coronary thrombosis

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thrombosis

 [throm-bo´sis]
formation, development, or presence of a thrombus; this can happen whenever the flow of blood in arteries or veins is impeded. Many factors can interfere with normal blood flow: heart failure or physical inactivity may retard circulation generally; a change in the shape or inner surface of a vessel wall may impede blood flow, as in atherosclerosis; a mass may grow inside the body and exert pressure on a vessel; the vessel wall may be injured and roughened by an accident, surgery, a burn, cold, inflammation, or infection; or the blood may thicken in reaction to the presence of a foreign serum or snake venom. adj., adj thrombot´ic.

Sometimes a thrombus detaches itself from the wall and is carried along by the bloodstream. Such a clot is called an embolus, and the condition is known as embolism. A thrombus may form in the heart chambers, such as after coronary thrombosis (see below) at the place where the wall of the heart is weakened, or in the dilated atria in a case of mitral stenosis. Because blood normally flows more slowly through the veins than through the arteries, thrombosis is more common in veins than in arteries.
Venous Thrombosis. This occurs most often in the legs or pelvis; it may be a complication of phlebitis, result from injury to a vein, or occur with prolonged bed rest. The symptoms—a feeling of heaviness, pain, warmth, or swelling in the affected part, and sometimes chills and fever—do not necessarily indicate its severity. Immediate medical attention is necessary in any case. Under no circumstances should the affected limb be massaged.



In thrombosis of superficial veins, bed rest with legs elevated and application of heat to the affected area may be all that is necessary. In thrombosis of deep veins, the affected part must be immobilized to prevent the clot from spreading or turning into an embolus, and anticoagulant drugs may be given. With proper treatment, recovery occurs within a short time unless an embolism develops. Practice management guidelines for venous thromboembolism in trauma patients note that a vena cava filter should be considered in patients at high risk who are not candidates for anticoagulants.
Prevention of Venous Thrombosis. Immobility is a prime factor in the development of thrombosis; hence, all patients should be mobilized as soon as possible after surgery or an illness that requires bed rest or produces paralysis. Those who cannot get out of bed should follow an exercise routine involving either active or passive motion of the extremities.  dehydration also plays a role in the development of thrombosis, and the patient should be kept well hydrated. The use of sequential compression devices, such as graded elastic stockings or automated devices providing intermittent compression to the legs, are widely used and accepted, but there are few clinical studies related to their use. They probably play a role in the prevention of stasis and should be combined with other methods to prevent thromboembolism. Clinical guidelines also support the use of low molecular weight heparin for patients at high risk when the bleeding risk is not considered a problem.
Arterial Thrombosis. The main types of arterial thrombosis are related to arteriosclerosis, although thrombosis can also result from infection or from injury to an artery. Arteriosclerosis may be hereditary or may be brought on by diabetes mellitus. Coronary thrombosis, arterial thrombosis in a coronary artery, is a complication of coronary atherosclerosis. A thrombus in one of these arteries will block part of the blood supply to the heart muscle and cause severe myocardial infarction, which is a medical emergency. Cerebral thrombosis is arterial thrombosis in one of the cerebral arteries; the thrombus obstructs the supply of blood to the brain and results in stroke syndrome. Causes include hardening of the cerebral arteries, hypertension, complications of syphilis or other infections, dehydration, diabetes mellitus, or a violent injury.



In advanced cases of arteriosclerosis, a thrombus may fill up whatever channel remains through a vessel, completely blocking off circulation and causing gangrene. This occurs most frequently in arteries of the legs and is called peripheral thrombosis. The onset, often sudden, is characterized by either a tingling feeling or numbness and coldness in the limb. Pain is not always present. Immediate treatment with anticoagulants is necessary to discourage clotting. If this is not effective, surgery may be required. This condition is most common in the elderly and in diabetics. There are now methods of treatment that may save the limb, such as surgical removal of a thrombus or embolus, or surgery of blood vessels to remove old, narrowed, or deteriorated vessels and replace them with grafts.
cerebral thrombosis arterial thrombosis of a cerebral vessel, which may cause stroke syndrome; see also thrombosis.
coronary thrombosis arterial thrombosis in a coronary artery, which may cause myocardial infarction. See also thrombosis.
deep venous thrombosis (DVT) venous thrombosis of one or more of the deep veins of the lower limb, characterized by swelling, warmth, and erythema; it is frequently a precursor of a pulmonary embolism. See also thrombosis.
venous thrombosis phlebothrombosis.

