Wide complex tachycardia resident survival guide

Wide Complex Tachycardia Resident Survival Guide Microchapters
Overview
Causes
FIRE
Diagnosis
Treatment
Do's
Don'ts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby, M.D. [2]; Amr Marawan, M.D. [3]

Overview

Wide complex tachycardia is characterized by a heart rate more than 100 beats per minute associated with a QRS interval of more than 120 ms. When wide complex tachycardia is present, it is important to determine whether the tachycardia is of a supraventricular or a ventricular origin. The diagnosis of wide complex tachycardia is very challenging as there is no fixed criteria to accurately determine the cause and type of the wide complex tachycardia. Hemodynamically unstable patients should receive urgent synchronized cardioversion unless the patient has polymorphic ventricular tachycardia for which unsynchronized cardioversion should be performed. If the QRS complex and the T wave can't be distinguished in unstable patients, then the patient should receive unsynchronized cardioversion.

Causes

Life Threatening Causes

Wide complex tachycardia may be a life-threatening condition and must be treated as such irrespective of the underlying cause.

Common Causes

• Atrial fibrillation with aberrancy
• Atrial fibrillation with pre-excitation
• Supraventricular tachycardia (SVT) with aberrancy
• Ventricular tachycardia

Click here for the complete list of causes.

FIRE: Focused Initial Rapid Evaluation

A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention.

Boxes in salmon color signify that an urgent management is needed.

Identify cardinal findings that increase the pretest probability of wide complex tachycardia ❑ Palpitations ❑ QRS complex > 120 ms ❑ Heart rate > 150 beats/min

Does the patient have any of the following findings that require urgent cardioversion? ❑ Hemodynamic instability ❑ Hypotension ❑ Cold extremities ❑ Peripheral cyanosis ❑ Mottling ❑ Altered mental status ❑ Chest discomfort suggestive of ischemia ❑ Decompensated heart failure

Yes

No

❑ Continue with the complete diagnostic approach below

Proceed with immediate cardioversion Perform the following without delaying cardioversion ❑ Maintain patent airway; assist breathing as necessary ❑ Administer oxygen (if the patient is hypoxemic) ❑ Monitor the cardiac rhythm ❑ Monitor blood pressure and oximetry ❑ Administer IV sedation if the patient is conscious

What is the type of arrhythmia?

VT/VF presenting as cardiac arrest

Polymorphic VT or undetermined rhythm

Atrial fibrillation with aberrancy

Atrial flutter and other SVTs with aberrancy

Monomorphic VT (regular form and rate)

Click here for cardiac arrest resident survival guide

Unsynchronized cardioversion ❑ Immediately deliver high-energy unsynchronized shocks ❑ Provide an initial shock of 200 Joules ❑ Increase the dose if no response to the first shock (eg, 300 J, 360 J, 360 J)

Synchronized cardioversion ❑ Provide an initial dose of biphasic cardioversion of 120-200 Joules (Class IIa, level of evidence A) ❑ If the initial shock fails, increase the dose in a stepwise fashion

Synchronized cardioversion ❑ Provide an initial dose of biphasic cardioversion of 50-100 Joules (Class IIa, level of evidence B) ❑ If the initial shock fails, increase the dose in a stepwise fashion ❑ If monophasic wave form is used, begin at 200 Joules and increase in stepwise fashion if not successful

Synchronized cardioversion ❑ Provide an initial dose of biphasic cardioversion of 100 Joules (Class IIb, level of evidence C) ❑ If the initial shock fails, increase the dose in a stepwise fashion

❑ After the stabilization of the patient, continue with the complete diagnostic approach below

Complete Diagnostic Approach

A complete diagnostic approach should be carried out after a focused initial rapid evaluation is conducted and following initiation of any urgent intervention.

Abbreviations: Afib: Atrial fibrillation; AP: Accessory pathway; AT: Atrial tachycardia; AVRT: Atrioventricular reentrant tachycardia; BPM: Beat per minute; ECG: Electrocardiogram; ICD: Implantable cardioverter defibrillator; LBBB: Left bundle branch block; RBBB: Right bundle branch block; S1: First heart sound; SVT: Supraventricular tachycardia; SR: Sinus rhythm; VT: Ventricular tachycardia; VF: Ventricular fibrillation

Characterize the symptoms: ❑ Palpitations ❑ Lightheadedness ❑ Dyspnea ❑ Diaphoresis ❑ Chest discomfort ❑ Syncope ❑ Seizures ❑ Altered mental status Characterize the timing of the symptoms: ❑ Onset ❑ First episode ❑ Recurrent ❑ Duration ❑ Frequency ❑ Termination of the episode ❑ Spontaneous ❑ Medication use ❑ Not terminated Inquire about the use of proarrhythmic drugs: ❑ Medications that prolong QT interval (eg, quinidine, anti-psychotic and azithromycin) Click here for the complete list of drugs ❑ Digoxin at plasma concentration of 2.0 ng/ml (especially with hypokalemia) ❑ Diuretics (can cause hypokalemia and hypomagnesemia leading to torsade de pointes)

