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WIDE QRS TACHYCARDIA

Jack CF Chong, MS, MD

新光急診 張志華醫師

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Favor VT

1. No RBBB or LBBB pattern

2. Extreme axis (northwest axis) • QRS positive in aVR and negative in I + aVF

3. QRS >160 ms

4. AV dissociation• P and QRS at different rates)

5. Capture beats • SA node transiently ‘captures’ the ventricles – normal QRS

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Favor VT

6. Fusion beats • Sinus and ventricular beat coincides to produce a hybrid QRS

7. Positive or negative concordance• V1-6: all positive (R) or all negative (QS), with no RS

8. Brugada’s sign • Distance from the onset of QRS to nadir of S > 100 ms

9. Josephson’s sign6. Notching near the nadir of the S

10. RSR’ (taller left rabbit ear)• This is the most specific finding in favor of VT

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Favor VT

Appearance in V1-2

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Favor VT

• Age > 35 Y (PPV 85%)

• Structural heart disease

• Ischemic heart disease / previous MI

• Congestive heart failure

• Cardiomyopathy

• Family history of sudden cardiac death (suggesting

conditions such as HOCM, congenital long QT syndrome,

Brugada syndrome or arrhythmogenic right ventricular

dysplasia that are associated with episodes of VT)

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Favor SVT with aberrancy

• Previous ECGs show identical BBB pattern

• Previous ECGs show WPW

(short PR, broad QRS, delta wave)

• PHx of PSVT

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Idiopathic VT

• Right ventricular outflow tract VT (RVOTVT)

• QRS duration > 100-140 ms ** usually > 160 ms in other VT

• LBBB Morphology

• Rightward / inferior axis (around +90 degree)

• AV dissociation, capture/fusion beats

• Idiopathic left fascicular VT (ILFVT)

• QRS duration > 100-140 ms ** usually > 160 ms in other VT

• RBBB Morphology

• Superior axis (around -90 degree)

• AV dissociation, capture/fusion beats

• Shorter RS (60-80 ms) ** usually > 100 ms in other VT

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Idiopathic VT

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VT mimics – how to approach?

1. HR >150 no pulse Defib. and ACLS

2. HR >150 unstable DC shock (sync. cardioversion 100J)

3. WPW + A-fib. DC shock or defib. / procainamide

4. Young / BBB SVT with aberrancy adenosine trial or vagal maneuvers

5. Regular really wide QRS (> 200 ms) sine waves hyperkalemia or Na channel blocking agents (e.g. TCA) calcium + NaHCO3

6. Dominant R’ in aVR, narrow R and deep wide S in V3-6 TCA toxicity NaHCO3

7. VT (HR >130, QRS > 160 ms) amiodarone / lidocaine / procainamide

8. Idiopathic VT (RVOT / LF) Adenosine / verapamil