Benign nature of atrial dissociation in pediatric patients

Abstract

Atrial dissociation is defined electrocardiographically by the presence of an ectopic atrial rhythm depolarizing independently of the basic sinus rhythm, and is characterized by entrance and exit block. Atrial dissociation is most often observed as an ominous sign in adults with severe myocardial dysfunction. We have observed atrial dissociation in 3 pediatric patients, aged 5 to 22 years, who were essentially asymptomatic from this arrhythmia. All 3 patients are well, without therapy for atrial dissociation, during a follow-up period of 1 to 5 years. The benign nature of atrial dissociation in the pediatric patient as compared with the adult is stressed.

Clinically silent atrial dissociation in a dog

“…8,9 The clinical importance of AD in humans is unclear as it may accompany end-stage cardiac disease, 10 but is considered a benign condition in pediatric patients. 3 The case presented in the veterinary literature was an 8-year-old dog with a history of coughing episodes, a left-sided, apical systolic heart murmur on physical examination, and generalized cardiomegaly. There was no identifiable cause for the AD other than a dilated left atrium, and possibly a region of diseased atrial myocardium that was isolated from the rest of the atrium.…”

“…1 It is defined by the presence of an ectopic atrial rhythm depolarizing independently from the underlying sinus rhythm due to entrance and exit blocks. 3 The propagation of the ectopic depolarization is always limited to a portion of one atrium, resulting in smaller P 0 waves of a different morphology that do not propagate to the ventricles. 4,5 AD has been described in human patients following surgical procedures, such as cardiac transplantation, 5 atrial compartmentalization for management of chronic atrial fibrillation, 6 Mustard operation, 7 and following acute myocardial infarction.…”

Atrial dissociation in a boxer with a carcinoma of the middle ear

“…11,12 Schliesslich wird ein benigne AD auch bei pädiatrischen Patienten beobachtet und benötigt in diesen Fällen keine Therapie. 13 Der Mechanismus der AD ist nicht vollständig geklärt. Eine komplette Interruption der Impulskonduktion zwischen dem rechten Atrium und dem Rest oder von Teilen des linken Atriums (Bachmann's bundle) wurde vermutet.…”

ECG of the Month

“…1,9,10 When a patient with AD is evaluated, differential diagnoses that should be taken into account include atrial parasystole, nonconducted atrial premature depolarizations, and artifacts. 1,[9][10][11][12][13][14] Similar to AD, atrial parasystole results from interaction between 2 distinct atrial pacemakers with different discharge rates, with the latent pacemaker protected from being overdriven by the dominant rhythm by an entrance block. 1,10,14 However, unlike AD, the block is unidirectional, so that activity from the ectopic pacemaker can cause depolarization whenever the surrounding myocardium is excitable.…”

“…1,10,14 In the dog described in the present report, atrial parasystole was unlikely because of the presence of 2 different P wave configurations, with the smaller P waves attributable to the ectopic focus, irregular P'-P' intervals that were not mathematically related, and P' waves that neither disturbed the basic sinus rhythm nor were conducted to the ventricles, suggesting the existence of an exit block. 1,9,10,[12][13][14] At first glance, when nonconducted atrial premature depolarizations occur almost regularly, the ECG pattern may resemble that of AD. However, in patients with nonconducted atrial premature depolarizations, the coupling interval between the ectopic P' wave to the preceding sinus P waves is usually constant.…”