Narrow complex tachycardia resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hilda Mahmoudi M.D., M.P.H.^[2]; Twinkle Singh, M.B.B.S. [3]; Rim Halaby, M.D. [4]; Amr Marawan, M.D. [5]

Synonyms and keywords: NCT, supraventricular tachycardia, SVT, paroxysmal supraventricular tachycardia, PSVT

Narrow Complex Tachycardia Resident Survival Guide Microchapters
Overview
Causes
Classification
Diagnosis FIRE Complete ECG Examples
Treatment General Specific arrhythmia
Do's
Don'ts

Overview

Narrow complex tachycardia is characterized by a heart rate > 100 beats per minute and a QRS complex of a duration < 120 milliseconds. Narrow complex tachycardia may originate in the sinus node, atria, AV node, bundle of His, or a combination of these tissues. The diagnosis of narrow complex tachycardia is based on the ECG findings. Hemodynamically unstable patients should receive urgent synchronized cardioversion.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Wolff-Parkinson-White syndrome (orthodromic atrioventricular reentrant tachycardia)
• Idiopathic fascicular ventricular tachycardia

Common Causes

• Atrial fibrillation
• Atrial flutter
• Atrial tachycardia
• Atrioventricular reentrant tachycardia (AVRT)
  
• AV nodal reentrant tachycardia (AVNRT)
  

Click here for the complete list of causes.

FIRE: Focused Initial Rapid Evaluation

The aim of FIRE is to identify urgent conditions that require immediate intervention in suspected narrow complex tachycardia based on the 2003 ACC/AHA/ESC and the ACLS guidelines.

Boxes in red signify that an urgent management is needed.

Identify cardinal findings that increase the pretest probability of narrow complex tachycardia ❑ Palpitations ❑ Heart rate > 100 beats/min ❑ QRS complex < 120 ms

Identify findings suggestive of hemodynamic instability ❑ Hypotension ❑ Cold extremities ❑ Peripheral cyanosis ❑ Mottling ❑ Acute altered mental status

❑ Hemodynamic instability present

❑ Hemodynamic instability absent

❑ Urgent synchronized cardioversion ❑ Narrow regular rhythm: 50-100 J ❑ Narrow irregular rhythm: 120-200 J biphasic or 200 J monophasic

❑ Continue with the complete diagnostic approach below

Complete Diagnostic Approach

Shown below is an algorithm depicting the complete diagnostic approach to narrow complex tachycardia according to the 2003 ACC/AHA/ESC guidelines.
Abbreviations: ECG: electrocardiogram; SVT: Supraventricular tachycardia; ms: milliseconds; bpm: beats per minute; AV: atrioventricular; AVNRT: atrioventricular nodal reciprocating tachycardia; MAT: multifocal atrial tachycardia; ms: milliseconds; PJRT: permanent form of junctional reciprocating tachycardia; RP interval: is the time between anterograde ventricular activation (R wave) and retrograde atrial activation (P wave)

Characterize the symptoms: ❑ Asymptomatic (most common presentation) ❑ Palpitations ❑ Sensation of a pause followed by a strong heart beat (suggestive of premature beats) ❑ Dyspnea ❑ Fatigue ❑ Chest discomfort ❑ Lightheadedness ❑ Syncope ❑ Polyuria Characterize the timing of the symptoms: ❑ Onset ❑ First episode ❑ Recurrent ❑ Duration ❑ Frequency ❑ Termination of the episode ❑ Spontaneous ❑ Medication use ❑ Not terminated

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

Examine the patient: Vitals ❑ Pulse ❑ Rate ❑ Tachycardia ❑ Rhythm ❑ Regular ❑ Regularly irregular ❑ Irregularly irregular ❑ Strength ❑ Weak ❑ Alternating in strength (atrial fibrillation) ❑ Respiration ❑ Tachypnea ❑ Blood pressure ❑ Normal (typical) ❑ Hypotension (in hemodynamically unstable patients) Neck ❑ Absent a wave in jugular venous pressure (in atrial fibrillation) Cardiovascular examination ❑ Auscultation ❑ Heart sounds ❑ Rapid regular or irregular beats ❑ Murmurs (suggestive of valvular diseases)

❑ Order and monitor the ECG Perform urgent cardioversion in unstable patients

Narrow QRS tachycardia ❑ Heart rate > 100 beats/min ❑ QRS duration < 120 ms

❑ Determine regularity of the rhythm

Regular rhythm

Irregular rhythm

Consider the following causes: ❑ AVRT ❑ AVNRT ❑ Atypical AVNRT ❑ Atrial tachycardia ❑ Atrial flutter

