Trifascicular block

Heart block If first-degree heart block develops, reduce dosage. If the block persists, drug continuation must depend upon the benefit compared with the risk of higher degrees of heart block. Development of second- or third-degree AV block or unifascicular, bifascicular, or trifascicular block requires discontinuation of therapy, unless ventricular rate is controlled by a ventricular pacemaker. 

Although the meaning of bifascicular block is obvious, that of trifascicular block is not as simple. The term trifascicular block is often used rather loosely as previously emphasized. Bilateral bundle branch block, despite 1 1 AV conduction, carries a poor prognosis and should be a Class 1 indication for pacing, even in an asymptomatic patient. 

Rosenbaum MB, Elizari MV, Lazzari JO. Clinical evidence of hemiblock syndrome of RBBB and intermittent LAH and LPH. Trifascicular block. In Rosenbaum MB, Elizari MV, Lazzari JO, (Eds.). The Hemiblocks. Oldsmar, FL, Tampa Tracings 1970 55-69. 

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