Arteyeva Natalia V, Azarov Jan E
Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia.
Department of Physiology, Medical Institute of Syktyvkar State University, Syktyvkar, Russia.
Ann Noninvasive Electrocardiol. 2017 Jan;22(1). doi: 10.1111/anec.12360. Epub 2016 Mar 28.
The changes in ventricular repolarization gradients lead to significant alterations of the electrocardiographic body surface T waves up to the T wave inversion. However, the contribution of a specific gradient remains to be elucidated. The objective of the present investigation was to study the role of the transmural repolarization gradient in the inversion of the body surface T wave with a mathematical model of the hypothermia-induced changes of ventricular repolarization.
By means of mathematical simulation, we set the hypothermic action potential duration (APD) distribution on the rabbit ventricular epicardium as it was previously experimentally documented. Then the parameters of the body surface potential distribution were tested with the introduction of different scenarios of the endocardial and epicardial APD behavior in hypothermia resulting in the unchanged, reversed or enlarged transmural repolarization gradient.
The reversal of epicardial repolarization gradients (apicobasal, anterior-posterior and interventricular) caused the inversion of the T waves regardless of the direction of the transmural repolarization gradient. However, the most realistic body surface potentials were obtained when the endocardial APDs were not changed under hypothermia while the epicardial APDs prolonged. This produced the reversed and increased transmural repolarization gradient in absolute magnitude. The body surface potentials simulated under the unchanged transmural gradient were reduced in comparison to those simulated under the reversed transmural gradient.
The simulations demonstrated that the transmural repolarization gradient did not play a crucial role in the cardiac electric field inversion under hypothermia, but its magnitude and direction contribute to the T wave amplitude.
心室复极梯度的变化会导致体表心电图T波发生显著改变，直至T波倒置。然而，特定梯度的作用仍有待阐明。本研究的目的是利用低温诱导心室复极变化的数学模型，研究跨壁复极梯度在体表T波倒置中的作用。
通过数学模拟，我们设定了兔心室心外膜上低温动作电位时程（APD）的分布，这是之前实验记录的结果。然后，在低温状态下，通过引入不同的心内膜和心外膜APD行为场景，导致跨壁复极梯度不变、反转或增大，来测试体表电位分布的参数。
无论跨壁复极梯度的方向如何，心外膜复极梯度（心尖-心底、前后和心室间）的反转都会导致T波倒置。然而，当低温下心内膜APD不变而心外膜APD延长时，可获得最符合实际的体表电位。这会产生反转且绝对值增大的跨壁复极梯度。与跨壁梯度反转时模拟的体表电位相比，跨壁梯度不变时模拟的体表电位降低。
模拟结果表明，跨壁复极梯度在低温下心脏电场反转中不起关键作用，但其大小和方向会影响T波振幅。
