Examination of pathological features of the right atrioventricular groove in hearts with Ebstein’s anomaly, and correlation with arrhythmias.
Marcondes L, Sanders SP, Del Nido PJ, Walsh EP.
Heart Rhythm. 2020 Jan 21. pii: S1547-5271(20)30026-6. doi: 10.1016/j.hrthm.2020.01.013. [Epub ahead of print]
Select item 31972995
Take Home Points:
- Cardiac anatomy in Ebstein’s anomaly (EA) is frequently characterized by a prominent muscular ridge along the inferior AV annulus.
- The presence of this ridge in postmortem hearts correlates with a clinical history of supraventricular tachycardia.
- The presence of an inferior annular ridge has important implications for the pathogenesis of accessory pathways in EA and may affect catheter ablation outcomes.
Commentary by Dr. Jeremy Moore (Los Angeles) Congenital and Pediatric Cardiac EP section editor: Marcondes and colleagues report on the pathological features of the right AV groove in hearts with EA and correlate it with clinical evidence of arrhythmia. The study points to a prominent inferior annular ridge in many gross specimens with EA and correlates this anatomical finding with the clinical presence of accessory pathways. The authors were able to identify thirty-three cardiac specimens with EA from their insitutional cardiac registry for morphometric analysis. At blinded gross examination, a prominent ridge was identified along the inferior AV annulus in nearly half of the specimens. In addition, when correlated with a clinical history of definite or suspected arrhythmia, the ridge was identified in 7 of 10 patients with arrhythmia versus only 3 of 14 patients without arrhythmia (70% vs 21%, p=0.03).
Due to the quality of the specimens that were up to 60 years old in some cases, the results of microscopic examination in this study were limited. Although accessory muscular connections were suspected by gross examination in 17 cases, this could not be verified by light microscopy. Therefore, a direct correlation between anatomic accessory connections and the presence of a fibromuscular inferior ridge could not be established in the present investigation. As the authors point out however, in the modern era, intact specimens have become a relatively rare commodity as operative outcomes have improved and surgical repair along the true tricuspid annulus is more commonly pursued.
Despite these limitations, the current study contributes greatly to our understanding of the relevant anatomy for catheter ablation of accessory connections in EA. Not only should the usual impedements to successful catheter ablation (i.e. multiple accessory connections, atrial enlargement, displaced AV system conduction, diseased atrial and ventricular myocardium) be expected, but the presence of a prominent annular ridge should be routinely anticipated. The present report also opens the door to future investigations of practical implications of the study findings. For instance, it is possible that the presence of an annular ridge may correlate with specific electrogram characteristics, broad insertions, or multiple accessory connections as often observed in EA. Specific strategies to improve outcomes, such as utilization of intracardiac echocardiography (as the authors suggest) or alternatively, use of pre-procedural advanced imaging with electroanatomical mapping data, could be routinely considered to facilitate technical success for EA. Finally, coronary angiography could be considered standard practice when the operator encounters an annular ridge eithe pre- or intra-procedurally to avoid collateral damage. Ultimately, this study may raise as many questions as it answers, but it represents a major step forward in our understanding of the anatomical correlates of electrophysiology in EA.