On-X Life Technologies, Inc. (On-X LTI) was formerly
Medical Carbon Research Institute (MCRI).
About Anticoagulation
While the following information is intended to be accurate and helpful, it does not constitute medical advice. Management of anticoagulation therapy should always be a joint effort of the patient and physician.
What is anticoagulation? Anticoagulation therapy is the use of drugs called anticoagulants, or blood thinners, to slow down or stop the formation of blood clots.
Why do prosthetic heart valves need anticoagulation? Clotting of the blood is part of the body’s natural response for healing injuries. When a prosthetic valve replaces the native cardiac valve, it introduces a foreign material into the blood stream, which can also stimulate a clotting response. This is a normal response to foreign material, but it is not desirable within the valve mechanism. Anticoagulants are given to supress the clotting potential just enough to prevent detrimental clots within the prosthetic valve.
Do all prosthetic heart valves require anticoagulation? Yes, although each type of valve is different; so the amount and type of anticoagulant is different for every valve and also different for every patient depending on the individual response to the drugs. It is not difficult, but it requires that patient and doctor work together to find the best dosage for the patient.
Are there different anticoagulants? Yes, there are many forms of anticoagulants. The most common types are warfarin (Coumadin), heparin, clopidrogrel (Plavix) and aspirin. Each works in a different way to slow the clotting process.
Which type of anticoagulant will I use? Initially, virtually all patients are given Coumadin therapy. Mechanical valve patients generally remain on Coumadin, sometimes in combination with aspirin. Most patients with tissue valves are eventually switched to aspirin, although Coumadin is often required for individual cases.
What are the risks of anticoagulants? Anticoagulation therapy is a balancing act. Too much anticoagulant results in increased bleeding and too little results in an increased risk of clotting. Both bleeding and clotting are uncommon but serious events that can lead to permanent damage or even death. The goal of anticoagulation therapy is to minimize the occurrence of both events.
How are these events minimized? Proper and consistent anticoagulation management is the best way to minimize the risks. Anticoagulants are very effective when managed correctly. Coumadin is effective at preventing clots without increasing bleeding when managed correctly. The difficulty with Coumadin is the need for regular monitoring of anticoagulant levels.
Why does Coumadin require monitoring? Daily diet and other medications interact with Coumadin, altering its effectiveness. For example, foods high in vitamin K, such as spinach, decrease its effect.
How is Coumadin managed? Normally, a simple test of the blood’s clotting ability is performed every 3-4 weeks to monitor and control Coumadin’s effect. The result of this test is expressed as a number called the INR (International Normalized Ratio). Coumadin dosage is adjusted to keep the INR within an established therapeutic range to minimize the risk of complications.
Can INR be monitored more closely? Studies have shown that patients who monitor their own INR levels at home on a weekly basis using a home monitoring test machine have increased success in maintaining targeted INR levels, and that this in turn reduces the risk of bleeding or clotting. Home monitoring is reimbursable by insurance and can be set up through a physician’s office.
What is the therapeutic INR range? The proper range for a patient is dependent upon many things and should be determined by a doctor. INR ranges currently recommended by the American Heart Association, American College of Cardiology and American College of Chest Physicians for patients with a bileaflet mechanical valve (like On-X), without complicating medical conditions, are 2.0 to 3.0 for aortic valve patients and 2.5 to 3.5 for mitral or multiple valve patients.
Doesn’t the On-X valve require less anticoagulant? There is an FDA approved reduced anticoagulation study to determine the lower limits of anticoagulation therapy for the On-X valve. Anticoagulation therapy for the On-X valve will remain the same as other carbon valves until there is incontrovertible evidence for doing otherwise.
If the study is successful can a patient now with an On-X valve reduce their anticoagulation? If, after thorough regulatory and peer review, a reduction of the anticoagulation therapy requirements for the On-X valve is allowed, current On-X valve recipients should be able to make appropriate therapy adjustments as prescribed by their physicians
Unless a reduction in anticoagulants is proven to be safe and is accepted by regulatory authorities, patients with On-X valves should continue using standard professionally recommended anticoagulant therapy.
For more information on Coumadin, visit: http://www.coumadin.com
For more information on Plavix, visit: http://www.plavix.com