At some time, you may need surgery. If you take an anticoagulant for a replacement mechanical heart valve, there is some additional risk. Most people are concerned that they have an increased risk of bleeding if they keep taking their treatment and an increased risk of thrombosis if they stop. How do we decide what is the safest way to manage surgery?
If you are going for surgery, you must talk to your surgeon and the anaesthetist at least a week before your operation. It is no good the surgeon finding out the day before surgery, or there will not be time to sort out your treatment. If you are going for a major operation, you will usually have a chance to talk about your anticoagulants at the preoperative anaesthetic clinic.
Every case is different and should have an individual assessment. The surgical team have to weigh up the risk of bleeding against the risk of thrombosis. Some surgery has a low risk of bleeding, such as removing skin lesions, whereas others are high-risk, such as brain surgery or major vascular surgery. The team also needs to know if you have other conditions that may cause problems or take other medication that could cause bleeding or clotting.
The first part of the assessment is to assess your risk of developing a blood clot during or after surgery.
Risk of thrombosis
If you have a mechanical aortic valve, you are at low risk of thrombosis. To some people, this seems surprising, but it is relatively safe to stop anticoagulants for a few days with no risk. The reason is that the blood flow through the aortic valve is very fast at high pressure. Therefore clots cannot easily form. However, the risk is higher if you have risk factors. These include
- Atrial fibrillation – an irregular heartbeat
- High blood pressure
- Heart failure – This is often people on water tablets for swollen ankles or feeling breathless
- Older than 75 years
If you just have one risk factor and are otherwise well, it is usually safe to stop warfarin for a short time around surgery.
If you have more than one, you will need “bridging anticoagulants”.
People with a mechanical mitral valve are regarded as high risk. This is because blood flow across the mitral valve is much slower than the aortic valve, so clots can form more easily. Therefore, all patients should have “bridging anticoagulants”.
This means you need to change to a short-acting anticoagulant for a few days around surgery. This is usually to a low molecular weight heparin; enoxaparin (Clexane) is used in New Zealand. I will discuss more details in a later post.
Check with your doctor.
It is vital that you tell the surgeon about your treatment. If the correct precautions are taken before surgery, the risk is very low.
I will discuss the risks of bleeding in a later post
Next post, I discuss surgery for people with atrial fibrillation.