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

2. 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

3. 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

4. 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?

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

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

7. 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

8. 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

9. 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

10. Atrial Arrhythmias: PAC: Premature Atrial Contraction
Atrial Tachycardias: SVT – with or without blocks, PAT
Atrial Flutter:
Atrial Fibrillation

11. Premature Atrial Contractions:
Ectopic
Triggered by: Alcohol, nicotine, anxiety, fatigue, fever, and infections
Usually benign
Clinical Manifestations: Palpitations or “skipped beats”

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

13. Atrial Tachycardias: Also: Supra Ventricular Tachycardia (PSVT)
Rates: 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!)

14. Afib – Aflut…

15. Atrial Fibrillation: Atrial Fib and/or
PSVT?

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

17. Fibrillation vs. Flutter?
One focus - organized
Rate: 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

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

19. Formation Arrhythmias
Junctional and Ventricular
Chapters 6-7

20. 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 ~ bpm
Responds to vagal stimulus
P Waves inverted, missing or after the QRS

21. 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

22. 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

23. Notice a Pattern in the PVC’s?

24. 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

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

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

27. 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

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

29. 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?

30. Winslow Homer: “The Stile”