Hemorrhage and thromboembolism are the most important long-term complications of anticoagulation therapy after mechanical heart valve replacement. The anticoagulation therapy intensity should be lowered in order to decrease the hemorrhagic complication. In recent years, the chief progresses of anticoagulation therapy are the using of International Normalized Ratio (INR) in anticoagulation therapy monitoring and the low intensity anticoagulation therapy. The proper anticoagulation intensities at home are INR 1.5-2.0 and prothrombin time ratio (PTR) 1.3-1.5. It is beneficial to adopt this low intensity anticoagulation therapy for decreasing the death rate from hemorrhage, protecting pregnant women and new borns from hemorrhage and malformation, and improving the life qualities of the patients.
Warfarin is one of the most frequently prescribed oral anticoagulant. Many researches have shown that the cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex 1 (VKORC1) genotypes have been strongly associated with warfarin maintenance doses. Warfarin maintenance doses can be accurately predicted by use of dosing algorithms including genetic and clinical information. Although several clinical trials demonstrated mixed results, calling into question the utility of this approach. The present data do not support genetic testing to guide warfarin maintenance doses, but in the setting where genotype data are available, use of this approach is reasonable. Ongoing trials are expected to provide more data, and more work is needed to define dosing algorithms that include appropriate variables in minority populations. All these work will further improve the clinical application of genotype-guided warfarin maintenance doses.
The management of women with mechanical heart valves during pregnancy remains difficult and controversial. The selection of prosthetic heart valve, management during pregnancy and delivery period, guidelines and anticoagulation strategy used in patients with a mechanical heart valve in China are summarized in this review.
Warfarin is one of the most frequently prescribed oral anticoagulant. Many researches have shown that the genotypes have been strongly associated with warfarin maintenance doses. Especially, it has been accepted in academia that cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex 1 subunit (VKORC1) could affect the warfarin maintenance doses. There are also many other genotypes that were reported to be related to warfarin doses, but the results have been in controversial so far. The studies found that the dose formula which contained the genetic factors and clinical information could accurately predict the maintenance dose of warfarin, however, its usefulness is suspected due to the inconsistent results of clinical trials. Large-sample and multi-center studies are necessary to verify the specific effects of gene and non-gene factors to warfarin dose; at the same time, testing constructed models or building new models help to improve the explained percentages of individual differences.
The body is at a hypo-coagulation status after the heart mechanic valve prosthesis replacement operation, and the incidence of anticoagulation complications is rather high because of that administration of warfarin may result in “anticoagulation vacuum” at an early stage. Moreover, the necessary application of other anticoagulation methods assisting the employment of warfarin have still not been scientifically normalized. Blood coagulation factor Ⅱ,Ⅶ, prothrombin fragment1+2 (F1+2 ), urine fibrimopeptide A (UFPA) , and International Normalized Ratio(INR), could exactly reflect the anticoagulation intensity 48-72 hours after the replacement operation,reasonable use of anticoagulant therapy as well as accurate and in-time monitoring methods is significant to reduce complications,elevate survival rate, and improve quality of life.