects: flushing, dyspnea & chest discomfort
Treatment of stable PSVTcalcium channel blockers (Class IIa, LOE B)
• verapamil– 2.5 mg to 5 mg IV bolus over 2 minutes– repeated doses of 5 -10 mg q 15-30 minutes to a total dose
of 20 mg– Contraindicated in impaired LV function or heart failure
• Diltiazem– 15 -20 mg IV over 2 minutes– maintenance infusion dose is 5-15 mg/hour
IV β-blockers (Class IIa, LOE C)
• metoprolol,atenolol, propranolol, esmolol• used with caution in patients with COPD or CCF
Wide–QRS-complex tachycardias
QRS > 0.12 second• Ventricular tachycardia (VT) • SVT with aberrancy• Pre-excited tachycardias [WPW] syndrome• Ventricular paced rhythms
Wide-Complex Tachycardia
Evaluation1. Stable or unstable patient – Unstable → immediate cardioversion
2. 12 lead ECG3. Regular or irregular
a. Regular VT or SVT with aberrancyb. Irregular atrial fibrillation with aberrancy or
polymorphic VT/torsades de pointes
Therapy for Regular stable Wide-Complex Tachycardias
IV adenosine• safe for both treatment and diagnosis (Class IIb, LOE B).• should not be given for unstable or irregular or
polymorphic widecomplex tachycardias• 6 mg rapid IV push → 12 mg → 12 mg• defibrillator should be availableStable likely VT• IV antiarrhythmic (procainamide, amiodarone or
sotalol)• Or elective cardioversion
Dysrhythmias Originating in the Ventricles
>0.12 seconds, bizarreQRS
NonePRI
If present, not associated with QRSP Waves
VentriclePacemaker Site
Usually regularRhythm
100–250Rate
Ventricular Tachycardia
Rules of Interpretation
Irregular Tachycardias
Irregular narrow-complex or wide-complex tachycardia:
1. atrial fibrillation (with or without aberrant conduction)
2. MAT3. sinus rhythm/tachycardia with frequent atrial
premature beats
AF
NormalQRS
NonePRI
None discernibleP Waves
Atrial (outside SA Node)Pacemaker Site
Irregularly irregularRhythm
Atrial rate 350–50Ventricular rate variesRate
Atrial Fibrillation
Rules of Interpretation
Treatment of AF
Rate control• >48 hours are at increased risk for cardioembolic events• Avoid Electric or pharmacologic cardioversion unless the
patient is unstable• IV β –blockers or calcium channel blockers such as
diltiazem • Digoxin and amiodarone
– Congestive heart failure• wide-complex irregular rhythm (AF with pre-excitation)
– Avoid AV nodal blocking agents such as adenosine, calcium channel, β blockers, digoxin
MAT
VariableQRS
Varies depending on source of impulsePRI
Organized, nonsinus P waves; at least 3 formsP Waves
Ectopic sites in atriaPacemaker Site
IrregularRhythm
More than 100Rate
Multifocal Atrial Tachycardia
Rules of Interpretation
PACs
Usually normalQRS
Varies dependent on foci of impulsePRI
Occurs earlier than expectedP Waves
Ectopic sites in atriaPacemaker Site
Usually regular except for the PACRhythm
Depends on underlying rhythmRate
Premature Atrial Contractions
Rules of Interpretation
Dysrhythmias Originating in the Atria
Usually normalQRS
Usually normalPRI
F waves are presentP Waves
Atrial (outside SA node)Pacemaker Site
Usually regularRhythm
Atrial rate 250–350Ventricular rate variesRate
Atrial FlutterRules of Interpretation
• Torsade de Pointes– Polymorphic VT.– Caused by the use of certain
antidysrhythmic drugs.– Exacerbated by
coadministration of antihistamines, azole antifungal agents and macrolide antibiotics, erythromycin, azithromycin, and clarithramycin.
Dysrhythmias Originating in the Ventricles
Polymorphic (Irregular) VTtorsades de pointes
• requires immediate defibrillation with the same strategy used for VF– stop medications known to prolong the QT interval– Correct electrolyte imbalance
• magnesium is commonly used – Polymorphic VT associated with familial long QT syndrome
• isoproterenol or ventricular pacing – Polymorphic VT with bradycardia and drug-induced QT
prolongation• IV amiodarone and β–blockers
– myocardial ischemia induced Polymorphic VT
Dysrhythmias Originating in the Ventricles
>0.12 seconds, bizarreQRS
If present, variesPRI
None produced by ventricular pacemakers;
pacemaker spikeP Waves
Depends upon electrode placementPacemaker Site
May be regular or irregularRhythm
Varies with pacemaker
Rate
Artificial Pacemaker Rhythm
Rules of Interpretation
• Pre-excitation Syndromes– Excitation by an impulse
that bypasses the AV node• Wolff-Parkinson-
White Syndrome (WPW)– Short PRI and long
QRS duration– Delta waves
– Treat underlying rhythm.
Dysrhythmias Resulting from Disorders of Conduction
• Hyperkalemia– Tall Ts
• Suspect in patients with a history of renal failure.
• Hypokalemia– Prominent U waves
• Hypothermia– Osborn wave (“J” wave)– T wave inversion, sinus
bradycardia, atrial fibrillation or flutter, AV blocks, PVCs, VF, asystole
ECG Changes Due to Electrolyte Abnormalities and Hypothermia
Summary
• The goal of therapy for bradycardia or tachycardia is to– rapidly identify and treat patients who are hemodynamically
unstable or symptomatic due to the arrhythmia• Drugs or when appropriate, pacing may be used to control
unstable or symptomatic bradycardia• Cardioversion or drugs or both may be used to control unstable
or symptomatic tachycardia• ACLS providers
– should closely monitor stable patients pending expert consultation and
– should be prepared to aggressively treat those with evidence of decompensation