Infarct

Infarct

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Infarct

 

Infarction

Infarction is the process of forming an Infarct. In comparison, the Infarct is an area of ischemic necrosis (Death of tissue due to a reduction in blood supply) caused by Occlusion of either arterial supply or venous drainage.

As we know, the blood gives oxygen and nutrients to the body tissue, so whenever there is a decrease in blood supply due to artery blockages, rupture, mechanical compression, or vasoconstriction, the tissue will receive less amount of oxygen and nutrients. Initially, at that moment, the tissue will try to adapt. Still, if this ischemia persists for a longer period, it will lead to irreversible damage to the cell, hence killing it, known as necrosis.

 

Causes of Infarction

 

Infarction causes can be classified as Arterial, Venous, and Microcirculation Occlusion.

 

 Arterial Occlusion

 

Arterial Occlusion is the most common cause of Infarction include intraluminal thrombosis and embolism in arterial supply.

 

  • Thrombosis

     It is the process of forming a thrombus, which is a blood clot (mainly contains blood platelets) in the blood vessel, obstructing blood flow.

 

  • Embolism

    It is the process of formation of emboli (solid, liquid, or gaseous mass) that is also produced from the constituent of streaming blood. But that emboli goes away from the site of origin does to a distant site, and then that occludes the distant blood vessel, and that Occlusion can lead to Infarction.

 

 

 

Thrombosis

 

Local Vessel Spasm

This Infarction is caused by inflammation of the blood vessel or vasculitis, when locally some area blood vessels may constrict due to inflammation, hence reducing the lumen’s diameter, and that results in diminished blood flow.

 

Extravascular

Extravascular causes are those causes developed due to compression of the blood vessel.

 

  • Compression of Artery by Tumor

     When a tumor present in the close vicinity of the artery starts growing, the tumor will tend to compress the artery, which will lead to Occlusion and later Infarction. 

 

  • Torsion of the Artery

     Occlusion, caused by the twisting of an organ that can happen in testicular torsion and bowel volvulus.

 

  • Rupture of the Blood Vessel

    Blood vessel rupture due to trauma can lead to Infarction.

 

  • Compression of the Artery by Edema Fluid

     When there is an increased amount of edema fluid built up in the anterior compartment of the leg that excess fluid compresses the blood vessel.

 

Venous Occlusion

 

Venous Occlusion happens due to the blockage of the venous circulation leading to stagnation and hypoxia. If left for a prolonged period may lead to Infarction of the organ. Here are some of the causes of Venous Occlusion:

 

  • Mesenteric Venous Thrombosis

 

  • Deep Vein Thrombosis

 

  • Blood trapped in the hernial sac

 

  • Cavernous sinus thrombosis

 

Microcirculation Occlusion

 

Microcirculation causes can also lead to Infarction in tissue.

 

  • Red Cells: This happens when blood circulation is blocked by red cells; example, Sickle Cell Anemia, Polycythemia vera(a type of Blood cancer)

 

  • White Cells: This occurs when there is an increase in white cell count; for example, Chronic Myeloid leukemia

 

  • Bed Sores: Excessive pressure developed due to bedsores causing compression of the microcirculation can also lead to Infarction in tissue.

 

Types of Infarction

 

Infarct can be classified according to its Colour, Age, Presence or Absence of infection, Location.

 

Colour

 

According to Colour, an Infarct can be Red(hemorrhagic) or Pale (Anemic).

 

  • Red Infarct: Red Infarct can develop due to Venous Occlusion. It can also happen in loose and spongy tissue, for example, lungs, intestines. It can also occur in tissue that has a dual blood supply, even seen in the tissue where there is congestion. It can also be seen in re-established blood flow, which was previously occluded.

 

  • Pale Infarct: It is also known as white Infarct. It usually occurs in organs having arterial circulation; for example, It can happen after arterial Occlusion in the heart or in the kidney or in the spleen.

 

Age

 

 Infarct classified according to Age

 

  • Fresh Infarct: A freshly developed Infarct is also referred to as New Infarct. They are poorly defined and slightly hemorrhagic.

 

  • Old Infarct: As the Infarct, which is healed by scarring and becomes older with a well-defined margin, as a result of congestion due to inflammation. It is also referred to as Healed Infarct.

 

Infection

 

Infarct classified according to Presence or Absence of infection.

 

  • Septic Infarct: When an infarct is infected, it is known as Septic Infarct

 

  • Bland Infarct: When there is no infection in the Infarct area and is free of bacterial contamination, it is known as Bland Infarct.

 

Location

 

Infarct classified according to Location.

 

  • Myocardial Infarction

 

 

  • Pulmonay Infarction

 

  • Renal Infarction

 

  • Bowel Infarction

 

  • Diabetic Dry Gangrene

 

Morphology

 

The infarct will be wedge-shaped (V-shaped), and the apex of the wedge is located at the site of Occlusion.

Infarction

 

Risk Factors of Infarct

 

  • If the person is anemic, then the slightest cause for hypoxia can lead to the tissue’s Infarction. If a person has sickle cell anemia, the sickle RBC blocks the microcirculation.

 

  • Single Artery: In a Single Artery, if it somehow gets blocked, it could lead to Infarction of the tissue.

 

  • Anatomy of the vascular supply: Organs which has a dual blood supply like the liver and the lungs will have less chance of Infarction as compared to a single artery. Even parallel arterial systems, as seen in hands and forearms(radial and ulnar artery), also prevent Infarction.

 

  • End Arteries: Kidney, Spleen is more susceptible to Infarction.

 

  • Tissue Vulnerability to Hypoxia: Different tissue have different levels of vulnerability to hypoxia, and that will also influence the development of an Infarction. example, the nerve cell (neuron) dies just within 3to 4 minutes if the blood supply has been deprived, whereas myocardial cell can survive for 20 to 30 minutes in an ischemic condition.

 

  • Rate of Occlusion in the Blood Vessel: If the rate of Occlusion is rapid, there is more chance of Infarction, and if the rate of Occlusion is gradual, there is less chance of Infarction.

Infarction, if left untreated, Infarct starts evolving, leading to serious complications.

 

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