Israel Medical Association Journal

Background: Familial dysautonomia is a hereditary disease characterized by dysfunction of the sensory and autonomic nervous systems. Studies in patients with familial dysautonomia have shown that abnormal cardiac autonomic denervation might influence repolarization. Autonomic tone also affects atrial conduction parameters and P-wave dispersion, which are predictive of atrial fibrillation.

Objectives: To examine the possible association of familial dysautonomia with abnormal atrial conduction and P-wave dispersion.

Methods: The study population included 12 patients with familial dysautonomia and age and sex-matched control subjects. All participants underwent a 12-lead electrocardiogram under strict conditions. P-wave lengths and P-wave dispersion were computed from a randomly selected beat and an averaged beat using designated computer software.

Results: There were no statistically significant differences between the groups in minimal, maximal, and average P-wave duration or P-wave dispersion for a randomly selected beat. P-wave dispersion for an averaged beat was also similar. During 6 months follow-up, no supraventricular arrhythmias were documented in either group.

Conclusions: We found that patients with familial dysautonomia had P-wave dispersion parameters not significantly different from those of controls. Further research is required to clarify the effects of dysautonomia on atrial conduction in familial dysautonomia.

Background: Familial dysautonomia is a genetic disease that affects the sensory and autonomic nervous systems with varying severity. The deep breath test is one of several measures used to assess the severity of autonomic diseases, but its value in familial dysautonomia has not yet been investigated.

Objectives: To determine the diagnostic value of the DBT[1] in patients with familial dysautonomia.

Methods: Eight patients with familial dysautonomia and eight healthy volunteers were examined by electrocardiography for 1 minute at rest and during forced deep breathing. The following values were recorded: maximum expiratory and minimum inspiratory heart rate and the difference between them (ΔE/I), standard deviation of the heart rate values, interbeat intervals, and E/I[2] ratio. Spectral power analysis of heart rate variability was also performed.

Results: The patients with familial dysautonomia showed a lesser change in heart rate in response to the change in breathing pattern than the controls. Mean values in the study group were significantly higher for minimal inspiratory heart rate and significantly lower for ΔE/I, heart rate standard deviation and E/I ratio, indicating a non-flexible heart response and abnormal parasympathetic function. These findings were supported by power spectral analysis.

Conclusions: Patients with familial dysautonomia have a significantly disturbed response to physiological stimuli. The DBT may serve as a reliable means to quantify autonomic dysfunction in this patient population.