Fibrinolytic Therapy in Mechanical Valve Thrombosis in a One-Year-Old Girl
This 16-month-old girl (weight 7 kg) was a patient with a complete form of endocardial cushion defect, and she received total correction at the age of 2 months. Severe mitral regurgitation persisted despite surgery, and mechanical valve replacement was performed at the age of 4 months. Two episodes of mitral valve thrombosis with severe mitral stenosis complicated her recovery, and she underwent 2 more operations for mitral valve replacement and double valve replacement with aortic root enlargement at the age of 6 months and 1 year, respectively. Impaired heart function and complete atrioventricular block complicated the operation, and a pacemaker was also inserted. She received warfarin therapy and was followed up regularly at our clinic.
Mitral valve thrombosis occurred again, with a presentation of progressive dyspnea and poor activity. Chest radiography and transthoracic echocardiography showed severe mitral stenosis with lung edema (Figures 1 and 2⇓A). Pulmonary hypertension was also found, with estimated systolic pulmonary artery pressure of 75 mm Hg. Intubation was provided with ventilator support, and inotropic agents were given, accompanied by heparin infusion. Fluoroscopy then showed poor motion of both leaflets of the mitral valve (Movie IA in the online-only data supplement). Because of the history of repeated operations and the family’s decision, fibrinolytic therapy with tissue plasminogen activator (tPA) was attempted. We discontinued warfarin first, checked the fibrinogen level, and then discontinued heparin and started tPA treatment. We gave a loading dose of 0.1 mg/kg first and then 6 courses of escalating doses of tPA at 0.1 mg · kg−1 · h−1 for 6 hours and then 0.15, 0.2, 0.3, 0.3, and 0.4 mg · kg−1 · h−1. The fibrinogen level was checked after each course of tPA therapy before heparin was resumed. Brain sonography and urinalysis were performed regularly during the procedure to detect possible bleeding complications. Her heart failure symptoms improved dramatically after the fibrinolytic therapy. Follow-up fluoroscopy showed normalized motion of both mitral valve leaflets (Movie IB in the online-only data supplement), and follow-up echocardiography showed an improved mitral inflow pattern and pulmonary hypertension (estimated systolic pressure 34 mm Hg; Figure 2B). She was then discharged uneventfully with oral warfarin and aspirin.
Although fibrinolytic therapy has been used for mechanical valve thrombosis in adult patients for a long time,1,2 the use of tPA in pediatric patients with mechanical valve thrombosis has been limited because of the difficulty in dose titration and the fear of complications. Our successful experience with fibrinolytic therapy in this child may provide a feasible option for treatment of mechanical valve thrombosis in the pediatric group.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/121/11/e244/DC1.