cor·o·nar·y throm·bo·sis

coronary occlusion by thrombus formation, usually the result of atheromatous changes in the arterial wall and usually leading to myocardial infarction.

coronary thrombosis

n.
Obstruction of a coronary artery by a thrombus, often leading to destruction of heart muscle.

coronary thrombosis

development of a thrombus that blocks a coronary artery, often causing myocardial infarction and death. Coronary thromboses commonly develop in segments of arteries with atherosclerotic lesions.

coronary thrombosis

Cardiology A thrombus in a coronary artery lumen, which may cause an acute MI; thrombi form when microscopic cracks in the atherosclerotic coronary artery wall expose collagen and trigger platelet adhesion and thrombus formation

cor·o·nar·y throm·bo·sis

(kōr'ŏ-nār-ē throm-bō'sis)
Coronary occlusion by thrombus formation, usually the result of atheromatous changes in the arterial wall and usually leading to myocardial infarction.

coronary thrombosis

A heart attack caused by clotting of blood at the site of narrowing of a coronary artery, so that the heart muscle is locally deprived of blood and part of the muscle dies. Coronary narrowing is almost always caused by ATHEROSCLEROSIS. See also CORONARY SYNDROME.

coronary thrombosis

the formation of a blood clot (thrombus) in a coronary artery.

cor·o·nar·y throm·bo·sis

(kōr'ŏ-nār-ē throm-bō'sis)
Coronary occlusion by thrombus formation, usually the result of atheromatous changes in the arterial wall and usually leading to myocardial infarction.

coronary

encircling in the manner of a crown.
1. a term applied to vessels, ligaments, nerves, the band at the skin-hoof junction.
2. blood vessels partially encircling the heart.

coronary arteries
two large arteries that branch from the ascending aorta and supply all of the heart muscle with blood. See also Table 9.
coronary artery anomaly
one or both arteries originate from the pulmonary artery instead of the aorta; anoxia of the myocardium leads to congestive heart failure.
coronary artery laceration
in foals during a difficult parturition and in cattle due to penetration by a reticular foreign body; sudden death due to cardiac tamponade.
coronary artery rupture
can result from perforation by a foreign body from the reticulum as part of the syndrome of traumatic reticular pericarditis. Cardiac tamponade results, causing acute or congestive heart failure.
coronary band
the junction of the skin and the horn of the hoof.
coronary chemoreflex
intravenous injection of chemicals such as veratridine causes cardiac slowing, hypotension and apnea due to reflex response by the myocardium. Called also Bezold-Jarisch reflex.
coronary cushion
the spongy, resilient hypodermis beneath the coronary corium of the hoof.
coronary emboli
lodgment of an embolus in a coronary artery is a rare occurrence in animals. Myocardial ischemia and asthenia result, the effect on the animal varying with the amount of muscle compromised.
coronary occlusion
the occlusion, or closing off, of a coronary artery. The occlusion may result from formation of a clot (thrombosis). Narrowing of the lumen of the blood vessels by the plaques of atherosclerosis, as occurs in humans, does not occur in animals. If there is adequate collateral circulation to the heart muscle at the time of the occlusion, there may be little or no damage to the myocardial cells. When occlusion is complete, however, with no blood being supplied to an area of the myocardium, myocardial infarction results.
coronary perfusion pressure
the difference between aortic diastolic and right atrial diastolic pressure; a determinant of the blood flow to cardiac muscle.
coronary thrombosis
formation of a clot in a coronary artery. See also myocardial infarction.