花生四烯酸受环氧化酶作用产生的化合物在血管内皮上形成前列腺素I2(PGI2),同样的化合物在血小板里却形成血栓素(TXA2)。两种化合物的血管活性作用正相反,前者使血管舒张,而后者使之收缩。PGI2还有抑制血小板凝聚的作用。若能增加PGI2的活性,抑制TXA2的生成,就能改善冠脉缺血状态及预防随着缺血伴发的心律失常。
阿司匹林、潘生丁、磺酰吡唑酮(Sulfinpyrazone,Auturane小板凝)、消炎痛有抑制环氧化酶的作用,所以用以抗血小板凝集治疗。表5-9是几种大系列的观察报告。阿司匹林lg反而增加了病死率和猝死率。小剂量阿司匹林可以选择性地抑制TXA2而不影响PGI2的合成,有减少病死率和猝死率的效果。磺酰比唑酮试验组,共1558例心梗后25~35天患者,24个月随访时间,与对照组比较,猝死率在用药组中减少43%(P<0.05)。这种差别在6个月以内尤为明显,而此时期正是心梗的高危阶段。
表5-9 抑制血小板药物在心肌梗死后的预防作用
|
%减少率(药物比对照) |
| |||||
研究 |
药物,日量 |
心梗后日期 |
例数 |
病死率 |
猝死 |
非致命性再梗 |
结 论 |
Elwood等(1974) |
Aspirin 300mg |
10周(平均) |
1329 |
25 |
- |
- |
有 利 |
冠脉药物计划 |
Aspirin 972mg |
7年(平均) |
1529 |
30 |
19 |
5 |
有 利 |
阿司匹林研究 |
|
||||||
德奥多中心试验 |
Aspirin 1.5g |
|
626 |
18 |
36 |
28 |
有 利 |
Elwood & |
Aspirin 900mg |
50%在7天内 |
1682 |
17 |
- |
34* |
有 利 |
Auturane 再梗死 |
Auturane 800mg |
25~35天 |
1558 |
30 |
43* |
25 |
开始6个月 |
阿司匹林心肌梗 |
Aspirin 1g |
25月(平均) |
4524 |
+11 |
+35 |
22 |
不应常规使 |
潘生丁、阿司匹 |
Aspirin 972mg |
2月~5年 80%在6月后 |
2026 |
18 16 |
+27 16 |
29 19 |
对总病死率 |
* 有统计学意义。
(选自Gelman & Mehta: Suddun Cardiac Death,ed by Mark E Josephson,F A Davis Co.,Philadelphia,1985,P.65)
心得安有改变血小板功能的作用,抑制ADP、肾上腺素、胶原、血栓素造成的血小板凝集。其机制不清楚,可能与血小板结合改变膜的性能,对促凝集物质不敏感。临床尚无心得安等β受体阻滞剂抑制血小板的研究报道。
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