Facts About Blood Blood Clots

• A blood clot is a mass formed by platelets and fibrin in the blood to stop bleeding.
• There are a variety of risk factors and illness that can lead to blood clot formation.
• Causes of blood clots may include:
  1. certain heart conditions,
  2. pregnancy,
  3. prolonged immobility,
  4. smoking,
  5. certain medications,
  6. surgery, and
  7. inherited blood clotting disorders.
• Symptoms of blood clots depend on their location in the body. Some blood clots produce no symptoms until they rupture or become dislocated and travel through the circulatory system to other sites.
• Signs of a blood clot depend on their location in the body. Blood clots can cause heart attack or stroke; or pain, swelling, redness and  tenderness in the area of the clot.
• The diagnosis is suggested by the history and physical examination and often confirmed with an imaging test.
• Treatment may require surgery, anti-coagulation medications, or a combination of the two.
• Prevention of blood clots involves attention to the risk factors for vascular disease.
• Serious complications can arise from blood clots, and individuals should seek medical care if     believe they may have a blood clot.

Blood flows through blood vessels, and is constantly in motion as the heart pumps blood through arteries to the different organs and cells of the body. Blood is then returned back to the heart by the veins. Blood returns to the heart when veins are squeezed and blood is pushed toward heart.
Blood clotting is an important mechanism to help the body repair injured blood vessels. Blood consists of:

1. red blood cells containing hemoglobin that carry oxygen to cells and remove carbon dioxide (the waste product of metabolism),
2. white blood cells that fight infection,
3. platelets that are part of the clotting process of the body, and
4. blood plasma, which contains fluid, chemicals and proteins that are important for bodily functions.

Complex mechanisms exist in the bloodstream to form clots where they are needed. If the lining of the blood vessels becomes damaged, platelets are recruited to the injured area to form an initial plug. These activated platelets release chemicals that start the clotting cascade, using a series of clotting factors produced by the body. Ultimately, fibrin is formed, the protein that crosslinks with itself to form a mesh that makes up the final blood clot.
The medical term for a blood clot is a thrombus (plural=thrombi). When a thrombus is formed as part of a normal repair process of the body, there is little consequence. Unfortunately, there are times when a thrombus (blood clot) will form when it is not needed, and this can have potentially significant consequences.
Blood clots form when there is damage to the lining of a blood vessel, either an artery or a vein. The damage may be obvious, such as a cut or laceration, or may not be visible to the naked eye. Blood also will begin to clot if it stops moving, and becomes stagnant, or in diseases that cause the blood to clot abnormally.
Blood clots in a vein (venous thrombosis) occur when a person becomes immobilized and muscles are not contracting to push blood back to the heart. This stagnant blood begins to form small clots along the walls of the vein. This initial clot can gradually grow to partially or completely occlude or block the vein and prevent blood from returning to the heart.
An analogy to this process is a slow moving river. Over time, weeds and algae start to accumulate along the banks of the river where the water flows more slowly. Gradually, as the weeds start to grow, they begin to invade the center of the river because they can withstand the pressure of the oncoming water flow.
Blood clots in an artery (arterial thrombi) occur by a different mechanism. For those with atherosclerotic disease, plaque deposits form along the lining of the artery and grow, which causes the vessel to narrow. This disease process may cause:

• heart attack,
• stroke, or
• peripheral artery disease.

If a plaque ruptures, a blood clot can form at the site of that rupture and can completely or partially occlude the blood flow at that point.
Blood clots in the heart. In atrial fibrillation, the upper chamber (atrium) of the heart does not beat in an organized manner. Instead, it jiggles, and blood tends to become stagnant along the walls of the atrium. Over time, this may cause small blood clots to form. Clots also can form in the ventricle after a heart attack when part of the heart muscle is injured and unable to contract normally. Since the damaged area doesn't contract with the rest of the heart, blood can start to pool or stagnate, leading to clot formation.
Blood leaking out of a blood vessel.  Blood clots can form when blood leaks out of a blood vessel, and can be very beneficial because the clot helps stop further bleeding at the site of injury. A few examples of how bleeding is controlled by the body's clotting mechanism are:

1. cuts or scrapes
2. broken bones,
3. sprains and strains, and
4. nosebleeds.

