what is embolism ?

What is embolism?

Embolus is an intravascular solid, liquid or gaseous mass that is carried to a site distant from its point of origin. Over 90% emboli arise in thrombi and are called thromboemboli.

Embolism is the travel of the embolus from its site of origin and resulting in impaction with partial or complete occlusion of a vessel too small to permit its further passage. Over 90% are thromboembolism.

Types of Emboli

There are nine major types of emboli. They are –

1. Thromboemboli

2. Malignant cell emboli

3. Athermatous debris from ruptured atherosclerotic plaques

4. Amniotic fluid

5. Droplets of fat

6. Air and nitrogen gas emboli

7. Parasites

8. Fragments of bone and bone marrow

9. Foreign bodies such as bullets, talc, silk.

1. Thromboemboli

Thromboemboli may lodge in pulmonary circulation leading to pulmonary thromboembolism or in systemic circulation leading to systemic thromboembolism. The emboli may be

A. Asceptic or bland emboli from phlebothrombosis

B. Septic or infected emboli from thrombophlebitis.

Clinical effects of pulmonary thromboembolism

a) Clinically silent,60-80%

b) Pulmonary haemorrhage

c) Pulmonary infraction

d) Pulmonary hypertension-chronic right heart failure

e) Sudden death

Clinical effects of systemic thromboembolism

a) Lower extremities (about 75%) peripheral vascular disease. Gangrene may develop.

b) Brain – If in middle cerebral artery it may cause death

c) Kidney – Infraction

d) Spleen – Infraction

e) Mesenteric vessel – Infraction

2. Malignant cell emboli

Carcinoma cell emboli usually spread in the lymphatics but also occur in blood. Sarcoma cell emboli usually spread through blood and may spread through lymphatics rarely.

Malignant cell emboli may form in the lymphatics and carried to regional lymph nodes where metastatic tunour is formed.

3. Athermatous debris

Rupture of atheromatous plaque discharge the debris into blood-stream producing microemboli which is cholesterol emboli or atheroemboli.

4. Amniotic fluid embolism

It is rare and occurs in about 1 in 50000 deliveries. It occurs as a grave complication of labour and immediate postpartum period.

Clinically a sudden grave complication that appears without warning –

Respiratory difficulty, cyanosis, vascular collapse. May be rapidly fatal. Bleeding from uterus and birth canal may occur due to DIC.

5. Fat embolism

In fat embolism microglobules of fat is present in the circulation. The main causes of fat embolism are fracture of shafts of long bones which have fatty marrow, trauma of adipose tissue, burn of adipose tissue. The fat embolism syndrome are pulmonary insufficiency, neurological symptoms, anemia, thrombocytopenia, adult respiratory distress syndrome, delirium and coma may develop.

6. Air embolism or gaseous embolism

Barotraumas is the injury caused by bubbles of air or gas within the circulation. These obstruct vascular flow and damage tissues. These bubbles of air act as physical masses. Many small bubbles may coalesce and occlude a major vessel in the lung or brain.

7. Parasitic emboli

The vegetative forms of Entamoba histolytica may be carried as emboli in portal venous system to liver. Other examples are microfilaria, schistosomas and their ova.