広島市立広島市民病院循環器小児科Department of Pediatric Cardiology, Hiroshima City Hiroshima Citizens Hospital ◇ Hiroshima, Japan
Warfarinによる経口抗凝固薬療法には，効果不足に起因する血栓性合併症と，効果過剰に起因する出血性合併症という双方のリスクが伴う．後者の中で特に重大な合併症である頭蓋内出血の死亡率は50％を超える．予後改善には早急かつ完全なWarfarin拮抗が必須である．新鮮凍結血漿が第一選択だが，Vitamin K依存性凝固因子の含有量が製剤間で異なり必要量が一概に予測できない，拮抗に時間を要する，容量負荷が大きいという側面を有する．緊急時には血液凝固第IX因子複合体が有用だが，適応外使用である．Warfarin拮抗の際には同時に血栓塞栓症の予防も念頭に置かなければならず，特に機械弁挿入患者では完全な止血を確認後，早期からヘパリンを併用し，発症1～2週間でWarfarin再開を考慮する．また機械弁不全をみた場合，血栓溶解療法を行うか否かには血栓弁とパンヌスの鑑別が重要である．さらに頭蓋内出血既往例が血栓弁を生じた場合，血栓溶解療法は禁忌に準じると考えるべきである．
Oral anticoagulant therapy (OAT) is associated with the following two complications: hemorrhagic complications caused by excessive coagulation and thrombotic complications caused by ineffective coagulation. Intracranial hemorrhage (ICH) is a severe complication of OAT, and the resulting mortality rate is ＞50％. Therefore, early and complete reversal of OAT is necessary to improve patient prognosis.
Although the first choice for OAT reversal is fresh-frozen plasma (FFP), the proportions of vitamin K-dependent coagulation factors vary in each unit of FFP; therefore, the efficacy of this treatment is unpredictable. Furthermore, the duration for FFP-mediated OAT reversal is long, and a rapid infusion of sufficient volume of FFP may be associated with an increased risk of transfusion-associated circulatory overload. Prothrombin complex concentrates (PCCs) are effective for emergent cases. However, their use in Japan is an off-label indication in patients with OAT-associated ICH.
Prevention of thrombosis is essential during the reversal of OAT. After complete OAT reversal in patients with prosthetic heart valves who experience ICH, it is advisable to begin treatment with heparin and to reintroduce OAT 1–2 weeks later.
The cause of prosthetic heart valve obstruction as either a thrombus or a pannus should be differentiated to determine whether thrombolytic therapy should be introduced or not. Furthermore, in patients with a history of ICH who experience a thrombosed prosthetic valve, thrombolytic therapy is inadvisable.
Key words: oral anticoagulation therapy; intracranial hemorrhage; mechanical prosthetic valve thrombosis; prothrombin international ratio; fresh-frozen plasma
© 2016 特定非営利活動法人日本小児循環器学会© 2016 Japanese Society of Pediatric Cardiology and Cardiac Surgery
This page was created on 2015-12-21T14:27:34.624+09:00
This page was last modified on 2016-01-25T20:06:00.116+09:00
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