Blood clots causing other medical problems.Sometimes, normal blood clotting can cause medical problems because of its location. For example, blood the urine may occur from any of a variety of reasons (such as infection, trauma, or tumor), and clots may form and prevent the bladder from emptying, causing urinary retention.
Clot formation in the uterus may cause pain when the clots are passed through the cervix and can lead to vaginal bleeding, either as part of menstruation or as abnormal vaginal bleeding (menorrhagia, dysmenorrhea).
The risk factors for arterial clots are those that are common to all diseases that cause narrowing of blood vessels, cholesterol plaque formation, and plaque rupture.

• High blood pressure
• High cholesterol levels
• Diabetes
• Smoking
• Family history
• Cancer

Blood clots in the veins are formed due to one of two main reasons: 1) immobility, and 2) genetic errors in the clotting mechanism. There are other associated risk factors including smoking and the use of birth control pills.

1. Immobility: Commonly, when the body stops moving, the risk of blood clots increases since muscle movement is required to pump blood toward the heart. Stagnant blood in a vein is prone to clot. Examples of how blood clots may occur from immobility include:

• a person being hospitalized or bedridden after illness or surgery;
• a person who takes long trips (such as in a car, train, or plane), when hours may pass without standing to move, walk, or stretch (blood pools in the leg veins and may potentially clot);
• a person who suffers orthopedic injuries and/or has casts placed over broken bones or limbs; and
• a woman who becomes pregnant; pregnancy is a risk factor for forming blood clots in the legs and pelvis, due to insufficient blood flow back to the heart.

2. Genetic errors in the clotting mechanism: There may be a genetic or inborn error in the clotting mechanism, making a person hypercoagulable (hyper=more + coagulation= clotting) and at greater risk for forming clots.Blood clots may cause life-threatening medical conditions, and are always considered in the differential diagnosis of any symptoms or signs. Differential diagnosis is the list of potential causes of a patient's condition, that is considered by the healthcare provider when caring for a patient and listening to them describe their signs and symptoms.
   

   Deep venous thrombosis (DVT) and pulmonary embolism

   Deep venous thrombosis (DVT)may lead to a pulmonary embolism.If there is a blood clot or thrombus in a deep vein, it has the potential to break off (embolize) and flow through the veins back through the heart, and into the lung where it can become lodged in a pulmonary artery, which prevents the lung from functioning. Pulmonary embolism is a medical emergency and can cause serious illness or death.
   An embolus is the medical term for a blood clot that has moved within the bloodstream to a different location. With pulmonary embolus (pulmonary embolism), two issues occur.
3. The lungs' blood supply is comprised and the affected area of lung tissue may infarct, or die.
4. Because of the blockage, the ability of the lung to provide oxygen to the body is decreased and hypoxia (decreased levels of oxygen in the blood and throughout the body) may occur.

Even if venous blood clots do not embolize, they may cause significant local problems with swelling and pain. Since blood cannot return to the heart if a vein is blocked by a clot, the limbs may chronically swell and have decreased function in a condition called chronic thrombophlebitis.

Arterial thrombus

An arterial thrombus stops the blood supply to the tissues beyond the blockage, depriving cells of oxygen and nutrients. This quickly leads to tissue death. Arterial thrombus is the mechanism that causes:

• heart attack (when it occurs in the coronary arteries that supply blood to the heart)
• stroke (when it occurs in arteries within the brain),
• peripheral vascular disease (occurring in the arteries of the legs), or
• ischemic bowel or mesenteric ischemia (when it occurs in the arteries that supply blood to the intestine)

Atrial fibrillation (AFib, AF)

In atrial fibrillation (AFib, AF), small clots may form along the walls of the atrium or the upper chambers of the heart. Should one of these clots break off, it may embolize, or travel in the bloodstream to the brain, blocking an artery and causing a stroke. Other arteries also may be involved when blood clots caused by the presence of AFib lodge and stop blood flow (embolize), including those that supply blood to the bowel. This can cause bowel ischemia and tissue death (potential necrosis) of the intestine. Clots also can affect blood supply to fingers and toes.

