Information for Patients and Caregivers
Deep vein thrombosis explained
A deep vein thrombosis (DVT) is a blood clot that has formed in one of the veins that lie deep inside the muscles of the leg. Most of the time, the ability of blood to clot is rather useful; it forms a plug that saves us from bleeding to death from a minor wound. However, sometimes the clotting process – known as coagulation – is triggered inappropriately, and a clot forms inside a vein when it is not needed to prevent blood loss. Well known risk factors for such unwanted coagulation include surgery, cancer, immobility, obesity, smoking and pregnancy.
Whatever the cause, a DVT can become large enough to act as a dam in the affected vein, trapping blood and leading to the classic symptoms of swelling of the leg and pain. But this is not the worst of it. Some or all of the clot can break away from where it was formed and travel out into the lungs via the heart, leading to a pulmonary embolism.
Pulmonary embolism explained
A pulmonary embolism (PE) is one of the most serious consequences of a deep vein thrombosis (DVT), although it is possible to have a PE without experiencing a prior DVT. When a PE occurs following a DVT it begins with either the whole clot, or more commonly part of the clot, breaking away from where it was formed in the leg vein and traveling onwards and upwards into the heart and then out into the lungs. Most of this journey is through rather large blood vessels, but once in the lungs these rapidly reduce in size as they branch and divide to cover the large surface area of each lung that is needed to capture life-giving oxygen.
Inevitably the clot reaches a blood vessel too small to permit further passage, preventing blood from reaching the area of lung that it serves. This effectively turns off the oxygen supply from part of the lung and is then called a PE. A PE can be fatal so it is very important that you are alert to the symptoms, which can include shortness of breath, chest pain, coughing up blood, and a racing heart. This is also why it is so important that a DVT is treated quickly and effectively, and thereafter you receive adequate protection against any recurrence of either a PE or DVT. Treatment is especially important if you have already had a PE in order to prevent recurrence.
If you think that you are experiencing the symptoms of a PE you should contact your doctor immediately.
Treating PE and DVT – and preventing recurrence
The treatment of pulmonary embolism (PE) and deep vein thrombosis (DVT) is aimed at preventing the formation of any further clots while providing the right conditions for the body’s natural processes to break down the existing clot. The drugs used to treat blood clots are called anticoagulants – because they act on the coagulation process. This is a complex series of steps that occurs in a specific sequence. Hence, by interrupting one or more of these steps it is possible to reduce the likelihood of a clot forming.
For many years the standard treatment of PE and DVT has been daily injections of one type of anticoagulant called a heparin followed by tablets of a second anticoagulant called a vitamin K antagonist. This standard treatment for PE and DVT is highly effective, but it does have a number of drawbacks. These include the need for injections, and the interaction of vitamin K antagonists (such as warfarin) with a number of common foods and with other drugs. As a result, frequent blood tests are needed throughout the whole treatment period to find the appropriate dosage – a process known as coagulation monitoring.
Developments have resulted in new anticoagulants such as direct thrombin inhibitor and oral, direct Factor Xa inhibitors. These drugs can be used as a single drug alternative to the dual drug approach of heparin injections and vitamin K antagonist tablets. In addition, these newer drugs have a low risk of interactions and consequently do not require routine monitoring. Whether a treatment is a single or dual drug approach is dependent on the NOAC. Rivaroxaban has a single drug approach, after an initial treatment with a twice daily dose for the first three weeks, within this indication.