Download Civic/Riverside Units - S. McCarter, September 2015

Approach to the ECG
Shannon McCarter
PGY2 FM Civic
99 Topics
General Approach to ECG
1.
2.
3.
4.
5.
6.
Rate
Rhythm
Axis
Rotation
Waves, Segments, Intervals
Hypertrophy
1. RATE

Regular rhythms:
Paper speed:
25mm/sec
– 300/# large square between R-R
– 1500/# small squares between R-R
– Countdown sequence 300-150-100-75-60 -50

Irregular rhythms:
– # of complexes on ECG (10seconds) x 6
2. Rhythm
Step 1: Is the QRS regular or irregular
– ?regularly irregular or irregularly irregular
 Step 2: Assess the QRS
 ?wide or narrow complex
 Step 3: P waves present?
 Step 4: Relationship of P wave with QRS

3. Axis

Look at Lead I and AVF (other methods
involve Lead II)
Lead I
AVF
Axis
+
+
Normal (-30 to 90)
+
-
Possible LAD
-
+
RAD
-
-
Extreme axis deviation
3. Axis

Another method:
– Examine isoelectric limb lead
– Most of electrical current moving
perpendicular to isoelectric lead
Lead Grouping
II, III, AVF – inferior leads
 V1, V2 – antero-septal leads
 V3, V4 – anterior leads
 V5,V6, I, aVL – lateral leads

4. Rotation
Looking at the heart in the transverse axis
 General rule:

– Heart rotates to hypertrophy and away from
infarct
Clockwise rotation: isoelectric QRS in V5, V6
 Counter-clockwise: isoelectric in V1, V2

5.Waves, Intervals, and
Segments
PR interval:
– 0.12-0.20 seconds
 QRS complex:
– 0.06-0.11 seconds
 QT interval
– N < 440msec men,<460 women
– Varies with HR. In General should be <1/2R-R
– Ventricular depolarization + repolarization
 Waves: assess morphology, voltage (P, Q, R, S, T)
 Segments assess for elevation or depression (PR, ST)

6. Hypertrophy
 Left Ventricular Hypertrophy
 S wave of V1/ V2 + R wave of V5/V6 > 35mm
 R wave in aVL >11 mm
 May also see LAE and LAD
 Right Ventricular Hypertrophy
 RAD +/- RAE
 R wave in V1 > 7mm or R/S ratio >1
Jeopardy
Life In The
Fast Lane
Took Me Right
Off My Feet
Achy, Breaky
Heart
Ah, Ah, Ah,
Ah…Staying
alive
Medication
Master
$100
$100
$100
$100
$100
$200
$200
$200
$200
$200
$300
$300
$300
$300
$300
$400
$400
$400
$FREE
$FREE
Final Jeopardy
1 - $100

This rhythm is the most common sustained
arrhythmia.

What is atrial fibrillation?
Atrial fibrillation

Most common sustained arrhythmia

Complications: cardiomyopathy, embolic events, CHF

Etiology: HTN, IHD, Valvular heart disease, infection,
electrolytes (hypoK, hypoMg), pulmonary (PE),
pericardial disease, drugs, endocrine (thyrotoxicosis,
pheo), acid-base disturbance, cardiomyopathies, preexcitation syndromes

ECG: irregularly irregular rhythm, no P waves, QRS
normally < 120msec
Atrial Fibrillation

Classification: first episode, recurrent (>2), paroxysmal
(< 7 days), persistent (>7 days), permanent (> 1 year)

Management:
– Anti-coagulant: CHADS2
– Rate control
– Rhythm Control
– Cardioversion
– **Treat underlying**

See Canadian Cardiovascular Guidelines for
Management of Atrial Fibrillation (2014)
1 - $200

This supraventricular tachycardia has a
characteristic saw-tooth pattern.

What is atrial flutter?
Atrial Flutter

Rate approximately 300bpm

Etiology: re-entrant circuit

Look for conduction 2:1, 3:1, 4:1

Saw tooth waves best seen in inferior leads

Mngt:
– Ablation
– Similar management to atrial fibrillation
1 - $300

Unless ACLS and shock is rapidly instituted, this
rhythm is invariably fatal

What is Ventricular fibrillation?
1 - $400

This mnemonic is instrumental in ACLS and
helpful for remembering the causes of cardiac
arrest.

What is 5 H’s and 5 T’s?
5 H’s and 5 T’s
– 5 H’s:
 Hypoxia
 Hypovolemia
 HyperK+
 Hydrogen ion
 Hypothermia
– 5 T’s:
 Tension pneumothorax
 Tamponade
 Toxins
 Thrombosis – heart
 Thrombosis - lung
2 - $100

This heart block often is benign and does not
require treatment.

