Transcript Document

ECGs and Acute
Cardiac Events Workshop
Dr. Stewart McMorran
Consultant in Accident and Emergency
MB, BCh, MRCS, FFAEM
Objectives
• Emergency management of common
cardiac events
• ST elevation MIs
• Tachyarrhythmias
• Bradyarrhythmias
• Overview of management
• Interactive case discussions
National Service Framework
• NSF for coronary artery disease established 2000
• Relevant to emergency medicine – need for timely
reperfusion therapy
• Door to needle time of 30 mins
• Call to needle time of 60 mins
• Results …
– 75% eligible patients thrombolysed within 30 minutes
of hospital arrival
Impact of NSF
• Emphasis on timely delivery of reperfusion
therapy
• Thrombolysis – most places
• Percutaneous Coronary Intervention:
– Primary – limited availability
– Rescue – local policy; if less than 50% resolution in ST
segment elevation after 90 minutes
• Coronary artery bypass graft
Impact on first line services
• Timely assessment of chest pain in A&E
• Extended skills of paramedics
• Availability of Air Ambulances
ECG Lead Placement
Wall affected
Leads
Artery
involved
Reciprocal
changes
Anterior
V2-4
LAD
II, III, aVF
LAD,
circumflex
LAD
II, III, aVF
Anterolateral I, aVL, V3-6
Anteroseptal
V1-4
Inferior
II, III, aVF RCA
I, aVL
Lateral
I, aVL, V5-6
circumflex
II, III, aVF
Posterior
V7-9
RCA
V1-3
Right
ventricular
RV4-6
RCA
Criteria for thrombolysis
• Chest pain, onset within last 12 hours plus any of:
• ST elevation 2 mm or more in two contiguous
chest leads
• ST elevation 1 mm or more in two contiguous
limb leads
• Dominant R wave and ST depression in V1-3
• New LBBB
Posterior MI
• Dominant R wave chest leads V1-3
• ST depression chest leads V1-3
• Turn ECG upside down and back to front –
see typical changes of STEMI
• Alternatively …
– Posterior leads V7-9
Left Bundle Branch Block and
MI
• ST segment elevation more than 1 mm concordant
(same direction) as QRS complex
• ST segment depression more than 1 mm in V1,2,3
• ST segment elevation more than 5 mm discordant
(opposite direction) from QRS complex
• Sgarbossa E et al. NEJM 1996 Feb 22:334(8)
481-7
Pericarditis
• Widespread ST elevation (in leads looking
at inflamed epicardium)
• Reciprocal depression in aVR and V1
• ST segment saddle shaped (concave
upwards)
• No Q waves
ST segment high take off
• Normal variant
• High take off or early repolarisation or J point
elevation
• Younger patients
• Usually follows an S wave
• T wave maintains independent wave form
• No reciprocal ST segment depression
• If in doubt, compare with earlier ECGs
Arrhythmias - principles of
treatment
• Choice of intervention
- drugs vs. electricity
• How symptomatic is patient
– How urgent is need for action
Choice of intervention
• Drugs:
– Not always reliable
– Side effects
– Every anti-arrhythmic is potentially pro-arrhythmic
• Electricity:
– Reliable
– Patient considerations
– Environmental considerations
How symptomatic is patient
• Signs of poor cardiac output
– Heart rate
• Too fast – depends on rhythm
• Too slow – depends on patient
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Systolic blood pressure < 90 mm Hg
Chest pain
Breathlessness
Altered level of consciousness
• Support ABCs: give oxygen; cannulate a vein
• Monitor ECG, BP, SpO2
• Record 12-lead if possible, if not record rhythm strip
• Identify and treat reversible causes (e.g. electrolyte abnormalities)
Tachycardia
Algorithm
Is patient stable?
Synchronised DC Shock*
Up to 3 attempts
Unstable
Signs of instability include:
1. Reduced conscious level
2. Chest pain
3. Systolic BP < 90 mmHg
4. Heart failure
(Rate related symptoms uncommon at less
than 150 beats min-1)
• Amiodarone 300 mg IV over 10-20
min and repeat shock; followed by:
• Amiodarone 900 mg over 24 h
Stable
Broad
Is QRS narrow (< 0.12 sec)?
Narrow
Narrow QRS
Broad QRS
Is rhythm regular?
Is QRS regular?
Irregular
Regular
Regular
Seek expert help
Possibilities include:
• AF with bundle branch block
treat as for narrow complex
• Pre-excited AF
consider amiodarone
• Polymorphic VT (e.g. torsade
de pointes - give magnesium
2 g over 10 min)
*Attempted electrical cardioversion is
always undertaken under sedation
or general anaesthesia
(with pulse)
If Ventricular Tachycardia
(or uncertain rhythm):
• Amiodarone 300 mg IV
over 20-60 min; then 900 mg
over 24 h
If previously confirmed SVT
with bundle branch block:
• Give adenosine as for regular
narrow complex tachycardia
• Use vagal manoeuvres
• Adenosine 6 mg rapid IV bolus;
if unsuccessful give 12 mg;
if unsuccessful give further 12 mg.
• Monitor ECG continuously
Irregular
Irregular Narrow Complex
Tachycardia
Probable atrial fibrillation
Control rate with:
• -Blocker IV or digoxin IV
If onset < 48 h consider:
• Amiodarone 300 mg IV 20-60
min; then 900 mg over 24 h
Normal sinus rhythm restored?
