Goto S, Kasahara H, Sakai H, Goto M, Ono M, Ikeda Y, Jorquera J I, Bravo M I, Handa S
Department of Medicine, Tokai University, School of Medicine, Isehara, Japan.
Int J Cardiol. 1998 Apr 1;64(2):171-7. doi: 10.1016/s0167-5273(98)00043-6.
Platelets are known to play a crucial role in normal hemostasis as well as in thrombus formation at sites exposed to blood flow, as in coronary thrombosis. Thus, low platelet count is a strong negative risk factor for the occurrence of arterial thrombosis, such as occurs in acute myocardial infarction. We encountered a patient with May-Hegglin anomaly, presenting with acute myocardial infarction in his sixth decade, even though his platelet counts had always been less than 50 x 10(3)/microl. We investigated the characteristics of his platelets under the effect of shearing and found that shear-induced platelet aggregation and binding of soluble von Willebrand factor (vWF) to platelets could be induced, even when the patient's platelet count was less than 10 x 10(3)/microl, but that virtually no aggregation or vWF binding by normal platelets could be induced by shearing when platelet counts were less than 50 x 10(3)/microl. We conclude that the low platelet counts in a patient with May-Hegglin anomaly can be functionally compensated for by larger individual platelets, in view of the vWF-dependent platelet thrombus formation occurring under the effect of blood flow and that that is why most patients with May-Hegglin anomaly do not have a bleeding tendency, even though their platelet counts are very low.
众所周知，血小板在正常止血过程以及血流暴露部位（如冠状动脉血栓形成时）的血栓形成中起着关键作用。因此，血小板计数低是动脉血栓形成（如急性心肌梗死时发生的）的一个强烈的负性危险因素。我们遇到一名患有May-Hegglin异常的患者，他在六十多岁时出现急性心肌梗死，尽管他的血小板计数一直低于50×10³/微升。我们研究了在剪切作用下他的血小板特性，发现即使患者血小板计数低于10×10³/微升，剪切诱导的血小板聚集以及可溶性血管性血友病因子（vWF）与血小板的结合仍可被诱导，但当血小板计数低于50×10³/微升时，正常血小板几乎不会因剪切而发生聚集或vWF结合。我们得出结论，鉴于在血流作用下发生的vWF依赖的血小板血栓形成，May-Hegglin异常患者的低血小板计数可通过单个较大的血小板在功能上得到补偿，这就是为什么大多数May-Hegglin异常患者即使血小板计数非常低也没有出血倾向的原因。
