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

Sinus Bradycardia

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

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).

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

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 II (Mobitz Type II)

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

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

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

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 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

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

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