What is: AV block: 2nd degree, Mobitz Type I
– Aka Wenckebach
Heart Blocks



1st degree: PR > 200ms
– Usually benign. No treatment required.
2nd degree
– Mobitz I (Wenckebach): progressive PR prolongation until
QRS dropped
 Rarely progresses to Type II, CHB
 Rx: asymptomatic do not require rx.
 Usually responds to atropine
– Mobitz II: PR interval stable with occasional dropped QRS
 High risk of syncope or CHB
 Requires temp pacing/ permanent pacemaker
Etiology: high vagal tone, age related, infectious, infarct,
drugs, electrolyte abN, post-cardiac surgery
Heart Blocks
 3rd
degree – Complete Heart Block
– Complete AV dissociation
– P waves not conducted
– Etiology: inferior MI, progression of Mobitz
Type I/ II, AV nodal blockers
– Require temporary pacing and permanent
pacemaker
2 - $200

What drugs should you avoid with a patient with this
condition?

What are AV blockers?
Pre-excitation syndrome: WPW
• Congenital accessory pathway (Bundle of Kent)
• Can cause AVRT (atrioventricular reentry tachycardia)
• ECG findings: PR < 120msec, delta wave, prolongation QRS,
ST segment and T wave discordant changes (opposite
direction of QRS complex)
• Treatment with AV nodal blockers  VT or VF
• Unstable: cardioversion
• Stable: procainamide
2 - $300

This syndrome is caused by a sodium
channelopathy.

What is Brugada?
Brugada
Brugada Syndrome
• Epidemiology: often Asian males, middle age
• ECG changes can be transient and unmasked by fever, drugs,
ischemia, hypothermia, hypoK
• Diagnosis requires: ECG changes + 1 clinical criteria
• ECG: Type I: Brugada sign: coved ST segments >2mm in
>1 of V1-V3 followed by negative T wave
• Type II: nondx - > 2mm of saddleback ST elevation in
V1-V3
• Clinical criteria: family history of SD < 45, Vfib/
polymorphic VT, Coved ECG changes in family, syncope,
inducible VT with electrical stimulation, nocturnal agonal
respirations
• Management: ICD
• No treatment SD age 40s
2 - $400
What is the name of this condition?
 Bonus marks: what is the clinical significance


What is Wellen’s Syndrome? It indicates critical
stenosis of the LAD.
Wellen’s Syndrome





Deep, symmetric or biphasic T wave inversion in
anterior precordial leads (V2, V3)
Indicates significant proximal LAD stenosis
Patients may be pain free initially but at high risk of
extensive anterior wall infarct in the upcoming
days/weeks
No ST segment changes. No Q waves.
Pathophysiology: sudden occlusion of LAD 
transient anterior STEMI reperfusion  biphasic T
waves  deep inverted T waves
3 - $100

This condition produces a characteristic chest
pain that is pleuritic in nature, worse with lying
flat, relieved with sitting forward and often is
associated with a viral infection.

What is pericarditis?
Pericarditis

ECG changes:
–
–
–
–
–


Diffuse concave ST segment elevation
Diffuse PR depression
Sinus tachycardia
Reciprocal changes in AVR
Progresses N ST segments + flat T waves T waves inverted (3+
weeks)  ECG normal
Etiology: infectious (viral –coxsackie), immunological (SLE),
uremia, post-MI, trauma, post-cardiac surgery, drug related,
post radiotherapy, paraneoplastic syndromes
Management: treat underlying
– NSAID + colchicine
– Glucocorticoids if refractory, autoimmune, connective tissue d/o,
uremia not responding to dialysis, contraindications to NSAIDs
– If associated effusion +/- drainage
3 - $200

This ECG belong to an individual with retro sternal
chest pressure, SOB and a history of smoking.

What is anterior STEMI?
3 - $300

These drugs should be used with caution in
patients presenting with inferior STEMI.

What is drugs that affect preload e.g. nitrates,
morphine?
Inferior STEMI
More favorable prognosis than anterior STEMIs
 40% have right ventricular infarction  GET right
sided leads

– Concern about posterior STEMI in ALL inferior and lateral
STEMIs  OBTAIN 15 lead ECG

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20% associated with bradyarrhythymias
Most common etiology RCA (80%), left circumflex
(20%)
ECG: ST elevation in II, III and AVF, reciprocal
changes in aVL
DO NOT MISS!

