Atrioventricular Block and Supraventricular Arrhythmias with X-linked Muscular Dystrophy

This report describes a family showing muscular dystrophy and atrioventricular block with an x-linked hereditary transmission. Among a known pedigree of 101 family members, 12 males were found to have skeletal muscle involvement and six needed pacemakers around age 30 years. Unlike the x-linked muscular dystrophies of Duchenne and of Becker, the predominant skeletal involvement was in humeral muscles, was usually very mild, and did not produce incapacitation. Cardiac involvement consisted of various atrial arrhythmias and atrioventricular block. The few sporadic reports of other families that describe the same disease under different names are briefly reviewed. Recognition of this subtle muscular dystrophy is important for early detection of incipient complete atrioventricular block to prevent fatal complications by pacemaker insertion.