Other types of blood clots

Blood should clot anytime it becomes stagnant. This also means that clots will form when blood leaks out of blood vessels.
Examples include some of the following:

• With bleeding peptic ulcers, patients may vomit liquid blood mixed with clot.
• Patients with rectal bleeding may also have clot mixed with the bloody stool if there has been time for the clot to form.
• Sometimes patients with urinary tract or bladder infections develop associated bleeding in their urine, and small clots can form. On occasion these clots may be so big that they cannot be passed and block the urethra, preventing urination and causing urinary retention.
• Vaginal bleeding is a normal event for most women in the reproductive years and occasionally, blood can pool in the vagina and form clots before being expelled. If clots form in the uterus, they may cause significant pain and pressure as they pass through the cervix while being expelled.Blood clots in the veins do not allow blood to return to the heart, and symptoms occur because of this "damming effect." These clots often occur in the legs or the arms, symptoms include:
• swelling,
• warmth,
• redness, and
• pain.

Blood clots in the arteries do not allow blood get to the affected area. Body tissue that is deprived of blood and oxygen begins to die and becomes ischemic. Symptoms of blood clots in the arteries are:

• Pain. Pain is the initial symptom of the oxygen deprivation (ischemia) due to loss of blood supply.
• Location of the blood clot: Other symptoms depend upon the location of the clot, and often the effect will be a loss of function, for example:
  • heart attack or stroke (self-explanatory),
  • in an arm or leg; in addition to pain, the affected limb may appear white, and weakness, loss of sensation, or paralysis may occur.
  • to an area of the bowel, in addition to intense pain, there may be bloody diarrhea.
  The initial step in making the diagnosis of a blood clot is obtaining a patient history. The blood clot itself does not cause a problem. It's the location of the blood clot and its effect on blood flow that causes symptoms and signs. If a blood clot or thrombus is a consideration, the history may expand to explore risk factors or situations that might put the patient at risk for forming a clot.
  Venous blood clots often develop slowly with a gradual onset of swelling, pain, and discoloration. Symptoms of a venous thrombus will often progress over hours.
  Arterial thrombi occur as an acute event. Tissues need oxygen immediately, and the loss of blood supply creates a situation in which symptoms begin immediately.
  There may be symptoms that precede the acute artery blockage, that may be warning signs of the potential future complete occlusion of the blood vessel.
• Patients with an acute heart attack (myocardial infarction) may experience angina in the days and weeks prior to the heart attack.
• Patients with peripheral artery disease may have pain with walking (claudication), and a TIA (transient ischemia attack, mini-stroke) may precede a stroke.

Physical examination can assist in providing additional information that may increase the suspicion for a blood clot.

• Venous thrombi may cause swelling of an extremity. It may be red, warm, and tender; sometimes the appearance is difficult to distinguish from cellulitis or an infection of the extremity. If there is concern about a pulmonary embolus, the clinician may examine the lungs, listening for abnormal sounds caused by an area of inflamed lung tissue.
• Arterial thrombus symptoms are much more dramatic. If a leg or arm is involved, the tissue may be white because of the lack of blood supply. As well, it may be cool to touch and there may be loss of sensation and movement. The patient may be writhing in pain.

Arterial thrombus is also the cause of heart attack (myocardial infarction) and stroke (cerebrovascular accident) and their associated symptoms.
Testing for venous blood clots
Venous blood clots may be detected in a variety of ways, though ultrasound is most commonly used. Occasionally, the patient's size and shape limit the ability for ultrasound to provide a definitive answer.
Venography is an alternative test to look for a clot. In this test, a radiologist injects contrast dye into a small vein in the hand or foot and using fluoroscopy (video X-ray), watches the dye fill the veins in the extremity as it travels back to the heart. The area of clot or obstruction can thus be visualized.
Sometimes, a blood test is used to screen for blood clots. D-Dimer is a breakdown product of a blood clot, and its levels in the bloodstream may be measured. Blood clots are not stagnant; the body tries to dissolve them at the same time as new clot is being formed. D-Dimer is not specific for a blood clot in a given area and cannot distinguish a "good" or needed blood clot, one that forms after surgery or due to bruising from a fall, from one that is causing medical problems. It is used as a screening test in low risk patients with the expectation that a negative result will conclude that there is no need to look further for blood clots. The healthcare professional usually counsels the patient that a positive blood test will likely require additional tests being considered.
Should a blood clot embolize to the lung, this may be a medical emergency. There are a variety of tests to look for pulmonary emboli. A plain chest X-ray will not show blood clots, but it may be done to look for other conditions that can cause chest pain and shortness of breath, which are the symptoms of a pulmonary embolus. An electrocardiogram (EKG) may show abnormalities suggestive of a pulmonary embolus and also may reveal other causes of chest pain.
Computerized tomography (CT scan) is often the test of choice when suspicion of pulmonary embolus is high. Contrast material is injected intravenously, and the radiologist can determine whether a clot is present in the pulmonary vessels. The contrast material injected into the body can be irritating to the kidney(s) and should not be used in patients who have impaired kidney function. In older patients, screening blood tests (serum creatinine) to check kidney function may be required before a dye study is considered.
On occasion, a ventilation perfusion (V/Q) scan is performed to look for pulmonary emboli. This test uses labeled chemicals to identify inhaled air into the lungs and match it with blood flow in the arteries. If a mismatch occurs, meaning that there is lung tissue that has good air entry but no blood flow, it may be indicative of a pulmonary embolus. It is less accurate and more subjective than a CT scan, and requires the skill and experience of a radiologist to interpret. Two radiologist may interpret a VQ scan differently and come to different conclusions. The VQ scan is often performed when a CT scan is contraindicated, for example, with a major dye allergy or in a patient with kidney compromise.