Identify possible triggers: ❑ Infection ❑ Caffeine ❑ Alcohol ❑ Nicotine ❑ Recreational drugs ❑ Hypovolemia ❑ Hyperthyroidism ❑ Hypoxia ❑ Acidosis ❑ Hypokalemia ❑ Hyperkalemia ❑ Hypoglycemia ❑ Hypothermia ❑ Toxins ❑ Pulmonary embolism ❑ Coronary thrombosis ❑ Cardiac tamponade ❑ Trauma

Examine the patient: Vitals ❑ Pulse ❑ Rate ❑ Tachycardia (> 100 bpm) ❑ Rhythm ❑ Regular (suggestive of VT and SVT with aberrancy) ❑ Irregular (suggestive of afib with aberrancy) ❑ Strength ❑ Weak ❑ Pulsus alternans (suggestive of afib with aberrancy) ❑ Respiration ❑ Tachypnea ❑ Blood pressure ❑ Hypotension (suggestive of hemodynamic instability) ❑ Marked fluctuation of blood pressure (suggestive of AV dissociation in VT) Neck ❑ Canonn A waves on examining the jugular venous pressure of the neck (suggestive of AV dissociation in VT) Extremities ❑ Cold extremities (suggestive of hemodynamic instability) ❑ Peripheral cyanosis (suggestive of hemodynamic instability) ❑ Mottling (suggestive of hemodynamic instability) Cardiovascular examination ❑ Inspection ❑ Midsternal incision (suggestive of previous cardiothoracic surgery) ❑ Palpation ❑ Pacemaker or ICD are usually palpable on the left pectoral area ❑ Auscultation ❑ Rapid regular or irregular beats ❑ Murmurs (suggestive of valvular diseases) ❑ Variability in the occurrence and the intensity of heart sounds especially S1 (suggestive of AV dissociation in VT) Neurologic ❑ Altered mental status (suggestive of hemodynamic instability)

Order labs and tests: ❑ Order and monitor the ECG Perform urgent cardioversion in unstable patients ❑ Chest x ray ❑ Cardiomegaly (suggestive of heart disease) ❑ Pacemaker and ICD appear in the x ray ❑ Invasive electrophysiological studies ❑ Serum electrolytes ❑ Hypomagnesemia ❑ Hypokalemia ❑ Plasma concentration of drugs (eg, digoxin, quinidine or procainamide)

Wide QRS complex tachycardia (QRS duration greater than 120 ms)

Is the rhythm regular?

Yes

No

❑ Atrial fibrillation ❑ Atrial flutter / atrial tachycardia with variable conduction and: ❑ BBB or ❑ Antegrade conduction via accessory pathway

Is there a 1 to 1 atrium to ventricle relationship?

Yes or unknown

No

QRS morphology in precordial leads

Ventricular rate faster than atrial rate

Atrial rate faster than ventricular rate

If the patient shows typical RBBB or LBBB

Precordial leads: ❑ Concordant ❑ No R/S pattern ❑ Onset of R to nadir longer than 100ms

RBBB pattern: ❑ qR, Rs or Rr' in V1 ❑ Frontal plane axis range from +90 degrees to -90 degrees

LBBB pattern: ❑ R in V1 longer than 30 ms ❑ R to nadir of S in V1 greater than 60 ms ❑ qR or qS in V6

VT

❑ Atrial tachycardia ❑ Atrial flutter

SVT

VT

VT

VT

Differentiating SVT from VT

Shown below is a table summarizing some clues that help differentiate SVT from VT.

Clues	Type of arrhythmia
Irregularly irregular rhythm	Atrial fibrillation or atrial flutter with aberrancy
Previous myocardial infarction or structural heart disease	Ventricular tachycardia
Ventricular rate faster than atrial rate	Ventricular tachycardia
Typical RBBB or LBBB	Supraventricular tachycardia
Precordial leads: ❑ Concordant ❑ No R/S pattern ❑ Onset of R to nadir longer than 100ms	Ventricular tachycardia
RBBB pattern: ❑ qR, Rs or Rr' in V1 ❑ Frontal plane axis range from +90 degrees to -90 degrees	Ventricular tachycardia
LBBB pattern: ❑ R in V1 longer than 30 ms ❑ R to nadir of S in V1 greater than 60 ms ❑ qR or qS in V6	Ventricular tachycardia

For more details about differentiating VT from SVT, click here

Treatment

Shown below is an algorithm depicting the treatment of wide complex tachycardia.

