Bifascicular block

Beck J, Salem D, Estes N, Pauker S. A computer-based Markov decision analysis of the management of symptomatic bifascicular block the threshold probability for pacing. J Am Coll Cardiol 1987 9 920-35. 

Preexisting second- or third-degree AV block, right bundle branch block when associated with a left hemiblock (bifascicular block), unless a pacemaker is present to sustain the cardiac rhythm if complete heart block occurs recent myocardial infarction (Ml) presence of cardiogenic shock hypersensitivity to the drug. 

Finally, the development of a bifascicular block (RBBB plus SAH, or RBBB plus inferoposterior hemiblock (IPH)) during the acute myocardial infarction usually is considered a poor prognosis, since this is indicative of a large infarction and the involvement of, at least, two territories (LAD and RCA or LCX). However, on the basis of HERO-2 trial, no data (Wong et al., 2006a) have been found showing that there was no difference in 30-day mortality. 

Especially when it is of new onset. As has been already stated (p. 223), the development of complete RBBB is characteristic of a LAD occlusion, proximal to the first septal branch (Figure 4.66). The prognosis is even worse in case of a bifascicular block. The prognosis is worst in cases of RBBB with wide QRS especially if the BB is of new appearance. 

Bergfeldt L, Edvardsson N, Rosenqvist M, VaUin H, Edhag O. Atrioventricular block progression in patients with bifascicular block assessed by repeated electrocardiography and a bradycardia-detecting pacemaker. Am J Cardiol. 1994 74 1129-1132. 

However, it is unknown whether underlying RBBB (unifascicular block) is prognostically different from underlying LBBB (bifascicular block) in the setting of asymptomatic type I second-degree infranodal block. 

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. 

Englund A, Bergfeldt L, Rosenqvist M. Pharmacological stress testing of the His-Purkinje system in patients with bifascicular block. PACE 1998 21 1979-1987. 

Asymptomatic postoperative bifascicular block with or without 1st degree AV block and without prior 3rd degree AV block... 

Bifascicular block appears to be less frequent, however, and right BBB is more likely to be transient, suggesting that reperfusion therapy may reduce ischemic damage to the bundle branches (14). 

Bellocci F, SantareUi P, Di Gennaro M, Ansalone G, Fenici R. The risk of cardiac complications in surgical patients with bifascicular block. A clinical and electro-physiologic study in 98 patients. Chest 1980 77 343-348. 

The ECG of a 23-month-old boy 1 h after an inadvertent double dose of 120 mg flecainide (9.2mg/kg) revealed sinus rhythm with a terminal R wave in aVR greater than 7 mm, a bifascicular block, prolonged QRS and... 

QTc intervals. Two hours postingestion the flecainide level was 1.4mg/L. After the administration of sodium bicarbonate a dramatic improvement in terminal R wave and bifascicular block was observed [26]. 

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. 

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