Yes
No
Seek expert help
Probable re-entry PSVT:
• Record 12-lead ECG in
sinus rhythm
• If recurs, give adenosine
again & consider choice of
anti-arrhythmic prophylaxis
Possible atrial flutter
• Control rate (e.g. -Blocker)
Example
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65 year old male
Presents to A&E
Palpitations /chest pain
MI 3 months ago
Sa02 95% on high flow oxygen
PR 190 BP 90/70
How do you know it is VT ?
• May be difficult to distinguish ventricular
tachycardia from atrial tachycardia with aberrant
conduction e.g. LBBB
• Default position – assume ventricular
• Look for confirmatory features:
– capture beats
– fusion beats
– concordance
– extreme axis deviation
Main learning points
• VT is a malignant arrhythmia
• DC cardioversion in presence of adverse
signs
• Check electrolytes especially K+ and Mg2+
• Amiodarone anti-arrhythmic of choice
Example
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25 year old female
Presents to A&E
Palpitations
Sa02 97% on high flow oxygen
PR 200 BP 110/70
• Support ABCs: give oxygen; cannulate a vein
• Monitor ECG, BP, SpO2
• Record 12-lead if possible, if not record rhythm strip
• Identify and treat reversible causes (e.g. electrolyte abnormalities)
Tachycardia
Algorithm
Is patient stable?
Synchronised DC Shock*
Up to 3 attempts
Unstable
Signs of instability include:
1. Reduced conscious level
2. Chest pain
3. Systolic BP < 90 mmHg
4. Heart failure
(Rate related symptoms uncommon at less
than 150 beats min-1)
• Amiodarone 300 mg IV over 10-20
min and repeat shock; followed by:
• Amiodarone 900 mg over 24 h
Stable
Broad
Is QRS narrow (< 0.12 sec)?
Narrow
Narrow QRS
Broad QRS
Is rhythm regular?
Is QRS regular?
Irregular
Regular
Regular
Seek expert help
Possibilities include:
• AF with bundle branch block
treat as for narrow complex
• Pre-excited AF
consider amiodarone
• Polymorphic VT (e.g. torsade
de pointes - give magnesium
2 g over 10 min)
*Attempted electrical cardioversion is
always undertaken under sedation
or general anaesthesia
(with pulse)
If Ventricular Tachycardia
(or uncertain rhythm):
• Amiodarone 300 mg IV
over 20-60 min; then 900 mg
over 24 h
If previously confirmed SVT
with bundle branch block:
• Give adenosine as for regular
narrow complex tachycardia
• Use vagal manoeuvres
• Adenosine 6 mg rapid IV bolus;
if unsuccessful give 12 mg;
if unsuccessful give further 12 mg.
• Monitor ECG continuously
Irregular
Irregular Narrow Complex
Tachycardia
Probable atrial fibrillation
Control rate with:
• -Blocker IV or digoxin IV
If onset < 48 h consider:
• Amiodarone 300 mg IV 20-60
min; then 900 mg over 24 h
Normal sinus rhythm restored?
Yes
No
Seek expert help
Probable re-entry PSVT:
• Record 12-lead ECG in
sinus rhythm
• If recurs, give adenosine
again & consider choice of
anti-arrhythmic prophylaxis
Possible atrial flutter
• Control rate (e.g. -Blocker)
Main learning points
• Supraventricular tachycardias are often well
tolerated
• Usually younger patients
• Vagal manoeuvres may be successful
• Adenosine is an effective anti-arrhythmic
Wolf Parkinson White
Wolf Parkinson White syndrome
• Uncommon cause of SVT
• Presence of accessory pathway (bundle of
Kent)
• Characteristic ECG features
– Short PR interval (<120 ms)
– Wide QRS (>120 ms)
– Delta wave (slurred upstroke)
• Unpredictable response to adenosine
Example
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55 year old man
Presents to A&E
1 hour history of central chest pain
Sa02 97% on high flow oxygen
PR 45 BP 80/50
BRADYCARDIA ALGORITHM
(includes rates inappropriately slow for haemodynamic state)
Adverse signs?
Yes
Atropine
500 mcg IV
Satisfactory
Response?
• Systolic BP < 90 mmHg
• Heart rate < 40 beats min-1
• Ventricular arrhythmias compromising BP
• Heart failure
No
Yes
No
Interim measures:
• Atropine 500 mcg IV
repeat to maximum of 3 mg
• Adrenaline 2-10 mcg min-1
• Alternative drugs
OR
• Transcutaneous pacing
Seek expert help
Arrange transvenous pacing
Risk of asystole?
Yes
• Recent asystole
• Möbitz II AV block
• Complete heart block
with broad QRS
• Ventricular pause > 3s
Observe
Main learning points
• Bradyarrhythmias may complicate inferior
myocardial infarction (RCA supplies AVN)
• Atropine may be effective
• Pacing for symptomatic bradycardias
resistant to atropine
Example
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75 year old female
Presents to A&E
Palpitations
Sa02 95% on high flow oxygen
PR 175 irreg BP 80/50
Atrial fibrillation
Treatment based on risk to patient from the arrhythmia
• High risk
– Rate > 150 beats min-1
– Chest pain
– Critical perfusion
• Intermediate risk
– Rate 100-150 beats min-1
– Breathlessness
– Poor perfusion
• Low risk
– Rate < 100 beats min-1
– Mild or no symptoms
– Good perfusion
Main learning points
• Management of AF is complex
• Universal agreement on high risk patients
• Anticoagulation essential to prevent
thromboembolic complications
Example
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35 year old male
Presents to A&E
Palpitations
Sa02 97% on high flow oxygen
PR 200 BP 110/70
Any Questions?
Summary
• Chest pain is a common cause of attendance
to hospital
• Important to recognise STEMI
• Arrhythmias may precede or complicate MI
• Standardised treatment algorithms for initial
management