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Tachydysrhythmias, Emergency Medicine

Basics

Description

- Torsades de pointes: - Paroxysmal form of VT with undulating axis and prolonged baseline QT interval - Secondary to either congenital or acquired abnormalities of ventricular repolarization - Often the result of drug therapy or electrolyte disturbances

- VF: - Oscillations without evidence of discrete QRST morphology - Accounts for 80 " 85% of sudden cardiac deaths - Frequently results from degeneration of sustained VT

- Atrial tachycardia: - Precipitated by a premature atrial or ventricular contraction - Electrolyte disturbances - Drug toxicity - Hypoxia

- Torsades de pointes: - Drug toxicity (antiarrhythmic class IA and III agents, antipsychotics, antibiotics, etc.) - Hypokalemia - Hypomagnesemia - Congenital QT prolongation

- VF: - Acute MI (most common) - Chronic ischemic heart disease - Hypoxia - Acidosis - Anaphylaxis - Electrocution - Shock - Hypokalemia - Initiation of quinidine therapy - Massive hemorrhage

  • Any disturbance of the hearts rhythm resulting in a rate >100 bpm
  • Sinus tachycardia:Narrow complex regular rhythm at a rate of 100 " 150 bpmMax. rate typically 220 minus ageFunctional response to physiologic stress caused by increased catecholamine tone or decreased vagal stimulation
  • Supraventricular tachycardia (SVT):A narrow complex tachycardia that originates above the His bundle
  • Regular SVT:Atrial tachycardiaJunctional tachycardia:Regular tachycardia without preceding depolarization waves
  • Irregular SVT:Atrial fibrillation (AF)Atrial flutterMultifocal atrial tachycardia
  • Ventricular tachycardia (VT): ≥3 consecutive ventricular ectopic beats at a rate of 100 bpmMost common initiating rhythm in sudden death in patients with previous MI
  • Torsades de pointes:Paroxysmal form of VT with undulating axis and prolonged baseline QT intervalSecondary to either congenital or acquired abnormalities of ventricular repolarizationOften the result of drug therapy or electrolyte disturbances
  • VF:Oscillations without evidence of discrete QRST morphologyAccounts for 80 " 85% of sudden cardiac deathsFrequently results from degeneration of sustained VT

Etiology

  • Sinus tachycardia:Acute MIAnemiaAnxietyCHFDrug intoxicationHyperthyroidismHypovolemiaHypoxiaInfectionPainPericardial tamponadePulmonary embolus
  • Atrial tachycardia:Precipitated by a premature atrial or ventricular contractionElectrolyte disturbancesDrug toxicityHypoxia
  • Junctional tachycardia:AV nodal re-entryMyocardial ischemiaStructural heart diseasePre-excitation syndromesDrug and alcohol toxicity
  • AF:HTNCoronary artery diseaseHyper-/HypothyroidismAlcohol intakeMitral valve diseaseChronic obstructive pulmonary diseasePulmonary embolusWolf " Parkinson " White (WPW) syndromeHypoxiaDigoxin toxicityChronic pericarditisIdiopathic AF
  • Atrial flutter:Ischemic heart diseaseValvular heart diseaseCHFMyocarditisCardiomyopathiesPulmonary embolusElectrolyte abnormalitiesRecent cardiac surgery
  • Multifocal atrial tachycardia:Hypoxic effects of chronic lung diseaseTheophylline toxicity
  • VT:Dilated cardiomyopathyCardiac ischemiaHypoxiaCardiac scarring/fibrosisAfter cardiac surgery or congenital anomaly repairDigoxin toxicityLong QT syndromeElectrolyte abnormalities
  • Torsades de pointes:Drug toxicity (antiarrhythmic class IA and III agents, antipsychotics, antibiotics, etc.)HypokalemiaHypomagnesemiaCongenital QT prolongation
  • VF:Acute MI (most common)Chronic ischemic heart diseaseHypoxiaAcidosisAnaphylaxisElectrocutionShockHypokalemiaInitiation of quinidine therapyMassive hemorrhage

Diagnosis

Signs and Symptoms

  • Asymptomatic
  • Palpitations
  • Lightheadedness
  • Dyspnea
  • Diaphoresis
  • Dizziness
  • Weakness
  • Chest discomfort
  • Angina
  • Syncope
  • Prominent neck veins
  • Signs of instability:HypotensionPulmonary edemaChest painMental status changes

