Narrow complex tachycardia resident survival guide

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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

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 tachycardias) ❑ Loop recorder (in patients with less frequent arrhythmias) ❑ Trans-esophageal atrial recordings (if other investigations have failed to document an arrhythmia)

Arrhythmia undocumented

Arrhythmia documented

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

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

❑ Treat accordingly

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.

Management

Figure 1: Differential diagnosis for narrow QRS tachycardia.

Narrow QRS tachycardia (QRS duration less than 120 ms)

Regular rhythm

Irregular rhythm

Visible P waves?

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 indicates atrioventricular; AVNRT, atrioventricular nodal reciprocating tachycardia; MAT, multifocal atrial tachycardia; ms, miliseconds; PJRT, permanent form of junctional reciprocating tachycardia; QRS, ventricular activation on ECG.
Algorithm based on the 2003 ACC/AHA/ESC guidelines for the management of supraventricular arrhythmias.

Figure 2: Acute management of patients with hemodynamically stable and narrow QRS regular tachycadia:

Hemodynamically stable regular tachycardia

Narrow QRS

SVT

Vagal maneuvers IV adenosine† IV verapamil/diltiazem IV beta blocker

Termination

Yes

No,persistent tachycardia with AV block

*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 indicates atrial fibrillation; AV, atrioventricular; BBB, bundle-branch block; DC, direct current; IV, intravenous; LV, left ventricle; QRS, ventricular activation on ECG; SVT, supraventricular tachycardia; VT, ventricular tachycardia.
Algorithm based on the 2003 ACC/AHA/ESC guidelines for the management of supraventricular arrhythmias.

Figure 3: Responses of narrow complex tachycardias to adenosine.

Regular narrow QRS complex tachycardia

IV adenosine

No change in rate

Gradual slowing then reacceleration of rate

Sudden termination

Persisting atrial tachycardia with transient high-grade AV block

Inadequate dose/delivery Condiser VT (fascicular or hight septal origin)

Sinus tachycardia Focal AT Nonparoxysmal junctional tachycardia

AVNRT AVRT Sinus node re-entry Focal AT

Atrial flutter AT

AT indicates atrial tachycardia; AV, atrioventricular; AVNRT, atrioventricular nodal reciprocating tachycardia; AVRT, atrioventricular reciprocating tachycardia; IV, intravenous; QRS, ventricular activation on ECG; VT, ventricular tachycardia.
Algorithm based on the 2003 ACC/AHA/ESC guidelines for the management of supraventricular arrhythmias.

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.

Don'ts

• Do not perform esophageal stimulation if an invasive electrophysiological investigation is planned.

References

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