Embolus Types

Embolus Types, Infarction, and Shock: A Detailed Summary

• Embolus is a detached intravascular substance that can be solid, liquid, or gaseous, which travels through blood to a site away from its origin.

• The most common type of embolus is thrombo-emboli, which is a detached complete thrombus or part of a thrombus. Other types of emboli include fat emboli, air emboli, atherosclerotic emboli, tumor emboli, and amniotic fluid emboli.

• Emboli may lodge anywhere in the vascular tree, causing vascular obstruction and infarction of the tissue distal to the point of obstruction.

• Pulmonary thrombo-embolism (PE) is a common and important preventable cause of death, with over 95% of cases caused by venous emboli originating from deep leg veins above the knee.

• The clinical outcome of PE depends on the size of pulmonary artery occluded, the severity of occlusion, the number of occluding emboli, and the cardio-respiratory status of the patient.

• Systemic thromboembolism is caused by emboli traveling within the arterial system, with over 80% of them originating in the heart, mostly associated with left ventricular infarction or vegetation on the valve.

• Fat embolism occurs in about 90% of patients with severe skeletal fractures, with the potential to cause pulmonary insufficiency, neurologic symptoms, anemia, and thrombocytopenia, which can be fatal.

• Air embolism can enter the circulation during obstetric procedures or as a consequence of chest wall injury, causing physical obstruction and occlusion of major vessels. Decompression sickness is a special type of air embolism seen in deep-sea divers.

• Amniotic fluid embolism is a rare complication of labor, causing dyspnea, cyanosis, shock, and DIC, with a mortality rate of about 40%.

• Infarction is a localized area of ischemic necrosis caused by sudden reduction or stoppage of arterial supply or less commonly obstruction to venous drainage.

• Infarctions are divided into two types according to the amount of blood present in the tissue: white infarcts and red infarcts. The former is usually seen in solid organs with end-arterial occlusion, while the latter is associated with haemorrhage.

• Septic infarcts occur when bacterial vegetation from a heart valve embolizes into the arterial system, and the infarct is converted into an abscess.

• Shock is systemic hypoperfusion caused by reduced cardiac output or ineffective circulatory blood volume, which can be caused by different mechanisms, including cardiogenic, hypovolemic, septic, neurogenic, and anaphylactic shock.

• Shock tends to be progressive and evolve through three stages: non-progressive (compensated) stage, progressive (decompensated) stage, and irreversible stage, with the aim of maintaining enough blood supply to vital organs.Aneurysms:

• Aneurysms are localized abnormal dilatations in the wall of a blood vessel or the heart.

• They can occur in any blood vessel, with examples including aneurysms of the circle of Willis in the brain, aortic aneurysms affecting the aorta, and abdominal aortic aneurysms.

• Aneurysms are a result of a weakened blood vessel wall, and can be a result of a hereditary condition or an acquired disease.

• As an aneurysm increases in size, the risk of rupture increases.

• A ruptured aneurysm can lead to bleeding and subsequent hypovolemic shock, leading to death; this is likely to occur with the abdominal aortic aneurysm.

• Cerebral aneurysm can be fatal by causing subarachnoid haemorrhage.

• The prevalence of abdominal aortic aneurysms is approximately 2-8% in men and 0.5-1.5% in women over the age of 50.

• The risk factors for developing aneurysms include smoking, hypertension, atherosclerosis, and a family history of aneurysms.

• Aneurysms are often asymptomatic and can be detected incidentally on imaging studies.

• Treatment options for aneurysms include observation, surgical repair, and endovascular repair.

• The decision to treat an aneurysm depends on various factors such as size, location, and the patient's overall health.

• The prognosis for patients with aneurysms depends on the location and size of the aneurysm, as well as the patient's overall health and the presence of any complications.