History

  • Acute onset of palpitations, lightheadedness, generalized weakness, or shortness of breath
  • Sudden collapse, often preceded for minutes " hours by chest pain
  • Prior history of cardiac disease common (ischemia, CHF)

Physical Exam

Determine if the patient is hemodynamically stable:

  • Assess mental status.
  • Assess heart rate.
  • Assess BP: Normal or hypotensive
  • Cardiac exam

Essential Workup

  • ABCs
  • Determination of unstable vs. stable patient
  • Detailed history
  • 12-lead EKG and rhythm strip to categorize the tachycardia

Diagnosis Tests & Interpretation

Lab

Studies should be ordered based on the presentation to evaluate underlying metabolic abnormalities or ischemia.

Diagnostic Procedures/Surgery

EKG:

  • SVT:Narrow complex, rate usually 130 " 160Uniformity of polarity and amplitudeNo P-waves visible
  • AF:Irregular, narrow QRS complex, rate <150 " 170 bpm
  • Atrial flutter:Regular atrial rate, usually >300Beat-to-beat uniformity of cycle length, polarity, and amplitudeSawtooth flutter waves directed superiorly and most visible in leads II, III, aVFAV block usually 2:1, but occasionally greater or irregular
  • Multifocal atrial tachycardia:3 distinctly different conducted P waves with varying pulse rate intervals
  • VT:QRS >0.12 sec and often >0.14 sec.
  • Torsades de pointes:Wide complex, ventricular rate >200 bpmQRS structure displays an undulating axis, with the polarity of the complexes appearing to shift around the baseline.Occurrence is often in short episodes of <90 sec.
  • VF:EKG shows oscillations without evidence of discrete QRST morphology.Oscillations are usually irregular and occur at a rate of 150 " 300 bpm.When the amplitude of most oscillations is 1 mm, the term "coarse " is used. "Fine " VF is used for oscillations <1 mm.

Treatment

Pre-Hospital

Cardiopulmonary resuscitation if pulseless

Initial Stabilization/Therapy

  • IV access
  • Oxygen
  • Cardiac monitor
  • Determine rhythm

Ed Treatment/Procedures

  • Irregular narrow complex (A fib):Rate control ²-Blockers or calcium channel blockersAnticoagulation if onset is >24 hrCardioversion for severe hemodynamic compromise
  • Regular narrow-complex tachydysrhythmia:Vagal maneuvers occasionally terminate the dysrhythmia:Beware of carotid disease in elderly.Adenosine:May be diagnostic, revealing underlying AF/atrial flutter
  • Stable wide-complex tachycardia:Determine whether VT or SVT with aberrancyAdministration of AV nodal-blocking agents (verapamil, adenosine) may result in VF:With WPW, use amiodarone, flecainide, procainamide, or DC cardioversion.Electrical cardioversion should be utilized when mechanism unknown.Antidysrhythmic drugs include procainamide and amiodarone.
  • Torsades de pointes:Magnesium, overdrive pacing, amiodaroneCorrect underlying abnormal electrolytes.Consider repletion of serum K to 4.5.
  • Polymorphic VT (variable QRS morphology):Ejection fraction (EF) normal: ²-Blockers, lidocaine, amiodarone, or procainamideEF abnormal:Amiodarone or lidocaine; then synchronized cardioversionTreat ischemia and correct electrolytes.
  • Monomorphic VT:EF normal:Procainamide preferred to amiodarone, sotalol, lidocaine; synchronized cardioversionEF abnormal:Amiodarone or lidocaineProcainamide with caution as may cause hypotension; synchronized cardioversion
  • VF or pulseless VT:Treatment per ACLS protocol

