Laboratory
An important component of long-term treatment with a blood thinner is the laboratory control of blood coagulation. The central blood value is the Quick or INR value. However, the determination of this value is only useful for treatment with Marcumar® or warfarin.
Both values provide information about the extent of blood dilution, whereby the INR is internationally comparable and is gradually replacing the Quick value. A Quick of 70-120% and an INR of 0.9-1.2 are standard values. It is important to know that the values behave contrary to each other.
This means that a blood that only coagulates poorly has a lower Quick value and a higher INR value. All patients who are taking Marcumar® or warfarin on a long-term basis should undergo regular blood checks in order to be able to assess the correct level of active ingredient. If it is too low, the drug does not have the desired effect, but too much can lead to dangerous bleeding.
There are defined target values for the different areas of application of these blood thinners. In general, it can be said that the thrombocyte inhibitors such as ASA act primarily on the arterial thigh with high blood pressure, whereas the anticoagulants such as Marcumar® or heparin are used for diseases of the venous blood system and pulmonary circulation, including the atria, where blood pressure is low. Blood thinners of the platelet aggregation inhibitor type are used for many forms of circulatory disorders.
A typical indication is the prevention of a new stroke or heart attack, which often occurs when an arterial vessel at the bottom of a previously damaged vessel wall is blocked by a thrombus. By blocking the blood platelets, the risk of a clot forming and thus of these events themselves can be significantly reduced. ASA is the first-choice remedy here, alternatively clopidogrel or ticagrelor are used.
Blood thinners such as ASA are also always used in the acute therapy of a heart attack to prevent the thrombus, which blocks a vessel supplying the heart, from growing. The same applies to strokes caused by the same mechanism. Another important indication for which blood thinners of this class are essential is follow-up after stent implantation.
A stent is a vascular support that can be used to keep open a vessel that is in danger of occlusion. However, since it would activate thrombocytes, ASA or clopidogrel, often in combination, are given prophylactically and permanently. They can also help to reduce the risk of re-occlusion in the treatment of peripheral arterial occlusive disease (paVk).
The indications for anticoagulants are similarly broad. The most common reason for a blood thinner in this category is thrombosis prophylaxis in patients with atrial fibrillation. Fibrillation causes the blood in the atria not to flow properly and slows down, which increases the probability of thrombus formation.
In the worst case, this can be pumped by the heartbeat into a cerebral vessel, where it can cause a stroke. To prevent this, blood thinners such as Marcumar must be given. The target INR value in atrial fibrillation is 2.0-3.0.
Another major indication is the treatment and prophylaxis of venous thrombosis such as deep vein thrombosis (DVT). It is a closure of a vein that causes local discomfort. The great danger is that the thrombus is loosened and carried away so that it closes a vessel in the lung (pulmonary embolism).
An anticoagulant blood thinner (Marcumar®) is given both during acute therapy and as a prophylaxis against recurrence for up to one year, in individual cases also permanently. Valve replacement with an artificial heart valve also entitles the patient to long-term therapy with a blood thinner, INR target value 3.0-4.0. Heparin is generally not used as a long-term therapy but is indispensable in acute situations such as myocardial infarction or DVT, as it acts quickly and reliably.
In contrast to the other drugs, however, which are taken orally, heparin must be injected. It is also standard in thrombosis prophylaxis during surgical interventions. Since blood thinners such as Marcumar® or warfarin only take effect after a few days, this time is bridged with heparin to ensure full protection against thrombosis.
Contraindication: Blood thinners of any kind should not be taken if there is an increased risk of bleeding. These include, for example, congenital diseases of the coagulation system or gastrointestinal bleeding. Surgery should also not be carried out under Marcumar®, so that 2 weeks before and after the planned operation, it must be avoided. Xarelto and What should be observed when discontinuing Xarelto?