Narrow complex tachycardia resident survival guide

File:Critical Pathways.gif

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hilda Mahmoudi M.D., M.P.H.^[2]

Definition

Narrow complex tachycardia is defined as a rhythm with heart rate > 100 beats per minute and a QRS complex duration < 120 milliseconds.

Causes

Life Threatening Causes

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

Initial Diagnosis

Shown below is an algorithm summarizing a stepwise approach to the initial diagnosis of an arrhythmia. Algorithm is according to the 2003 ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias.

Charcterize the symptoms

Examine the patient

Order tests ❑ ECG ❑ Echocardiography ❑ In patients with sustained SVT† ❑ 24 hour holter monitor ❑ In patients with frequent but transient tachycardia ❑ Loop recorder ❑ In patients with less frequent arrhythmias ❑ Trans-esophageal atrial recordings ❑ If other investigations have failed to document an arrhythmia

Undocumented arrhythmia

Documented arrhythmia

❑ History suggests extra premature beats. ❑ Surface ECG is normal.

❑ History suggests paroxysmal arrhythmia. ❑ 12 lead ECG doesn't suggest any mechanism for arrhythmia.

Stable patient

Unstable patient

Rule out following: ❑ Caffeine ❑ Alcohol ❑ Nicotine ❑ Recreational drugs ❑ Hyperthyroidism

❑ Refer for an invasive electrophysiological study AND/OR ❑ Catheter ablation ❑ Teach vagal maneuvers to patients. ❑ Consider beta blocking agent.

❑ Treat according to the type of arrhythmia.

❑ Obtain a monitor strip form the defibrillator. ❑ Immediate direct current cardioversion.

† In patients with sustained SVT, echocardiography is performed to rule out structural heart disease.
SVT: Supra ventricular tachycardia; ECG: Electrocardiograph

Management

Differential Diagnosis for Narrow QRS Tachycardia

Shown below is an algorithm summarizing the approach to differentiate various types of narrow complex tachycardia. Algorithm is according to the 2003 guidelines issued by ACC/AHA/ESC for the management of patients with supraventricular arrhythmias.

Narrow QRS tachycardia (QRS duration less than 120 ms)

Regular rhythm

Irregular rhythm

❑ Analyze presence of P waves

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

No

Yes

Atrial rate greater than ventricular rate?

Yes

No

Atrial flutter or atrial tachycardia

Analyze RP interval

Short (RP shorter than PR)

Long (RP longer than PR)

RP shorter than 70 ms

RP longer than 70 ms

Atrial tachycardia PJRT Atypical AVNRT

AVNRT

AVRT AVNRT Atrial tachycardia

† Echocardiographic examination is required in patients with documented sustained supraventricular tachycardia to rule out structural heart disease.

• Patients with focal junctional tachycardia may mimic the pattern of slow-fast AVNRT and may show AV dissociation and/or marked irregularity in the junctional rate.
  

AV: Atrioventricular; AVNRT: Atrioventricular nodal reciprocating tachycardia; MAT: Multifocal atrial tachycardia; ms: miliseconds; PJRT: Permanent form of junctional reciprocating tachycardia; QRS: Ventricular activation on ECG

Differential Diagnosis of Narrow Complex Tachycardias According to Adenosine Response

Shown below is an algorithm summarizing the approach to differential diagnosis of narrow complex tachycardia according to the adenosine response. Algorithm is according to the 2003 guidelines issued by ACC/AHA/ESC for the management of patients with supraventricular arrhythmias.

Regular narrow QRS complex tachycardia

❑ Administer IV adenosine

❑ Analyze changes on ECG

No change in rate

Gradual slowing then re-acceleration of rate

Abrupt termination

Persisting atrial tachycardia with transient high-grade AV block

❑ Consider inadequate dose/delivery ❑ Consider VT (fascicular or high septal origin)

❑ Consider following ❑ Sinus tachycardia ❑ Focal AT ❑ Nonparoxysmal junctional tachycardia

Consider following causes: ❑AVNRT ❑AVRT ❑ Sinus node re-entry ❑Focal AT

❑ Consider atrial flutter OR ❑ Atrial tachycardia (AT)

AV: Atrioventricular; AVNRT: Atrioventricular nodal reciprocating tachycardia; AVRT: Atrioventricular reciprocating tachycardia; IV:Intravenous; QRS: Ventricular activation on ECG; VT: Ventricular tachycardia

Acute management of Hemodynamically Stable Narrow QRS Regular Tachycadia

Show below is an algorithm summarizing the approach to management of narrow complex tachycardia. Algorithm is according to the 2003 guidelines issued by ACC/AHA/ESC for the management of patients with supraventricular arrhythmias.

Hemodynamically stable regular tachycardia

❑ Confirm diagnosis of narrow QRS complex tachycardia

❑ Perform vagal maneuvers ❑ Valsalva maneuver ❑ Carotid massage ❑ Facial immersion in cold water ❑ Administer IV adenosine† ❑ First dose: 6 mg; second dose: 12 mg; third dose: 18mg if required. ❑ 50-250 ug/Kg in pediatric patients ❑ Administer IV verapamil/diltiazem ❑ Verapamil: 5 mg IV over 2 minutes followed in 5-10 min by 5-7.5 mg if required. ❑ Diltiazem: 20 mg followed by 25-35 mg if required. ❑ Administer IV beta blocker (metaprolol)

Arrhythmia terminated

Persistent tachycardia with AV block

❑ Administer IV ibutilide‡ PLUS ❑ AV-nodal-blocking agent ❑ Overdrive pacing/DC cardioversion, and/or ❑ Rate control

† Adenosine should be used with caution in patients with severe coronary artery disease and may produce AF, which may result in rapid ventricular rates for patients with pre-excitation.
‡ Ibutilide is especially effective for patients with atrial flutter but should not be used in patients with EF less than 30% due to increased risk of polymorphic VT.
AF: Atrial fibrillation; AV: Atrioventricular; BBB: Bundle-branch block; IV:Intravenous; QRS: Ventricular activation on ECG; VT: Ventricular tachycardia; LV: Left ventricle; SVT: Supraventricular tachycardia

Do's

• Refer narrow complex tachycardic patients with following characteristics to a cardiac arrhythmia specialist:

• Patients with drug resistance
• Patients with intolerance to drugs
• Patients who do not want any drug therapy.
• Patients with severe symptoms such as syncope and dyspnoea during palpitations.

• Refer all the patients with Wolff-Parkinson-White syndrome (WPW syndrome) to a cardiac arrhythmia specialist.
• Consider invasive electrophysiological investigation in presence of pre-excitation and severe disabling symptoms.
• Order a 12 lead ECG during use of adenosine or carotid massage.
• Consider esophageal pill electrodes in cases of invisible P waves.
• Administer higher doses of adenosine in patients taking theophylline.
• Administer IV adenosine or DC cardioversion in patients with PSVT requiring a rapid therapeutic effect.

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.

References

Template:WikiDoc Sources