Association of right bundle-branch block with left superior or inferior intraventricular block. Its relation to complete heart block and Adams-Stokes syndrome.

Abstract

In recent years, most authors (Lev, 1957;Grant, 1957; Uhley and Rivkin, 1959;Spach et al., 1963;Lev, 1964;Pryor and Blount, 1966;van Bogaert, 1967) have considered that the fibres of the left bundle-branch may be thought of as being arranged into superior and inferior divisions. If a lesion involves a sufficiently large number of fibres of one radiation, the sequence of excitation of the left ventricle is altered. The electrocardiographic patterns of the left superior intraventricular block (Grant, 1956;Pryor and Blount, 1966) and of the left inferior intraventricular block (Pryor and Blount, 1966) have been described.Either of these two conduction disturbances may coexist with complete right bundle-branch block and can be properly diagnosed since right bundlebranch block does not alter the beginning of ventricular activation (Grishman and Scherlis, 1952;Sodi-Pallares et al., 1963;Pryor and Blount, 1966;Castellanos et al., 1966;Saltzman, Linn, and Pick, 1966).The association of a left superior or inferior intraventricular block with a right bundle-branch block may be rationally considered as a hazardous condition, since, in such cases, the atrioventricular conduction theoretically relies on the integrity of only one division of the left bundle. Patients giving evidence of such an association might therefore be prone to complete atrioventricular block.The purpose of the present paper is to report 16 ELECTROCARDIOGRAPHIC CRITERIA First degree atrioventricular block was considered present when the P-R interval, corrected for heart rate, was 0-21 sec. or longer.Right bundle-branch block was diagnosed when the electrocardiogram showed: (1) a QRS duration of 012 sec. or more; (2) a delayed onset of intrinsicoid deflection in the right praecordial leads (0 09 sec. or more), with ventricular activation time of less than 0-06 sec. in V6 (Lenegre, 1957;Lepeschkin, 1964).For the diagnosis of left superior and left inferior intraventricular block in the presence of right bundlebranch block, the vectors that occur within the first 60 msec. of QRS interval were analysed and the criteria proposed by Pryor and Blount (1966) were applied.In left superior intraventricular block, activation travels initially through the inferior division, and finally spreads over the left anterior ventricular wall. The initial forces (20 msec.) are oriented downward (r wave in leads II, III, and aVF, and small q wave in aVL), and the 40-60 msec. vectors are oriented in a superior direction (-30°or higher), causing left axis deviation (Fig.1). In left inferior intraventricular block activation travels initially through the superior division and finally spreads over the left inferior ventricular wall. The initial vector (20 msec.) therefore starts upward (small q wave in leads II, III, aVF, and small r wave in lead aVL), and the 40-60 msec. vectors are oriented in an unusual downward direction. An inferior terminal vector may be normal in young people or in adults who are tall and slender. On the contrary, according to Pryor and Blount (1966), in...

ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities

“…Syncope is common in patients with bifascicular block. Although syncope may be recurrent, it is not associated with an increased incidence of sudden death (73,(102)(103)(104)(105)(106)(107)(108)(109)(110)(111)(112). Even though pacing relieves the neurological symptoms, it does not reduce the occurrence of sudden death (108).…”

ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities

“…Although syncope may be recurrent, it is not associated with an increased incidence of sudden death. 73,[102][103][104][105][106][107][108][109][110][111][112] Even though pacing relieves the neurological symptoms, it does not reduce the occurrence of sudden death. 108 An electrophysiological study may be helpful to evaluate and direct the treatment of inducible ventricular arrhythmias 113,114 that are common in patients with bifascicular block.…”

“…64,114,115 Finally, if the cause of syncope in the presence of bifascicular block cannot be determined with certainty, or if treatments used (such as drugs) may exacerbate AV block, prophylactic permanent pacing is indicated, especially if syncope may have been due to transient thirddegree AV block. [102][103][104][105][106][107][108][109][110][111][112]116 Of the many laboratory variables, the PR and HV intervals have been identified as possible predictors of third-degree AV block and sudden death. Although PR-interval prolongation is common in patients with bifascicular block, the delay is often at the level of the AV node.…”

2012 ACCF/AHA/HRS Focused Update Incorporated Into the ACCF/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities

“…102 Furthermore, no single clinical or laboratory variable, including bifascicular block, identifies patients at high risk of death due to a future bradyarrhythmia caused by bundle-branch block. [102][103][104][105][106][107][108][109][110][111][112]116 Of the many laboratory variables, the PR and HV intervals have been identified as possible predictors of third-degree AV block and sudden death. Although PR-interval prolongation is common in patients with bifascicular block, the delay is often at the level of the AV node.…”