Brothers R Matthew, Bhella Paul S, Shibata Shigeki, Wingo Jonathan E, Levine Benjamin D, Crandall Craig G
Presbyterian Hospital of Dallas, Institute of Exercise and Environmental Medicine, 7232 Greenville Ave., Ste. 435, Dallas, TX 75231, USA.
Am J Physiol Heart Circ Physiol. 2009 Apr;296(4):H1150-6. doi: 10.1152/ajpheart.01069.2008. Epub 2009 Feb 13.
During a whole body heat stress, stroke volume is either maintained or slightly elevated despite reduced ventricular filling pressures and central blood volume, suggestive of improved cardiac diastolic and/or systolic function. Heat stress improves cardiac systolic and diastolic function in patients with congestive heart failure, although it remains unknown whether similar responses occur in healthy individuals, which is the hypothesis to be tested. Nine male volunteers underwent a whole body heat stress. Echocardiographic indexes of diastolic and systolic function were performed following a supine resting period, and again following an increase in internal temperature of approximately 1.0 degrees C via passive heat stress. Despite previous reports of heat stress-induced decreases in ventricular filling pressures and central blood volume, no changes in indexes of diastolic function were identified during heating [i.e., unchanged early diastolic mitral annular tissue velocity (E'), mitral inflow during the early diastolic phase (E), the E/E' ratio, and isovolumetric relaxation time]. Heat stress increased late diastolic septal (P = 0.03) and lateral (P = 0.01) mitral annular tissue velocities (A'), mitral inflow velocity during atrial contraction (P < 0.001), and the relative contribution of atrial contraction to left ventricular filling during diastole (P = 0.01), all indicative of improved atrial systolic function. Furthermore, indexes of ventricular systolic function were increased by heat stress [i.e., increased septal (P = 0.001) and lateral (P = 0.01) mitral annular systolic velocities and isovolumic acceleration at the septal (P = 0.03) and lateral (P < 0.001) mitral annulus]. These data are suggestive of improved atrial and ventricular systolic function by the heat stress. Together these data support previous findings, which used the less precise measure of ejection fraction, that heat stress improves indexes of systolic function, while diastolic function is maintained.
在全身热应激期间，尽管心室充盈压和中心血容量降低，但每搏输出量要么维持不变，要么略有升高，这表明心脏舒张和/或收缩功能得到改善。热应激可改善充血性心力衰竭患者的心脏收缩和舒张功能，不过健康个体是否会出现类似反应尚不清楚，这正是有待检验的假设。九名男性志愿者接受了全身热应激。在仰卧休息一段时间后，以及通过被动热应激使体内温度升高约1.0摄氏度后，分别进行了舒张和收缩功能的超声心动图指标检测。尽管此前有报道称热应激会导致心室充盈压和中心血容量降低，但在加热过程中未发现舒张功能指标有变化[即舒张早期二尖瓣环组织速度（E'）、舒张早期二尖瓣血流（E）、E/E'比值和等容舒张时间均未改变]。热应激使舒张晚期室间隔（P = 0.03）和侧壁（P = 0.01）二尖瓣环组织速度（A'）、心房收缩期二尖瓣血流速度（P < 0.001）以及心房收缩对舒张期左心室充盈的相对贡献增加（P = 0.01），所有这些均表明心房收缩功能得到改善。此外，热应激使心室收缩功能指标增加[即室间隔（P = 0.001）和侧壁（P = 0.01）二尖瓣环收缩速度以及室间隔（P = 0.03）和侧壁（P < 0.001）二尖瓣环的等容加速度增加]。这些数据表明热应激可改善心房和心室的收缩功能。这些数据共同支持了先前的研究结果，即热应激可改善收缩功能指标，同时维持舒张功能，不过先前的研究使用的是不太精确的射血分数测量方法。