Medication

  • Adenosine: 6 mg (peds: 0.1 mg/kg up to 6 mg) rapid IV push; if no response after 1 " 2 min, then 12 mg (peds: 0.2 mg/kg up to 12 mg), may repeat 12 mg (0.2 mg/kg)
  • Amiodarone:VT/SVT with pulse: 150 mg IV over 10 min (peds: 5 mg/kg IV over 20 " 60 min, redose up to 15 mg/kg, 300 mg max), then 1 mg/min for 6 hr and 0.5 mg/min for next 18 hr.VF/pulseless VT: 300 mg IV push (peds: 5 mg/kg IV), may give 150 mg IV push 3 " 5 min after if no response (peds: redose up to 15 mg/kg or 300 mg max), followed by infusion as above.
  • Diltiazem: 0.25 mg/kg IV (usually 10 " 20 mg) over 2 min, followed in 15 min by 0.35 mg/kg IV over 2 min
  • Epinephrine: 1 mg (peds: 0.01 mg/kg) IV push q3 " 5min; 2.5 mg (peds: 0.1 mg/kg) endotracheally q3 " 5min
  • Lidocaine: 1 " 1.5 mg/kg (100 mg) (peds: 1 mg/kg) IV push, may repeat q5 " 10min, max. dose 3 mg/kg
  • Magnesium sulfate: 2 g diluted in 100 mL D5W IV over 2 min (peds: 25 " 50 mg/kg, max. 2 g, IV over 10 " 20 min)
  • Metoprolol: 5 " 15 mg slow IV push at 5-min intervals to total of 15 mg
  • Procainamide:VF/pulseless VT: 30 mg/min (peds: Not recommended) IV load until rhythm resolves, hypotension, QRS widens >50% or max. 17 mg/kg, then 1 " 4 mg/min IVPerfusing VT: 20 mg/min (peds: 15 mg/kg IV over 30 " 60 min) IV load until rhythm resolves, hypotension, QRS widens >50% or max. 17 mg/kg, then 1 " 4 mg/min IVSVT: 15 " 17 mg/kg IV at 20 " 30 mg/min or 100 mg IV q5min slow IV push until rhythm resolves or max. dose 1,000 mg (peds: 3 " 6 mg/kg IV over 5 min, max. 100 mg/dose, may repeat q5 " 10min as needed to total dose 15 mg/kg)
  • Vasopressin: 40 U (peds: Not recommended) IV push once

Follow-Up

Disposition

Admission Criteria

  • VT or VF
  • Possible cardiac ischemic event
  • Persistent SVT
  • Underlying metabolic abnormalities

Discharge Criteria

Terminated supraventricular rhythm without organ hypoperfusion

Issues for Referral

Electrophysiologic testing:

  • Diagnostic but not required emergently
  • Determines therapy for accessory pathways

Pearls and Pitfalls

  • Always suspect a ventricular rhythm with a wide complex rhythm, especially in the older patient.
  • Antidysrhythmic administration may increase success rate of cardioversion.
  • Rapid, uninterrupted chest compressions may increase the success rate of defibrillation for a patient with a pulseless rhythm.

Additional Reading

  • Anderson BR, Vetter VL. Arrhythmogenic causes of chest pain in children. Pediatr Clin North Am. 2010;57:1305 " 1329.
  • Hood RE, Shorofsky SR. Management of arrhythmias in the emergency department. Cardiol Clin. 2006;24:125 " 133.
  • Link MS. Clinical practice. Evaluation and initial treatment of supraventricular tachycardia. N Eng J Med. 2012;367(15):1438 " 1448.
  • Neumar RW, Otto CW, Link MS, et al. Part 8: Adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010;122(18 suppl 3):S729 " S767.
  • Roberts-Thomson KC, Lau DH, Sanders P. The diagnosis and management of ventricular arrhythmias. Nat Rev Cardiol. 2011;8:311 " 321.

See Also (Topic, Algorithm, Electronic Media Element)

  • Atrial Fibrillation
  • Supraventricular Tachycardia
  • Ventricular Tachycardia

Codes

ICD9

  • 427.0 Paroxysmal supraventricular tachycardia
  • 427.1 Paroxysmal ventricular tachycardia
  • 785.0 Tachycardia, unspecified
  • 427.31 Atrial fibrillation
  • 427.32 Atrial flutter
  • 427.89 Other specified cardiac dysrhythmias

ICD10

  • I47.1 Supraventricular tachycardia
  • I47.2 Ventricular tachycardia
  • R00.0 Tachycardia, unspecified
  • I48.91 Unspecified atrial fibrillation
  • I48.92 Unspecified atrial flutter

SNOMED

  • 6285003 Tachyarrhythmia (disorder)
  • 6456007 Supraventricular tachycardia (disorder)
  • 25569003 Ventricular tachycardia (disorder)
  • 49436004 Atrial fibrillation (disorder)
  • 11092001 Sinus tachycardia (finding)
  • 251165007 atrioventricular junctional (nodal) tachycardia (disorder)
  • 276796006 Atrial tachycardia (disorder)
  • 419166005 Junctional ectopic tachycardia (disorder)
  • 5370000 Atrial flutter (disorder)