ORIGINAL RESEARCH article
Front. Physiol.
Sec. Cardiac Electrophysiology
Evaluation of bi-atrial dynamic electrophysiological properties in atrial septal defect patients
Provisionally accepted
Louisa O'Neill1,2
Keeran Vickneson3
Ali Gharaviri3,4Iain Sim1Daniel O'Hare1,2
John Whitaker1,5Rahul Mukherjee1Steven Niederer1,6
Una Buckley1,7Matthew Wright1,5Matthew Jones5Eric Rosenthal5Alessandra Frigiola5Vivienne Ezzat8
Steven E Williams1,3*Mark D. O'Neill1,5- 1King's College London, London, United Kingdom
- 2Blackrock Clinic, Blackrock, Ireland
- 3University of Edinburgh, Edinburgh, United Kingdom
- 4Universitair Ziekenhuis Brussel, Brussels, Belgium
- 5Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
- 6Imperial College London, London, United Kingdom
- 7St Vincent's Hospital, Fairview, Ireland
- 8Saint Bartholomew's Hospital Barts Heart Centre, London, United Kingdom
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Abstract Background Atrial septal defects (ASD) are associated with an increased incidence of atrial arrhythmias, but their electrophysiological consequences are poorly defined. We hypothesised that conduction and repolarisation would be preferentially altered in the right atrium of ASD patients. Objective To quantify atrial conduction and repolarisation in ASD patients and determine the impact of structural remodelling on restitution properties. Methods Patients with an ASD (n=22) underwent bi-atrial electroanatomic mapping and quantification of effective refractory periods, longitudinal and transverse local conduction. The control group comprised 24 patients without an ASD undergoing ablation for paroxysmal AF. Results Bipolar voltage was significantly lower in ASD patients (right atrium: 1.53±0.46mV versus 1.98±0.59 mV, P=0.017; left atrium: 1.71±0.36mV versus 2.06±0.63mV, P=0.039). There was no significant difference in global conduction velocity in either atrium between ASD and control patients. Effective refractory periods at 600ms were not significantly different between patient groups (right atrium: 247±34.7ms versus 224±36.5ms, P=0.071; left atrium: 244±23.9ms versus 232±40.4ms, P=0.29). However, both conduction and repolarisation demonstrated greater rate adaptation in ASD patients in both atria. Conclusion Right atrial remodelling, characterised by atrial dilatation and increased low voltage, is present in ASD patients. During fixed rate pacing, conduction and repolarisation properties are similar between ASD and AF patients. However, the restitution properties of both conduction and repolarisation are more pronounced in ASD than AF patients.
Keywords: Atrial septal defect, right atrium, Voltage mapping, Atrial refractory period, conduction velocity, Atrial arrhythmia
Received: 15 Sep 2025; Accepted: 25 Nov 2025.
Copyright: © 2025 O'Neill, Vickneson, Gharaviri, Sim, O'Hare, Whitaker, Mukherjee, Niederer, Buckley, Wright, Jones, Rosenthal, Frigiola, Ezzat, Williams and O'Neill. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Steven E Williams
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