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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Rapid ventricular tachycardia (VT), usually with left bundle branch block morphology

  • Generally occurs with advanced nonischemic dilated cardiomyopathy

  • HV interval during the tachycardia is usually the same as in sinus rhythm

GENERAL CONSIDERATIONS

  • The impulse reenters within the bundle branch conduction system

  • Right bundle antegrade in 90% and left bundle retrograde conduction

  • Left bundle antegrade in 10% and right bundle retrograde conduction

  • Intraventricular conduction system disease is common

  • This type of VT is also occasionally seen in valvular cardiomyopathy

  • Delay within the conduction system is critical for reentry to sustain this arrhythmia

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Syncope

  • Cardiac arrest

PHYSICAL EXAM FINDINGS

  • Features of cardiomyopathy

  • During tachycardia, patients typically experience hypotension and tissue hypoperfusion

  • S3 may be present secondary to cardiomyopathy

DIFFERENTIAL DIAGNOSIS

  • Intramyocardial reentrant VT

  • Supraventricular tachycardia with aberrancy

  • Mahaim tachycardia

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • Basic metabolic panel

  • Thyroid-stimulating hormone

  • Serum magnesium level

ELECTROCARDIOGRAPHY

  • ECG during tachycardia typically shows left bundle branch block morphology tachycardia

  • ECG in sinus rhythm usually shows intraventricular conduction delay

IMAGING STUDIES

  • Echocardiography to evaluate left ventricular function and valvular abnormalities

DIAGNOSTIC PROCEDURES

  • Invasive electrophysiologic study to establish mechanism of arrhythmia and determine feasibility of ablation

TREATMENT

CARDIOLOGY REFERRAL

  • All patients with suspected bundle branch reentry VT should be referred to a cardiac electrophysiologist

HOSPITALIZATION CRITERIA

  • All patients with this condition require hospitalization for management

MEDICATIONS

  • No effective medication therapy exists

THERAPEUTIC PROCEDURES

  • Invasive electrophysiologic study followed by ablation of the right bundle branch

SURGERY

  • Implantable cardioverter-defibrillator (ICD) is recommended concurrent with ablation because of the risk of sudden death associated with poor left ventricular function

MONITORING

  • Ablation is curative

  • Patients with an ICD require follow-up of the device every 3 months

DIET AND ACTIVITY

  • Once treated, no special restrictions required other than for the underlying heart disease

ONGOING MANAGEMENT

HOSPITAL DISCHARGE CRITERIA

  • Twenty-four hours after successful ablation

FOLLOW-UP

  • Follow-up for cardiomyopathy and ICD

COMPLICATIONS

  • Once treated, no complications occur

  • Patients remain at risk for sudden cardiac death secondary to the substrate of cardiomyopathy

PROGNOSIS

  • Once the condition ...

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