Deep Venous Thrombosis

Deep Venous Thrombosis (DVT) is a condition wherein a blood clot develops in a deep vein that accompanies an artery, mostly in the lower limbs. Consequently, the clot affects blood circulation. Usually thrombosis sets in when the coagulation function is impaired or imbalanced due to abnormalities in the blood, altered blood flow or damage to the blood vessels. Typically the main veins affected by deep venous thrombosis are inner thigh, calf, groin and lower abdomen. A person suffering from deep vein thrombosis is likely to experience pain and swelling in the affected limbs. The pain in the affected leg can become so severe that the person is unable to bear weight on it. This condition is different from arterial thrombosis where the clot forms in the arteries. The main risk factor associated with deep venous thrombosis is that the clot may break off and travel along the blood stream to lodge itself in the lungs, heart or brain. This disease is usually noticed in adults over 60 years.

Deep Venous Thrombosis - DVT is brought about by reduced blood flow or thickening of the blood. Persons who have undergone surgery and been given anti-clotting drugs are likely to develop this condition. Long car or plane journeys, fractures, birth control pills and surgery are potential conditions that may lead to this disease. Those with a history of polycythemia vera or hypercoagulability are more likely to suffer this condition. One of the potential dangers of deep venous thrombosis is pulmonary embolism. Pulmonary embolism is a serious, life-threatening condition where the embolism blocks or closes the artery in the lung. Another complication of deep venous thrombosis is post-thrombotic syndrome characterized by edema, hyper pigmentation and skin ulceration.

Some of the diagnostic tests that help detect deep venous thrombosis are Ultrasound Doppler, Venography of the legs and D-dimer blood test. The Doppler ultrasound aids in studying the reduced blood flow in the affected limbs. The venogram is a special x-ray that reveals any blood clot that is responsible for obstructed blood flow. Magnetic Resonance (MR) Venography with Gadolinium contrast is considered as a prime imaging modality in the diagnosis of DVT.

The blood tests can reveal the clotting tendency. Heparin is an anticoagulant that has been intravenously given to a patient along with oral Warfarin. These medications cause an increase in clotting time. But careful monitoring is of the essence so as to avoid the risk of hemorrhage.

Blood thinners

Doctors prescribe medicines for varied reasons, to cure an ailment, to prevent or stop an infection, to ease symptoms, to reduce risks etc. But if there is one particular group of medicines where there is a need for rigorous monitoring regime when taken, it is blood thinners. Not without a reason. Though approved by the FDA, if not handled properly, prolonged use of blood thinners can be unsafe.

Need for Blood thinners

Blood thinners reduce the ability of the blood to clot. Blood thinners belong to a class of drugs called anticoagulants. Immediately after an injury, a scrape or a cut, the blood coagulates and seals the wound, forming a scab to protect from infection. The blood clots formed will be naturally dissolved in the body after the injury is healed. Here blood clotting is a saver and is essential for the body.

The mechanism is regarded as dangerous when blood clots form in the blood stream without an obvious injury and if the blood clot fails to dissolve naturally after the injury heals. The situation poses great risks as it can block circulation; the blood clot can travel to the arteries or veins in the brain, heart, kidneys, lungs and limbs. This in turn can lead to life-threatening conditions such as heart attack, stroke, damage body's organs and in extreme cases result in loss of life.

An updated (February 2014) American Academy of Neurology (AAN) guideline recommends people with an irregular heartbeat to take blood thinners to reduce the risk of stroke. As per doctor's prescription, every year around 2 million people take blood thinner medications every day. It is strongly recommended that blood thinner be taken only under medical supervision.

New vs. old blood thinners

Warfarin was introduced sixty years ago. It is regarded as the oldest anticoagulant blood thinner medication. For decades, Warfarin was the only blood thinner available to lower risks of stroke. There are new additions. A recent study has showed that new blood thinners might be more effective than older medications.

• Dabigatran (Generic name) approved by FDA in October 2010
  
• Rivaroxaban (Generic name) approved by FDA in October 2011
  
• Apixaban (Generic name) approved by FDA in December 2012.
  

Detailed studies comparing Warfarin with the new addition state the following:

• New drugs are similar or even better than warfarin in preventing stroke.
  
  
• As the optimal dose of Warfarin varies from patient to patient, blood levels of patients on Warfarin need to be checked periodically.
  
  
• New blood thinner medications are regarded as more convenient because the patients taking them do not need to have blood levels checked.
  
  
• A study on effectiveness reflected that new blood thinners were approximately 20% more effective in reducing the risk of stroke and 10 % more effective in reducing the risk of death when compared to warfarin.
  
  
• New blood thinners, in addition to being more convenient, are potentially more effective than and similar in safety to warfarin.
  
  
• New blood thinners are more expensive than Warfarin.
  
  
• Long-term safety and side effects of new blood thinners is not yet available.
  
  
• With Warfarin, it is easier to reverse the blood thinning effect if a patient is bleeding or needs urgent surgery.

