Intro to ECGs

8/16/2019 Intro to ECGs

1/63

An early Electrocardiograph


2/63

Einthoven’s first publishedEKG, 1902


3/63

“I do not however imagine that the

string galvanometer…is likely to

find any very extensive use in thehospital”

August D. Waller, 1909


4/63

The Electrocardiogram

(ECG/EKG)Most Commonly Utilized

Cardiovascular Lab Test100 Million Performed per Year$5 Billion Cost per YearReimbursements have droppedKey to Therapy for ACS/MI

Diagnosis of Arrhythmias


5/63

Indications For An ECGChest or EpigastricPain or Sensation

CHF Signs orSymptoms Abnormal PulseHypotensionUnexplainedWeakness

Altered Mental State(Coma, CVA)

Drug OverdoseChest TraumaSyncope or NearSyncopeSystemic IllnessMetabolic Disease

Screening??


6/63

P’s and Q’s of

Electrocardiography

Atrial

Depolarization

Ventricular

Depolarization

Ventricular

Repolarization

http://medstat.med.utah.edu


7/63RL/LL- side does not matter, place anywhere below umbilicus


8/63

The Electrocardiogram

(ECG/EKG)

Rhythms

ST Segments


9/63


10/63


11/63


12/63


13/63


14/63


15/63

LAD 95%

1


16/63

LAD 95%

1


17/63

1

LAD 95%


18/63

1


19/63

1

LAD 0%

Post PCI


20/63

Basic Principles of ECGInterpretation

Place electrodes correctly (??)Be Careful to Get Correct DataConsider Clinical Context/SettingChest pain? … consider ST segments

Compare to Previous ECGBe Systematic

Rate, Rhythm, ?Pacemaker SpikesQRS duration, Other intervals AxisQ waves

Pattern read


21/63

QRS Prolongation (=>120msec, 3 40 msec boxes)

Ventricular OriginPVCsVentricular TachycardiaVentricular Electronic Pacemaker

SVT with Aberrant ConductionBundle Branch Block

Right (rabbit ears on the right)Left (rabbit ears on the left)

WPW

IntraVentricular Conduction Delay


22/63

Why is QRS Prolongation so

important except for RBBB??? Q waves not diagnostic

ST Depression not diagnostic

Possibly Ventricular Origin

Usually High Risk


23/63

.000

.250

.500

.750

.000

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.

1 (130ms): N=61 (6.6%)

Follow-up (yrs)

S u r v i v

a l


24/63


25/63

Rabbit Ears

InvertedTwave


26/63


27/63

RBBB


28/63

LBBB


29/63

Rabbit Ears

InvertedTwave


30/63

IVCD


31/63

WPW


32/63

WPW


33/63


34/63

RAD


35/63

LAD


36/63

S1S2S3


37/63

Criteria For Infarction Q

WavesEqual or Greater than .04 seconds (onemillimeter box horizontal width, 40

milliseconds)

Q Wave Amplitude must be 25% or

greater of following R Wave

Pathophysiology: no muscle to generateR wave


38/63


39/63


40/63

Basic Principles of ECGInterpretation

Place electrodes correctly (??)Be Careful to Get Correct DataConsider Clinical Context/Setting

Chest pain? … consider ST segments Compare to Previous ECGBe Systematic

Rate, Rhythm, ?Pacemaker SpikesQRS duration, Other intervals AxisQ waves

Pattern read


41/63

inverted

Qw, P/Tup ordown

Rightventricularinvolvement:RVH, RBBB

Left ventricularinvolvement:LVH, LBBB


42/63

Pattern Reading of the ECG

Diagonal Line Rulebox around aVR (everything inverted)

line thru III, aVL, V1every thing else upright

Parallel Line RuleR waves increase then drop off in V6S waves decrease from greatest in V1Rabbit ears on right side (V1-2) for RBBB,

on left side for LBBB

Th 5 C d f ECG


43/63

The 5 Commandments of ECGInterpretation

• Be systematic

• Put into the clinical context

• Find an old ECG

• Watch out for bad data

– Strive for good data

• Do NOT be afraid to get help

Watch out for bad

data


44/63


45/63

RA/LA reversed

V1/V3 reversed


46/63

What happened?


47/63


48/63

Intervals, segments, and durations


49/63

Intervals

QRS durationPR interval QT IntervalNormal: .12-.20 sec

(3-5 small boxes)

Normal: .07-

.10 sec

Normal (corrected for

rate or QTc): .440-.470sec

• QT Interval

• PR Interval

• QRS Duration


50/63

Intervals: Conduction

System AbnormalitiesCongenital Syndromes

Electrolyte/Metabolic AbnormalitiesIntrinsic Cardiac DiseaseMedicationsCNS Disorders

Systemic Illnesses


51/63

Electrolyte Abnormalities and

the ECGPotassiumHyper: tall, peaked T waves (also

ischemia), atrial arrestHypo: prominent U waves, low T wave

CalciumHyper: short QT

Hypo: long QT (also Quinidine, ischemia)MagnesiumHyper: short QT interval

Hypo: long QT interval


52/63

L QT i t l


53/63

Long QT intervals(>50% of the RR interval)

• Congenital

HypoMg/CA

anti-arrhythmics

Myocarditis

Hypokalemia

Ischemia

Phenothiazines

Tricyclics

CNS--SubarachnoidHemorrhage

Torsades des Pointes

The QT interval


54/63

The QT intervalLong QT (>50% of the RR interval) CongenitalHypomagnesiumHypocalcemiaIA anti-arrhythmicsIschemiaTorsades de Pointes

PhenothiazinesTricyclicsMyocarditisHypokalemia

Short QT Hypercalcemia

HypermagnesiumHyperkalemiaDigoxinThyrotoxicosis


55/63


56/63


57/63

Other Patterns

• Atrial Abnormalities

• R>S V1

http://medstat.med.utah.edu


58/63

SANode


59/63

Atrial AbnormalitiesRight (P-pulmonale)Right atrium right heart border, first hump

tall, peaked in inferior leads (>2.5mm)

Left (P-mitrale)Left atrium posterior, second hump

broad P wave (>120msec) with negativecomponent in V1-2 (> 1mm x 1mm)

Normal=2.5x2.5 boxes (100msec x .25Mv)


60/63

P pulmonale or

RAA


61/63

P mitrale or LAA

Computerized LAA with/without P wave prolongation


62/63

0.0

0.2

0.4

0.6

0.8

1.0

0.0 2.0 4.0 6.0 8.0 10.0

a. LAA (-), P duration 120ms n=4,476 (2.0%)

c. LAA (+), P duration 120ms n=407 (4.7%)

p p g

S u

r v i v a l

Years Follow up


63/63

R>S V1RVH

RBBBInferior Posterior MIWPWNormal Variant

Intro to ECGs

Documents

Transcript of Intro to ECGs