Left anterior hemiblock masking the diagnosis of right bundle branch block

Ortega-Carnicer, Julián; Malillos, M.; Muñoz, Luis; Rodríguez-García, Julián

doi:10.1016/s0022-0736(86)80014-0

Cited by 3 publications

(2 citation statements)

References 4 publications

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“…Such a situation is the result of not only purely LAFB but also with left ventricular hypertrophy (LVH) and/or focal block due to scar (extensive anterior MI) or fibrosis (cardiomyopathy). Sometimes this specific ECG pattern is mistaken as LBBB [9,10].…”

Section: Rbbb and Lafb With No Or Small S Wave In Lead Imentioning

confidence: 99%

Masquerading bundle branch block

Kukla¹,

Baranchuk

Jastrzębski³

et al. 2014

Kardiol Pol

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We here describe a surface 12-lead electrocardiogram (ECG) of a 72-year-old female with a prior history of breast cancer and chemotherapy-induced cardiomyopathy. An echocardiogram revealed left ventricular dysfunction, ejection fraction of 23%, with mild enlarged left ventricle. The 12-lead ECG showed atrial fibrillation with a mean heart rate of about 100 bpm, QRS duration 160 ms, QT interval 400 ms, right bundle branch block (RBBB) and left anterior fascicular block (LAFB). The combination of RBBB features in the precordial leads and LAFB features in the limb leads is known as ''masquerading bundle branch block''. In most cases of RBBB and LAFB, the QRS axis deviation is located between - 80 to -120 degrees. Rarely, when predominant left ventricular forces are present, the QRS axis deviation is near about -90 degrees, turning the pattern into an atypical form. In a situation of RBBB associated with LAFB, the S wave can be absent or very small in lead I. Such a situation is the result of not only purely LAFB but also with left ventricular hypertrophy and/or focal block due to scar (extensive anterior myocardial infarction) or fibrosis (cardiomyopathy). Sometimes, this specific ECG pattern is mistaken for LBBB. RBBB with LAFB may imitate LBBB either in the limb leads (known as 'standard masquerading' - absence of S wave in lead I), or in the precordial leads (called 'precordial masquerading' - absence of S wave in leads V₅ and V₆). Our ECG showed both these types of masquerading bundle branch block - absence of S wave in lead I and in leads V₅ and V₆.

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Section: Rbbb and Lafb With No Or Small S Wave In Lead Imentioning

confidence: 99%

Masquerading bundle branch block

Kukla¹,

Baranchuk

Jastrzębski³

et al. 2014

Kardiol Pol

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“…( 6 ), as described earlier. Other reported variations of masking include left anterior hemiblock concealing RBBB ( 8 ). To our knowledge, a specific case of LBBB masking RBBB has not been reported, but the case presented here ( 3 ) could be regarded as such an example, albeit occurring intermittently.…”

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confidence: 99%

The Hidden Meaning Behind Alternating Bundle Branch Block

Johar

Lim

2020

JACC: Case Reports

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Masquerading bundle branch block: a variety of right bundle branch block with left anterior fascicular block

Elizari

Baranchuk

Chiale

2013

Expert Review of Cardiovascular Therapy

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The so-called 'masquerading' type of right bundle branch block is caused by the simultaneous presence of a high-degree left anterior fascicular block often accompanied with severe left ventricular enlargement and/or fibrotic block in the anterolateral wall of the left ventricle. These conditions tend to reorient the terminal electrical forces of the QRS complex towards the left and upwards, in such a way that the characteristic slurred S wave in lead I becomes smaller or even disappears. In many cases of standard masquerading right bundle branch block, a small Q wave in lead I is present due to the initial forces of the left anterior fascicular block, which are oriented rightwards and inferiorly. However, in some cases, the Q wave in lead I also vanishes, and the mimicking of a left bundle branch block becomes perfect in standard leads. This is commonly associated with an inferior myocardial infarction or severe inferior fibrosis in cardiomyopathies. The typical QRS changes of right bundle branch block may eventually be concealed even in the right precordial leads; under such circumstances, the ECG diagnosis may be mistaken and the right bundle branch block totally missed. The masquerading right bundle branch block carries a poor prognosis, since it always implies the presence of a severe underlying heart disease.

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Left anterior hemiblock masking the diagnosis of right bundle branch block

Cited by 3 publications

References 4 publications

Masquerading bundle branch block

Masquerading bundle branch block

The Hidden Meaning Behind Alternating Bundle Branch Block

Masquerading bundle branch block: a variety of right bundle branch block with left anterior fascicular block

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