Sick sinus syndrome in a patient with familial PR prolongation

[Familial sick sinus syndrome associated to strabismus and persistent left superior vena cava]

We report a family in which the mother and her three sons suffered sick sinus syndrome and strabismus. Two members had a persistent left superior vena cava with drainage into coronary sinus. The illness in all members of this family was oligosymptomatic, and well tolerated with mild symptoms like dizziness, fatigue and exercise dyspnea associated with nodal rhythm. Three of them, had episodes of paroxysmal atrial fibrillation. All patients remain asymptomatic after pacemaker implantation.

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.

Sinuatrial disease in young people

A survey at three cardiac centres disclosed nine patients under the age of 25 years with sinus node dysfunction in the absence of other forms of heart disease. All were male and seven were above the 90th centile for height. Ambulatory monitoring was performed on all the first-degree relatives of six of the patients and three families showed conducting system disturbances in the form of sinuatrial disorders or delayed atrioventricular conduction. A genetic factor may be involved in the aetiology of sinuatrial disease in young people.

Familial sinus node dysfunction with autosomal dominant inheritance

A large family with sinus node dysfunction is described, spanning three generations and with an autosomal dominant trait. There was an obvious association between the grade of mental retardation and the severity of the sinoatrial disorder.

De subitaneis mortibus. X. Familial congential heart block

Complete heart block was found shortly after birth in a brother and sister (not twins). Both were treated by electronic pacing because of symptoms attributable to inadequate cardiac output and electrical instability of heart. The boy has done well with his artificial pacemaker and is now six years old. His sister died of complications due in part to the large size of her pacemaker and small size of her body. At necropsy special studies of her heart included the centers for normal impulse formation and concuction. The primary abnormalities were at the junction of atrial septum with atrioventricular (A-V) node, and at the origin of the two bundle branches from the His bundle. The A-V node was isolated by collagen at all its margins except its junction with the His bundle. The proximal His bundle was essentially normal, but from that point on through the initial protions of both the left and right bundle branches there was extensive caseous degeneration which interrupted any possible conduction. These findings are discussed in relation to fetal and postnatal development of the human A-V node, and the His bundle and its branches; and in the context of a recently observed mathematical relationship between sinus rate and two forms of experimentally produced A-V junctional escape rhythms.

Familial atrial dysrhythmia with A-V block. Intracellular microelectrode, clinical electrophysiologic, and morphologic observations

This study is of a family with a syndrome of atrial fibrillation or flutter with advanced or complete atrioventricular (A-V) block, involving four members in two generations. Less serious arrhythmias were documented in another 15 members (three generations). Inheritance was by autosomal dominance with varying degrees of expression. An atrial biopsy was obtained in one of the members, a 40-year-old female who had atrial flutter with advanced A-V block proximal to the His bundle (H-V interval of 39 msec). Intracellular action potential (IAP) recordings from this tissue revealed: 1) partially depolarized cells with depressed IAP amplitude, 2) phase IV diastolic depolarization with spontaneous firing, 3) diminished excitability and responsiveness, and 4) decremental conduction with local block and re-entry. Histological findings revealed vacuolar degeneration, hypertrophy, and early necrosis of atrial cells.

In conclusion, the multiple IAP and pathologic abnormalities provide a basis for atrial dysrhythmia in this family. The etiology of the disease is unknown.