Testing for arterial blood clots

Arterial thrombosis is an emergency, since tissue cannot survive long without blood supply before there is irreversible damage. When this occurs in an arm or leg, often a surgeon is consulted on an emergency basis. Arteriography may be considered, a test in which contrast material is injected into the artery in question to look for blockage on imaging studies. Sometimes, if there is a large artery that is occluded, this test is done in the operating room with the presumption that a surgical procedure will be needed to open the vessel and restore blood flow.
For a heart attack (acute myocardial infarction, MI), the EKG may establish the diagnosis, although blood tests may be used to look for enzymes (troponin) that leak into the bloodstream from irritated heart muscle. In an acute heart attack, the diagnostic and therapeutic procedure of choice is a heart catheterization.
For an acute stroke (cerebrovascular accident, CVA), the test of choice is a computerized tomography (CT) scan of the head to look for bleeding or tumor as the cause of stroke symptoms. If the symptoms resolve, the diagnosis is a transient ischemic attack (TIA, mini-stroke), and further tests may include carotid ultrasound to look for blockages in the major arteries of the neck and echocardiography to look for blood clots in the heart that may embolize to the brain.
Depending upon their location, blood clots may be aggressively treated or may need nothing more than symptomatic care.
Blood clots in the veins (venous blood clots)
What is the treatment for blood clots?Depending upon their location, blood clots may be aggressively treated or may need nothing more than symptomatic care.

Blood clots in the veins (venous blood clots)

Clots may develop in the superficial or deep veins of the leg. Treatment for a superficial blood clot is directed at managing pain and decreasing inflammation with medication (for example, acetaminophen [Tylenol and others] or ibuprofen [Advil, Motrin, etc.]). The risk of these clots lodging and obstructing (embolizing) in the vein is low because of the anatomy of the leg. Specialized veins (perforator veins) connect the superficial veins to the deep veins, and have valves that act like strainers to prevent clots from travelling to the lung.

Blood thinners

Clots located above the knee in the deep vein system may need to have the blood "thinned" with anticoagulation medications.

Warfarin (Coumadin)

Warfarin (Coumadin) is one type of anticoagulation medication that has been used for many years to treat blood clots. It blocks clotting factors II, VII, IX and X, those that depend upon Vitamin K, and is usually prescribed as soon as DVT (deep venous thrombosis) or blood clot is diagnosed. Because if take a few days to effectively thin the blood, low molecular weight heparin (enoxaparin) or regular heparin is used to immediately cause anticoagulation.
Heparin is injected subcutaneously under the skin and can be administered in an outpatient setting.
Regular heparin is given intravenously, and the patient will need to be admitted to the hospital to receive this drug. Once the warfarin effectively thins the blood, the heparin is discontinued. Warfarin effectiveness is measure by a blood test and the INR needs to have a value between 2.0 and 3.0.

Newer anticoagulation drugs

Newer anticoagulation medications have been approved that inhibit blood factor X. These act almost immediately to thin the blood and include:

• apixaban (Eliquis),
• rivaroxaban (Xarelto),
• dabigatran (Pradaxa) and
• edoxaban (Savaysa).

