Bundle Branch Reentrant Ventricular Tachycardia

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 ...