Familial atrial standstill and inexcitability in childhood

Atrial standstill presenting as cerebral infarction in a 7-year-old girl

Atrial standstill is a rare arrhythmia defined by the absence of mechanical and electrical activity in the atria. Few cases of atrial standstill have been described in children, none of which have presented with cerebral infarction confirmed by imaging. We report a unique case of a 7-year-old girl presenting with expressive aphasia, central facial palsy and irregular pulse with cerebral infarction secondary to atrial standstill. This case illustrates that cardiogenic cerebral embolism in children can be caused by rare conditions like atrial standstill and should be considered in paediatric patients undergoing evaluation for stroke. There are no established treatment guidelines for atrial standstill. We recommend that treatment be directed towards any potential underlying cause. All patients with atrial standstill should receive long-term oral anticoagulation treatment and a permanent cardiac pacemaker implant to reduce the risk of further strokes or other cardiac events.

Persistent atrial standstill in noncompaction cardiomyopathy

Atrial standstill is a rare form of bradyarrhythmia and consists of a transitory or permanent loss of the electrical and mechanical activity of the atria. It has been described in a few cases of long-standing valvular disease, amyloidosis, myocarditis, and muscular dystrophy. We report on a young female with noncompaction cardiomyopathy that progressed to congestive heart failure. Electrocardiogram showed persistence atrial standstill that was confirmed clinically and by electrocardiomyopathy, Doppler two-dimensional echocardiogram, and tissue Doppler imaging. We assume that worsening of asymptomatic noncompaction and progression to the congestive form of cardiomyopathy could be presaged by the presence of persistent atrial standstill. Thus, persistence of atrial standstill in asymptomatic cardiomyopathy is a sign of poor prognosis.

Familial Atrial Standstill in Association with Dilated Cardiomyopathy

. Atrial standstill is an extremely uncommon arrhythmia that rarely appears to be familial and genetically determined. Atrial standstill has been associated with several conditions including, but not restricted to, congenital heart disease, valvular heart disease, conduction disturbances, Brugada syndrome, myocardial infarction, and amyloidosis. Only a few cases of familial clustering of atrial standstill have been reported so far. This report represents a family with atrial standstill associated with syncope, dilated cardiomyopathy, and sudden cardiac death.

Congenital sick sinus syndrome caused by recessive mutations in the cardiac sodium channel gene (SCN5A)

Sick sinus syndrome (SSS) describes an arrhythmia phenotype attributed to sinus node dysfunction and diagnosed by electrocardiographic demonstration of sinus bradycardia or sinus arrest. Although frequently associated with underlying heart disease and seen most often in the elderly, SSS may occur in the fetus, infant, and child without apparent cause. In this setting, SSS is presumed to be congenital. Based on prior associations with disorders of cardiac rhythm and conduction, we screened the alpha subunit of the cardiac sodium channel (SCN5A) as a candidate gene in ten pediatric patients from seven families who were diagnosed with congenital SSS during the first decade of life. Probands from three kindreds exhibited compound heterozygosity for six distinct SCN5A alleles, including two mutations previously associated with dominant disorders of cardiac excitability. Biophysical characterization of the mutants using heterologously expressed recombinant human heart sodium channels demonstrate loss of function or significant impairments in channel gating (inactivation) that predict reduced myocardial excitability. Our findings reveal a molecular basis for some forms of congenital SSS and define a recessive disorder of a human heart voltage-gated sodium channel.

A cardiac sodium channel mutation cosegregates with a rare connexin40 genotype in familial atrial standstill

Atrial standstill (AS) is a rare arrhythmia that occasionally appears to be genetically determined. This study investigates the genetic background of this arrhythmogenic disorder in a large family. Forty-four family members were clinically evaluated. One deceased and three living relatives were unambiguously affected by AS. All other relatives appeared unaffected. Candidate gene screening revealed a novel mutation in the cardiac sodium channel gene SCN5A (D1275N) in all three affected living relatives and in five unaffected relatives, and the deceased relative was an obligate carrier. In addition, two closely linked polymorphisms were detected within regulatory regions of the gene for the atrial-specific gap junction protein connexin40 (Cx40) at nucleotides -44 (G-->A) and +71 (A-->G). Eight relatives were homozygous for both polymorphisms, which occurred in only approximately 7% of control subjects, and three of these relatives were affected by AS. The three living AS patients exclusively coinherited both the rare Cx40 genotype and the SCN5A-D1275N mutation. SCN5A-D1275N channels showed a small depolarizing shift in activation compared with wild-type channels. Rare Cx40 genotype reporter gene analysis showed a reduction in reporter gene expression compared with the more common Cx40 genotype. In this study, familial AS was associated with the concurrence of a cardiac sodium channel mutation and rare polymorphisms in the atrial-specific Cx40 gene. We propose that, although the functional effect of each genetic change is relatively benign, the combined effect of genetic changes eventually progresses to total AS.

