Tachydysrhythmias, Emergency Medicine

Basics

Description

Any disturbance of the hearts rhythm resulting in a rate >100 bpm
Sinus tachycardia:
- Narrow complex regular rhythm at a rate of 100 " 150 bpm
- Max. rate typically 220 minus age
- Functional 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 tachycardia
- Junctional tachycardia:
  - Regular tachycardia without preceding depolarization waves
Irregular SVT:
- Atrial fibrillation (AF)
- Atrial flutter
- Multifocal atrial tachycardia
Ventricular tachycardia (VT):
- ≥3 consecutive ventricular ectopic beats at a rate of 100 bpm
- Most 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 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

Etiology

Sinus tachycardia:
- Acute MI
- Anemia
- Anxiety
- CHF
- Drug intoxication
- Hyperthyroidism
- Hypovolemia
- Hypoxia
- Infection
- Pain
- Pericardial tamponade
- Pulmonary embolus
Atrial tachycardia:
- Precipitated by a premature atrial or ventricular contraction
- Electrolyte disturbances
- Drug toxicity
- Hypoxia
Junctional tachycardia:
- AV nodal re-entry
- Myocardial ischemia
- Structural heart disease
- Pre-excitation syndromes
- Drug and alcohol toxicity
AF:
- HTN
- Coronary artery disease
- Hyper-/Hypothyroidism
- Alcohol intake
- Mitral valve disease
- Chronic obstructive pulmonary disease
- Pulmonary embolus
- Wolf " Parkinson " White (WPW) syndrome
- Hypoxia
- Digoxin toxicity
- Chronic pericarditis
- Idiopathic AF
Atrial flutter:
- Ischemic heart disease
- Valvular heart disease
- CHF
- Myocarditis
- Cardiomyopathies
- Pulmonary embolus
- Electrolyte abnormalities
- Recent cardiac surgery
Multifocal atrial tachycardia:
- Hypoxic effects of chronic lung disease
- Theophylline toxicity
VT:
- Dilated cardiomyopathy
- Cardiac ischemia
- Hypoxia
- Cardiac scarring/fibrosis
- After cardiac surgery or congenital anomaly repair
- Digoxin toxicity
- Long QT syndrome
- Electrolyte abnormalities
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

Diagnosis

Signs and Symptoms

Asymptomatic
Palpitations
Lightheadedness
Dyspnea
Diaphoresis
Dizziness
Weakness
Chest discomfort
Angina
Syncope
Prominent neck veins
Signs of instability:
- Hypotension
- Pulmonary edema
- Chest pain
- Mental 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 " 160
- Uniformity of polarity and amplitude
- No P-waves visible
AF:
- Irregular, narrow QRS complex, rate <150 " 170 bpm
Atrial flutter:
- Regular atrial rate, usually >300
- Beat-to-beat uniformity of cycle length, polarity, and amplitude
- Sawtooth flutter waves directed superiorly and most visible in leads II, III, aVF
- AV 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 bpm
- QRS 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 blockers
- Anticoagulation if onset is >24 hr
- Cardioversion 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 aberrancy
- Administration 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, amiodarone
- Correct 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 procainamide
- EF abnormal:
  - Amiodarone or lidocaine; then synchronized cardioversion
- Treat ischemia and correct electrolytes.
Monomorphic VT:
- EF normal:
  - Procainamide preferred to amiodarone, sotalol, lidocaine; synchronized cardioversion
- EF abnormal:
  - Amiodarone or lidocaine
  - Procainamide 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 IV
- Perfusing 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 IV
- SVT: 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.

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)

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