Consider the following causes: ❑ Atrial fibrillation ❑ Atrial tachycardia/flutter with variable AV conduction ❑ MAT

❑ Determine P wave morphology

❑ Determine P wave morphology

❑ P waves are not visible

❑ P waves are visible

❑ > 3 P wave morphologies

❑ Absent P waves

❑ Sawtooth appearance of P waves

❑ Consider AVNRT

❑ Determine if atrial rate is greater than ventricular rate

❑ Consider MAT

❑ Consider atrial fibrillation

❑ Consider atrial flutter

Atrial rate > ventricular rate

Atrial rate ≤ ventricular rate

Consider the following causes: ❑ Atrial flutter ❑ Atrial tachycardia

❑ Determine if RP interval > PR interval

RP < PR

RP > PR

❑ Determine the duration of RP interval

Consider the following causes: ❑ Atrial tachycardia ❑ PJRT ❑ Atypical AVNRT

< 70 ms

> 70 ms

Consider the following cause: ❑ AVNRT

Consider the following causes: ❑ AVRT ❑ AVNRT ❑ Atrial tachycardia

ECG Examples

Shown below is a table depicting the ECG findings of thesifferent types of narrow complex tachycardia.

Type of Arrhythmia	EKG (lead II)†	Clues
Sinus tachycardia		Onset and termination: gradual Rhythm: regular Rate: >220 minus the age of the patient Response to adenosine: transient decrease of the rate
Atrial fibrillation		Onset and termination: abrupt Rhythm: irregular Rate:100-180 bpm Response to adenosine: transient decrease of the ventricular rate
Atrial flutter		Onset and termination: abrupt Rhythm: Regular Rate: >150 bpm Response to adenosine: transient decrease of the rate Presence of saw-tooth appearance
AVNRT		Onset and termination: abrupt Rhythm: regular Rate: 150-250 bpm Response to adenosine: termination of the arrhythmia
AVRT		Onset and termination: abrupt Rhythm: regular Rate: 150-250 bpm Response to adenosine: termination of the arrhythmia
Focal atrial tachycardia		Onset and termination: abrupt Rhythm: regular Rate: 150-250 bpm
Nonparoxysmal junctional tachycardia		Rhythm: regular Retrograde P wave Most commonly due to ischemia or digitalis toxicity
Multifocal atrial tachycardia		Onset and termination: gradual Rhythm: irregular Rate: 100-150 bpm Response to adenosine: no effect 3 different P wave morphologies

† ECG strips are courtesy of ECGpedia.

Treatment

General Treatment of SVT in a Hemodynamically Stable Patient

Shown below is an algorithm summarizing the management of narrow complex tachycardia according to the 2003 ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias.
Abbreviations: AF: atrial fibrillation; AV: atrioventricular; AVNRT: atrioventricular nodal reciprocating tachycardia; AVRT: atrioventricular reciprocating tachycardia; BBB: bundle-branch block; ECG: electrocardiography; IV: intravenous; LV: left ventricle; SVT: supraventricular tachycardia; VT: ventricular tachycardia

Assess the hemodynamic status of the patient Signs of hemodynamic instability include: ❑ Hypotension ❑ Acute altered mental status ❑ Signs of shock ❑ Acute heart failure ❑ Chest discomfort suggestive of ischemia

Hemodynamic instability present

Hemodynamic instability absent

Urgent synchronized cardioversion ❑ Narrow regular rhythm: 50-100 J ❑ Narrow irregular rhythm: 120-200 J biphasic or 200 J monophasic

Does the patient have any of the following? ❑ Atrial fibrillation (irregularly irregular rhythm, absent P waves) ❑ Atrial flutter (regular rhythm, sawtooth pattern)

No

Yes

Acute management: ❑ Perform vagal maneuvers (Class I, level of evidence B) ❑ Valsalva maneuver ❑ Carotid sinus massage Carotid massage is contraindicated in case of prior MI, transient ischemic attack or stroke within the last three months, previous history of ventricular fibrillation or fibrillation tachycardia, and in case of carotid bruits. ❑ Monitor ECG continuously

Click on the below link for the detailed management ❑ Atrial fibrillation ❑ Atrial flutter

If vagal maneuvers fail: ❑ Administer IV adenosine (Class I, level of evidence A) ❑ First dose: 6 mg rapid IV push, followed by 20 mL of normal saline bolus ❑ Second dose: 12 mg (if no response in 1-2 min) Adenosine is contraindicated in cardiac transplant patients. Use adenosine with caution in severe obstructive lung disease. ❑ Monitor ECG continuously

