INFARCTION. .

INFARCTION. .

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  INFARCTION
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  Infarction is tissuedeath or necrosis due to inadequate blood supply to the affected area. ETIOLOGY Most Commonly, Infarcts are caused by interruption in Arterial blood supply, called Ischemic Necrosis. Less commonly, they are caused by venous obstruction, these infarcts are termed Stagnant Hypoxia. Generally, complete and continuous occlusion by embolism or thrombosis. Torsion of a blood vessel Traumatic rapture or vascular compromise by edema Non occlusive circulatory insufficiency DEFINITION
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  PATHOGENESIS OF INFARCTION 1.Atherosclerosis Formation: The process often begins with atherosclerosis, where fatty deposits, cholesterol, and other substances accumulate on the inner walls of coronary arteries, narrowing them. NB: there can also be non-atherosclerotic causes like embolism ,trauma, coronary vasospasm etc. but atherosclerotic causes contributes more than 75% of myocardial infarctions and is therefore more predominant. 2. Plaque Rupture or Erosion: The atherosclerotic plaque can become unstable and vulnerable to rupture or erosion. This exposes the underlying tissue to the bloodstream.
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  3. THROMBUS FORMATION:When the plaque ruptures or erodes, it exposes the inner layers of the artery, including collagen fibers. Platelets in the blood stick to these collagen fibers, initiating the formation of a blood clot (thrombus). 4. OCCLUSION OF CORONARY ARTERY: As the blood clot grows, it can partially or completely block the coronary artery, reducing or completely cutting off blood flow to the downstream heart muscle. 5. ISCHEMIA: The lack of oxygen-rich blood (ischemia) in the affected area of the heart can cause chest pain (angina) and other symptoms. PATHOGENESIS OF INFARCTION
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  TYPES OF INFARCTION 1.BASED ON COLOR  Pale(white) or anaemic infarction o This is infarction in which little or no bleeding into tissue spaces occurs when the blood supply is obstructed. White infarcts occurs in; o Arterial occlusion in organs with a single blood supply. o Solid organs such as the heart, spleen, kidneys, where the solidity of the tissue limits the amount of haemorrhage that can percolate or seep in to the area of ischemic necrosis from the nearby capillaries.
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   Red orhaemorrhagic infarction o Results from infiltration of blood from collateral vessels into necrotic area. This kind of infarct occurs in; Venous occlusions as in ovarian torsion, Loose tissues such as the lung which allow blood to collect in infarct zone. Tissues with dual circulations (eg. the lung), permitting flow of blood from unobstructed vessel in to necrotic zone. 2.DEPENDING ON AGE I. Recent or fresh II. Old or healed 3. PRESENCE OR ABSENCE OF INFECTION o Bland infarct-An uninfected infarct o Septic infarct- An infected infarct
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  PHYSIOLOGICAL CHANGES OFINFARCTION When an infarction occurs, it means that a part of an organ or tissue is deprived of its blood supply, leading to a lack of oxygen and nutrients. This results in a series of physiological changes:  Ischemia: This is the initial phase where blood flow to the affected area is reduced. Cells begin to experience oxygen and nutrient deprivation.  Hypoxia: As ischemia progresses, cells become hypoxic, meaning they are not receiving enough oxygen. This leads to a decrease in cellular energy production.  Cellular Injury: Without sufficient oxygen and nutrients, cells cannot maintain normal cellular functions. The sodium-potassium pump fails, leading to an influx of sodium ions and water, causing cell swelling.
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  PHYSIOLOGICAL CHANGES OFINFARCTION  Cell Death: If blood supply is not restored promptly, irreversible cellular damage occurs. This is typically due to a process called apoptosis or, in severe cases, necrosis.  Inflammatory Response: After cell death, the immune system responds to remove dead cells and initiate the healing process. This can lead to the release of inflammatory mediators, causing swelling and redness in the affected area.
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  1. HEART: Myocardialinfarction- This is most commonly due to blockage of a coronary artery following the unstable collection of lipids and white blood cells in the wall of the artery. 2. BRAIN: Cerebral infarction- This infarction occurs when the blood supply to the brain is reduced. This often occurs due to an embolus originating from the carotid arteries. It presents as a stroke and the symptoms depend on the part affected. INFARCTION OF DIFFERENT ORGANS
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  3. LUNG: Pulmonaryinfarction or Lung infarction- The infarction occurs with a medium-large sized embolus which travels down the pulmonary tree and obstructs a medium-sized pulmonary artery branch. 4. SPLEEN: Splenic infarction- It occurs when the splenic artery or one of it's branches are occluded. INFARCTION OF DIFFERENT ORGANS
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  CLINICAL MANIFESTATIONS OFINFARCTION 1. MYOCARDIAL INFARCTION o Chest pain, shortness of breath, Sweating, Nausea, Vomiting, Anxiety, Fast heart rate, Pressure in the chest 2. CEREBRAL INFARCTION o Numbness or weakness in the face, arm or leg o Confusion trouble speaking or understanding speach o Dizziness, loss of balance or coordination to trouble walking o Severe headache with no cause
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  3. PULMONARY INFARCTION oDyspnea, chest pain, and Swelling or pain in a unilateral lower extremity, fever, Haemoptysis 4. RENAL INFARCTION o abdominal or flank pain, Nausea, Vomiting , Fever, Gross Microscopic Haematuria is often present 5. SPLENIC INFARCTION o Left sided abdominal pain, Blood- borne malignancy, and Blunt abdominal Trauma 6. RETINA INFARCTION o blurry vision o partial or complete loss of vision CLINICAL MANIFESTATIONS OF INFARCTION
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  MANAGEMENT OF INFARCTION Infarctionis Managed through treatment regimen such as; 1. ASPIRIN - which helps in prevention of blood clotting 2. MORPHINE - helps in pain relief 3. ANTICOAGULANT - prevent clots from getting larger 4. Oxygen - helps in increasing oxygen levels to the ischemic area tissue or organ 5. SEDATIVES - it helps in limiting the size of infarction
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  SUMMARY ■ Infarcts areareas of ischemic necrosis most commonly caused by arterial occlusion (typically due to thrombosis or embolization); venous outflow obstruction is a less frequent cause. ■ Infarcts caused by venous occlusion or occurring in spongy tissues with dual blood supply and where blood can collect typically are hemorrhagic (red); those caused by arterial occlusion in compact tissues typically are pale (white). ■ Whether or not vascular occlusion causes tissue infarction is influenced by collateral blood supplies, the rate at which an obstruction develops, intrinsic tissue susceptibility to ischemic injury, and blood oxygenation
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