Supernormal Conduction and Suppression of Spatial Discord in Alternans of Cardiac Action Potentials
Spatially discordant alternans (DA) of action potential durations (APD) is thought to be more pro-arrhythmic than concordant alternans. Super normal conduction (SNC) has been reported to suppress formation of DA. An increase in conduction velocity (CV) as activation rate increases, i.e. a negative C...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2016-01-01
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| Series: | Frontiers in Physiology |
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| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fphys.2015.00407/full |
| _version_ | 1819010168218714112 |
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| author | Linyuan eJing Anuj eAgarwal Abhijit ePatwardhan |
| author_facet | Linyuan eJing Anuj eAgarwal Abhijit ePatwardhan |
| author_sort | Linyuan eJing |
| collection | DOAJ |
| description | Spatially discordant alternans (DA) of action potential durations (APD) is thought to be more pro-arrhythmic than concordant alternans. Super normal conduction (SNC) has been reported to suppress formation of DA. An increase in conduction velocity (CV) as activation rate increases, i.e. a negative CV restitution, is widely considered as hallmark of SNC. Our aim in this study is to show that it is not an increase in CV for faster rates that prevents formation of DA, rather, it is the ratio of the CV for the short relative to the long activation that is critical in DA suppression. To illustrate this subtlety, we simulated this phenomenon using two approaches; (1) by using the standard, i.e. S1S2 protocol to quantify restitution and disabling the slow inactivation gate j of the sodium current (INa), and (2) by using the dynamic, i.e. S1S1 protocol for quantification of restitution and increasing INa at different cycle lengths (CL). Even though both approaches produced similar CV restitution curves, DA was suppressed only during the first approach, where the CV of the short of the long-short action potential (AP) pattern was selectively increased. These results show that negative CV restitution, which is considered characteristic of SNC, per se, is not causal in suppressing DA, rather, the critical factor is a change in the ratio of the velocities of the short and the long APs. |
| first_indexed | 2024-12-21T01:07:58Z |
| format | Article |
| id | doaj.art-b79d7381b7dc4644b93413a78d867b0f |
| institution | Directory Open Access Journal |
| issn | 1664-042X |
| language | English |
| last_indexed | 2024-12-21T01:07:58Z |
| publishDate | 2016-01-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Physiology |
| spelling | doaj.art-b79d7381b7dc4644b93413a78d867b0f2022-12-21T19:21:00ZengFrontiers Media S.A.Frontiers in Physiology1664-042X2016-01-01610.3389/fphys.2015.00407161063Supernormal Conduction and Suppression of Spatial Discord in Alternans of Cardiac Action PotentialsLinyuan eJing0Anuj eAgarwal1Abhijit ePatwardhan2University of KentuckyUniversity of KentuckyUniversity of KentuckySpatially discordant alternans (DA) of action potential durations (APD) is thought to be more pro-arrhythmic than concordant alternans. Super normal conduction (SNC) has been reported to suppress formation of DA. An increase in conduction velocity (CV) as activation rate increases, i.e. a negative CV restitution, is widely considered as hallmark of SNC. Our aim in this study is to show that it is not an increase in CV for faster rates that prevents formation of DA, rather, it is the ratio of the CV for the short relative to the long activation that is critical in DA suppression. To illustrate this subtlety, we simulated this phenomenon using two approaches; (1) by using the standard, i.e. S1S2 protocol to quantify restitution and disabling the slow inactivation gate j of the sodium current (INa), and (2) by using the dynamic, i.e. S1S1 protocol for quantification of restitution and increasing INa at different cycle lengths (CL). Even though both approaches produced similar CV restitution curves, DA was suppressed only during the first approach, where the CV of the short of the long-short action potential (AP) pattern was selectively increased. These results show that negative CV restitution, which is considered characteristic of SNC, per se, is not causal in suppressing DA, rather, the critical factor is a change in the ratio of the velocities of the short and the long APs.http://journal.frontiersin.org/Journal/10.3389/fphys.2015.00407/fullAction Potentialsventricular arrhythmiaConduction Velocity Restitutiondiscordant alternansSupernormal conduction |
| spellingShingle | Linyuan eJing Anuj eAgarwal Abhijit ePatwardhan Supernormal Conduction and Suppression of Spatial Discord in Alternans of Cardiac Action Potentials Frontiers in Physiology Action Potentials ventricular arrhythmia Conduction Velocity Restitution discordant alternans Supernormal conduction |
| title | Supernormal Conduction and Suppression of Spatial Discord in Alternans of Cardiac Action Potentials |
| title_full | Supernormal Conduction and Suppression of Spatial Discord in Alternans of Cardiac Action Potentials |
| title_fullStr | Supernormal Conduction and Suppression of Spatial Discord in Alternans of Cardiac Action Potentials |
| title_full_unstemmed | Supernormal Conduction and Suppression of Spatial Discord in Alternans of Cardiac Action Potentials |
| title_short | Supernormal Conduction and Suppression of Spatial Discord in Alternans of Cardiac Action Potentials |
| title_sort | supernormal conduction and suppression of spatial discord in alternans of cardiac action potentials |
| topic | Action Potentials ventricular arrhythmia Conduction Velocity Restitution discordant alternans Supernormal conduction |
| url | http://journal.frontiersin.org/Journal/10.3389/fphys.2015.00407/full |
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