Antithrombotic Therapy in Children: Biological Prosthetic Heart Valves
Biological Prosthetic Heart Valves
Valvular heart diseases in childhood encompass a wide variety of abnormalities with greatly variable presentations. The valve lesion may be isolated, or an integral part of more complex intracardiac lesions, or the result of treatment of the underlying congenital defect. Thromboembolic events, either of the valve or of a CVA, are some of the most serious complications of successful cardiac valve replacement.
The failure of biological prosthetic heart valves in children poignantly illustrates the fallacy of extrapolating recommendations for adults to children without evaluation in clinical trials. Commercially prepared biologic prosthe-ses became available in 1971 and achieved excellent early results in adult patients. Biological prosthetic heart valves rapidly became the “valve of choice” for the pediatric age group. Subsequently, it became evident that premature degeneration and calcification of porcine valves occurred in the majority of children. The accelerated failure of biological prosthetic heart valves in children was confirmed by many groups. Current recommendations are that, in general, mechanical prosthetic heart valves be used in the mitral and aortic positions in children and that biological prosthetic heart valves be reserved for patients who require tricuspid or pulmonary valve replacements. Children with biological prosthetic heart valves are treated following adult recommendations and are followed for evidence of valve dysfunction. ventolin inhaler
Mechanical Prosthetic Heart Valves
Antithrombotic therapy with oral anticoagulants is clearly indicated for adults with mechanical prosthetic heart valves. Alternatives to oral anticoagulants have been pursued for children because of the issue of safe monitoring.
No Therapy: With no antithrombotic therapy, throm-boemboli occurred at a rate of 5.7% patient-years with St. Jude valves65 and at rates of 6.8 to 27.3% patient-years for other types of valves (Table 14). There was one death due to mitral valve thrombosis.
Table 14—Thromboembolic and Hemorrhagic Complications of Mechanical Prosthetic Heart Valves With No Antithrombotic Therapy
|Source, yr||Level||No.||Age||Valve Type||Position||TE/% pt-yr||HEM/% pt-yr||Deaths|
|Sade et al, 1988||V||48||5 mo-21 yr||St. Jude||Ao, M||NRt||0||1 M\|
|Ao + M||NR||0|
|Solymar et al, 1991||V||(186)§||1-19 yr||Various||Ao||6.8||0|