scholarly journals Idiopathic Ventricular Fibrillation Characterized by Spatial Heterogeneity of Action Potential Duration and Its Restitution Kinetics

2008 ◽  
Vol 49 (6) ◽  
pp. 733-740 ◽  
Author(s):  
Sonoko Ashino ◽  
Ichiro Watanabe ◽  
Masayoshi Kofune ◽  
Kimie Ohkubo ◽  
Yasuo Okumura ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Action Potential ◽  
Spatial Heterogeneity ◽  
Action Potential Duration ◽  
Idiopathic Ventricular Fibrillation

scholarly journals Intramural optical mapping of Vm and Cai2+ during long-duration ventricular fibrillation in canine hearts

2012 ◽  
Vol 302 (6) ◽  
pp. H1294-H1305 ◽  
Author(s):  
Wei Kong ◽  
Raymond E. Ideker ◽  
Vladimir G. Fast
Keyword(s):  
Ventricular Fibrillation ◽  
Action Potential ◽  
Short Duration ◽  
Action Potential Duration ◽  
Cycle Length ◽  
The Other ◽  
Membrane Voltage ◽  
Long Duration ◽  
Intracellular Ca ◽  
Rapid Pacing

Intramural gradients of intracellular Ca2+ (Cai2+) Cai2+ handling, Cai2+ oscillations, and Cai2+ transient (CaT) alternans may be important in long-duration ventricular fibrillation (LDVF). However, previous studies of Cai2+ handling have been limited to recordings from the heart surface during short-duration ventricular fibrillation. To examine whether abnormalities of intramural Cai2+ handling contribute to LDVF, we measured membrane voltage ( Vm) and Cai2+ during pacing and LDVF in six perfused canine hearts using five eight-fiber optrodes. Measurements were grouped into epicardial, midwall, and endocardial layers. We found that during pacing at 350-ms cycle length, CaT duration was slightly longer (by ≃10%) in endocardial layers than in epicardial layers, whereas action potential duration (APD) exhibited no difference. Rapid pacing at 150-ms cycle length caused alternans in both APD (APD-ALT) and CaT amplitude (CaA-ALT) without significant transmural differences. For 93% of optrode recordings, CaA-ALT was transmurally concordant, whereas APD-ALT was either concordant (36%) or discordant (54%), suggesting that APD-ALT was not caused by CaA-ALT. During LDVF, Vm and Cai2+ progressively desynchronized when not every action potential was followed by a CaT. Such desynchronization developed faster in the epicardium than in the other layers. In addition, CaT duration strongly increased (by ∼240% at 5 min of LDVF), whereas APD shortened (by ∼17%). CaT rises always followed Vm upstrokes during pacing and LDVF. In conclusion, the fact that Vm upstrokes always preceded CaTs indicates that spontaneous Cai2+ oscillations in the working myocardium were not likely the reason for LDVF maintenance. Strong Vm-Cai2+ desynchronization and the occurrence of long CaTs during LDVF indicate severely impaired Cai2+ handling and may potentially contribute to LDVF maintenance.

scholarly journals 706-4 Preconditioning Shortens Action Potential Duration and Lowers Ventricular Fibrillation Threshold in Pig Hearts

1995 ◽  
Vol 25 (2) ◽  
pp. 43A
Author(s):  
Michel Ovize ◽  
Jean F Aupetit ◽  
Gilles Rioufol ◽  
Joseph Loufoua ◽  
Xavier André-Fouët ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Action Potential ◽  
Action Potential Duration ◽  
Ventricular Fibrillation Threshold

Effects of [K+]o on electrical restitution and activation dynamics during ventricular fibrillation

2000 ◽  
Vol 279 (6) ◽  
pp. H2665-H2672 ◽  
Author(s):  
Marcus L. Koller ◽  
Mark L. Riccio ◽  
Robert F. Gilmour
Keyword(s):  
Ventricular Fibrillation ◽  
Action Potential ◽  
Action Potential Duration ◽  
Maximum Amplitude ◽  
Spatiotemporal Organization ◽  
Activation Dynamics ◽  
Spontaneous Frequency ◽  
Upstroke Velocity

To test whether hyperkalemia suppresses ventricular fibrillation (VF) by reducing the slope of the action potential duration (APD) restitution relation, we determined the effects of the extracellular K+concentration ([K+]o) ([KCl] = 2.7–12 mM) on the restitution of APD and maximum upstroke velocity ( V max) the magnitude of APD alternans and spatiotemporal organization during VF in isolated canine ventricle. As [KCl] was increased incrementally from 2.7 to 12 mM, V max was reduced progressively. Increasing [KCl] from 2.7 to 10 mM decreased the slope of the APD restitution relation at long, but not short, diastolic intervals (DI), decreased the range of DI over which the slope was ≥1, and reduced the maximum amplitude of APD alternans. At [KCl] = 12 mM, the range of DI over which the APD restitution slope was ≥1 increased, and the maximum amplitude of APD alternans increased. For [KCl] = 4–8 mM, the persistence of APD alternans at short DI was associated with maintenance of VF. For [KCl] = 10–12 mM, the spontaneous frequency during VF was reduced, and activation occurred predominantly at longer DI. The lack of APD alternans at longer DI was associated with conversion of VF to a periodic rhythm. These results provide additional evidence for the importance of APD restitution kinetics in the development of VF.

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