Types of blood thinners

It is chemical formulations that contribute to preventing clotting in various ways. Broadly blood thinner medications are classified into anticoagulant and anti platelet blood thinners.

Anticoagulant blood thinners

Anticoagulant blood thinner medications help decrease the tendency of blood clot formation. There are two ways to decrease the formation of blood clots in the body. Anticoagulants can interfere with platelets or block the body's production of clotting substances. Anticoagulant blood thinners are prescribed for people who have had a condition caused by a blood clot or are at risk of developing one.

Anticoagulant blood thinners are usually given by mouth. In some cases anticoagulants are given intravenously or by injecting them just under the skin (subcutaneously).

Warfarin: Warfarin is the generic drug. In the US, Warfarin is sold under the brand names Coumadin and Jantoven. Doctors prescribe Warfarin for two reasons, to prevent the formation of harmful blood clots or treat an existing blood clot. Some conditions for which Warfarin is prescribed include:

• Atrial fibrillation
  
• Stroke
  
• After a heart attack
  
• Clotting disorder
  
• Heart valve disease or heart valve replacement
  
• Treatment or prevention of Deep Venous Thrombosis (blood clots in the veins) and/or pulmonary embolism (blood clots in the lungs).

Patients prescribed Warfarin ought to know how Warfarin works. Knowing helps limit the intake of vitamin K rich foods like dark green vegetables such as broccoli, spinach, turnip greens, green peas etc. At any time, the blood needs certain proteins to clot. These proteins are made in the liver. To enable the liver in the process, Vitamin K is required.

When Warfarin is administered, it reduces the liver's ability to use Vitamin K. Warfarin and Vitamin K work against each other. Thus, the formation of blood clot becomes harder. The interaction between Warfarin and Vitamin K explains the need to partake a diet that is constant in Vitamin K while on Warfarin. The dosage of Warfarin may vary from person to person. A blood test may be recommended to determine the dosage. This blood test, Prothrombin Time or International Normalized Ratio is required to monitor the body's response to Warfarin. Based on test results, Warfarin dose will be determined.

Side effects of Warfarin

Warfarin or Heparin, a common side effect of any anticoagulant medication is the risk of excessive bleeding. As these medicines prolong or lengthen or makes blood clot formation harder, it increases the time for formation of blood clots. If the time taken is too long, there is a possibility of excessive bleeding. There are other symptoms to look out for which are more common with Warfarin. Patients on Warfarin should immediately seek medical attention for any these common Warfarin side effects.

• passing blood in your urine or feces (stools)
  
• passing black feces
  
• severe bruising
  
• prolonged nosebleeds for more than 10 minutes
  
• bleeding gums
  
• blood while throwing up (vomiting)
  
• coughing up blood
  
• unusual headaches
  
• sudden severe back pain
  
• difficulty breathing or chest pain

Women who take Warfarin should contact health care provider if they experience heavy or increased bleeding during menstruation or any other bleeding from the vagina.

Irrespective of the gender, some patients may experience rashes, diarrhea, nausea, hair loss while on Warfarin. These are not common side effects but are termed as additional side effects of Warfarin.

Doctors do advice patients to seek help if the patient is involved in a major accident, experiences a significant blow to the head and finds it difficult to stop bleeding, if any. As Warfarin can interact with many other medicines, so do inform the doctor about all the medications being taken.

Warfarin during pregnancy: Warfarin should be avoided during pregnancy and women with certain health conditions like high blood pressure, ulcer in the digestive tract should not take Warfarin as it can lead to severe health complications.

Long terms risks of using Warfarin: Extensive research on prolonged use of Warfarin suggests that the risk increases with age. The patient is at risk of serious or even fatal bleeding including internal bleeding. In particular the risks are:

• Bleeding strokes, or brain strokes (hemorrhage strokes)
  
• Calcium build-up in the arteries and narrowing of the aortic valve that goes from the heart and carries oxygen to the body (aortic valve stenosis)

Heparin: Heparin is the generic name. In US, Heparin is available under the brand names Lipohepin, liquaemin and Panheparin. Heparin decreases the clotting ability of the blood and also prevents existing clots from getting larger. Thereby, the normal body systems dissolve the clots that are already formed. Heparin is usually administered as an injection. Heparin can be injected subcutaneously or as an intravenous infusion. The advantage of IV is that it can be turned off quickly for safety reasons. Heparin is prescribed for conditions such as:

• Deep venous thrombosis
  
• Arterial embolism
  
• Pulmonary embolism
  
• Prevention of blood clot during heart surgery, dialysis or blood transfusions
  
• Peripheral artery obstruction by a foreign substance or a blood clot
  
• Treatment to prevent peripheral artery thrombo-embolism.

It helps to know how heparin works. Heparin ensures that an anti-clotting protein which is present in the body works better, thus decreasing the clotting ability of the blood.