Familial atrial standstill with coexistent atrial flutter

A child with familial atrial standstill and a ventricular pacemaker had syncope due to atrial flutter that was treated by His-bundle ablation. Bradycardia protection alone may be insufficient in patients with atrial standstill.

[Cardiac involvement in neuromuscular diseases]

Many neuromuscular disorders involve the heart, occasionally with overt clinical disease. Muscular dystrophies (dystrophinopathies, limb girdle muscular dystrophy, Emery-Dreifuss muscular dystrophy, Steinert's myotonic dystrophy), congenital myopathies, inflammatory myopathies and metabolic diseases (glycogenosis, periodic paralysis, mitochondrial diseases) may produce dilated or hypertrophic cardiomyopathy and heart rhythm or conduction disturbances. Furthermore the heart is commonly involved in some hereditary and degenerative diseases (Friedreich's ataxia and Kugelberg-Welander syndrome) and acquired (Guillain-Barré syndrome) or inherited (Refsum's disease and Charcot-Marie-Tooth syndrome) polyneuropathies. A cardiologist's high clinical suspicion and a simple but systematic skeletal muscle and peripheral nerve investigation, including muscle enzymes quantification, neurophysiological study and muscle biopsy, are necessary for an accurate diagnosis. In selected patients, more sophisticated biochemical and genetic analysis will be necessary. In most cases, endomyocardial biopsy is not essential for the diagnosis.

Total atrial paralysis after permanent dual chamber cardiac pacing

A 73 year old woman with known ischaemic heart disease and ischaemic ventricular tachycardia underwent temporary dual chamber pacing as part of the treatment to suppress tachycardia. Insertion of a permanent dual chamber system seven days later was uncomplicated. Total atrial paralysis, with inability to pace the atrium or obtain an atrial electrocardiogram from four atrial sites, developed within 24 hours of the permanent system being implanted. Atrial electrical and mechanical function recovered over several weeks.

Persistent atrial standstill--clinical, electrophysiological, and morphological study

Persistent atrial standstill (PAS) is a rare disorder characterized by absence of atrial activity on the surface and intracavity electrograms, absence of atrial mechanical activity, and inability to electrically stimulate the atria. Four patients (ages 18-60 years) with PAS were evaluated. One of these (no. 3) only had right atrial (RA) standstill, whereas left atrium (LA) showed spontaneous activity and could be stimulated electrically. As RA biopsy is not possible, right ventricular (RV) endomyocardial biopsy (EMB) was obtained to identify possible atrial pathology that revealed inflammatory myocarditis, 2; amyloidosis, 1; and myocardial hypertrophy with fibrosis, 1. Three patients were given permanent pacemakers. One of these with amyloidosis died suddenly. One is lost to follow-up. The others cases are persisting with PAS.

Mendelian etiologies of stroke

There are many genetic disorders associated with an increased risk for stroke that may easily be overlooked in the evaluation of both adult and pediatric acute stroke victims. The recognition of a genetic disorder as the cause of a stroke has important implications not only for the immediate care of the stroke victim, but often also for others in the patient's family who may be at risk for the same disease and for whom preventive measures sometimes can be taken. We present here a comprehensive review of genetic disorders associated with stroke in the nongeriatric age groups for which a causative role in the evolution of stroke has been recognized or is likely. For each disorder, the major clinical and biochemical characteristics as well as the probable pathogenetic mechanisms of stroke are discussed, together with the appropriate testing required to screen for and confirm the diagnosis. The great variety of genetic disorders and mechanisms causing stroke underscores the increasing importance of understanding genetic disease for appropriate diagnosis and treatment of a common clinical problem affecting both children and adults.

Benign X-linked (Emery-Dreifuss) muscular dystrophy is not benign

Emery-Dreifuss muscular dystrophy is sometimes referred to as benign X-linked muscular dystrophy. We present two young patients with this disorder who had severe cardiovascular complications including: conduction disease, major thromboembolic events, valvular dysfunction with congestive cardiac failure, ventricular tachyarrhythmias, and sudden cardiac death. Of these cardiac problems, only conduction disease has been previously emphasized. This form of muscular dystrophy is not benign--it has malignant cardiac manifestations.