Tanabe Masaki, Onishi Katsuya, Dohi Kaoru, Ito Masaaki, Nakano Takeshi, Suga Hiroyuki
First Department of Internal Medicine, Mie University School of Medicine, Tsu, 514-8507 Japan.
Jpn J Physiol. 2004 Feb;54(1):87-91. doi: 10.2170/jjphysiol.54.87.
An organ-level assessment of the total Ca2+ handled in the excitation-contraction coupling in a beating heart has been accomplished in canine left ventricles (LVs). This approach combines the intramyocardial Ca2+ recirculation fraction (RF) with the cardiac O2 consumption for the excitation-contraction coupling. The RF has conventionally been obtained from the exponential decay of the postextrasystolic (PES) potentiation of myocardial contractility. However, in canine LVs, the PES contractility in terms of Emax (end-systolic pressure-volume ratio) has been shown to decay generally in alternans under both physiological and pathological conditions. Nevertheless, the RF can be obtained from the exponential decay component in the PES Emax alternans decay. We expected that the same Ca2+ assessment could be applied to the human heart. As the first step, we investigated whether the PES Emax would decay in alternans or exponentially in patient LVs. We retrospectively analyzed 13 patient cases that had stable regular beats unexpectedly interrupted by a spontaneous extrasystole followed by a PES compensatory pause during their diagnostic examination. These patients had either mitral regurgitation, old myocardial infarction, or dilated cardiomyopathy. Their LV Emax decayed consistently in alternans within the first several PES beats. These Emax alternans decays resemble those reported in canine LVs. This finding suggests for the first time the applicability of the same organ-level RF assessment method developed for canine hearts to human hearts.
在犬类左心室（LVs）中，已完成对跳动心脏兴奋 - 收缩偶联过程中总Ca2+处理的器官水平评估。该方法将心肌内Ca2+再循环分数（RF）与兴奋 - 收缩偶联的心脏耗氧量相结合。传统上，RF是从心肌收缩力的早搏后（PES）增强的指数衰减中获得的。然而，在犬类左心室中，无论是在生理还是病理条件下，以Emax（收缩末期压力 - 容积比）衡量的PES收缩力通常会以交替变化的形式衰减。尽管如此，RF可以从PES Emax交替变化衰减中的指数衰减成分中获得。我们期望相同的Ca2+评估方法也能应用于人类心脏。作为第一步，我们研究了患者左心室中PES Emax是会以交替变化的形式还是指数形式衰减。我们回顾性分析了13例患者病例，这些患者在诊断检查期间有稳定的规则心跳，但意外地被一次自发性早搏打断，随后出现PES代偿性间歇。这些患者患有二尖瓣反流、陈旧性心肌梗死或扩张型心肌病。在最初的几次PES心跳中，他们的左心室Emax持续以交替变化的形式衰减。这些Emax交替变化衰减与犬类左心室中报道的情况相似。这一发现首次表明，为犬类心脏开发的相同器官水平RF评估方法适用于人类心脏。
