Dysrhythmias

Dysrhythmia Types:

• Bradycardia
• Tachycardia
• Supraventricular arrhythmias
• Ventricular arrhythmias
• Heart block

Brady- 

impaired or delayed electrical impulse (SA node or CNS activation); <60bpm

100bpm (unstable >150bpm)

• Coronary artery disease
• Aging
• Respiratory (pediatrics)
• Cardiac defects
• Drugs (beta/calcium channel blockers, digoxin, clonidine)

Causes:

• Coronary artery disease
• Aging
• Respiratory (pediatrics)
• Cardiac defects
• Drugs (beta/calcium channel blockers, digoxin, clonidine)

Presentation:

• Hypotensive
• Altered mental status
• Shock
• Chest pain
• Acute heart failure

Interventions:

• Fix cause
• Asymptomatic – observation
• Stable – Atropine, IV fluids
• Unstable – dopamine/epinephrine infusion, transcutaneous pacing

Tachy-

100bpm (unstable >150bpm)

Causes:

• Acute pain, fever, activity
• Coronary artery disease
• Cardiac defects
• Electrolyte imbalances
• Excessive drug use/overdose

Presentation:

• Anxiety, diaphoresis
• Palpitations, chest discomfort § Shortness of breath
• Dizziness, syncope
• Hypotension, shock
• Loss of vital signs
• Mental status changes

Interventions:

• Fix cause
• Stable – amiodarone
• Unstable
  • Cardioversion (sedation)
    • Regular – 50-100j biphasic
    • Irregular – 120-200j biphasic
• Pulseless – defib, CPR, epi q3-5 minutes, amiodarone
• Cardiac workup, electrophysiology consult, cath lab, surgery (cardioverter defibrillator, pacemaker)

Supraventricular-

An abnormally fast heart rhythm due to improper electrical activity in the upper part of the heart.

• Originate in atria
• Premature atrial contractions (PACs)
• Paroxysmal supraventricular tachycardia (PSVT)
• Wolff-Parkinson-White
  • Fast heart rate because of extra (abnormal) pathway between the atria and ventricles
  • Presence of delta-wave
• Atrial fibrillation (quivering)
  • Lack of coordinated atrial activity
  • Rapid ventricular response (RVR) – ventricular rate above 100bpm
• Atrial flutter
  • One or more rapid circuits in the atrium
  • organized and regular rhythm
  • Sawtooth

Causes:

• Conduction abnormalities
• Coronary artery disease
• Cardiac defects
• Aging
• Excessive drug use

Presentation:

• 100–250 beats/min
• Normotensive, hypotensive, or hypertensive
• Shortness of breath, dyspnea
• Palpitations, chest tightness
• Mental status changes

Interventions:

• Stable – vagal maneuvers, pharmacologic cardioversion
• Unstable – synchronized cardioversion
  • 50-200 J biphasic
  • Amiodarone

Ventricular arrhythmias-

Abnormal rapid heart rhythms that originate in the lower chambers of the heart (the ventricles)

• Electrical impulses originate in ventricles (SA node failure, ventricle-generated impulse)
• Premature ventricular contraction (PVC)
  • “Skipped” heartbeat
  • >3 PVCs in a row = VT
• Ventricular tachycardia (VT)
  • With pulse or pulseless
  • Torsades de pointes
    • Polymorphic VT
    • Variable QRS amplitude
• Ventricular fibrillation (VF) (quivering)
  • Always pulseless
  • No blood ejection from chambers

Causes:

• Blunt trauma
• Underlying conditions (e.g., prolonged QT syndrome)
• Diseased heart (e.g., heart failure, cardiomegaly, cardiac hypertrophy)
• Severely hypoxic myocardium
• Torsades is common in heavy ETOH users (they need MgSO4)
• Electrolyte disturbances (e.g., magnesium, potassium)

Presentation:

• Heart rate: 150–300 beats/min
• Palpitations, chest discomfort
• Syncope
• Dyspnea
• Hypotension
• Loss of vital signs

Interventions:

• Pulse – cardioversion, magnesium (torsades de pointes)
• Pulseless – defib, CPR, epinephrine
  • Treat underlying cause

Heart Block: Atrioventricular Block (AVB)- 

A type of heart block that occurs when the electrical signal traveling from the atria, or the upper chambers of the heart, to ventricles, or the lower chambers of the heart, is impaired.

• First degree – benign, long PR-interval
• Second degree type I (Wenckebach) – gradual prolonging PR-interval then drop (longer, longer, longer, drop; now you have a wenckebach)
• Second degree type II – consistent PR-interval before blocked P wave
• Third degree – no coordination between atria and ventricle
  • P-P waves equal, QRS-QRS waves equal

Causes:

• Aging
• Coronary artery disease
• Drug overdose

Interventions:

• Atropine for low degree
• Transcutaneous pacing for high degree
• Treat underlying cause

Linchpins: (Key Points)

Electrical malfunction of the heart

• Bradycardia – slow
• Tachycardia – fast
• Supraventricular arrhythmias – up
• Ventricular arrhythmias – down
• Heart block – delayed/blocked