What are thromboses?
Thromboses are blood clots that block a blood vessel (artery or vein) and thus lead to a lack of blood flow in the corresponding region of the body (legs, arms, lungs, heart, brain, kidneys, etc.) with damage to the organ, which can be life-threatening. Blood clots can also be carried in the bloodstream to other parts of the body (embolism). Thromboses do not occur to seal a vascular injury, but as a result of excessive blood clotting within the blood vessel.
Why do thromboses occur in children?
Thromboses are generally rare in children, but are a significant complication in seriously ill children with various underlying diseases (heart defects, cancer, premature babies, operations, etc.), where several triggering factors often come together. The most common triggers are central venous catheters, which are required for the treatment of the underlying disease. Thromboses without recognisable triggers (spontaneous thromboses) are extremely rare in children, but occur more frequently in adolescents, similar to adults. Sometimes congenital changes in the blood contribute to the development of thrombosis (thrombophilia), but there are usually additional triggers (e.g. surgery, immobilisation of a leg due to plaster treatment).
What are the symptoms of thrombosis in children?
Children with thromboses are characterised either by signs of blood congestion (swelling, redness, warmth, pain) or signs of a lack of blood supply (pallor, coldness, dysfunction, severe pain) in a limb or organ. Catheter thromboses usually develop slowly and are often not even noticed at first. However, they can impair the functioning of the venous catheter, which then has to be replaced, and the blockage of deep veins in the body can cause serious complications in the long term. The most serious complication is pulmonary embolism, which can be fatal.
How are thromboses treated?
Thrombosis is treated by means of "blood thinning therapy" (anticoagulation), whereby the blood is made less coagulable to such an extent that there is no major risk of bleeding. Anticoagulation is intended to prevent the blood clot from growing further or being carried away (embolised). During anticoagulation, the body's own processes slowly dissolve the thrombosis, allowing the blood vessels to partially or completely open up again. Dissolving clots with medication (thrombolysis) has a very high risk of bleeding and is therefore very rarely carried out.
What is the treatment with and for how long?
The strength of anticoagulation and the medication chosen depend on the underlying disease, the risk of thrombosis and bleeding, and the condition of the child. Anticoagulation can be administered via the vein (heparin), injection under the skin (low-molecular-weight heparin) or via tablets (vitamin K antagonists, e.g. MarcoumarR) or platelet inhibitors (e.g. aspirin). In order to achieve a good therapy setting that minimises the risk of (re)thrombosis and bleeding, regular blood checks are required in children during anticoagulation. The duration of anticoagulation depends on how high the risk of a recurrence of thrombosis is estimated to be and is usually between 3 and 6 months. For some diseases, lifelong anticoagulation may be necessary.
Preventive anticoagulation
In some children who have not yet had a thrombosis, it may be necessary to give preventive (prophylactic) anticoagulation due to a high risk of thrombosis. Typical situations are children with certain heart diseases (cardiomyopathy, arrhythmia, artificial heart valves, shunts, e.g. Fontan shunt, stents), cardiac catheterisation, central venous catheters, haemodialysis, etc.. Depending on the situation, prophylactic anticoagulation is only given temporarily or long-term.