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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Monomorphic ventricular tachycardia (VT)

  • Nonsustained: 3 or more consecutive QRS complexes of uniform configuration and of ventricular origin at a rate of more than 100 bpm

  • Sustained: lasts more than 30 seconds, requires intervention for termination, or is hemodynamically significant

  • Polymorphic: beat-to-beat variation in QRS configuration

GENERAL CONSIDERATIONS

  • VT along with ventricular fibrillation causes 400,000 sudden cardiac deaths (SCDs) per year in the United States

  • Most common with ischemic substrate and depressed left ventricular function

  • Idiopathic dilated cardiomyopathy is also a frequent cause

  • Bundle branch reentry occurs most often with idiopathic dilated cardiomyopathy

  • VT can occur in a structurally normal heart, albeit this is rare

  • Myocardial infarction (MI)–induced scar plays an integral role in reentry that facilitates monomorphic VT

  • Acute ischemia facilitates polymorphic VT

  • Wide QRS tachycardia is mostly secondary to VT

  • Aberrant conduction as a cause of wide QRS tachycardia is rare

  • In patients with a history of MI, wide QRS tachycardia is almost always VT

  • Hemodynamic stability does not exclude VT

  • Sustained versus nonsustained VT does not imply clinical significance

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Resuscitated sudden cardiac death

  • Syncope

  • Near syncope

  • Palpitations

  • Lightheadedness

  • Can be asymptomatic

PHYSICAL EXAM FINDINGS

  • Cannon a waves

  • Hypotension if there is hemodynamic disturbance

DIFFERENTIAL DIAGNOSIS

  • Supraventricular tachycardia with aberrancy

  • Wolff-Parkinson-White syndrome with antidromic tachycardia

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • CBC, basic metabolic panel

  • Serum magnesium

  • Cardiac biomarkers

  • Arterial blood gases if patient is hypoxic

ELECTROCARDIOGRAPHY

  • ECG with rhythm strip to confirm VT and identify location of VT

    • – Atrioventricular dissociation, presence of fusion beats, and duration of R wave to nadir of S wave > 110 ms in chest leads help to differentiate VT from supraventricular tachycardia with aberrancy

  • Outpatient cardiac monitoring to identify frequency, duration, and burden of VT

IMAGING STUDIES

  • Echocardiogram to evaluate left ventricular function and hypertrophic cardiomyopathy (apical variety may be associated with monomorphic VT)

DIAGNOSTIC PROCEDURES

  • Coronary arteriography to identify and quantify coronary artery disease along with ventriculogram and hemodynamic assessment

  • Electrophysiology study to establish diagnosis and determine suitability for ablation

TREATMENT

CARDIOLOGY REFERRAL

  • All patients should be seen by a consulting cardiologist and possibly a cardiac electrophysiologist

HOSPITALIZATION CRITERIA

  • All symptomatic patients must be hospitalized initially in an intensive care unit

MEDICATIONS

  • Medication for stable patients:

    • – Amiodarone (150 mg IV over 10 minutes, then 1 mg/min IV for 6 hours, then 0.5 mg/min for 18 hours) or

    • – Lidocaine (100 mg IV ...

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