Mohri S, Araki J, Imaoka T, Iribe G, Maesako M, Shimizu J, Matsubara H, Ohe T, Hirakawa M, Suga H
Department of Physiology II, Okayama University Medical School, Japan.
Heart Vessels. 1999;14(2):82-9. doi: 10.1007/BF02481747.
We have reported that the postextrasystolic potentiation (PESP) decays in alternans or monotonically, respectively, depending on whether the first postextrasystolic beat interval has a compensatory pause or not, in the canine left ventricle. To get better mechanistic insight into the alternans PESP decay, we hypothesized that the myocardial mechanical restitution and potentiation could partly account for both types of PESP decay. To test this hypothesis, we simulated PESP decay on a computer using a documented equation combining myocardial mechanical restitution and potentiation. We changed the first postextrasystolic beat interval after a fixed extrasystolic beat interval without changing regular and other postextrasystolic beat intervals. The simulated PESP decayed in alternans or monotonically as a function only of the first postextrasystolic beat interval. Thus, the myocardial mechanical restitution and potentiation could partly account for both alternans and monotonic decay of PESP. We conclude that myocardial mechanical restitution and potentiation may partly underlie the initial two alternating beats, the first beat being the most potentiated and the second beat being the most depressed, of alternans PESP decay in the canine heart.
我们已经报道过，在犬类左心室中，早搏后增强（PESP）分别以交替或单调的方式衰减，这取决于早搏后的第一个心动周期是否有代偿间歇。为了更好地从机制上理解交替性PESP衰减，我们假设心肌机械恢复和增强可能部分解释了这两种类型的PESP衰减。为了验证这一假设，我们使用一个记录在案的结合心肌机械恢复和增强的方程在计算机上模拟了PESP衰减。我们在固定的早搏心动周期后改变早搏后的第一个心动周期，而不改变正常和其他早搏后的心动周期。模拟的PESP仅作为早搏后第一个心动周期的函数以交替或单调的方式衰减。因此，心肌机械恢复和增强可能部分解释了PESP的交替和单调衰减。我们得出结论，心肌机械恢复和增强可能部分是犬心交替性PESP衰减最初两个交替搏动的基础，第一个搏动增强最明显，第二个搏动抑制最明显。
