Researchers report distinct initial atrial activation patterns in noncoronary aortic sinus-atrial tachycardia
Liu X. J Am Coll Cardiol. 2010;56:796-804.
An almost simultaneous activation of the biatrial paraseptal region and diffuse area of initial activation in each of the atria are included as the distinctive initial activation patterns of noncoronary aortic sinus-atrial tachycardia, researchers have documented in a new study.
The group of researchers from China, France and the United Kingdom utilized 3-D electroanatomic mapping during noncoronary aortic sinus-atrial tachycardia (NCAS-AT) in 13 patients and during pacing sequentially from the noncoronary aortic sinus (NCAS) and the para-Hisian atrial area in 15 reference patients. Researchers also used CT in 25 additional reference patients — and gross and microscopic anatomic examination in 12 human hearts — to analyze the spatial relationship between the NCAS and the contiguous atria.
According to study results, the para-Hisian area of the right atrium and the anteroseptal region of the left atrium were activated almost simultaneously during NCAS-AT. Researchers also reported that the initial activation area was relatively wide (9.3 ± 2.6 cm² on the right atrium map; 8.1 ± 2.1 cm² on the left atrium map).
Additionally, NCAS pacing in reference patients reproduced a biatrial activation pattern of NCAS-AT and resulted in a wider initial activation area than para-Hisian atrial pacing within first 20 ms of right atrium activation.
“These activation patterns have implications in improved diagnosis of NCAS-AT, thereby minimizing the risk of inadvertent ablation in the para-Hisian region,” the researchers commented in the concluding statement of their study. “Moreover, in the absence of myocardial tissue in the NCAS, peri-NCAS-AT may be an appropriate terminology.”
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Intra-atrial reentrant tachycardia found lower than previous studies
Stephenson EA. J Am Coll Cardiol. 2010;56:890-896.
Rates of intra-atrial reentrant tachycardia were lower in a recent cross-sectional, multicenter study than previous studies had reported, which researchers attribute in part to changes in surgical strategy.
The Pediatric Heart Network Fontan Cross-Sectional study was composed of 520 children from seven centers who were aged 6 to 18 years. Each of the children had undergone a Fontan procedure at least 6 months before entering the study. Study data within 3 months of enrollment featured echocardiograms, electrocardiograms, exercise testing results, health status questionnaires and medical history from a review of the medical record.
Supraventricular tachycardias were reported in 9.4% of patients, whereas intra-atrial reentrant tachycardia (IART) was present in 7.3% of the population. Four to 6 years after Fontan, the hazard of IART decreased, but it increased after this time period.
Researchers identified the following independent associations of time to occurrence of IART: lower Child Health Questionnaire physical summary score (P<.001); predominant rhythm (P=.002; highest risk with paced rhythm); and type of Fontan operation (P=.037; highest risk with atriopulmonary connection).
“This contemporary cohort of Fontan survivors represents one of the largest datasets available in this unique population,” the researchers wrote. “Overall prevalence of IART (7.3%) is lower in the current cohort than in previous reports. Independent associated factors of IART development include a paced rhythm, lower functional status, and an atriopulmonary connection Fontan, a previously suspected risk factor for atrial tachycardia.”
In an accompanying editorial, George F. Van Hare, MD, from Washington University/St. Louis Children’s Hospital, St. Louis, commented on the Fontan procedure and its role in clinical practice.
“It is disappointing, but perhaps not altogether surprising, that one observes some atrial arrhythmias in patients with the external conduit Fontan,” he said. “The Fontan is not a legacy operation like the Senning procedure for transposition, and with improved survival for the Norwood/Sano operation, more and more children will be coming to surgery for Fontan completion, and so the management of these arrhythmias will continue to occupy us.”
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