ECG InterpretationECG Interpretation

Arrhythmias of Arrhythmias of FormationFormation

Chapters 4-5Chapters 4-5

Types of Arryhthmias:Types of Arryhthmias:Sinus Problems: Formed in the sinus

node, but irregularEctopic Problems: Formed outside

of the sinus nodeConduction Problems: Formed in the

sinus node, but conduction in errorPre-Excitation Problems: “Short

circuits” in normal conduction

Causes of Arrhytmias: Causes of Arrhytmias: Hypoxia: Lung disease Ischemia: CAD, angina (local hypoxia) Sympathetic Stimulation: Nervous,

exercise, CHF, hyperthyroidism Drugs: Caffeine, cocaine, stimulants…many

antiarryhtmic drugs… Electrolyte Disturbances: K+, Ca++, Mg++

Bradycardia: “Escape” rhythms… Stretch: CHF, hypertrophy, valve disease

Rhythm ID: AlgorithmRhythm ID: Algorithm

P-Wave: rate and rhythmQRS: rate and rhythm - shapeP-R Interval: Is AV conduction

normal? P:QRS regular?T Wave and QT IntervalAny unusual complexes?IS IT DANGEROUS?

Clinical Manifestations:Clinical Manifestations:Asymptomatic – generally benignPalpitations – Awareness may

cause anxietyCompromised CO – SyncopeMyocardial Ischemia – tachyCHF – Chronic insufficiency Sudden Death – Cardiac arrest

Define “Normal”Define “Normal”Regular Atrial and Ventricular

Rhythms: 1P : 1 QRSRates: 60-100P Morphology: small, round, regular

and positive in Lead IIQRS Morph: Similar size and shapePositive T waves in Lead II

P-Wave: P-Wave: 1.SA Node “fires” 2. Right and Left

Atria Depolarize 3. AV Node

“pauses” Questions:

P waves present?

Regular rhythm?

1/QRS?

SA Node

LA/RADepol

AV Node

Sinus RhythmsSinus RhythmsNormal Sinus Rhythm:

1P/QRS: 60-100 bpmSinus brady: 1P/QRS: <60 bpmSinus tachy: 1P/QRS: >100 bpmSinus Arrhythmia: 1P/QRS

Normal Irregularities caused by inspiration/expiration – more noticeable in children / elderly

ABSENT PQRS Complex: ABSENT PQRS Complex: Sinus Arrest: Sinus Arrest: Causes:

Heart disease, acute infection, VAGAL stimulation (Bush’s Pretzel Problem?)

Sick Sinus Syndrome: Usually in elderly – more irregular

DANGER?Rare and asymptomaticFrequent and symptomatic

Atrial Arrhythmias: Atrial Arrhythmias:

PAC: Premature Atrial Contraction

Atrial Tachycardias: SVT – with or without blocks, PAT

Atrial Flutter:Atrial Fibrillation

Premature Atrial Contractions:Ectopic Triggered by: Alcohol, nicotine,

anxiety, fatigue, fever, and infections

Usually benignClinical Manifestations:

Palpitations or “skipped beats”

PAC - ID:PAC - ID:

Irregular P-R rhythmsPremature, irregular P waves

(sometimes “lost” in the T wave)

Atrial Tachycardias:Atrial Tachycardias:Also: Supra Ventricular Tachycardia

(PSVT)Rates: 100-250 bpmRegular Rhythms“Hidden” P waves (could be inverted

– indicating a Junctional focus PSVT)PAT = Common in warm-up/cool down

and doesn’t respond to Carotid Massage (don’t try this!)

Afib – Aflut…Afib – Aflut…

Atrial Fibrillation: Atrial Fib and/or PSVT?

Atrial Flutter: 2:1 Ventricular “capture”Ventricles can only respond to every other Atrial conduction

Fibrillation vs. Flutter?Fibrillation vs. Flutter?Multi-focal

origins -chaoticRate: >400 bpm IRREGULAR-RAtrial Cardiac

Output is lost :

One focus - organized

Rate: 200-400 bpm

Atrial Cardiac Output is compromised

Atria contribute ~20% of the totalCardiac output: A-Fib is non-lethal

Summarize: Sinus and Atrial Summarize: Sinus and Atrial RhythmsRhythms

Sinus: Normal, Tachy, BradyAbsent P: Sinus Arrest, A-fib,

Junctional (PSVT), PATWeird P: A-Flut, PAC

Formation ArrhythmiasFormation Arrhythmias

Junctional and Junctional and Ventricular Ventricular

Chapters 6-7Chapters 6-7

Junctional:Junctional:Form in the AV (Junction) NodeMay be an “Escape” rescue if SA

node fails to fire or conductEscape Rate ~40-60 bpm

May be an “Ectopic” Irritable FocusEctopic Rate ~ 60-100 bpm

Responds to vagal stimulus P Waves inverted, missing or after

the QRS

Ventricles: QRS RhythmsVentricles: QRS RhythmsRegular rhythms?

R-R intervals equivalentRegular “irregular” rhythms?

R-R intervals equivalent with occasional irregularities

Irregular rhythms?R-R intervals irregular

Regular “Irregular”Regular “Irregular”Premature Beats: PVC

Widened QRS, not associated with preceding P wave

Usually does not disrupt P-wave regularity

T wave is “inverted” after PVCOften Followed by

compensatory ventricular pause

Notice a Pattern in the PVC’s?

PVC Patterns:PVC Patterns:PVC: 1 Isolated beatCouplet: 2 consecutive PVC’sBigeminy: PVC every other

beatNon-Sustained VT: >3 beats

for less than 1 minuteSustained VT: > 1 minute of

ventricular tachycardia

Irregular Ventricular Irregular Ventricular Rhythms: CHAOTICRhythms: CHAOTICVentricular Fibrillation:

Multi-focal originsIrregular wave morphologiesCardiac Output = 0Coarse vs. Fine V-Fib

Clinical Manifestations – Clinical Manifestations – PVC’sPVC’s Often benign

BUT Compromised

CO Possibly

precipitate a lethal arrhythmia: Vtach, VFib

More on PVC’sMore on PVC’sCardiac Output: Pulse deficit =

reduced CO (~20%)One PVC usually asymptomaticSymptoms: LOC or dizziness

demand treatment Risk of Lethal Arrhythmias:

V-Tach more dangerous in CAD

Rules of Malignancy: Rules of Malignancy:

Frequency: > 6 / minuteRuns: 3+ consecutiveMultiform“R on T”PVC’s during MI

What is the threat of What is the threat of sustained Ventricular sustained Ventricular Tachycardia?Tachycardia? 1. What happens to diastole? 2. What happens to Cardiac Output? 3. What happens to myocardial perfusion? 4. What happens to myocardial VO2?

Winslow Homer: “The Stile”