ST elevation in aVR with diffuse ST
depression indicates left main disease, triple
vessel disease or proximal LAD occlusion
STEMI Management

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ABCs, cardiac monitoring
Oxygen if O2 sats < 90%
Reperfusion
– PCI: <90 minutes
– Fibrinolytics
Anti-platelet:
– ASA
– Clopidogrel (if fibrinolytic candidate)
– Ticagrelor (if PCI)
Anti-coagulant: Heparin
Nitrates: 3 SL then IV. Caution if preload dependent
Morphine: caution as can increase mortality
B-blockers: caution in heart failure, low CO, high risk of cardiogenic
shock, bradycardia, reactive airway disease
Statins: as early as possible
3 - $400

These criteria are useful in differentiating a LBBB
from an acute myocardial infarction.

What are the sgarbossa criteria?
4 - $100

This is the textbook ECG finding for pulmonary
embolism even though the most common finding
is sinus tachycardia.

What is S1, Q3, T3 pattern?
Pulmonary embolism
Findings on ECG not sensitive, non-specific
 DDX: any cause of acute/chronic cor pulmonale:
– Acute: pneumonia, COPDAE, pneumothorax, recent
pneumonectomy
– Chronic: COPD, CF, ILD, OSA, recurrent small PEs
 ECG findings:
– #1 sinus tachycardia
– RBBB
– Right ventricular strain pattern, RAD
– Right atrial enlargement
– S1Q3T3
– T wave inversions in inferior leads

4 - $200

The phenomenon of electrical alternans produced
by the heart swinging (QRS height varies from
beat to beat) and low voltage on an ECG can be
indicative of this condition that may require a tap?

What is severe pericardial effusion and cardiac
tamponade?
4 - $300

A patient presents with the following rhythm strip to
the ED after being prescribed levofloxacin. Translated
this conditions means twisting of the spikes.

What is Torsades de pointes? (Secondary to
Prolonged QT)
Prolonged QT



Symptoms:
– Most episodes revert spontaneously to sinus rhythm
– Palpitations, dizziness, syncope, sudden cardiac death
Pathophysiology: prolonged repolarization gives rise to early after
depolarizations  PVCs  If PVC occurs in preceding T wave = R on T
phenomenon  Torsade's de Pointes  VF
Etiology:
–
–
–
–

Drugs: anti-psychotics, tramadol, abx, type I anti-arrhythmic
Metabolic (low Mg, Low K, low Ca)
Congenital prolonged QT syndromes
Increased ICP
Management:
–
–
–
–
Treat underlying + stop offending agent
Replace electrolytes
MgS04 +/- antiarrhythmic drugs
Overdrive pacing, defibrillation
5 - $100
This ECG demonstrates a common pattern that is useful for
DDX VT versus SVT with aberrancy.

What is fusion beat?
VT versus SVT with aberrancy
– Features that suggest VT
 Absence of RBBB/LBBB
 Extreme axis deviation
 Broad complexes >160ms
 Capture beats
 Fusion beats
 RSR’ complex with taller left rabbit ear
 AV dissociation
– Clinical history that increases likelihood of VT
 Age >35
 Structural heart disease
 IHD
 Previous MI
 CHF
 Family history of sudden death
5 - $200

This medication can be used as an antidote to
treat most beta-blocker overdoses.

What is glucagon *?
Beta-Blocker Overdose





**Propranolol causes sodium channel blockage QRS widens 
Give NaHCO3
**Sotalol causes K efflux blockage  Long QT  TdP
S/S: heart failure, bronchospasm, hyperK, hypoglycemia, coma,
seizure
ECG findings: bradycardia, heart block,
Management:
– Fluid, B-agonists, Vasopressors
– Atropine, Pacing
– Antidotes:
 Glucagon
 High dose insulin
 Intralipid if refractory
5 - $300
This ECG strip has a characteristic T wave
pattern of an acute metabolic disturbance.
 Bonus: What are the treatment options?


What is treatment of hyperkalemia?
Hyperkalemia
Pathophysiology: high K+ > 5.5 levels decrease myocardial excitability
 Etiology:
– renal failure, dialysis,
– Drugs: ACEI, K sparing diuretics, K+ supplements, NSAIDS, digoxin toxicity,
succinylcholine
– Release from cells (Rhabdo, burns, hemolysis, shifts – acidosis/low insulin/bblockers
 ECG findings: peaked T waves (symmetrical),
– P wave widens, PR segment lengthens  P waves eventually disappear
– QRS prolonged, sinus bradycardia, conduction blocks
– Sine wave (LATE)
 Treatment:
– Calcium gluconate
– Temporary Measures
 Insulin, Salbutamol
– Elimination
 Hemodialysis, Kayexalate, Loop diuretics

Final Jeopardy

This traditional Newfoundland musical
instrument (featured in the picture) is fashioned
out of household and toolshed items.

What is the ugly stick?