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 (WCT) 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 WCT. Hemodynamically unstable patients should receive urgent synchronized cardioversion. 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 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

Prepare the patient for immediate cardioversion and simultaneously do the following: ❑ Maintain patent airway; assist breathing as necessary ❑ Adminster oxygen (if the patient is hypoxemic) ❑ Cardiac monitor to identify rhythm; monitor blood pressure and oximetry ❑ Give IV sedation if the patient is conscious ❑ Don't delay cardioversion to sedate the patient ❑ Consider expert consultation

VT/VF presenting as cardiac arrest Click here for Cardiac arrest resident survival guide

Unsynchronized cardioversion ❑ If a patient has polymorphic VT and is unstable, treat the rhythm as VF and 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

Atrial fibrillation with aberrancy ❑ 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

Arial flutter and other SVTs with aberrancy ❑ 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

Monomorphic VT (regular form and rate) ❑ 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

If you can't determine the type of arrhythmia or you aren't sure, go for immediate unsynchronized cardioversion

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: ECG: Electrocardiogram; VT: Ventricular tachycardia; VF: Ventricular fibrillation; ICD: Implantable cardioverter-defibrillator; BPM: Beat per minute; AT: Atrial tachycardia; RBBB: Right bundle branch block; LBBB: Left bundle branch block; SVT: supraventricular tachycardia; AP: Accessory pathway; AVRT: Atrioventricular reentrant tachycardia; SR: Sinus rhythm; A: Atrial; V: Ventricular

Characterize the symptoms: ❑ Palpitations ❑ Lightheadedness ❑ Dyspnea ❑ Diaphoresis ❑ Chest discomfort ❑ Shock ❑ Syncope ❑ Seizures ❑ Cardiac arrest Characterize the timing of the symptoms: ❑ Onset ❑ First episode ❑ Recurrent ❑ Duration ❑ Frequency ❑ Termination of the episode ❑ Spontaneous ❑ Medication use ❑ Not terminated History of usage of proarrhythmic drugs: ❑ Medications that prolong QT interval (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 (eg, VT and SVT with aberrancy) ❑ Irregular (eg, afib with aberrancy) ❑ Strength ❑ Weak ❑ Alternating in strength (eg, afib with aberrancy) ❑ Respiration ❑ Tachypnea ❑ Blood pressure ❑ Hypotension (suggestive of hemodynamically unstable patients) ❑ Marked fluctuation of blood pressure (suggestive of AV dissociation in VT) Neck ❑ Canon A waves on examining the jugular venous pressure of the neck (suggestive of AV dissociation in VT) Cardiovascular examination ❑ Inspection ❑ Midsternal incision (sugestive of previous cardiothoracic surgery) ❑ Palpation ❑ Pace maker or ICD are usually palpapable on the left pectoral area ❑ Auscultation ❑ Heart sounds ❑ 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)

Order labs and tests: ❑ Order and monitor the ECG Perform urgent cardioversion in unstable patients ❑ Chest x ray ❑ Cardiomegaly (suggestive of heart disease) ❑ Pace maker 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)

Regular or irregular?

Regular

Irregular

Is QRS identical to that during SR? If yes, consider: - SVT and BBB - Antidromic AVRT

Atrial fibrillation Atrial flutter / AT with variable conduction and: a) BBB or b) Antegrade conduction via AP

Vagal maneuvers or adenosine

Previous myocardial infarction or structural heart disease? If yes, VT is likely.

1 to 1 AV relationship?

Yes or unknown

No

V rate faster than A rate

A rate faster than V rate

QRS morphology in precordial leads

VT

Atrial tachycardia Atrial flutter

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

SVT

VT

VT

VT

The above algorithm is adapted from the 2003 American College of Cardiology.

Click here for more details about classification of wide complex tachycardia.

Treatment

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

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

Wide complex tachycardia QRS ≥ 120ms

Begin initial management ❑ Assess and support CAB as needed ❑ Give oxygen ❑ Monitor ECG, blood pressure, oxymetry ❑ Establish IV access ❑ Identify and treat reversible causes

Determine if the patient has any unstable sign or symptom ❑ Chest pain ❑ Congestive heart failure ❑ Hypotension ❑ Loss of consciousness ❑ Seizures

❑ Yes

No

Continue with the FIRE algorithm above

Determine the regularity of the rhythm

Irregular rhythm

Regular rhythm

VT or uncertain rhythm ❑Procainamide (Class IIa, level of evidence B) ❑ Adminster 20-50 mg/min IV untill arrhythmia suppressed, hypotension ensues, QRS duration increase by 50 %, or maximum dose of 17 mg/kg is given ❑ Maintenance infusion: 1-4 mg/min ❑ Avoide procainamide if prolonged QT interval or CHF ❑Amiodarone (Class IIb, level of evidence B) ❑ Give amiodarone 150 mg IV over 10 min ❑ Repeat amiodarone as needed for a maximal dose of 2.2g/24h ❑Sotalol (Class IIb, level of evidence B) ❑ Adminster 100 mg (1.5 mg/kg) IV over 5 minutes ❑ Avoid if patients has prolonged QT ❑ Prepare for elective synchronized cardioversion

SVT with aberrancy ❑ Attempt vagal maneuvers ❑ Give adenosine 6 mg rapid IV push ❑ If no conversion give 12 mg IV push ❑ May repeat 12 mg dose once

Afib with aberrancy ❑ Consider expert consultation ❑ Control rate e.g diltiazem or beta blockers

Pre-excited Afib (Afib + WPW) ❑ Consider expert consultation ❑ Avoid AV nodal blocking agents e.g adenosine, digoxin, diltiazem and verapamil ❑ Consider amiodarone 150 mg IV over 10 min

Recurrent polymorphic VT ❑ Consider expert consultation ❑ Torsade de pointes ❑ Polymorfic VT associated with familial long QT syndrome: treated with IV magnesium, pacing and/or beta blockers ❑ Polymorfic VT associated with myocardial ischemia: IV amiodarone and beta blockers can be used ❑ Catecholamenercic VT and Brugada syndrome

Torsade de pointes(polymorphic VT associated with long QT syndrome) ❑ Load with magnesium 1-2 g over 5-60 min, then infusion

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

Antiarrhythmics

Shown below is a table summarizing the choices of the antiarrhythmic drugs for the different types of tachycardia according to the 2003 ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias.

BBB: Bundle branch block; LV: Left ventricle; SVT: Supraventricular tachycardia

Management of wide complex tachycardia Ventricular tachycardia or wide QRS tachycardia of unknown origin ▸ Procainamide (Class I, level of evidence B) OR ▸ Sotalol (Class I, level of evidence B) OR ▸ Amiodarone (Class IIb, level of evidence B) 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) Wide QRS tachycardia of unknown origin + poor LV function ▸ Amiodarone (Class I, level of evidence B) OR ▸ Cardioversion (Class I, level of evidence B) SVT + BBB ▸ 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) SVT or atrial fibrillation + Preexcitation ▸ Flecainide (Class I, level of evidence B) OR ▸ Ibutilide (Class I, level of evidence B) OR ▸ Procainamide (Class I, level of evidence B) OR ▸ Cardioversion (Class I, level of evidence C)

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.

Dont's

• 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 known to be of supraventricular origin.

References