Case reportPartial atrioventricular canal defect with inverted atrioventricular nodal input into an inferiorly displaced atrioventricular node
Introduction
Arrhythmias figure prominently among the issues encountered in adults with congenital heart disease.1 Transcatheter ablation of perinodal targets may be particularly challenging when atrioventricular (AV) conduction tissue is displaced, as in AV canal defects.2, 3 Advances in mapping and ablation technology now permit detailed elucidation of complex substrates that further our understanding of arrhythmia mechanisms and render catheter ablation feasible and safe. In this report, we describe a patient with a partial AV canal defect, AV nodal reentrant tachycardia, and inverted AV nodal input successfully treated by an approach combining electroanatomic mapping with cryoablation.
Section snippets
Case report
A 25-year-old woman with a surgically repaired partial AV canal defect was referred for paroxysmal supraventricular tachycardia. When the patient was age 4 years, an anterior mitral valve cleft was sutured and a primum atrial septal defect closed with a Teflon patch via a right atriotomy. At age 9, she experienced recurrent palpitations of sudden onset that spontaneously subsided within 10 to 15 minutes. Over the years, palpitations occurred with increasing frequency and duration despite
Discussion
Partial AV canal defects account for 1% to 2% of all congenital heart malformations and are characterized by a primum atrial septal defect, clefts of mitral and occasionally tricuspid valves, an intact ventricular septum, and two separate AV valve annuli.4 Prior histopathologic studies have defined the course of the altered AV conduction system. Typically, the compact AV node occupies an inferior position outside of the triangle of Koch, anterior to the mouth of the coronary sinus and adjacent
Conclusion
AV nodal reentrant tachycardia was diagnosed in a patient with a surgically repaired partial AV canal defect. The retrograde fast pathway was electroanatomically mapped below the inferoposteriorly displaced AV node. The anterograde slow pathway was cryomapped and successfully cryoablated superior to the His bundle. The combination of technologies used allowed elucidation of the arrhythmia substrate and safe interruption of slow pathway conduction. Whether inversion of AV nodal inputs is
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Cited by (26)
Catheter Cryoablation: Biophysics and Clinical Applications
2019, Catheter Ablation of Cardiac ArrhythmiasIntroduction to the Congenital Heart Defects: Anatomy of the Conduction System
2017, Cardiac Electrophysiology ClinicsChapter 2. Usefulness of three-dimensional mapping in patients with nodal tachycardia and anomalous pathway tachycardias
2016, Revista Colombiana de CardiologiaPACES/HRS expert consensus statement on the recognition and management of arrhythmias in adult congenital heart disease: Developed in partnership between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the governing bodies of PACES, HRS, the American College of Cardiology (ACC), the American Heart Association (AHA), the European Heart Rhythm Association (EHRA), the Canadian Heart Rhythm Society (CHRS), and the International Society for Adult Congenital Heart Disease (ISACHD)
2014, Heart RhythmCitation Excerpt :Little has been written beyond case reports of patients who have undergone clinically successful ablation of AV nodal reentrant tachycardia in complex CHD. The site of the slow pathway has in some cases been imputed to be at nonstandard anatomical locations, based on apparent response to ablation.231,232 In small subsets of cases reported in the context of larger series on Ebstein anomaly and transposition of the great vessels, successful slow pathway modification was successful at the expected posterior aspect of the AV septum.237,245,246
PACES/HRS Expert Consensus Statement on the Recognition and Management of Arrhythmias in Adult Congenital Heart Disease
2014, Canadian Journal of CardiologyCitation Excerpt :Caution should be exercised when operating in this vicinity or ablating in the right inferior paraseptal region. Inversion of the fast and slow components of the AV node has been reported; this knowledge is critical if considering ablation for AV nodal reentrant tachycardia in a patient with an AV septal defect.232 In patients with congenitally corrected transposition of the great arteries, the conduction tissue is displaced anteriorly and laterally, with an elongated and fragile His bundle coursing anterior along the pulmonary valve.43-46
This work was supported in part by the Canada Research Chair in Electrophysiology and Adult Congenital Heart Disease to Dr. Khairy.
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Dr. Dubuc is a consultant for CryoCath Technologies.