Anticoagulation early after mechanical heart valve replacement

Objective： To explore the changes of coagulation activity and the characters of anticoagulation early after mechanical heart valve replacement. Methods： All patients only took warfarin orally for anticoagulation. The predicted international normalized ratio （INR） was 1.5 to 2.0. Several coagulation markers were monitored early after valve replacement. Complications associated with anticoagulation were recorded and analyzed. The patients were divided into three groups based on the number and position of mechanical valve prothesis, including group M （mitral valve replacement）, group A （aortic valve replacement） and group D （mitral and aortic valve replacement）.Comparison was made between the three groups. Results： Three events of mild cerebral embolism and five events of mild bleeding occurred during the early postoperative period. One patient suffered from mild cerebral embolism on the 4th day after operation, accompanied by large volume of pericardial drainage. Two patients with bleeding had lower INRs than predicted range. However, INR in one patient with mild cerebral embolism was in the predicted range. There was no significant difference in thrombo time （TT）, activated partial thromboplastin time （APTT） and 1NR on the 3rd day after operation compared to those before operation; meanwhile, plasma fibrinogen （FIB） concentration was higher than that before operation （P〈0.05）. 1NR had no significant changes on the 2nd day after the beginning of anticoagulation compared to that before operation; however, 1NR was significantly elevated on the 4th day （P〈0.05）. Warfarin doses and INRs were similar among the three groups, but FIB concentrations in plasma were higher in groups M and D than in group A （P〈0.01）. Conclusion： Hypercoagulabale state exists early after mechanical heart valve replacement. When anticoagulation begins is determined by the change of coagulation markers, not by the volume of chest or pericardial drainage. INR can not accurately reflect the coagulation state sometimes, especially during the first 3 days after anticoagulation. The number and position of mechanical valve prothesis could affect coagulation state. Therefore, anticoagulation therapy should be regulated accordingly.

Role of thrombus precursor protein in assessment of anticoagulation in patients with atrial fibrillation after mechanical heart valve replacement

Objective: To explore the role of thrombus precursor protein (TpP) in assessment of anticoagulation and predict the risk of thromboembolism in the patients with atrial fibrillation (AF) after mechanical heart valve replacement. Methods: TpP plasma concentration and international normalization ratio (INR) were measured in 45 patients with atrial fibrillation and 45 patients with sinus rhythm both after mechanical heart valve replacement. Twenty patients with non valvular heart diseases were selected as the control. Furthermore, the patients with AF were divided into groups based on different TpP plasma concentration and TpP plasma concentration and INR were analyzed. Results: After mechanical heart valve replacement, those with AF had higher TpP plasma concentration than those with sinus rhythm. It was found that discordancy existed between INR and TpP plasma concentration in the patients with AF. There were 28 AF patients with TpP plasma concentration lower than 6 μg/ml and without bleeding, who might be at the optimal anticoagulant state. The 95% confidence of the mean INR value was 1.90-2.30 in these patients and TpP plasma concentration was between 2.84-5.74 μg/ml. Conclusion: Patients with AF might face higher risk of thromboembolism after mechanical valve replacement; INR between 1.90-2.30 and TpP plasma concentration between 2.84-6 μg/ml might be the optimal anticoagulant range for patients with AF after mechanical valve replacement.