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Cardiology

Right Bundle-Branch Block Pattern in Precordial Leads and Left Bundle-Branch Block Pattern With Left Axis Deviation in Frontal Plane Leads—What Does This Mean?

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JAMA Internal Medicine

Published Online: October 24, 2022

Challenges in Clinical Electrocardiography

Article Information and Disclosures

Matheus Kiszka Scheffer, MD¹;

Mariana Fuziy Nogueira De Marchi, MD¹;

Ana Carolina Muniz Costa, MD¹

Author Affiliations

¹Dante Pazzanese Institute of Cardiology, São Paulo, Brazil

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A patient in their 70s presented to the emergency department with a history of syncope that occurred 7 days before admission without preceding signs or symptoms. Since then, the patient had been experiencing fatigue, mainly from exertion. The patient had a history of hypertension, heart failure, and aortic valve replacement surgery in 2020, complicated on follow-up by prosthetic valve thrombosis. The patient had been taking warfarin, furosemide, metoprolol succinate, and spironolactone. Initial evaluation revealed a heart rate of 61 beats/min, blood pressure of 114/74 mm Hg, oxygen saturation of 96%, and temperature of 36.6 °C. The physical examination was unremarkable, and a 12-lead electrocardiogram (ECG) was obtained (Figure).

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The condition MBBB is a rare form of bifascicular block associated with a high prevalence of progression to advanced atrioventricular block and poor prognosis.¹ The term was coined by Richman and Wolff² in 1954 to describe the electrocardiographic pattern of RBBB in precordial leads and LBBB in limb leads. Initially, the analysis of the vectorcardiogram of these exams was interpreted as LBBB modified by extensive septal and posterolateral infarctions. However, later studies including anatomopathological assessment of the cardiac conduction system showed severe damage to the conduction system in both the right and the left bundle branch, associated with severe fibrosis and substantial left ventricular hypertrophy.³

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Article Information

Corresponding Author: Matheus Kiszka Scheffer, MD, Dante Pazzanese Institute of Cardiology, Avenida Dr Dante Pazzanese, N° 500—Vila Mariana, São Paulo/SP 04012909, Brazil (matheus.scheffer@dantepazzanese.org.br).

Published Online: October 24, 2022. doi:10.1001/jamainternmed.2022.4708

Conflict of Interest Disclosures: None reported.

Additional Information: Matheus Kiszka Scheffer, MD, took the lead in writing the manuscript. All authors provided critical feedback and helped shape the research, analysis, and manuscript. All authors have seen and approved the final version of the manuscript.

References

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Rosenbaum MB , Yesurón J , Lázzari JO , Elizari MV . Left anterior hemiblock obscuring the diagnosis of right bundle branch block. Circulation. 1973;48(2):298-303. doi:10.1161/01.CIR.48.2.298 PubMed Google Scholar Crossref

Surawicz B , Childers R , Deal BJ , et al; American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; American College of Cardiology Foundation; Heart Rhythm Society; Endorsed by the International Society for Computerized Electrocardiology. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. J Am Coll Cardiol. 2009;53(11):976-981. doi:10.1016/j.jacc.2008.12.013 PubMed Google Scholar Crossref

Rosenbaum MB , Elizari MV , Lázzari JO . Los Hemibloqueos. Paidos; 1968.

Puerta RC , González EC , Elizundia JMC , Torres YT . El bloqueo de rama disfrazado revisitado. Revista de la Federación Argentina de Cardiología. 2012;41(2):75-79.Google Scholar

Bayés de Luna A , Torner P , Oter R , et al. Study of the evolution of masked bifascicular block. Pacing Clin Electrophysiol. 1988;11(11 Pt 1):1517-1521. doi:10.1111/j.1540-8159.1988.tb06267.x PubMed Google Scholar Crossref

Schroder e Souza TG , Almeida RL , Targueta GP et al Abstract 14845: masquerading bundle branch block: an electrocardiographic marker of poor prognosis. Circ. 2015;132(suppl_3). doi:10.1161/circ.132.suppl_3.14845 Google Scholar Crossref

Gómez Barrado JJ , Turégano Albarrán S , García Rubira JC , et al. Características clínicas y electrocardiográficas del bloqueo bifascicular disfrazado. Rev Esp Cardiol. 1997;50(2):92-97. doi:10.1016/S0300-8932(97)73185-3 PubMed Google Scholar Crossref

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Credit Designation Statement: The American Medical Association designates this Journal-based CME activity activity for a maximum of 1.00  AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to:

1.00 Medical Knowledge MOC points in the American Board of Internal Medicine's (ABIM) Maintenance of Certification (MOC) program;;
1.00 Self-Assessment points in the American Board of Otolaryngology – Head and Neck Surgery’s (ABOHNS) Continuing Certification program;
1.00 MOC points in the American Board of Pediatrics’ (ABP) Maintenance of Certification (MOC) program;
1.00 Lifelong Learning points in the American Board of Pathology’s (ABPath) Continuing Certification program; and
1.00 CME points in the American Board of Surgery’s (ABS) Continuing Certification program

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