Yanagi N, Maruyama T, Uehata S, Wakimoto Y, Sasaki Y, Arita M
First Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka.
J Cardiol. 1998 Sep;32(3):197-204.
Electrical and mechanical abnormalities were studied in the heart of a schizophrenic male patient with severe hyponatremia and concomitant low plasma osmolarity induced by excessive water intake (so-called "water intoxication syndrome") by recording electrocardiography and echocardiography. There was a significant positive correlation between the plasma osmolarity and serum sodium concentration. The QRS duration of electrocardiography, an index of the ventricular electrical conduction velocity, tended to be prolonged and the left ventricular ejection fraction calculated by echocardiography decreased in proportion to the reduction of the serum sodium concentration. Lowering extracellular sodium concentration theoretically slows electrical conduction velocity, and was observed in this patient. On the other hand, low external sodium concentration should increase cardiac contractility via suppression of the forward mode operation of the sodium-calcium exchange mechanism, thereby increasing the intracellular free calcium concentration. However, this was not the case in our patient, because ejection fraction was not increased but rather significantly decreased with the lowering of serum sodium concentration. We speculate that in patients with water intoxication, the negative inotropism of the heart caused by low plasma osmolarity prevails over the positive inotropism caused by low serum sodium concentration.
通过记录心电图和超声心动图，对一名患有严重低钠血症且因饮水过多导致血浆渗透压降低（所谓的“水中毒综合征”）的精神分裂症男性患者的心脏进行了电学和力学异常研究。血浆渗透压与血清钠浓度之间存在显著正相关。心电图的QRS时限（心室电传导速度的指标）趋于延长，超声心动图计算的左心室射血分数与血清钠浓度的降低成比例下降。理论上，降低细胞外钠浓度会减慢电传导速度，在该患者中观察到了这一点。另一方面，低细胞外钠浓度应通过抑制钠钙交换机制的正向模式运转来增加心肌收缩力，从而增加细胞内游离钙浓度。然而，在我们的患者中并非如此，因为随着血清钠浓度的降低，射血分数并未增加反而显著降低。我们推测，在水中毒患者中，低血浆渗透压导致的心脏负性肌力作用超过了低血清钠浓度导致的正性肌力作用。
