Cardiac Rhythms

Normal Sinus Rhythm (NSR)

60-100 bpm

Normal P wave, QRS, PR interval

Sinus Bradycardia

< 60 bpm (normal in atheltes)

Signs:  Hypotension, pale/cool skin, weakness, angina, SOB, confusion, dizziness or syncope (from reduced cerebral perfusion).

Administer IV Atropine. Pacemaker, dopamine, or epinephrine infusion if needed.

Sinus Tachycardia

101 to 180 bpm

Signs: Dizziness, dyspnea, hypotension, angina in patients with CAD.

β-blockers, adenosine, calcium channel blockers

Premature Atrial Contraction (PAC)

Contraction starting from an ectopic focus in the atrium (location other than SA node)

Distorted P wave.

Signs: Palpitations (awareness of weird heartbeat), heart "skips a beat".

Paroxysmal Supraventricular Tachycardia (PSVT)

151 to 220 bpm

a PAC triggers a run of repeated premature beats. "Paroxysmal" indicates abrupt onset and termination.

Signs: Palpitations, dyspnea, angina, hypotension.

IV Adenosine, IV β-blockers, Calcium channel blockers

Atrial Flutter

Atrial Rate: 200 to 350 bpm

Symptoms result from high ventricular rate and loss of atrial "kick"

Atrial Fibrillation (AFib)

Atrial Rate: 350-600 bpm with chaotic, fibrillatory waves replacing P waves

amiodarone. ECG, anticoag., ablation, Left atrial Appendage Occlussion (prevents clots)

Junctional Dysrhythmias

AV node becomes the pacemaker when the SA node fails to fire or the impulse is blocked

Serves as a safety escape mechanism—do not suppress escape rhythms. Treat if symptomatic (Atropine for escape rhythm)

First-Degree AV Block

Prolonged PR interval; associated with aging, disease states, and certain drugs.

Usually not serious and patients are asymptomatic. No immediate treatment required.

Second-Degree AV Block, Type 1 (Mobitz I / Wenckebach)

Progressive lengthening of PR interval until a QRS complex is dropped

Treat if symptomatic with Atropine or temporary pacemaker. If asymptomatic, observe closely.

Second-Degree AV Block, Type 2 (Mobitz II)

Constant PR interval with non-conducted P waves (dropped QRS complexes).

Requires transcutaneous pacing or temporary/permanent pacemaker.

Third-Degree AV Block (Complete Heart Block)

No impulses conducted from atria to ventricles. Results in severe bradycardia, decreased CO, ischemia, HF, shock, and syncope.

Pacemaker therapy is required. Drugs (epinephrine/dopamine) to increase HR while awaiting pacing.

Premature Ventricular Contractions (PVCs)

Premature, wide, and distorted QRS complex

Administer β-blockers, lidocaine, or amiodarone if needed.

Accelerated Idioventricular Rhythm (AIVR)

Develops when intrinsic pacemaker rate (SA/AV node) falls below rate of ventricular ectopic pacer. Rate is 40 to 100 beats/min.

Do NOT suppress the rhythm. Administer Atropine if patient is symptomatic, or use temporary pacing.

Ventricular Tachycardia (VT)

Ectopic focus takes over as pacer. Life-threatening due to severe decrease in CO and risk of deterioration to VF.

Causes: Heart disease, long QT syndrome, electrolyte imbalances, drug toxicity, CNS disorders, hypoxia.

VT with Pulse

(Stable): Antidysrhythmics (amiodarone) or synchronized cardioversion.

Polymorphic VT with prolonged QT

(Torsades de Pointes): IV Magnesium, isoproterenol, or antitachycardia pacing.

Pulseless VT

Emergency CPR and rapid defibrillation.

Ventricular Fibrillation (VF)

Severe, chaotic electrical activity with no effective ventricular contraction or CO. Pt is unresponsive, pulseless, and apneic. Fatal within minutes if untreated.

Immediate high-quality CPR, ACLS measures, rapid defibrillation, and epinephrine/amiodarone.

Asystole & Pulseless Electrical Activity (PEA)

Asystole: Total absence of ventricular electrical activity

PEA: Electrical activity is observed on ECG, but no pulse.

High-quality CPR, ACLS measures, intubation, IV Epinephrine. Defibrillation is NOT indicated for Asystole/PEA.