If adenosine fails, administer ONE of the following: ❑ IV verapamil 5 mg IV every 3-5 min, maximum 15 mg (Class I, level of evidence A) ❑ IV diltiazem (Class I, level of evidence A) ❑ 0.25 mg/kg over 2 minutes ❑ Additional 0.35 mg/kg over 2 minutes ❑ Maintenance infusion of 5-15 mg/hour ❑ IV beta blocker (Class IIb, level of evidence C) ❑ Metoprolol ❑ 5 mg over 2 minutes ❑ Up to 3 doses within 15 minutes ❑ Esmolol ❑ 250-500 μg/kg over 1 minute ❑ Maintenance with 50-200 μg/kg over 4 minutes (if needed) ❑ Propranolol ❑ 0.15 mg/kg over 2 minutes ❑ Monitor ECG continuously

Terminated arrhythmia

Persistent arrhythmia

No further therapy is required if: ❑ Patient is stable ❑ LV function is normal ❑ Normal sinus rhythm on ECG

❑ Administer AV-nodal-blocking agent AND one of the following ❑ IV ibutilide Ibutilide is especially indicated for patients with atrial flutter but should not be used in patients with ejection fraction less than 30% as it increases risk of polymorphic VT. ❑ 1 mg over 10 minutes (if ≥ 60 kg) ❑ 0.01 mg/kg over 10 minutes (if <60 kg) ❑ Repeat once after 10 minutes if needed ❑ IV procainamide ❑ 30 mg/min infusion, maximum 17 mg/kg ❑ Maintenance 2-4 mg/min ❑ IV flecainide 2mg/kg over 10 min OR ❑ DC cardioversion

Treatment of Specific Supraventricular Arrhythmia

Focal Atrial Tachycardia

Management of focal atrial tachycardia Acute treatment Conversion in hemodynamically unstable patient ▸ DC cardioversion (Class I, level of evidence B) Conversion in hemodynamically stable patient ▸ Adenosine (Class IIa, level of evidence C) OR ▸ Verapamil (Class IIa, level of evidence C) OR ▸ Diltiazem (Class IIa, level of evidence C) OR ▸ Beta blocker (Class IIa, level of evidence C) OR ▸ Amiodarone (Class IIa, level of evidence C) OR ▸ Sotalol (Class IIa, level of evidence C) OR ▸ Procainamide (Class IIa, level of evidence C) OR ▸ Flecainide (Class IIa, level of evidence C) OR ▸ Propafenone (Class IIa, level of evidence C) Rate control ▸ Verapamil (Class I, level of evidence C) OR ▸ Diltiazem (Class I, level of evidence C) OR ▸ Beta blocker (Class I, level of evidence C) OR ▸ Digoxin (Class IIb, level of evidence C) Prophylactic therapy Recurrent symptomatic atrial tachycardia ▸ Catheter ablation (Class I, level of evidence B) OR ▸ Beta blockers (Class I, level of evidence C) OR ▸ Diltiazem (Class I, level of evidence C) OR ▸ Verapamil (Class I, level of evidence C) OR ▸ Disopyramide (Class IIa, level of evidence C) OR ▸ Amiodarone (Class IIa, level of evidence C) OR ▸ Sotalol (Class IIa, level of evidence C) OR ▸ Flecainide (Class IIa, level of evidence C) OR ▸ Propafenone (Class IIa, level of evidence C) Asymptomatic or symptomatic incessent atrial tachycardia ▸ Catheter ablation (Class I, level of evidence B) Asymptomatic and non-sustained atrial tachycardia ▸ No therapy (Class I, level of evidence C) OR ▸ Catheter ablation (Class III, level of evidence C)

Focal and Nonparoxysmal Junctional Tachycardia

Management of focal and nonparoxysmal junctional tachycardia Focal junctional tachycardia ▸ Beta blockers (Class IIa, level of evidence C) OR ▸ Amiodarone (Class IIa, level of evidence C) OR ▸ Sotalol (Class IIa, level of evidence C) OR ▸ Flecainide (Class IIa, level of evidence C) OR ▸ Propafenone (Class IIa, level of evidence C) OR ▸ Catheter ablation (Class IIa, level of evidence C) Non paroxysmal junctional tachycardia ▸ Reverse digitalis toxicity (Class I, level of evidence C) AND ▸ Correct hypokalemia (Class I, level of evidence C) AND ▸ Treat myocardial ischemia (Class I, level of evidence C) OR ▸ Beta blockers (Class IIa, level of evidence C) OR ▸ Calcium channel blockers (Class IIa, level of evidence C)