Available in different strengths, the doctor must prescribe the strength depending on the purpose for which it is prescribed. During the course of treatment, the doctor may increase or decrease the dosage.

Side effects of heparin

A unique possible side effect of Heparin is that several weeks after stopping the injection, bleeding episodes may occur. If the patient notices bruising or unusual bleeding such as a nosebleed, blood in the urine or stools, black or tarry stools or any other bleeding that doesn't cease, contact your healthcare provider.

Besides the common side effects of anticoagulant medications, Heparin's other side effects are visible at that point where the solution is injected.

• Swelling
  
• Pain
  
• Irritation
  
• Bruising

Herparin during pregnancy: FDA category for Heparin is C meaning there isn't established information that proves whether Heparin affects the fetus. It is best for pregnant women as well as breast-feeding mothers to use Heparin only if the medicine is prescribed by the doctor.

Long term risks of using Heparin

Prolonged use of Heparin particularly in the elderly may cause osteoporosis, a condition in which the bones become weak and may break easily.

Antiplatelet blood thinners

Antiplatelet blood thinner medications work to prevent the platelets (small cells in the blood) from clumping together to form a blood clot. This happens by inhibiting the production of thromboxane, a chemical that signals other platelets to come together. By inhibiting the production of thromboxane, platelets cease to come together to form the blood clot.

Thromboxane's role is helpful for a normal healthy individual who has suffered a wound. It acts as a self-sealing material. But, in the case of a stroke survivor, thromboxane's ability to bind and form a blood clot is potentially life-threatening. Hence, the need to use an antiplatelet blood thinner which are usually available in the form of tablets only.

Doctors prescribe antiplatelet Aspirin to patients who have had a stroke or TIA (transient ischemic attack) so as to reduce the risk of having another stroke. This is possible with Aspirin as it interferes with the blood's clotting action. The dosage varies from patient to patient and is largely guided by the patient's health condition.

Though Aspirin is available OTC (over the counter), doctors recommend low doses of Aspirin for patients with the following medical history.

• Patients who have had prior heart attacks
  
• Patients who have had prior strokes
  
• Patients with exertional and unstable angina
  
• Patients with TIAs (transient ischemic attack called mini-stroke)
  
• Patients at risk of atherosclerosis.

Aspirin is prescribed to patients who are considered to be at risk of having heart attack or stroke. Anyone with high cholesterol, high blood pressure, diabetic and smoke aggressively are regarded to be at risk of having heart attack or stroke.

Side effect of Aspirin

Most common side effect of taking low doses of Aspirin (100 mg dose) is heartburn and stomach upset. Seldom has there been a very serious side effect related to taking Aspirin as a blood thinner medication. However it is best to be aware of possible serious side effects such as bruising/bleeding, difficulty hearing, ringing in the ears, and change in urine amount, persistent or severe nausea /vomiting, unexplained tiredness, dizziness, dark urine, yellowing of eyes or skin.

Aspirin during pregnancy

The FDA has not assigned formally a pregnancy category. Aspirin is not recommended for use during pregnancy and while breast-feeding as it excretes into breast milk in small amounts.

Other antiplatelet blood thinners

Besides Aspirin, other antiplatelet medicines that are prescribed to prevent the platelets from sticking together include the following. Doctors prescribe a specific antiplatelet blood thinner taking into account the specific health condition and relative effectiveness of the blood thinner medicine. New drugs are continually added to the list with FDA approval.

• Aspirin plus clopidogrel (brand name Plavix) is prescribed for patients who are diagnosed with coronary syndrome such as unstable angina or have had a heart attack, if stent is implanted or if the patient has had a stroke or mini stroke.
  
  
• Aspirin plus extended dipyridamole (brand name Aggrenox) is prescribed for patients who have had a stroke or mini stroke (TIA).
  
  
• Clopidogrel (brand name Plavix) is recommended by doctors if Aspirin is not suitable for a patient who has been diagnosed with acute coronary syndrome or had a stent implanted.

Long term risks of using Aspirin

Daily use of aspirin can have serious side effects including internal bleeding. Prolonged use of aspirin at higher doses (> 500 mg) can cause stomach ulcers, and can also prolonged bleeding.

Plethysmography

Plethysmograph is a diagnostic tool that is used to measure flow or pressure. Body plethysmography test involves sitting inside an airtight box and breathing to a particular volume. Blood pressure cuffs are placed around your arm and leg. The patient undergoing plethysmography test must remove clothing on arm and leg and refrain from smoking at least half hour prior to the test. The consequent expansion and decompression of the chest volume allows physicians to rule out any blockages in the limbs as it measures systolic blood pressure. Any abnormal readings can be indicative of arterial occlusive disease, vascular disease or blood clots or even deep venous thrombosis. This test is also referred to as arterial plethysmography and is a vital pulmonary function test. Plethysmography is often used to determine bronchial reactions to histamine or metacholine. But this test is not as accurate as arteriography.