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ACLS Rhythms and Interpretation

Please purchase the course before starting the lesson.

STEP 1: RECAP THE PQRST PROPERTIES

PROTOTYPICAL ECG TRACING
P-wave Electrical activity is traveling through the atria.
Synonymous with atrial depolarization.
Reflects atrial contraction.
QRS
Complex
Electrical activity is traveling through the ventricles.
Depolarization of the left and right ventricles.
Reflects ventricular contraction.
T-wave Synonymous with ventricular repolarization.
Reflects the start of ventricular relaxation.
PR Interval Onset of the P-wave to the start of the QRS complex.
Reflects conduction through the atrioventricular (AV) node.
PR Segment End of the P-wave to the start of the QRS complex.
Reflects time delay between atrial and ventricular activation.
ST Segment End of the S-wave (J point) to the start of the T-wave.
Reflects ventricular repolarization.
QT Interval Onset of the QRS complex to the end of the T-wave.
Reflects the period between ventricular depolarization and ventric-
ular repolarization.

STEP 2: IDENTIFY THE COMMON CATEGORIES OF ACLS RHYTHMS WITH A FEW EXAMPLES

Sinus rhythms:

  • Normal sinus rhythm (NSR)
  • Sinus bradycardia
  • Sinus tachycardia

Bradyarrhythmias:

  • 1st degree AV block (pulseless VT)
  • 2nd degree AV block Type I (Mobitz Type I, Wenckebach’s)
  • 2nd degree AV block Type II (Mobitz Type II)
  • 3rd degree AV block (complete heart block, CHB)

Tachyarrhythmias:

  • Supraventricular tachycardia (SVT)
  • Atrial flutter
  • Atrial fibrillation (aFib)
  • Wide-complex tachycardias Tachyarrhythmias:

Pulseless rhythms:

  • Pulseless ventricular tachycardia (pulseless VT)
  • Ventricular fibrillation (vFib)
  • Pulseless electrical activity (PEA)
  • Asystole

STEP 3: IDENTIFY THE MOST COMMON ACLS RHYTHMS

Normal Sinus Rhythm (NSR)

  • Normal P-wave
  • Normal QRS Complex
  • Normal T-wave
  • HR: 60-100 BPM (at rest)
  • Treatment: n/a

Normal Sinus Rhythm (NSR)

Sinus Bradycardia

  • Normal P-wave
  • Normal QRS Complex
  • Normal T-wave
  • HR: <60 BPM (at rest)
  • Tx: Atropine, Dopamine (infusion), Epinephrine (infusion)

Sinus Bradycardia

Sinus Tachycardia

  • Normal P-wave
  • Normal QRS Complex
  • Normal T-wave
  • HR: >100 BPM (at rest)
  • Tx: Treat the potential or primary cause of this rhythm, such as fever, anxiety,
    exercise, etc., and/ or use beta-blockers (Metoprolol or Sotalol).

Sinus Tachycardia

1st degree AV block

  • Prolonged PR interval due to delay in AV signal transmission
  • P-wave may be buried in the preceding T-wave
  • Tx: n/a

1st degree AV block

2nd degree AV block Type I (Mobitz Type I, Wenckebach’s)

  • Progressive lengthening of the PR interval
  • Progression occurs until the QRS complex is dropped
  • Tx: Atropine, Dopamine, Transcutaneous pacing

2nd degree AV block Type I (Mobitz Type I, Wenckebach’s)

2nd degree AV block Type II (Mobitz Type II)

  • Intermittent drop of QRS complex that is not in a 2nd degree AV block Type I
    pattern

2nd degree AV block Type II (Mobitz Type II)

3rd degree AV block (complete heart block, CHB)

  • No identifiable relationship between the P-wave and QRS waves
  • P-P intervals are normal but do not relate to the QRS complex
  • Tx: Transcutaneous pacing

3rd degree AV block (complete heart block, CHB)

Supraventricular Tachycardia (SVT)

  • Profoundly rapid atrial rhythm with narrow QRS complexes
  • Occurs when the signal impulse originates over the bundle branches
  • HR: 150-250 BPM
  • Tx: Vagal maneuvers, Adenosine, synchronized cardioversion

Supraventricular Tachycardia (SVT)

Atrial Fibrillation (aFib)

  • Common arrhythmia
  • Uniquely characterized by an absence of P-waves before the QRS complex
  • HR: Highly irregular with significant fluctuation
  • Tx: beta-blockers (Metoprolol, Sotalol, etc.), Ca++ channel blockers
    (Diltiazem, Verapamil, etc.), Digoxin, synchronized cardioversion.

Atrial Fibrillation (aFib)

Atrial Flutter

  • Supraventricular arrhythmia
  • Uniquely characterized by a saw-toothed flutter appearance
  • Toothed fluttering represents multiple P-waves for a single QRS complex
  • Tx: synchronized cardioversion, beta-blockers (Metoprolol, Sotalol, etc.),
    Ca++ channel blockers

Atrial Flutter

Ventricular Tachycardia (vTach)

  • Abnormally-patterned wide QRS complex
  • No P-waves
  • High likelihood of rapid deterioration to a state of ventricular fibrillation
    (vFib)
  • Often responsive to electrical defibrillation
  • HR: >100 BPM

Ventricular Tachycardia (vTach)

Pulseless Ventricular Fibrillation (vFib)

  • Characterized by a chaotic wave pattern
  • Patient has no palpable pulse
  • Often responsive to electrical defibrillation
  • Tx: Defibrillation, epinephrine, amiodarone, lidocaine HCl

Pulseless Ventricular Fibrillation (vFib)

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