AVNRT

Management of recurrent AVNRT AVNRT with hemodynamic intolerance ▸ Catheter ablation (Class I, level of evidence B) OR ▸ Verapamil (Class IIa, level of evidence C) OR ▸ Diltiazem (Class IIa, level of evidence C) OR ▸ Beta blockers (Class IIa, level of evidence C) OR ▸ Amiodarone (Class IIa, level of evidence C) OR ▸ Sotalol (Class IIa, level of evidence C) OR ▸ Flecainide (Class IIa, level of evidence C) OR ▸ Propafenone (Class IIa, level of evidence C) Recurrent symptomatic AVNRT ▸ Catheter ablation (Class I, level of evidence B) OR ▸ Verapamil (Class I, level of evidence B) OR ▸ Diltiazem (Class I, level of evidence C) OR ▸ Beta blockers (Class IIa, level of evidence C) OR ▸ Digoxin (Class IIb, level of evidence C) Recurrent AVNRT unresponsive to beta blockers and calcium channel blockers, patient not desiring radiofrequency ablation ▸ Flecainide (Class IIa, level of evidence B) OR ▸ Propafenone (Class IIa, level of evidence B) OR ▸ Sotalol (Class IIa, level of evidence B) OR ▸ Amiodarone (Class IIb, level of evidence C) Single episode of AVNRT or infrequent AVNRT in patients desiring complete control of arrhythmia ▸ Catheter ablation (Class I, level of evidence B) Documented PSVT with only dual AV nodal pathways OR single echo beats documented during electrophysiological study AND no other cause of arrhythmia identified ▸ Verapamil (Class I, level of evidence C) OR ▸ Diltiazem (Class I, level of evidence C) OR ▸ Beta blockers (Class I, level of evidence C) OR ▸ Flecainide (Class I, level of evidence C) OR ▸ Propafenone (Class I, level of evidence C) OR ▸ Catheter ablation (Class I, level of evidence B) Infrequent, well tolerated AVNRT ▸ No therapy (Class I, level of evidence C) OR ▸ Vagal maneuvers (Class I, level of evidence B) OR ▸ Pill in the pocket (Class I, level of evidence B) OR ▸ Verapamil (Class I, level of evidence B) OR ▸ Diltiazem (Class I, level of evidence B) OR ▸ Beta blockers (Class I, level of evidence B) OR ▸ Catheter ablation (Class I, level of evidence B)

Inappropriate Sinus Tachycardia

Management of inappropriate sinus tachycardia ▸ Beta blockers (Class I, level of evidence C) OR ▸ Verapamil (Class I, level of evidence C) OR ▸ Diltiazem (Class I, level of evidence C) OR ▸ Catheter ablation (Class I, level of evidence B)

Do's

• Consider the arrhythmia to be paroxysmal if it is recurrent and abruptly begins and terminates.

• Identify possible triggers and educate the patient to avoid them.

• Refer patients with narrow complex tachycardia with any of the following to a cardiac arrhythmia specialist:

• Drug resistance
• Intolerance to drugs
• Refusal of drug therapy
• Severe symptoms such as syncope and dyspnea
• Wolff-Parkinson-White syndrome

• Consider trying different types of anti-arrhythmic agents in case the SVT is refractory; however, closely monitor the blood pressure and heart rate.

• Consider invasive electrophysiological investigation in the presence of pre-excitation and severe disabling symptoms.

• Monitor the 12 lead ECG during the administration ofadenosine or carotid massage.

• Make sure the equipment for resuscitation is available during the administration of adenosine in case of the occurrence of any complication, such as ventricular fibrillation or bronchospasm.

• Administer higher doses of adenosine in patients taking theophylline.
• Perform the following tests when indicated:

• Echocardiography in case of sustained SVT to rule out structural heart disease
• 24 hour holter monitor in case of frequent but transient tachycardia
• Loop recorder in patients with less frequent arrhythmia
• Trans-esophageal atrial recordings if other investigations have failed to document an arrhythmia

Don'ts

• Do not perform esophageal stimulation if an invasive electrophysiological investigation is planned.
• Do not initiate treatment with anti-arrhythmic agents in a patient with undocumented arrhythmia.
• Do not administer adenosine in patients with severe bronchial asthma or heart transplant recipients.

References

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