Familial atrioventricular heart block; an autosomal dominant trait

Progressive cardiac conduction defect and cardiomyopathy in siblings with syncope

Three siblings evaluated for syncope were found to have left bundle-branch block. Progression to complete heart block occurred in all. Pacemaker implantation eliminated syncopal epidoses in each case. Echocardiographic manifestations of cardiomyopathy were present in each child despite normal roentgenographic heart size. Careful family study identified no other affected members with conduction defects. These children area believed to represent a form of familial cardiomyopathy in which clinical manifestations of cardiac conduction system disease predominate.

Hereditary bundle branch defect: right bundle branch blocks of different causes have different morphologic characteristics

Hereditary bundle branch defect is an autosomal dominant genetic disease that, in a large Lebanese family, was mapped to the long arm of chromosome 19. Affected individuals have various combinations of conduction defects such as right bundle branch block, left or right QRS frontal-axis deviation, or atrioventricular blocks. We now further characterize this disease with the presentation of a two-decade follow-up and analysis of electrocardiographic features and mutation-carrier status. The conduction block may be overt in the first year of life, and among affected individuals, there is a worsening of the conduction block in 5% to 15% of cases, leading to complete atrioventricular block and possibly to sudden death. A group of individuals had QRS anomalies in right precordial leads such as rsr's', rss', or rSr', which may account for partial right bundle branch blocks. In this group, which we referred to as having an "r' pattern," 53% were actually mutation carriers, and 19% evolved toward a complete fascicular block. By contrast, mutation carriers with a normal electrocardiogram remained normal. The QRS morphologic appearance in the right precordial leads of affected individuals and r' pattern mutation carriers is notable for the absence or weakness of negative forces resulting in a rsR' or rR' morphology. In addition, an r' pattern is highly suggestive of a mutation carrier status in the presence of a broad r wave in aVR and s in V6 or a frontal-axis deviation. Finally, mutation carriers demonstrate a conduction block significantly more often in males than females (75% and 50%, respectively). This incomplete penetrance and slow evolution suggest that the actual prevalence of hereditary bundle branch defect is very much underestimated.

Familial neonatal atrial tachycardia

A father and his two sons each presented with atrial tachycardia in the newborn period. The father went on to develop dilated cardiomyopathy. The first son (who also had transposition of the great arteries) died from the arrhythmia after surgery. The second son is currently successfully managed pharmacologically.

Familial atrioventricular heart block of adult onset: electrocardiogram and HLA typing analysis

A family was investigated because of heart block and sinus arrhythmia. The electrical characteristics were: (1) adult onset in all members; (2) complete heart block with atrial fibrillation in 2, and first- or second-degree heart block in 7 members; and (3) sinus arrhythmia in 3 members. Human leukocyte antigen (HLA) typing was performed. HLA A2, B39, Cw7, and DR12 were positive in 4 of 5 members in the heart block group. In the sinus arrhythmia group, HLA DR12 was positive in all members. In the normal group, none of these HLA typings was positive except one. These findings indicate a tighter relationship between heart block and the HLA locus than previously thought.

Hereditary atrioventricular conduction defect in a child

Hereditary atrioventricular conduction defect is an uncommon cause of acquired complete heart block in children. We report a father and son, both of whom presented with seizures as the initial manifestation of acquired complete heart block and required permanent pacemaker implantation. A review of the variations of this entity and the histopathological findings of previously reported cases is presented. Family members of patients with acquired heart block of uncertain etiology should be examined for the presence of conduction abnormalities that may progress to complete heart block.

Familial combined sinus node and atrioventricular conduction dysfunctions

Eighteen members of a family were investigated for cardiac conduction abnormalities following the discovery of a second-degree atrioventricular block in a fetus at 35 weeks of gestation. The conduction disturbance was diagnosed by ultrasonography. Seven of the family members were diagnosed as suffering from sinus node dysfunction and/or various degrees of atrioventricular block. Three of them were children aged 9 months to 6 years and all were asymptomatic. The symptomatic family members were two adults. One of them had a pacemaker inserted for a complete atrioventricular block and Adam-Stokes attacks while the other had had several fainting attacks. The clinical, electrocardiographic and ultrasonographic findings of the family members are presented. Previous reports in literature have documented the dominant transmission of familial sinus node dysfunctions or of familial cardiac conduction disturbances. The coexistence of both dysfunctions in the same family has not been emphasized in previous reports. A review of these previously reported families, as well as our patients, suggests the need of investigation and follow-up of the families in which one member of any age is diagnosed as suffering from an "idiopathic" disturbance of the cardiac conduction system.

Autoantibodies directed against sicca syndrome antigens in the neonatal lupus syndrome

Clinical and serologic studies on three infants who had the neonatal lupus syndrome and studies on their mothers revealed an association with antibodies to sicca syndrome antigens. From initial studies and a 2-year follow-up, there is evidence that indicates transplacental passage of autoantibodies directed against Sjögren's (sicca) syndrome-associated nuclear antigens from asymptomatic mothers to newborns who subsequently developed neonatal lupus. Besides the presence of antinuclear antibodies, the mothers of these infants also showed high rheumatoid factor titers, and two had evidence of mild decreasing tearing on ophthalmologic examination. On follow-up examination 2 to 3 years later, both infants and mothers lacked evidence of active disease, and only the mothers continued to demonstrate the serologic abnormalities seen initially. Based on our findings, we postulate newborns of mothers with serologic or clinical evidence of Sjögren's (sicca) syndrome may be at greater risk for developing neonatal lupus.

Hereditary bundle branch system defect. A new genetic entity?

A familial survey demonstrated mendelian inheritance in three large kindreds with conduction abnormalities and heart block. The trait was autosomal dominant, with varying expressivity and penetrance, apparent male preponderance, and congenital onset. Manifestations included right bundle branch block, left axis deviation, and right bundle branch block associated with left axis deviation. Complete heart block proved almost always to be a late event, and developed in all documented cases from bilateral bundle branch block. An r' pattern, most likely representing a right ventricular conduction delay, is discussed.