Afib: Atrial fibrillation; BBB: Bundle branch block; CAB: Circulation, airway and breathing; LV: Left ventricle; SVT: Supraventricular tachycardia; VT: Ventricular tachycardia; WPW: Wolff Parkinson White

Wide complex tachycardia ❑ Palpitations ❑ QRS complex > 120 ms ❑ Heart rate > 150 beats/min

Does the patient have any of the following findings that require urgent cardioversion? ❑ Hemodynamic instability ❑ Hypotension ❑ Cold extremities ❑ Peripheral cyanosis ❑ Mottling ❑ Altered mental status ❑ Chest discomfort suggestive of ischemia ❑ Decompensated heart failure

Yes

No

Begin initial management ❑ Assess and support circulation, airway, and breathing as needed ❑ Give oxygen ❑ Monitor ECG, blood pressure, oximetry ❑ Establish IV access ❑ Identify and treat reversible causes

Proceed with cardioversion Check the FIRE algorithm above for the type of cardioversion

Determine the type of arrhythmia

Ventricular tachycardia or wide QRS tachycardia of unknown origin

Wide QRS tachycardia of unknown origin + poor LV function

Recurrent polymorphic VT

SVT + BBB

SVT or atrial fibrillation + Preexcitation

Administer one of the following: ▸ Procainamide (Class I, level of evidence B) ❑ Administer 20-50 mg/min IV until arrhythmia suppressed, hypotension ensues, QRS duration increase by 50 %, or maximum dose of 17 mg/kg is given ❑ Maintenance infusion: 1-4 mg/min OR ▸ Sotalol 100 mg (1.5 mg/kg) IV over 5 minutes OR ▸ Amiodarone (Class IIb, level of evidence B) ❑ Administer amiodarone 150 mg IV over 10 min ❑ Repeat amiodarone as needed for a maximal dose of 2.2g/24h OR ▸ Cardioversion (Class I, level of evidence B) OR ▸ Lidocaine (Class IIb, level of evidence B) OR ▸ Adenosine (Class IIb, level of evidence C) OR ▸ Beta blocker (Class III, level of evidence C) OR ▸ Verapamil (Class III, level of evidence B)

Administer one of the following: ▸ Amiodarone (Class I, level of evidence B) OR ▸ Cardioversion (Class I, level of evidence B)

❑ Torsade de pointes (polymorphic VT associated with long QT syndrome) ❑ Load with magnesium 1-2 g over 5-60 min, then infusion ❑ Polymorphic VT associated with familial long QT syndrome ❑ Administer IV magnesium, pacing and/or beta blockers ❑ Polymorphic VT associated with myocardial ischemia: ❑ Administer IV amiodarone and beta blockers

Administer one of the following: ▸ Vagal maneuvers (Class I, level of evidence B) OR ▸ Adenosine (Class I, level of evidence A) OR ▸ Verapamil (Class I, level of evidence A) OR ▸ Diltiazem (Class I, level of evidence A) OR ▸ Beta blocker (Class IIb, level of evidence C) OR ▸ Amiodarone (Class IIb, level of evidence C) OR ▸ Digoxin (Class IIb, level of evidence C)

Avoid the use of AV node blocking agents such as digoxin, calcium channel blockers, beta blockers and adenosine. ❑ Administer procainamide, 100 mg infusion diluted to 100mg/ml at a rate of 25-50 mg/min every 5 minutes ❑ Administer until the arrhythmia is suppressed or until 500 mg has been administered ❑ Wait 10 minutes or longer to administer new dosage Contraindications: third degree AV block, lupus erythematosus, idiosyncratic hypersensitivity, torsades de pointes Or ❑ Administer ibutilide 1 mg IV infusion over 10 minutes ❑ Repeat the dosage if the tachycardia continues Contraindications: hypersensitivity to ibutilide or any component of the formulation, QTc >440 msec Or ❑ Administer flecainide 50 mg every 12 hours ❑ Increase 50mg BID every four days until efficacy is achieved ❑ Maximum dose recommended for SVT is 300 mg/day Contraindications: pre-existing second degree AV block or third degree AV block , right bundle branch block associated with a left hemiblock unless a pacemaker is present, cardiogenic shock, hypersensitivity to the drug

Do's

• Use high energy unsynchronized cardioversion immediately if you aren't sure of the type of arrhythmia.
• Monitor the patient all the time as he might be unstable or pulseless at anytime.
• Consider adenosine as a safe and potentially effective therapy in the initial management of stable undifferentiated regular monomorphic wide complex tachycardia.
• Refer the patient to an arrhythmia specialist when the tachycardia causes syncope or dyspnea as well as when the wide complex tachycardia is of unknown cause.
• Place an ambulatory 24 hour Holter when the tachycardia is frequent and transient.
• Treat the patient as having a ventricular tachycardia when the diagnosis of supraventricular tachycardia can not be made.
• Suspect ventricular tachycardia in a patient with wide complex tachycardia and previous myocardial infarction or a history of structural heart disease.
• Use beta blockers with caution in pulmonary diseases or congestive heart failure.
• Balance the use of IV analgesics or sedatives with the risk of further hemodynamic deterioration.
• Consider rate control with either diltiazem or beta blockers for patients with atrial fibrillation with aberrancy. An expert consultation is advised.

Don'ts

• Don't rely on the hemodynamic status of the patient and the heart rate to differenciate SVT from VT and this might lead to inappropriate dangerous therapy.
• Don't delay cardioversion to sedate or to establish an IV line to the patient.
• Don't adminster verapamil for wide complex tachycardia unless the wide complex tachycardia is known to be of supraventricular origin.

References