These drugs are taken orally and become effective in thinning the blood within a couple of hours. They also do not need blood tests to monitor dosage.
The decision to prescribe a type of anticoagulation medication (Vitamin K antagonist v. Factor X/thrombin inhibitor) depends upon the patient's situation. All patients who take anticoagulation medications are at risk for bleeding. At present there is no antidote approved in the United States to reverse the effects of the Factor X inhibitors, should the need arise. There are reversal strategies available for warfarin and heparin.
Pulmonary emboli are treated similarly to deep venous thrombosis, but depending on the severity of the symptoms, amount of clot formation, and the underlying health of the patient, admission to the hospital for treatment and observation may be needed. This is especially the case if lung function is compromised and the patient is short of breath or is experiencing hypoxia, (low oxygen levels in the blood). Patients who are critically ill and display symptoms of heart strain or shock may be candidates for thrombolytic therapy using drugs known as tissue plasminogen activators (TPAs). TPAs may be injected into a peripheral vein in the arm to immediately thin the blood and act as a clot busting drug.

Arterial blood clots

Arterial blood clots are often managed more aggressively. Surgery may be attempted to remove the clot, or medication may be administered directly into the clot to try to dissolve it. Alteplase (Activase, TPA) or tenecteplase (TNKase) are examples of tissue plasminogen activator (see above) medications that may be used in peripheral arteries to try to restore blood supply.This is the same approach that is used for heart attack. If possible, cardiac catheterization is performed to locate the blocked blood vessel and a balloon is used to open the occluded area, restore blood flow, and place a stent to keep it open. This is a time-sensitive procedure and if a hospital is not available to do the procedure emergently, TPA or TNK is used intravenously to try to dissolve the thrombus and minimize heart damage. Eventually, the patent, when stable, will be transferred for potential heart catheterization to evaluate the heart anatomy and decide whether stents may be needed to keep an artery open or whether bypass surgery might be needed to restore blood supply to the heart.
Stroke is also treated with TPA if the patient is an appropriate candidate for this therapy.
Blood clots prevent proper circulation of blood.
Deep vein thrombosis of the leg or arm may cause permanent damage to the veins themselves and cause persistent swelling of the extremity. The life-threatening issue that may arise from deep venous clots is a clot that breaks off and embolizes to the lungs (pulmonary embolus), causing problems with lung function and oxygenation of the blood.
Arterial thrombus often is a life- or limb threatening event, since organs and cells do not get enough oxygen.
Prevention is key in thrombosis or clot formation.

Arterial thrombosis

• For arterial thrombosis, the most likely precipitating event is a plaque rupture with clot formation in the artery.
• Minimizing the risk of vascular disease requires life-long attention to the risk factors that lead to plaque buildup and "hardening" of the arteries.
• Blood pressure and cholesterol control, diabetes management, and refraining from smoking all minimize the risk of arterial disease.
• Although family history is an important risk factor, one needs to be even more vigilant about the other risk factors if there is a family history of early heart attack or stroke.

Deep vein thrombosis

The main risk factor for deep vein thrombosis risks is immobilization. It is important to move around routinely so that blood can circulate in the venous system. On long trips, it is recommended to get out of the car every couple of hours and in an airplane routinely get up and stretch.
Physicians and nurses work hard at getting people moving after surgery or while in the hospital for medical conditions. The low molecular weight heparin known as enoxaparin (Lovenox) can also be used in low doses to prevent clot formation. Patients are often given tight stockings to promote blood return from the legs and prevent pooling of blood.
In patients with atrial fibrillation (AFib), warfarin (Coumadin) was traditionally used to prevent clot formation and minimize the risk of embolus and stroke. Newer medications have been developed that prevent blood clot formation similar to warfarin and have been approved for use in patients with atrial fibrillation. These medications include apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran (Pradaxa), and edoxaban (Savaysa). These newer drugs have advantages of reduced susceptibility to diet and drug interactions and convenience (lack of need for routine blood testing of the international normalized ratio or INR, as is required for warfarin therapy). Unfortunately, there is no medication available in the United States to reverse the anticoagulation action of these medications, should that need arise.
The decision as to which medication to use for atrial fibrillation depends upon the clinical situation. Aspirin may also be an appropriate drug to use in low risk patients. That risk may be measured by the CHADS2 scoring system for atrial fibrillation that assigns a score for potential stroke based on age and history of high blood pressure, congestive heart failure, diabetes and previous stroke or TIA history.

SOURCE: http:www.basicfactsaboutthrombosis/google.html