By Dr. Tonya Henderson-Meyer
I take warfarin (Coumadin and Jantoven) each day to prevent blood clots from forming on my mechanical heart valve. When I began my research into treatment options to repair my bicuspid aortic valve and thoracic aortic aneurysm, I wanted to avoid a mechanical heart valve because I didn’t want to take warfarin. Some of my consulting surgeons suggested I educate myself about warfarin and really find out what the risks meant for me instead of avoiding it out of fear and misinformation. So far, warfarin has not caused the major change in lifestyle I had feared. For me, warfarin is a much better alternative to going through a repeat aortic root replacement in the future.
Warfarin is the blood thinner also known by its brand names of Jantoven and Coumadin. It is a commonly used medication that is used to prevent or treat the formation of blood clots. This type of medication is termed anticoagulant therapy because it actually thins the blood. All patients with mechanical heart valves need to take this medication. Without it, there is a high likelihood that blood clots will form on the mechanical heart valve. Besides patients with mechanical heart valves, warfarin is used for several other conditions to either treat or prevent the formation of blood clots.
1. INR Monitoring (International Normalization Ratio): Taking warfarin requires that its levels be monitored so that the blood is not too thin or too thick. Monitoring measures how thin the blood is, not the levels of warfarin per se. This is termed the International Normalization Ratio or INR. The target INR varies depending on what the warfarin is being used for. Traditionally, this has required that patients taking warfarin go to their physician’s office/lab to have their blood drawn and checked monthly. Many patients use a clinic that specializes in managing warfarin, but this still requires a blood draw each month at a minimum. There are many factors, including one's lifestyle, which can alter a patient’s INR, so that many patients require a check of their INR more than once a month. This could mean lots of trips to the lab.
Recently, several home INR monitors have become available. These INR monitors offer the same accuracy of a lab visit, but without the subsequent inconvenience and damage to the veins. INR monitors work much like the machines that diabetics use to check their glucose. They require a drop of blood from a fingertip and give the results within minutes. Although many medical insurance plans & HMO’s cover the cost of INR monitors for their patients who require life-long anticoagulation, some do not. Unfortunately, my health plan did not cover the purchase of my INR monitor. Having the ability to check my INR at home was a major lifestyle issue for me so I made the decision to purchase one on my own. The use of the INR monitor has minimized some of the inconvenience associated with warfarin use and, to me, is worth every penny. Even though I check my INR at home I do not make decisions or adjust the dose on my own. My health plan has an anticoagulation clinic staffed with pharmacists who help me make any adjustments to my dose. It is my belief that health plans should support the use of home INR monitors and I hope that in the near future, they will be made available to other patients that require life-long warfarin therapy.
2. Dietary Considerations: Vitamin K is crucial to normal clotting function. As a result, increased intake of vitamin K decreases the effectiveness of warfarin, causing the blood to become less thin, and causing the INR to fall below the target range. Patients taking warfarin must educate themselves on foods that are high in vitamin K (See Table 1) and monitor their intake of these foods. Green leafy vegetables are among the best sources of vitamin K. This does not mean that foods with vitamin K should be avoided. Instead, it means that the amount of vitamin K intake should not vary widely day to day. I have tried to educate myself about foods rich in vitamin K and try to keep my intake consistent.
3. Interactions with other medications: Many different medications interact with warfarin. Some cause the INR to increase, while others cause it do decrease. The list of medications that affect warfarin is long. It is important that you consult with your physician and pharmacist before any new medications are started.
4. Physical Exercise: There are no consistent recommendations available regarding the safety of certain sports and exercise. I asked about strenuous exercise with all of the surgeons that evaluated me and they all varied somewhat. Everyone agrees that any sports with a high risk of trauma, especially head trauma, should be avoided. Since I never did any skydiving, Formula 1 racing, or bungee jumping, the elimination of high-risk sports did not require much of an adjustment in my exercise regimen. It’s the sports somewhere between Monopoly and skydiving that are less clear. What about sports like skiing? Probably okay, as long as you already know how to ski, stay on gentle slopes and wear a helmet. What about running a marathon? This sport makes the surgeons step back and rub their chins a bit. Running short distances for exercise is fine, but running a marathon, well… Most patients who require surgery like mine aren’t asking questions about this level of exercise, so the answer is not clear. My exercise regimen is increasing slowly, under close supervision. So far, warfarin has not caused the major change in my exercise program I had feared. I am back to running, lead an active life and because I have a mechanical valve, I do not have to think about the possibility of another surgery.
Since I have four children already, this is not an issue for me. However every surgeon, cardiologist or obstetrician I consulted with recommended no pregnancy while on warfarin. My ob/gyn said that it could be done but it would be a high-risk pregnancy. Most cardiac surgeons recommend a tissue valve replacement first if a woman plans to have children and then replace it in the future with a mechanical heart valve. So most physicians advise against getting pregnant on warfarin, not only for the birth defect risk, but also due to the increased possibility of bleeding complications that can be far more serious during pregnancy, especially at the time of delivery.
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