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Spatiotemporal Evolution and Prediction of [Ca 2+ ] i and APD Alternans in Isolated Rabbit Hearts
Author(s) -
VISWESWARAN RAMJAY,
McINTYRE STEPHEN D.,
RAMKRISHNAN KARTIK,
ZHAO XIAOPENG,
TOLKACHEVA ELENA G.
Publication year - 2013
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/jce.12200
Subject(s) - medicine , cardiology , t wave alternans , ventricular fibrillation , sudden cardiac death
Prediction of Alternans in the Heart Introduction Action potential duration (APD) alternans can be accompanied by alternans in intracellular calcium transients ([Ca 2+ ] i ), leading to electromechanical alternans. Electromechanical alternans is considered a substrate for ventricular fibrillation. Although some techniques have been developed to predict APD alternans, the onset of [Ca 2+ ] i alternans has never been predicted. Methods and Results Simultaneous mapping of voltage and calcium was performed in 8 Langendorff‐perfused rabbit hearts. APD, [Ca 2+ ] i amplitude (CaA) and duration (CaD) alternans were induced using a perturbed downsweep protocol. Local onset of alternans (B onset ) was defined as the cycle length (BCL) at which at least 10% of the RV exhibited alternans. We observed that the local onset of CaA alternans always occurred first, followed by APD and then CaD alternans. We constructed APD, CaD, and CaA restitution portraits for 2 regions of the heart defined at B onset : the 1:1 alt region, which developed alternans, and the 1:1 region, which did not. Our results also show that the slopes S 12 Maxand S Dyn were higher in 1:1 alt region (S Dyn = 0.99 ± 0.04 vs 0.73 ± 0.06; S 12 Max = 0.95 ± 0.13 vs 0.65 ± 0.1, P < 0.05) prior to onset of CaD alternans, while S 12 and S 12 Maxwere significantly higher in the 1:1 alt region (S 12 = 0.59 ± 0.19 vs 0.19 ± 0.02; S 12 Max = 1.09 ± 0.1 vs 0.61 ± 0.08, P < 0.05) prior to onset of CaA alternans. Conclusion We successfully applied the restitution portrait technique to the prediction of [Ca 2+ ] i (both CaA and CaD) alternans. The slopes of the APD/CaD/CaA restitution portrait are definitive indicators of APD, CaD, and CaA alternans.