Vídeo 9 - Isquemia e Infarto

Summary

This educational video discusses the concepts of ischemia and infarction, explaining how reduced blood flow leads to tissue damage and death. It distinguishes between white (anemic) infarction caused by arterial occlusion in organs with terminal circulation, and red (hemorrhagic) infarction, which occurs in tissues with collateral circulation or venous obstruction. The video also highlights the pathophysiology of ischemia, including its effects on organs like the kidneys, heart, and intestines, and the role of revascularization in altering the appearance of infarction. The importance of understanding these processes in clinical contexts is emphasized throughout.

Takeaways

• 😀 Ischemia refers to the reduced or complete lack of oxygen and nutrients to tissues, caused by either arterial blockage or venous congestion.
• 😀 Infarction occurs when ischemia leads to irreversible tissue damage and necrosis, forming a pathological condition in the affected organ.
• 😀 White infarction (infarto branco) is caused by arterial blockage in organs with terminal circulation, resulting in pale tissue due to lack of oxygen and nutrients.
• 😀 Hemorrhagic infarction (infarto hemorrágico) occurs due to venous congestion or partial arterial blockage, resulting in a red appearance due to blood accumulation.
• 😀 Infarctions can affect various organs, including the heart (myocardial infarction), kidney (renal infarction), intestines, testicles, ovaries, and spleen.
• 😀 White infarction is primarily seen in organs with terminal blood supply, like the kidney, where the area affected by arterial blockage becomes pale and lacks blood flow.
• 😀 In hemorrhagic infarction, the affected area becomes red due to blood accumulating in the tissue, commonly seen in organs with collateral blood supply, such as the lungs and intestines.
• 😀 Ischemia can be caused by arterial obstruction, where blood flow to tissues is interrupted, or venous obstruction, which prevents proper drainage of blood.
• 😀 The severity of infarction depends on the duration of ischemia, with potential for reversible damage if blood supply is restored within a short period.
• 😀 Histopathological features of infarction include the loss of cell function, protein coagulation, absence of nuclei, and infiltration of inflammatory cells to repair the affected tissue.

Q & A

What is the main difference between ischemia and infarction?

Ischemia refers to the reduced or absence of blood supply to tissues, leading to a lack of oxygen and nutrients. Infarction, on the other hand, is the process where ischemia leads to tissue death or necrosis, typically caused by a complete obstruction of blood flow.

Can all organs suffer from ischemia or infarction?

Yes, all organs that are vascularized and depend on oxygen and nutrients delivered via blood flow can experience ischemia or infarction. This includes the heart, brain, kidneys, intestines, and other organs such as the spleen, ovaries, and testes.

How does an obstruction lead to ischemia?

Obstruction, whether arterial or venous, prevents adequate blood flow to tissues. Arterial obstruction reduces the delivery of oxygen and nutrients, while venous obstruction causes blood to accumulate in the tissue, but this blood is poor in oxygen and nutrients.

What is the characteristic morphological feature of ischemic necrosis?

The characteristic feature of ischemic necrosis, or coagulative necrosis, is the preservation of the tissue's basic structure, but with the absence of nuclei. The proteins in the tissue may coagulate, leading to a firm and pale area that lacks proper blood supply.

What is an 'infarction'?

An infarction is a tissue necrosis resulting from prolonged ischemia. It occurs when blood supply to a particular area is obstructed, leading to cell death. The tissue turns pale and undergoes coagulative necrosis.

What is the difference between a white infarction and a hemorrhagic infarction?

A white infarction, or anemic infarction, occurs due to arterial obstruction in organs with terminal circulation, like the kidneys. A hemorrhagic infarction, on the other hand, involves a combination of arterial or venous obstruction and occurs in tissues with collateral circulation, leading to blood accumulation and a red or hemorrhagic appearance.

Why does a white infarction appear pale?

A white infarction appears pale because there is a lack of blood supply due to arterial obstruction. The area becomes ischemic and pale, with no blood flow to deliver oxygen and nutrients to the affected tissue.

What are the causes of hemorrhagic infarction?

Hemorrhagic infarction can be caused by venous obstruction, where blood backs up into the tissue without being drained. It can also occur with arterial obstruction in organs that have collateral circulation, where blood from smaller vessels cannot supply the tissue sufficiently, leading to localized bleeding.

How does a venous obstruction lead to ischemia and infarction?

Venous obstruction prevents blood from being drained out of the tissue, causing blood to accumulate. This blood is poor in oxygen and nutrients, leading to ischemia. If the ischemia persists, it progresses to infarction, resulting in tissue death.

What happens during the revascularization of a previously infarcted tissue?

Revascularization of infarcted tissue can sometimes result in hemorrhagic infarction. If blood flow is restored after a period of ischemia, the tissue may hemorrhage as blood leaks into the damaged area, creating a red or hemorrhagic appearance in the infarcted region.