Arrhythmias of Formation Chapters 4-5 ECG Interpretation Arrhythmias of Formation Chapters 4-5

Types of Arryhthmias: Sinus Problems: Formed in the sinus node, but irregular Ectopic Problems: Formed outside of the sinus node Conduction Problems: Formed in the sinus node, but conduction in error Pre-Excitation Problems: “Short circuits” in normal conduction

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: Algorithm P-Wave: rate and rhythm QRS: rate and rhythm - shape P-R Interval: Is AV conduction normal? P:QRS regular? T Wave and QT Interval Any unusual complexes? IS IT DANGEROUS?

Clinical Manifestations: Asymptomatic – generally benign Palpitations – Awareness may cause anxiety Compromised CO – Syncope Myocardial Ischemia – tachy CHF – Chronic insufficiency Sudden Death – Cardiac arrest

Define “Normal” Regular Atrial and Ventricular Rhythms: 1P : 1 QRS Rates: 60-100 P Morphology: small, round, regular and positive in Lead II QRS Morph: Similar size and shape Positive T waves in Lead II

P-Wave: 1/QRS? 1.SA Node “fires” 2. Right and Left Atria Depolarize 3. AV Node “pauses” Questions: P waves present? Regular rhythm? 1/QRS? AV Node SA Node LA/RA Depol

Sinus Rhythms Normal Sinus Rhythm: 1P/QRS: 60-100 bpm Sinus brady: 1P/QRS: <60 bpm Sinus tachy: 1P/QRS: >100 bpm Sinus Arrhythmia: 1P/QRS Normal Irregularities caused by inspiration/expiration – more noticeable in children / elderly

ABSENT PQRS Complex: Sinus Arrest: Causes: Heart disease, acute infection, VAGAL stimulation (Bush’s Pretzel Problem?) Sick Sinus Syndrome: Usually in elderly – more irregular DANGER? Rare and asymptomatic Frequent and symptomatic

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 benign Clinical Manifestations: Palpitations or “skipped beats”

PAC - ID: Irregular P-R rhythms Premature, irregular P waves (sometimes “lost” in the T wave)

Atrial Tachycardias: Also: Supra Ventricular Tachycardia (PSVT) Rates: 100-250 bpm Regular 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…

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? One focus - organized Rate: 200-400 bpm Atrial Cardiac Output is compromised Multi-focal origins -chaotic Rate: >400 bpm IRREGULAR-R Atrial Cardiac Output is lost : Atria contribute ~20% of the total Cardiac output: A-Fib is non-lethal

Summarize: Sinus and Atrial Rhythms Sinus: Normal, Tachy, Brady Absent P: Sinus Arrest, A-fib, Junctional (PSVT), PAT Weird P: A-Flut, PAC

Formation Arrhythmias Junctional and Ventricular Chapters 6-7

Junctional: Form in the AV (Junction) Node May be an “Escape” rescue if SA node fails to fire or conduct Escape Rate ~40-60 bpm May be an “Ectopic” Irritable Focus Ectopic Rate ~ 60-100 bpm Responds to vagal stimulus P Waves inverted, missing or after the QRS

Ventricles: QRS Rhythms Regular rhythms? R-R intervals equivalent Regular “irregular” rhythms? R-R intervals equivalent with occasional irregularities Irregular rhythms? R-R intervals 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 PVC Often Followed by compensatory ventricular pause

Notice a Pattern in the PVC’s?

PVC Patterns: PVC: 1 Isolated beat Couplet: 2 consecutive PVC’s Bigeminy: PVC every other beat Non-Sustained VT: >3 beats for less than 1 minute Sustained VT: > 1 minute of ventricular tachycardia

Irregular Ventricular Rhythms: CHAOTIC Ventricular Fibrillation: Multi-focal origins Irregular wave morphologies Cardiac Output = 0 Coarse vs. Fine V-Fib

Clinical Manifestations – PVC’s Often benign BUT Compromised CO Possibly precipitate a lethal arrhythmia: Vtach, VFib

More on PVC’s Cardiac Output: Pulse deficit = reduced CO (~20%) One PVC usually asymptomatic Symptoms: LOC or dizziness demand treatment Risk of Lethal Arrhythmias: V-Tach more dangerous in CAD

Rules of Malignancy: Frequency: > 6 / minute Runs: 3+ consecutive Multiform “R on T” PVC’s during MI

What is the threat of sustained Ventricular Tachycardia. 1 What is the threat of sustained Ventricular 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”