Which syndromes are associated with pediatric right bundle branch block?

Updated: Jul 26, 2018
  • Author: Glenn T Wetzel, MD, PhD; Chief Editor: Syamasundar Rao Patnana, MD  more...
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Answer

Duchenne muscular dystrophy is an X-linked myopathy characterized by early onset and rapid progression with muscular weakness and pseudohypertrophy seen in the second year of life. Cardiac findings include mitral valve prolapse, pulmonary flow murmur, and an S3 or S4 gallop. (See Muscular Dystrophy.)

Myotonic dystrophy is characterized by muscular dystrophy, myotonias, hypogonadism, frontal balding, and cataracts. Congenital muscular dystrophy manifests with neonatal hypotonia, paresis, and myotonia. The adult form of myotonic dystrophy is the most common muscular dystrophy seen in adults. ECG findings may include first-degree AV block, left anterior fascicular block, and intraventricular conduction delay. Patients may have arrhythmias, Stokes-Adams attacks, or both. (See Muscular Dystrophy.)

Kearns-Sayre Syndrome is a mitochondrial myopathy with the physical findings of ptosis, chronic progressive external ophthalmoplegia, and abnormal retinal pigmentation. Patients are at risk for heart block and sudden death. [8] Rarely, patients present with dilated cardiomyopathy and heart failure.

Brugada syndrome is a channelopathy mediated by the SCN5A gene. The right bundle branch block pattern seen in patients with this syndrome is not actually right bundle branch block but is a function of the unusual repolarization abnormality. There are subtle differences in the QRS morphology, specifically the latter portion R'. [9] The ECG shows ST-segment elevation in leads V1-V3, and patients are at risk for sudden cardiac death. Cocaine consumption or the use of the antiarrhythmic drugs propafenone, ajmaline, flecainide or procainamide may reveal ECG findings consistent with Brugada syndrome. [10]

The presence of right bundle branch block influences is the diagnostic criterion for patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), a condition associated with T-wave inversions in leads V1-V3. [11]

Patients may have isolated right bundle branch block or right bundle branch block with a left anterior fascicular block.

Right bundle branch block has been associated with blunt chest trauma and polymyositis.

Right bundle branch block may disguise the characteristic QRS morphology associated with ventricular pre-excitation (see Supraventricular Tachycardia, Wolff-Parkinson-White Syndrome). In patients with known right bundle branch block (eg, tetralogy of Fallot) and Wolff-Parkinson-White syndrome with a left-sided accessory pathway, the presence of the pathway is often undetected. In patients with right bundle branch block and a right-sided accessory pathway, the QRS may appear relatively normal without the expected right bundle branch block pattern.


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